Class Note for BME 510 at UA
Popular in Course
Popular in Department
This 18 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Arizona taught by a professor in Fall. Since its upload, it has received 14 views.
Reviews for Class Note for BME 510 at UA
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/06/15
Movement Dmorders Vol 21 No 11 2006 pp 180671823 2006 Movement Disorder Society Review Ubiquitin Proteasome System and Parkinson s Disease C Warren Olanow MD and Kevin St P McNaught PhD Department of Neurology Mount Sinai School of Medicine New York New York USA Abstract Increasing genetic pathological and experimental evidence suggest that neurodegeneration in both familial and sporadic forms of Parkinson s disease PD may be related to a defect in the capacity of the ubiquitiniproteasome system UPS to clear unwanted proteins resulting in protein accumu lation aggregation and cytotoxicity This concept is supported by in vitro and in vivo laboratory experiments which show that inhibition of UPS function can cause neurodegeneration cou pled with the formation of Lewy bodyilike inclusions This hypothesis could account for the presence of protein aggregates and Lewy bodies in PD the other biochemical features seen in the disorder and the agerelated vulnerability of the substantia nigra pars compacta It also suggests novel targets for putative neuroprotective therapies for PD 2006 Movement Disorder Society Key words ubiquitin proteasome Parkinson s disease protein accumulation alphasynuclein Parkinson s disease PD is a progressive neurolog ical illness and the second most common neurodegen erative disorder2 PD is de ned pathologically by a loss of melanized dopaminergic neurons in the sub stantia nigra pars compacta SNc coupled with cyto plasmic inclusions known as Lewy bodies3gt4 Neuro degeneration can also occur in other brain regions including the locus coeruleus LC dorsal motor nu cleus of the vagus DMN nucleus basalis of Meynert NBM and the olfactory system 5 as well as in nerve cells of peripheral autonomic ganglia eg su perior cervical ganglion and mesenteric plexus6 Treatment is largely based on a dopamine replacement strategy However longterm treatment is associated with motor complications and the development of potentially disabling features such as falling and de Correspondence to Dr C Warren Olanow Department of Neurolr ogy Mount Sinai School of Medicine Annenberg 14773 One Gustave L Levy Place New York NY 10029 Email warrenolanowmssmedu Received 4 November 2005 Revised 30 January and 9 March 2006 Accepted 12 March 2006 Published online 13 September 2006 in Wiley InterScience www intersciencewileyc0m DOI 101002mds21013 1 806 mentia that are not controlled with dopaminergic ther apies Thus there is an active search for a neuropro tective therapy that might stop or slow disease progression Toward this end insight into the cause of cell death in PD would be invaluable The etiology of PD is not known in the large ma jority of cases Approximately 10 to 15 of cases are thought to be genetic in origin and to date ll different linkages with 6 different gene mutations have been identi ed Table l79 Most cases N90 occur sporadically and are of unknown cause Epidemiolog ical studies suggest that environmental factors play an important role in these patients10 but speci c agents have not yet been identi ed and it is possible that many cases occur as a consequence of an interaction between different genetic and environmental factors The pathogenic mechanism responsible for neurode generation in PD is also not established although there is pathological evidence to suggest that cell death occurs by way of a signalmediated apoptotic process11 and involves a cascade of events that in cludes oxidative stress12 mitochondrial dysfunction13 in ammation14 and excitotoxicity15 However each Mavement DLsmders V471 2 N47 1 2005 TABLE 1 Genetic and sparadie farms 0f Parkinsan s disease passible basis far altered pmtein handling Locus Chromosome location Gene product and properties Mutations Inheritance Age of onset pattern yr Clinical spectmm possible theoretical basis for altered protein pathological features handling PARK 1 4q21q23 and 4 PARK 2 6q2524q27 PARK 5 41314 PARK 6 PARK 7 11335411336 lp36 PARK 8 12131124 Sporadic PD 12q311 olesynuclein 140 amino acidsl4 kDa protein localized to synaptic terminals function unknown possibly play a role in synaptic activity Point mutations A53T A3013 and E46K duplication triplication Parkin 465 amino acids52 kDa protein expressed in cytoplasm golgi complex nuclei and processes function E3 ubiquitin ligase Ubiquitin Ceteiminal hydrolase L1 230 amino acids26 kDa protein neurone speci c protein function deubiquitinating enzyme possible E3 activity also PINK 1 581 amino acids628 kDa protein localized to mitochondria function unknown may be a protein kinase DU 189 amino acids 20 kDa protein more prominent in the cytoplasm and nucleus of astrocytes compared to neurons function unknown possible antioxidant molecular chaperone and protease Deletions point mutations multiplications Missense mutation 193 M Missense truncating Deletion truncating missense DardarinLRRK2 2482 Missense 2527 amino acids function unknown may be a protein kinase Autosomal dominant Range 3060 mean 45 Autosomal recessive Rarely autosomal dominant Range 758 mean 261 Autosomal 49 and 50 dominant AR Range 3248 AR Range 2040s mean mid 30s AD Range 3579 mean 574 Mean approximately 60 years Levodopasresponsive rapid progression prominent dementia E46K and multiplication cases demonstrate overlap with dementia with Lewy bodies Levodopasresponsive and severe dyskinesias foot dystonia diurnal fluctuations hyperreflexia slow progression Typical PD Levodopasresponsive slow progression Levodopasresponsive dystonia psychiatric disturbance slow progression Typical PD features slow progression dementia present features of motor neuron disease reported can duplicate features of sporadic PD Levodopasresponsive resting tremor rigidity bradykinesia gait dysfunction asymmetry gradually progressive Neuronal loss in the SNc LC and DMN Lewy bodies are rare and tau accumulation occurs in some A53T cases extensive Lewy bodies in E46K and multiplication cases triplication cases demonstrate degeneration in the hippocampus vacuolation in the cortex and glial cytoplasmic inclusions Selective and severe destruction of the SNc and Lc generally Lewy bodymnegative olesynuclein is prone to misfold and mutations enhance this property mutations overproduction of olssynuclein could lead to a cycle of events that include d4 synuclein misfolding aggregation proteasomal dysfunction generalized protein aggregation and neurodegeneration Parkin is a ubiqu n ligase Parkin mutations could impair ubiqui mation of target proteins which might then accumulate aggregate and cause cell death Lewy bodies reported in a single UCHsLl is a deubiquitinating enzyme failure case to deubiquitinate might prevent ubiquitinated proteins from being able to enter the proteasome and be degraded it might also limit the supply of ubiquitin monomers necessary for the clearance of additional unwanted proteins Neuropathology not yet determ ined PIN39Kl prevents proteasome inhibitorminduced mitochondrial dysfunction and cell death but protection is lost with mutations found in PD mutations in PlNKl could render neurons vulnerable to toxins that act as proteasome inhibitors PIN39Kl mutations could also impair mitochondrial function Antioxidant or sensor of oxidative stress molecular structure suggests that it has molecular chaperone and protease activity interacts with parkin and CHIPHSP70 mutations as in PD destabilize D141 and inactivate its proteolytic activity overexpression protects cultured cells from oxidative stress wh39le knockdown increases susceptibi ty to oxidative stress endoplasmic reticulum stress and proteasomal inhibition wildstype DJsl inhibits aggregation of olesynuclein and effect is lost when D141 is mutated as in PD Sequence suggest that the mutation might lead to increased kinase activity which could promote altered phosphorylation and misfolding of substrates Neuropathology not yet determ ined SNc degeneration some cases show extensive Lewy bodies some do not have Lewy bodies also intranuclear inclusions taueimmunoreactive inclusions and neuroiibriallry tangles may be present Degeneration in SNc with Lewy bodies degeneration with Lewy bodies in selected additional locations including neurons of LC N39BM DMV olfactory autonomic system Reduced olssubunits of 20S proteasome reduced proteasomal enzyme activity reduced compensatory responses in proteasome activators UBI Q UI TIN PR 0 TEAS OME SYSTEM 1807 1808 CW OLANOW AND KSP MCNAUGHT of these factors is not present in all patients and it has not been established that cell death in PD occurs exclusively by way of a single pathogenic process If a common mechanism underlying the different forms of PD could be de ned it would aid considerably in identifying targem for neuroprotective therapies that might have bene t across the full spectrum of causes of the disease Recently a body of genetic postmortem and experimental evidence has converged to suggest that a failure of the ubiquitiniproteasome system UPS to degrade unwanted proteins might play a major role in the etiopathogenesis of both familial and sporadic forms of PD9gt16gt17 In this review we will examine the various defects that occur in the different genetic and sporadic forms of PD described to date and consider how they might possibly be linked to a defect in UPS function We will also consider how this concept could account for Lewy body formation and other key fea tures of PD PROTEIN HANDLING IN CENTRAL NERVOUS SYSTEM The ubiquitiniproteasome system UPS is the major pathway that mediates the degradation of unwanted in tracellular soluble proteins ie mutant misfolded de natured misplaced or damaged in the cytoplasm nu cleus and endoplasmic reticulum of eukaryocytic cells1821 The process whereby the UPS clears these unwanted proteins typically involves the following se quence of events ATPdependent activation of ubiquitin monomers labeling of unwanteddamaged proteins with chains of activated ubiquitin molecules transport of ubi quitinated proteins to the proteasome by chaperone mol ecules eg heat shock proteins recognition and un folding of ubiquitinated proteins by proteasome regulators and ATPdependent degradation of unwanted proteins by the proteasome13 21 Proteasomal degrada tion yields short peptide fragments 2725 residues that are further degraded by peptidases into their constituent amino acids and are then recycled to form new pro teins22 Prior to entry into the proteasome ubiquitin chains are detached from protein conjugates and disas sembled by deubiquitinating enzymes ubiquitin Cter minal hydrolases into monomeric ubiquitin molecules that can be recycled to facilitate the clearance of addi tional unwanted proteins Some proteins eg oxida tively damaged proteins or short peptides can be directly degraded by the 20S proteasome the catalytic core of the 26S proteasome in an ATPindependent manner without prior ubiquitination23 Proteins that are excessively mis folded or aggregated resist degradation and can inhibit Mavemem Dmarders Val 21 N0 1 2005 proteasomal function by blocking the inner chamber of the proteasome2325 These processes are described and illustrated in Figures 1A and 2 Heat shock proteins HSPs such as HSP70 and HSP90 play an important role in the management of unwanted proteins They upregulate in the presence of excess levels of misfolded proteins and promote their refolding to their native state They also act as chaper ones to transport abnormal proteins to the proteasome for degradation2 gt26gt27 HSPs also activate phosphatases that block the formation of proapoptotic proteins such as Junkinase2 High levels of protein aggregates can bind HSPs and prevent their exerting these protective functions Cells normally maintain a dynamic balance between the generation and clearance of unwanted proteins Dis turbance of this equilibrium either by excess formation of unwanted proteins or by impaired protein degradation leads to an adverse state called proteolytic stress9gt2 gt21gt28 Under these circumstances proteins accumulate and ag gregate with each other as well as with other normal proteins These protein aggregates can interfere with normal UPS function impair critical intracellular pro cesses eg axonal transport synaptic plasticity and neurotransmission inactivate HSPs and induce cytotoxicity20gt233932 UPS AND PARKINSON S DISEASE In this section we will consider the different types of PD described to date and consider how neurodegenera tion in these conditions might be related to proteolytic stress Fig 1B In some instances the evidence for a link to UPS dysfunction is relatively compelling while in others it is more theoretical and awaits further exper imentation for con rmation Familial Forms of PD Parkin Mutations A Defect in Protein Ubiquitination An autosomal recessive form of PD was rst recog nized in Japanese families ARJ P and linked to chro mosome 6q252q27 PARK 233gt34 Several deletions multiplications and point mutations were identi ed in this gene which encodes a 4657amino acid52kDa pro tein called parkin7gt35gt36 The clinical features of ARJP resemble sporadic PD but differ in that there is a very early age of onset average 261 years and a slow rate of disease progression37 Pathology in ARJ P also differs somewhat from sporadic PD in that neurodegeneration is con ned to the SNc and LC Lewy bodies are typically absent38 although lateonset cases with parkin mutations UBIQ UIFINePROTEASOME SYSTEM 1809 no1 The ublqtnunepaoeaenne system The synthens tag and abue orpmtems lneyrtably leadw the generabon orunwanted preterm Thzss lnclude shnnrhvedleguhwry lmnnplete matam msrnlded denatured axldlzed and athzrwms damaged pm ams Beam Lhasa pmo mu baye a tendency w aggregate antenrere wnh cellular pmceses and lnduce cymmlclly they must be renamed w marntarn cell ylabllrty Th2 ublqumlr pmteaeome system as the pnmary muacellular mechanrsna respnnnble tor the degradauon and clearance or unwanted preterm N The pmcesx occurs largely an two ssqmnual steps unqurunauon and pmteasoanal deggadauon lntbe rst step a ublqurbn nnlecule la 76ma and x slaua polypepudel ls abacbed w the unwarnad proteln yra a covalem lenpepude bond betweentbe carbuxy ggoup ordne Crtzxrmnal rende lGlyl or unquun and an memal Lys rende or the substrate pmtern Adduonal ublqumn molecules are abacbed w the preyrouely conjuga zd unquun lat a Lys renduel m a ssqmnual manner to heme apolyunquuncbarn Thzss reacuons requre ATP and are nedrated by aublqumn acuyaung emyn39e lull when acuyates uhlqmun by rennrng a manta aconyugabng enzyme E2 thatcanles acuyated ublqumn as atlnoester and a unquun hgm um that uansrers acbyated ublqurbn tn the sombate pmtern selecuylty orpmteln ublqurbnabonls aeroaded by the ram that there are many B enzymes that are speclnc her one or only a yery rew dl arem substrate pm ams Further enme preterm redone pnetuanslauonal nndncauon bernre they can be ublqurunared le g plnspboaylauon or IKE whmh prnyldes an addmunal deggee afsslecuvlly ln addman conyugabon or acham or at least rnur unqurun rmlecule hnkzd though lynne 42 um acts as a ngnal roa proteaenmal reengnauon and degradabonm whale monoublqmbnabon at m or polyublqmbnabon llnked Lhmugh lynne 63 K63 targets preterm rnr pammpa an In other cellular runcbons le g gene eapaesnon and transport 2 ln the second step ortbe ups pnlyubmurbnated preterm are transported w the pmteaennne by nnlecular cbapemnee deublqmunated by deunquunauon enzymes lubmurun ceternnnal hymlms unrnlded anduanslocatedlnto the core ortbe 25 proteaennne complex where they are degraded m anATszpendzln manner lee Fag 2fo detarlsl Th2 degradauon pmo mu are small pepude flayman39s lzezs renduesltbat undergo bydrolyns by pepudm w pandane then coneument annm aclds whmh can then be recycledln new protem syntbens 2 Monoanenc ublquun whlch as detached none protem conyagates can also be recycled w famhm39z the clearance or other unwanted pm ams some preterm le g omdauyely damaged preterm andposnbly arsynmlem are deggaded drectly by the 2m pmteaennne the catalybc core the 25 pm39zammz mtlnuttle nem roa ublqurbnabon abdlnanarpandependent manner 23mm B passable nteswbere drrrerentrnnmor PD nngntmenere wadrune up schemauc rapxessmauan ortbe up llluetaabng pnsnble sates where parkm matauom uclleLl mutauom arsynmlem matauom and speradc PD nngnt anterrere wnh normal up runcaon caunng pmteolyuc stress pmteln accumulauon and agggegauon and cell death have been desorlbed wrth a more typlcal PD plcture and Lewy bodles at postmortem A Parkm ls expressed m the cytoplasm nuclem golgl apparatus and processes ot neurons and is now known to be a ublqultln llgase that attaches ublqultln molecules to subsuate protemSM Slmllar to other ublqultln he gases parkm has a modular structure contalnlng a ublqe ultlnelllse U BL domaln at the Netermlnus a oentral llnkel reglon and a RING nger domaln at the Ce termmm Parkm acts 1 conjunctlon wrth the E2 enzymes ch ubcH7 and ubcHd to ublqultlnate a varlety ot subsuztes whlch are thought to lnclude synphlllnel CDCrelel parhneassoclated endothellnelllse reoeptor Paella oeglycosylated lsotorm ot osynucleln mSpZZ cyclln E wdetubulln p38 subunlt ot amlnoe acyHRNA synthetase complex and synaptotagmln x1 1mm Parkln through m U BL domaln lnteracts wrth the 265 proteasome subunlt anlOssa whlch along wrth the Rptsso39 subunlt plays a role In the recognltlon ot ublqultlnated substrates by the PA700 regulatory cap m7 Parkm also blnds to a heat shock proteln complex CHIPHSWO and may promote lts acthltyAW The mechanlsm by whlch mutatlons m parkm lnduce neurodegeneratlon ls not rmly establlshed but lt ls reasonable to conslder that a loss ot ublqultln llgase actlvrty could lead to a reduoed capaclty to label sube suate protelns tor proteasomal degadatlon In support of thls concept patlenm wrth ARV have markedly reduoed parkln proteln and enzyme acthlty ln areas that degene erate SM and Lcl mu and nonublqultlnated parkm substrates PaeleK u5p22 accumulate In these re glonsws Thls conoept is further supported by the deme onstratlon that parkln proteln prevenw oell death lnduoed by overexpresslon ot Paelelz In both cultured oells and Drosophllamw Thus m PD parkm mutatlons could lmpalr ublqultlnatlon and subsequent degradatlon ottare get protelns that ml 1t then accumulate aggegate and came cell death Interestlngly parkm also protects agalnst oell death lnduced by overexpresslon ot oesynucleln even though thls ls not thought to be a parkln substrate suggestlng that parkln my act through other mechanlsms such as an enhanced chapere one function 52 Thus lt ls posslble that the pathogenesls ot parklne lmked tamlllal PD lnvolves dystunctlon ot the UPS anrummee Vol 21 No 1 20m 1810 C W OLANOW AND KS P MCNAUGHT ms 0 ms Prulcmlm anew1mde Momma n ass Promch an ass Wash no 2 Orgnnlznhon orthe pm39zasumz Th2 plntemne ls a mul calalyuc enzyme Lhatcanexlstm d enntrorms Wlthlnthe can as the can the 2m prmzmn39e or attacked to a hm or a PA700 the as prmzmn39e acuvawr a Th 20 plntemne 670 kDa ls an menhly ortwo ollrer n and two lnher Bl hephnlenc nngs sucked axla y 03 form a halklw cyhldncal sunshlre ln whlch proreolyns occur ll A enzyman actlvlty ls located wl39thhz two lnher Brnlgs whlch are composed afssven dlerelent Ermbum39s three afwhlch lnst dlrrerem emymauc mes on the lnher Surface orthe onmplex Thzss plnteolyucally ashve sues nednte the hymnlynsorprorelns ntthe crtennlnlls orhymnphohchansor aadm renalns and are rerened w as the chynnu39ypmr uypnm and paWdylglutamprepJ hydrolyuc PGPH ashvmes lespechvely The two ollrer henth are each commmed or men dlererem armbumu whlch do mt contnn enzyman acnvlly hut serve as an anchor rel the nnllhsllhunlt PAZR ll or PA7OO m and lvl prmamrre acnvamx h The hm 11legl awry complex or acuvawr 200 kDa ls a hetero or honnleptnmenc nng commmed or PAZRlx lamp or PAYRy suhunlts hm mud w elther or buthends orthe 2m plntemne nndplnnntesthe opening orthe chanrel Lhmugthz pm39zmmal campr ln whchenzymanc amwlty occur notshownl Thls process ls ATPrlndzpen llt nndmedntesthe degradnhon or nnluhqulumted plntems or pephdes and ls Lhnught 03 he pamwlarly lmpnmnt for clennng axlde protelns and rel mugen plessnlaaan ln the lmmrme systemm c The RUDD19 xegulawr or acnvamx 700 kDa mud to elther or hnthsndsorthe ms proteasome w hlnnthe as prmamrre carrlplzx whlch ls campussd or over 60 suhunltsz 5 MDa mm The mm quot52 amenMad rlnm two uhcamplexzs a ham that comms snl ATPase plus two normrpm sllhunlts and an attached lld that ls commmed or several normrpm suhunlts plum parfum several lmportnnt ATPrcbpen llt nlhauons recagm and blnds polyuhlqulunnted protelns vn the anIOSSa and RpLSS suhunltsl unfolds 0122 protelns hl pennlt then entry lnhl the catalyuc cure and opens the chanrel thnlugh the 2m plntemne whlch ls normally gated by the Nr zn39mm or the armbum39s 222 ll Hecmn mcmgxaph or a as prmamrre onmplex from yeast Sammmmwa Gaelmm Reproduced from thkman and ca eagms 227 although thls concept remalns to be proven Interest lngly nelther uansgenlc mlce that express parkln mutzr tlons nor parkln knockout mloe develop nlgostrlatal degeneratlonszm Further the frequency ofparkm polnt mutatlons ls slmllar ln PD patlents 3 8 and control subjecm 3 1 53 These obselyatlons ralse the posslbllr lty that addltlonal genetlc alteratlons or exposure to em vlronmental toxlns are requlred to trlgger neurodegenr eratlon ln patlents wlth parkln mutatlons UCHLl Mutau39o A Defect ln Deuhlqultlnau39on of Uhlqultlnated Proteins A PD syndrome was descrlbed ln 2 German slbllngs wlth an I93M mlssense mutatlon ln the gene 4p14 PARK 5 encodlng ublqultln Crtelmlnzl L1 UCHV L1 59 The patlenm had a cllnlcal plcture that closely resembled sporadlc PD lncludlng a good response to levodopa but symptoms emerged at a relatlvely early age 49 and 51 years Postmortem study ln one noted the presence of Lewy bodles m Genetlc screenlng has falled to detect UCHrLl mutatlons ln other PD par tlents suggestlng that thls mutatlon ls a rare came of PD Several studles suggested that the UCHrLl gene ls a susoeptlblllty locus and that polymorphlsms pzlr tlcularly the 518 substltutlorl conter some degree of protectlon agalnst developlng the lllness 52 However a more recent study falled to show any assoclatlon ber Mama boomers VoL 21 u 112006 tween the SY18 polymorhplsm ln UCHrLl and pro tectlon agalnst developlng PD 61 UCHrLl ls a Z30rzmmo zoldZ rsz proteln that ls expressed excluslvely ln neurons ln many areas of the CNS and constltutes 1 to 2 ofsoluble protelns ln the bmmm UCHrLl ls a deublqultlnatlng enzyme that removes ublqultln from proteln adducts prlor to thelr entry lnto the proteasome 59 Mutatlons ln UCHV L1 such as found ln PD came a reductlon ln deublqr ultlnatlng actlvlty and reduced ublqultln levels ln vltro WM lnhlbltlon of ublqultln Crtelmlnzl hydlor lases ln rat ventral mldbraln oell cultures causes der generatlon of dopamlnerglc neurons wlth the formar tlon of Lewy bodyillke moluslonsm Mlce wlth a mutatlon ln UCHrLl develop gaclle axonal dystrophy GAD and have reduced deublqultlnatlng actlvlty and neuronal degeneratlon wlth lnclmlons although Inter estlngly these changes occur ln the cerebellum and not the substantla nlgan There ls also some evldence suggestlng that UCHrLl may have ublqultln llgase actlvlty and may play a role ln targetlng protelns fol proteasomal degzdztlon In PD patlents wlth a UCHrLl mutatlon lt can by hypotheslzed that tallure to deublqultlnate mlght prevent ublqultlnated protelns from belng able to enter the proteasome and undergo degadatlon Thls mutatlon mlght also llmlt the supply UBIQ UITINPROTEASOME SYSTEM 1 81 1 of ubiquitin monomers necessary for the clearance of additional unwanted proteins xSynuclein Mutations Excess Protein Production and Aggregation The rst gene to be identi ed in association with familial PD was described in a large Italian family the Contursi kindred with an autosomal dominant pattern of inheritance72gt73 A53T A30P and E46K mutations have been identi ed in the gene that encodes for OLsynuclein a 1407amino acidl4kDa protein of unknown func tion 76 More recently PD has been described in pa tients with duplication77gt78 and triplication79gt80 of the normal orsynuclein gene The clinical characteristics of PD linked to orsynuclein mutations share similarities with sporadic PD but there is a relatively early age of onset mean of approximately 40 years and a high occurrence of de mentia Indeed some patients with multiplication of the normal orsynuclein gene present with a clinical picture suggestive of dementia with Lewy bodies77 82 Patholog ically patients with the A53T mutation showed a marked increase in OLsynucleinipositive protein aggregates in various brain regions but SNc Lewy bodies are rare Another difference from typical PD includes prominent accumulations of orsynuclein and tau in the cerebral cortex and striatum813334 Patients with triplication of the orsynuclein gene were also found to have vacuoliza tion in the cortex neurodegeneration in the hippocam pus and glial cytoplasmic inclusions which are not features of sporadic PD81 OLsynuclein so called because of its localization to synapses and the nuclear envelope 86 belongs to a family of related proteins that include 3 and ysynucle ins87 orsynuclein is expressed throughout the CNS and is enriched in presynaptic terminals lipid membranes and vesicles 87 The function of orsynuclein is un known but it is thought to play a role in synaptic neu rotransmission and plasticity 88 although knockout of orsynuclein is not associated with synaptic change neu rodegeneration or PDlike behavior89 Since the discovery of OLsynucleinilinked familial PD there has been a great deal of effort aimed at deci phering how mutations in this protein induce neurode generation The dominant mode of inheritance suggests a gain of function Wildtype orsynuclein is monomeric and is intrinsically unstructurednatively unfolded at low concentrations but in high concentration it has a propen sity to oligomerize and to aggregate into Bpleated sheem 91 Mutations in the protein increase this poten tial for misfolding oligomerization and aggrega tion9 gt 95 Oligomerization of orsynuclein produces in termediary species proto brils that form annular structures with porelike properties that permeabilize synthetic vesicular membranes92 94 It has been sug gested that proto brils are the toxic orsynuclein species that are responsible for cell death94gt95 but this concept is largely based on studies of the biophysical and confor mational properties of orsynuclein in vitro With the discovery that Lewy bodies in patients with sporadic PD stain positively for OLsynuclein it has been considered that orsynuclein might also play an important role in the development of sporadic PD96 There are several reasons to consider that cell death associated with orsynuclein mutationsoverproduction could be linked to the UPS and involve defective clear ance of the protein Wildtype orsynuclein is a substrate for both the 26S and 20S proteasome and is preferen tially degraded in a ubiquitinindependent manner 98 In vitro and in vivo studies have demonstrated that mutant orsynuclein resists proteasomal degradation99gt100 High levels of undegraded or poorly degraded orsynuclein protein have a tendency to selfaggregate induce aggre gation of other proteins interfere with intracellular func tions and induce cytotoxicity31 Aggregates of orsynuclein can also induce proteasomal damage which may account for why mutations in this protein are asso ciated with the accumulation of a wide range of other intracellular proteins1 gt101 Recent studies indicate that orsynuclein can also be broken down by the 20S protea some through endoproteolytic degradation that does not involve the N or C terminus of the protein102 This type of degradation yields truncated orsynuclein fragments which are particularly prone to aggregate promote ag gregation of the fulllength protein as well as other proteins and cause cytotoxicity103 A case can thus be made for cell death associated with orsynuclein mutations or overexpression being related to proteolytic stress Mutationsoverproduction of orsynuclein could lead to a cycle of events that include orsynuclein misfolding aggregation proteasomal dys function with generalized protein aggregation and neu rodegeneration Overexpression of mutant orsynuclein has been shown to induce degeneration of dopaminergic neurons and to accelerate cell death induced by other toxins104 In Drosophila overexpression of mutant ASST A30P or wildtype orsynuclein results in motor impairment loss of SNc dopamine neurons and inclu sion body formation105 Similarly SNc dopamine cell loss occurs following adenovirus delivery of A53T mu tant or wildtype orsynuclein into the SNc of primates106 Interestingly overexpression of wildtype or mutant orsynuclein is associated with aggregate formation in transgenic mice but does not cause degeneration of Mavemem Dmarders Val 21 N0 1 2005 1812 CW OLANOW AND KSP MCNAUGHT dopamine neurons or parkinsonism107 It is also notewor thy that normal orsynuclein in some animal species has a threonine in the alanine position as is found with the human mutation74 but does not lead to aggregate forma tion or neurodegeneration possibly because orsynuclein is degraded differently in these species orsynuclein can also be degraded by the lysosomal system108 and there is evidence of impaired clearance by autophagy of the mutant form of the protein109 The relative roles of the UPS and lysosomal systems in the degradation of wild type and mutant orsynuclein have not yet been clearly de ned and it is possible that defects in the lysosomal systems could contribute to the protein accumulation and aggregation found in orsynucleinilinked familial PD Other Mutations Associated With Familial PD DJ1 PINKl LRRKZ A number of other mutations have been identi ed in association with familial cases of PD The normal func tion of these proteins is unclear how they cause PD is unknown and they are less clearly linked to a defect in the UPS or to protein misfolding Nevertheless the avail able evidence allows one to speculate on how neurode generation in these patients might theoretically be related to a defect in the UPS and consequent proteolytic stress DJl Mutations An autosomal recessive form of parkinsonism has been linked to chromosome lp36 PARK 7110 and is associated with deletion truncating and missense muta tions in the gene that encodes the 1897amino acid20 kDa protein DJl111113 The clinical picture is charac terized by an earlyonset mid30 years levodopa responsive form of PD with slow progression dystonia and psychiatric disturbances111gt112 The neuropathology of patients with DJl mutations has not been reported DJl is widely expressed in the cytosol and nucleus of cells in the CNS and is more prominent in astrocytes than neurons11 gt115 The function of DJ1 is unknown but there is evidence to suggest that it acts as an antioxidant or a sensor of oxidative stress116gt117 In addition its molecular structure and in vitro properties suggest that it has molecular chaperone and protease activity118 120 DJl has also been shown to interact with parkin and CHIPHSP70 suggesting a possible link to these proteo lytic systems121 Mutations as occur in PD eg L166P destabilize DJl inactivate and impair its proteolytic activity and promote its misfolding and rapid degrada tion by the proteasome122gt123 Overexpression of DJ1 protecm cultured cells from oxidative stress while knockdown increases susceptibility to oxidative stress endoplasmic reticulum stress and proteasomal inhibi Mavemem Dmarders Val 21 N0 1 2005 tion116gt117 lmportantly wildtype DJl inhibits the ag gregation of orsynuclein but this effect is lost when DJl is mutated as in PD124 These ndings raise the possibility that a mutation in DJl could be linked to a defect in UPS function by promoting protein aggregation and limiting protein clearance although no evidence of proteolytic stress has been observed in transgenic mice with a deletion of DJ1125 PINKl Mutations Several families with autosomal recessive earlyonset PD were found to have missense and truncating muta tions in a gene located at chromosome lp35 PARK 6 which encodes for a protein designated as PINKl PTEN phosphatase and tensin homolog deleted on chromo some lOinduced kinase 11126429 The clinical expres sion of PD in these patients is characterized by early onset 32748 years slow progression and a good re sponse to levodopa126gt129 PlNKl is a 5817amino acid628 kDa protein that is localized to mitochondria128 The normal function of PlNKl is unknown but its structure suggests that it might be a serinethreonine protein kinase that phosphor ylates proteins involved in signal transduction path ways128 In cultured cells wildtype PlNKl prevents proteasome inhibitoriinduced mitochondrial dysfunction and cell death but protection is lost with the mutations found in PD patients128 These observations raise the possibility that mutations in PlNKl could render neurons vulnerable to toxins that inhibit proteasome function PlNKl mutations could also impair mitochondrial func tion and diminish ATP production necessary for normal UPS function It is interesting that familial PDrelated mutations in PlNKl have been found in normal control subjects who do not have clinical features of parkinson ism130 again raising the possibility that multiple factors may be necessary for the development of PD in patients with this mutation LRRKZ Mutations An autosomal dominant form of PD with incomplete penetrance has been linked to a mutation on chromosome l2pll2 q13l PARK831gt132 It has recently been re ported that PD in these patients is associated with mis sense mutations in the gene encoding for the protein leucinerich repeat kinase2 LRRKZ also known as Dardarin from the Basque word for l remor133gt134 Not all subjects with these mutations develop PD suggesting again the possible requirement of other contributing eti ological factors135 Patients with dardarinLRRKZ mutations can have a clinical phenotype similar to sporadic PD with an age of UBIQ UITINPROTEASOME SYSTEM 1 813 onset ranging from 35 to 78 years older than has been described with other gene mutations in PD136 At pathol ogy variable patterns have been described even in pa tients from the same family and with the same mutation All subj ects had nigrostriatal degeneration but some had Lewy bodies in the SNc while others did not some had extensive cortical Lewy bodies consistent with a diagno sis of dementia with Lewy bodies and some had tau immunoreactive glial and neuronal inclusions131gt134gt137 Interestingly some patients with this mutation have a lateonset form of PD with no family history and pathol ogy characteristic of sporadic PD It has been estimated that the LRRK2 mutation might account for as many as 7 of familial cases and 15 to 3 of cases of sporadic PD39132135136 LRRK2 is a cytoplasmic protein that is widely ex pressed throughout the brain and is bound to the mito chondrial outer membrane133 Its normal function is not known but it resembles the family of tyrosinelike ki nases and is predicted to encode a 248225277amino acid protein that based on sequence homology with other proteins might be a cytoplasmic kinase133gt134 Little is known about how this mutation causes cell death How ever predictions based on its sequence suggest that the mutation might lead to increased kinase activity which could promote altered phosphorylation and misfolding of substrates Indeed recent in vitro kinase assays using fulllength recombinant LRRK2 reveal an increase in activity caused by familiallinked mutations in both au tophosphorylation and the phosphorylation of a generic substrate These results suggest a gainoffunction mech anism for LRRK2linked disease with a central role for kinase activity in the development of PD138 Coimmu noprecipitation studies in tissue culture demonstrate that LRRK2 interacts with parkin but not with OLsynuclein In addition overexpression of wildtype LRRK2 leads to protein aggregates that are increased by coexpression of parkin and mutant LRRK2 causes neuronal degeneration in both SHSY5Y cells and primary neuronal cultures139 It is noteworthy that some proteins such as IKB require phosphorylation as a prerequisite to their ubiquitination and proteasomal degradation140 These studies raise the possibility that mutations in LRRK2 lead to altered phos phorylation with increased aggregation of such target proteins SPORADIC PARKINSON S DISEASE A DISORDER OF PROTEASOME FUNCTION Sporadic PD is characterized by protein accumulation and proteinaceous Lewy bodies so it is reasonable to consider that protein mishandling is a key feature of the disease Indeed it has now been shown that proteasome structure and function are altered in the SNc in PD A reduction N40 has been found in the content of OLsubunits but not Bsubunits in comparison to age matched control subjects141 whereas OLsubunit expres sion is increased in the cerebral cortex N9 and stri atum N29 Immunohistochemical staining similarly demonstrates reduced expression of 208 proteasomal OLsubunits but not Bsubunits in SNc dopaminergic neurons in PD subjects compared to agematched con trols141 While proteasomal enzyme activity resides within the Bsubunits of the proteasome OLsubunits are required for normal proteasomal stability and function and in PD there is a reduction of approximately 45 to 55 in each of the chymotrypsinlike trypsinlike and peptidyl glutamyl peptide hydrolytic PGPH proteaso mal enzymatic activities as compared to controls141144 In contrast there is increased proteasomal enzyme activ ity in regions that do not degenerate in PD such as the frontal cortex striatum hippocampus pons and cerebel lum suggesting that these regions were capable of mounting a compensatory response that protected against neurodegeneration141143 Similar ndings were observed in both mildly and severely affected patients suggesting that altered proteasomal function occurs early in the pathogenic process in PD143 Interestingly a recent study showed that proteasomal function is also impaired in lymphocytes in PD but not Alzheimer s disease patients145 PD is also associated with altered levels of expression of proteasome activators PA700 is comprised of more than 20 different subunim with varying molecular weights19 In the SNc in PD there was either no change 42 46 and 95 kDa bands or a loss of up to 33 525 75 and 81 kDa bands in these respective PA700 sub unis140 In contrast there was a marked increase in the levels of the 81 75 525 and 42 kDa PA700 subunits in the frontal cortex andor striatum of PD subjects com pared to controls PA28 expression and immunoreactiv ity were almost undetectable in the SNc in PD and signi cantly less than in controls141 Importantly levels of the PA28 proteasome activator in the SNc of control subjects are much lower than in other brain regions examined perhaps accounting for the vulnerability of this region in PD141 These studies illustrate that proteasomal function is impaired in sporadic PD They also suggest that there is a compensatory upregulation of proteasomal function in spared regions raising the possibility that affected re gions cannot mount a satisfactory compensatory re sponse The relevance of proteasome function to the etiopathogenesis of PD is supported by in vitro studies Mavemem Dmarders Val 21 N0 1 2005 1814 CW OLANOW AND KSP MCNAUGHT showing that administration of proteasome inhibitors in duces a selective degeneration of dopamine neurons cou pled with inclusion bodies that stain positively for both OLsynuclein and ubiquitin7 gt146 Stereotactic injections of proteasome inhibitors into the SNc or striatum also in duce degeneration of dopamine neurons with inclusions in rats1 7gt148 More recently we have shown that sys temic administration of the proteasome inhibitors ep oxomicin or PSI induces a model of PD in rats149 After a latency of several weeks animals developed a gradu ally progressive levodopaapomorphineresponsive PD like syndrome Positron emission tomography PET demonstrated a progressive loss of dopaminergic nerve terminals in the striatum and postmortem analyses showed progressive striatal dopamine depletion and neu rodegeneration with inclusion bodies in the SNc as well as in the LC DMN nucleus basalis of Meynert NBM and peripheral autonomic neurons At sites of neurode generation there was a 43 to 82 inhibition of pro teasomal enzyme function while enzyme activity was upregulated in areas that did not degenerate replicating the pattern of what is found in PD This model illustrates that inhibition of proteasomal function can induce behavioral imaging pathological and biochemical features that closely mirror what is seen in PD and supports the concept that proteasomal dys function could be a key factor in the pathogenesis of the disorder However this model remains to be validated Since publication of the model several groups have sought to replicate these ndings We are aware that some groups have been able to reproduce the model but several laboratories have not see articles in Annals of Neurology 2006 volume 60 The reason for this vari ability is at present unknown Veri cation of the obser vation that systemic exposure to proteasome inhibitors induces a syndrome that closely approximates the behav ioral and pathological features of PD would provide a strong argument for implicating defects in proteasomal function in the etiopathogenesis of sporadic PD It is noteworthy that toxins that inhibit proteasomes can be found in the environment150 and can be manufactured by bacteria eg actinomycetes151gt152 fungi eg Apios para montagne153 plants15 156 and the chemicalphar maceutical industry150gt157 Lactacystin and epoxomicin are among the most potent proteasome inhibitors They are naturally produced by actinomycetes Streptomyces bacteria are found globally in the soil and aquatic hab itats of gardens and farmland and have the potential to infect root vegetables eg carrots and potatoes causing scab formation153gt159 Thus humans could be exposed to proteasome inhibitors through drinking water contami nated food or living in a rural environment Mavemem Dmarders Val 21 N0 1 2005 DISCUSSION Proteolytic stress occurs when levels of unwanted proteins within a cell exceed its capacity to degrade and clear them This can result in protein accumulation ag gregation disruption of critical intracellular functions and cytotoxicity23gt28 30 There is now a growing body of evidence suggesting that protein mishandling due to in creased production or a failure of the UPS to clear unwanted proteins may be a common feature in the different familial and sporadic forms of PD Fig 1B In support of this concept it is noted that PD is associated with OLsynuclein mutations which could result in excess levels of misfolded and aggregated proteins that resist proteolysis and cause secondary damage to the protea some parkin mutations which could prevent ubiquiti nation of target proteins UCHLl mutations which could impair deubiquitination of ubiquitinated proteins thereby preventing their degradation and limiting the supply of ubiquitin monomers necessary for clearing additional proteins with reduced proteasomal function and failed compensatory upregulation of proteasomal activators Further proteolytic stress has been shown to cause relatively selective dopaminergic degeneration with inclusions in both in vitro and in vivo laboratory models Mutations in several as yet uncharacterized genes are associated with familial PD and it will be interesting to determine if these encode proteins that are components of the UPS or where the mutation makes them prone to misfold and aggregate If failure of the UPS to clear abnormal proteins is a key factor in the etiopathogenesis of PD then this defect should also be able to account for other characteristic features of the disease including Lewy body formation agerelated vulnerability of the SNc and other biochem ical defects found in PD Further if it can be established that UPS failure plays a central role in neurodegenera tion this could provide novel targets for developing neuroprotective therapies that could have diseasemodi fying bene ts Possible Role of UPS in Lewy Body Formation Lewy bodies are 8 to 30 pm in diameter intacytoplas mic inclusions that are characteristically found at sites of neurodegeneration in PD In the SNc the Lewy body has a dense central core surrounded by a light halo when stained with hemotoxylin and eosin Fig 3 Immuno staining and electron microscopy studies show that the core is comprised of punctate aggregates of ubiquitinated proteins while the outer region consism of radiating lamenm 7720 nm in diameter comprised of brillar OLsynuclein and neuro laments29gt160 The mechanism underlying the formation of Lewy bodies and their role UBIQ UIFINePROTEASOME SYSTEM 1815 rn the neurodegenemtlve process has been the tocus ot consrderable debate oresynuclern has been postulated to be fundamental to Lewy body tormatron as Lewy bodres are rrch rn oresynuclernlmm and oresynuclern proto brrls promote zggegzuon and mclmlon body tormatron rn vltlo9u95 However not all protern aggegates or lewy bodres starn posrtrvely tor oresynuclernm and not all PD cases have Lewy bodres m Alternatrvely rt has been proposed that Lewy bodres may torm and tunctron rn a manner srmrlar to an aggree some 51 Aggesomes are cytoprotectrve rnclusrons that torm at the oentrosome a perrnuclear structure lmked to the mrcrotubular system rn response to excess levels ot mrstolded proterns m Mrstolded and aggegmed proe terns that cannot be cleared regronally are transported vra the mrcrotubular system to the oentrosome whrch exe pands to become an zggesome 1554 Srmultaneously componenm of the proteasome system are recrurted to the oemrosomezggesome to tacrlrtate the clearance ot these unwanted proterns In PD rt can be hypothesrzed that the aggesomzl rnclusron cannot adequately clear unwanted proterns became of the rmparrment rn proteae somal tunctron andor the overwhelmmg productron ot mutantdamaged proterns and expands to become a Lewy body Flg 3 mm In support ot thrs concept rt rs notee worthy that Lewy bodres are structurally srmrlar to age gesomes starn posrtrvely tor the specl c zggesome markers yetubulm and perrcentrrn and contarn the vane m Humltw th Wm cottgtartrrrerwtt rtar ttttutttatetntuttt mimepmtbttttrotttttrwtut tea at rtworatt tyrt Pmlmlyllrmulllhrmm t t t t t trttt W terrortun rtarrrbne arms trurrrrrtrr mvy BODY annotate trrvttrattrtrttttgttttntrttttltr Wtquotrpttmttttmtttmtrrt ttr attenuator turntttttartttn rtttwttttgwttmut rutlmr mt brawl trttrturtttrtrrnrgrttrttrtrwtt no 3 A protern aggregates and lewy body rnclusrons rn dopamrnergrc neurons or the ch rn sporadtc PD postmortem mam ecuom were rmrnunostarned usrng astandard Vector ABCpmwcal wrth 3339dlammbenzldm2H202 as a brown cmanngen and novel arrrbodres that are hrghly ssrmhve ror detectrng uhlqmurrprmzmcanjuga as lLvPcl lrl mere rs yery lrttle upc starnrng rnthe nonnal ch lneryl preence or numerous drscrete aggregates or ubrqurbnated proterns lanowsl rn the nerye ternnnals and cell bodres or neuronelanrnprgnented neutons rnthe ch rn PD lrrerestrngly panel ry shows what could mpxessnl the transport and coalescrng or ubrqurbnated protern aggregates to rorm a lewy body rn an agyewrrerhkz manner lylrwo lewy bodres starnrng ror asynuclern lyrlra lewy body starnrngror the protern undng dye msrn lyrrlnre nbnllary nabrre or lewy bodes when eramrned usrng an electron nncroscope a A propoed model suggestmg that lewy bodes ronnrn an aggresomerelated manner Under normal physrologrcal candmum there rs a dynamtc balanre between the productron or unwarred proterns and then degradabon by the unqurumproteasome system luvs l proteolybc stress rs rnduced as a result or rmparred degradatron andor ercess productron or unwanted proterns lmurant mtsrolded denatured and damaged proterns u Unwanted proterns that begn to accumulate and aggregate lnrl are acbyely transported along nncrobrbules to the pennuclear cenuosoneaggresome wnrch rs rderrrned by specrnc starmng ror yrmbuhn and pencentrrn lryl srmultaneously up enrynesproteamee components proteasome actryators llsps andublqumn lubl are recrurtedto the cerrrosome to racrlrtate the degradabon or equestered proterns lyl sequestered cornponerrs are emmd by cytoslteletal elements such as neuronlaments to ronn an aggresome wrth a dstrnct core and a perrpberal halo as rllustrated lyl lr sequestered proterns are successrully degraded proteolytrc murlrbnum rs restored lyrl We posbrlate that rr proteolysrs rn aggresomes rarls as a result or derects rn the protern degradauon machrnery or the oyerwlelnnng productron or amonnal proterns the aggresome contmues to expand androrms an rnsoluble mas or proterns that rs rderrrned as a lewy body lyrrl Denyed nom olanow and colleagues in Mowrursmee Vol 21 up 11 mar 1816 CW OLANOW AND KSP MCNAUGHT ous UPS components28 This concept implies that the Lewy body formation is a cytoprotective event aimed at combatting proteolytic stress rather than a toxic species as has been previously considered Indeed inhibition of inclusion body formation in models of proteolytic stress is associated with more rapid and more severe cell death169gt170 Failure to ubiquitinate proteins might pre clude their transport to the centrosomeaggresome and explain the absence of Lewy bodies in patients with parkin mutations Lack of this protective response might also account for why parkin patients experience early onset disease with severe neuronal degeneration Possible Role of UPS in AgeRelated Susceptibility of SNc There is a propensity to develop proteolytic stress with advancing age as aging is associated with an increased production of damaged proteins combined with a pro gressive decline in proteasomal function171174 Speci cally with aging there is an increase in protein carbonyls oxidatively damaged proteins and a reduction in 26S proteasomal mRNA levels and enzymch activity171175 Thus with aging there is an increased propensity for protein accumulation aggregation and cell death Nerve cells are particularly prone to accumulate ab normal proteins as they do not regenerate Among brain cells the SNc may be most vulnerable because the oxi dative metabolism of dopamine promotes free radical formation and protein oxidation174 proteasomal activity pronouncedly declines with aging173 and dopamine can interact with orsynuclein to promote the formation of toxic proto brils and protein aggregation176gt177 In addi tion levels of the PA28 proteasome activator are mark edly reduced in the SNc in comparison to other brain regions in normal controls141 PA28 is thought to play an important role in the degradation of proteins that have been damaged by oxidative stress Why dopamine neu rons which are prone to form oxidatively damaged pro teins are de cient in this proteasome activator is puzzling Collectively these ndings suggest that SNc neurons are prone to develop proteolytic stress with aging which may account for their vulnerability in PD Indeed mild neuronal loss and Lewy bodies have been found in the SNc in 10 to 15 of individuals over the age of 65 years who die without clinical evidence of neurological illness using conventional HampE stains and the percent age is likely to be much higher with the more sensitive techniques that are currently available178 Aging may be the nal straw that leads to proteolytic stress and degen eration of neurons Studies to assess the effect of age in other brain regions affected in PD are currently underway Relationship Between UPS and Other Biochemical Changes in PD PD is associated with a number of biochemical abnor malities and it is possible that a defect in UPS function could contribute to their development T able 2 The UPS plays a major role in controlling transcription and levels of shortlived regulatoryfunction proteins linked to a variety of cellular processes179 that are affected in PD including antioxidant defense mechanisms18 gt181 mitochondrial activity182gt183 in ammatory responses184 and antiapoptotic signaling pathways180gt185 Indeed inhi bition of proteasomal function has been shown to cause oxidative stress186 mitochondrial dysfunction184gt186 in ammatory reactions187 and apoptosis149gt185 and theoret ically could account for these ndings in PD Further cell damage induced by proteasome inhibitors is syner gistically increased by oxidative stress or agents that pro mote protein misfolding183192 It should also be appreci ated that proteasomal damage and UPS dysfunction could be a secondary event and occur consequent to oxidative stress and mitochondrial dysfunction131gt132gt189gt19 195 TABLE 2 Alterations in UPSlinked cellular processes in sporadic Parkinson s disease Cellular processes linked to the UPS Alterations in spomdic Parkinson s disease Degmdation and clearance of abnormal proteins21 Antioxidant defense mechanismsl73vl79v13 v186 Mitochondrial functionl wvmovzul23 In ammatory responselmvm Immune processes220 Apoptotic signaling 183 Synaptic function and neurotmnsmission j Signal transduction228 Protein tmnsportjtmf cking229 Gene transcription230 Development and differentiation115 Regulation of cell cycle and division232 Yes protein accumulation and aggregation 5 Yes oxidative stressl vl50 Yes complex I activity impaired Yes microglial activation and gliosis Yes complement activation16 Yes apoptotic cell death13 Yes altered basal ganglia compensationzuvzZ7 Yes altered neuronal activityu 27 Yes Lewy neurites and inclusionst29 Yes altered gene expression231 Movement DLsorders Vol 2 No I 2005 UBIQ UITINPROTEASOME SYSTEM 1 81 7 Does UPS Provide Novel Targets for Putative Neuroprotective Therapies in PD The possibility that failure of the UPS to prevent protein accumulation might play a central role in the initiation or progression of the pathogenic process in PD raises the possibility that neuroprotective therapies could be developed that target this system This might be accomplished through drugs or gene therapies aimed at preventing or reversing protein damagemisfolding or stimulating UPSmediated protein degradation HSPs have been shown to protect cells from toxicity induced by inhibition of proteasomal function or excess levels of unwanted proteins32gt193gt196 In vitro HSPs pro tect cultured cells from the cytotoxic effects of protea some inhibitors or overexpression of wildtypemutant OLsynuclein196gt197 HSP70 has also been shown to atten uate proteasome inhibition and protein aggregation in duced by aggregated OLsynucleinl93gt199 Heat shock pro teins also prevent the degeneration of dopaminergic neurons induced by overexpression of wildtype or mu tant OLsynuclein in Drosophila200 Interestingly inclu sion bodies persist in this model consistent with the notion that they represent a protective and not cytotoxic response Coexpression of HSP70 in transgenic mice expressing mutant OLsynuclein similarly reduces OLsynuclein aggregation198 In contrast coexpression of OLsynuclein with Hsc4K7lS a dominantnegative mu tant of the constitutively expressed y HS P70 enhanced dopaminergic cell death in Drosophila200 These ndings suggest that induction of HSP expression can protect dopamine neurons from a variety of types of proteolytic stress and might be protective in PD Pharmacological inhibition of protein aggregation us ing compounds such as the antibiotic radicicol and the naturally occurring benzoquinone ansamycin geldana mycin is effective in preventing or reducing cytotoxicity induced by abnormal proteins oli207 Geldanamycin in hibits OLsynuclein aggregation and prevents toxicity sec ondary to overexpression of wildtype or mutant OLsynuclein in cultured cells and Drosophila208209 Geldanamycin is thought to bind to an ATP site on HSP90 blocking its normally negative regulation of heat shock transcription factor 1 HSFl204208 This pro motes synthesis of HSPs such as HSP70 which inhibit the aggregation of various proteins including OLsynuclein by promoting their refolding or proteaso mal degradation3119119830030 210 Glucocorticoids such as dexamethasone can stimulate UPSmediated proteol ysis by enhancing the expression of ubiquitin211212 E2 and E3 enzymes213215 proteasome core subunits 16 and subunits of the PA700 proteasome activator217 These effects have been demonstrated in several in vitro and in vivo model systems although not yet in models of PD Trehalose is a disaccharide that upregulates under conditions of proteolytic stress and prevents aggregation of denatured proteins Trehalose has been shown to re duce protein aggregation in a mouse model of Hunting ton s disease213gt219 and deletion of a gene that encodes a protein involved in trehalose synthesis enhances OLsynuclein toxicity in yeast220 Thus one may speculate that trehalose or similar agents might reduce protein aggregation and pathology in PD Another exciting ap proach involves the use of vaccination as a means of reducing protein aggregates Masliah and colleagues221 immunized human h0Lsynuclein transgenic mice with puri ed recombinant hasynuclein and demonstrated de creased accumulation of aggregated OLsynuclein and re duced neurodegeneration Finally we have recently shown that cell death induced by proteasome inhibitors involves early nontranscriptional activation of the pro apoptotic protein p53 Inhibitors of p53 activation with agents such as pi thrinOL block dopaminergic cell death induced by proteasome inhibitors in culture222 and war rant further testing in animal models of PD SUMMARY AND CAVEATS This review has addressed the hypothesis that proteo lytic stress secondary to genetic or environmentally based defects in the capacity of the UPS to clear un wanted proteins might be a common factor underlying the different forms of PD This concept could account for Lewy body formation and identi es novel targets for the development of putative neuroprotective agents for PD There remain several caveats First a relationship be tween UPS dysfunction and familial cases of PD has not been unequivocally established for any gene mutation A better understanding of why individual mutations cause PD is required before we can directly implicate the UPS in these forms of PD Second it has not yet been estab lished that the proteasomal defects in sporadic PD are primary and do not occur secondary to an altenrate etiology Indeed mitochondrial damage or oxidative stress can induce secondary proteasomal dam age131gt182gt189gt193195 Finally the animal model of PD caused by systemic exposure to proteasome inhibitors149 remains to be validated An understanding of why some groups but not others have been able to reproduce this model is of critical importance A determination that systemic exposure to a proteasome inhibitor induces a predictive reproducible progressive model of PD that mirrors the behavioral biochemical and pathological changes seen in the disease would provide strong support MatEmma Dmarders Val 21 N0 1 2005 1818 for the concept that proteolytic stress is a key factor in the etiopathogenesis of PD Acknowledgments This study was supported by grants from the National Institutes of HealthNational Institute of Neurological Disorders and Stroke 1 R01 NS04599901 the BachmannStrauss Dystonia and Parkinson Foundation Inc the Bendheim Parkinson s Disease Center and the Monis and Alma Schapiro Fund 10 11 12 13 14 15 16 17 18 19 20 21 22 REFERENCES Lang AE Lozano AM Parkinson s disease I N Engl J Med 1998339104471053 Lang AE Lozano AM Parkinson s disease 11 N Engl J Med 1998339113071143 Fomo LS Neuropathology of Parkinson s disease J Neuropathol Exp Neurol 199655259 7272 Bmak H Tredici KD Rub U de Vos RA Jansen Steur EN Braak E Staging of bmin pathology related to spomdic Parkinson s disease Neurobiol Aging 2003241977211 Zarow C Lyness SA Mortimer JA Chui HC Neuronal loss is greater in the locus coeruleus than nucleus basalis and substantia nigm in Alzheimer and Parkinson diseases Arch Neurol 2003 60 337734 1 Wakabayashi K Takahashi H Neuropathology of autonomic nervous system in Parkinson s disease Eur Neurol 1997 38Supp1 2277 Hattori N Mizuno Y Pathogenetic mechanisms of parkin in Parkinson s disease Lancet 20043647227724 Moore DJ West AB Dawson VL Dawson TM Molecular pathor physiology of Parkinson s disease Ann Rev Neurosci 200525 5 7 4 McNaught KS Olanow CW Proteolytic stress a unifying con cept in the etiopathogenesis of familial and sporadic Parkinson s disease Ann Neuro1200353Supp1 1S73786 Tanner CM Is the cause of Parkinson s disease environmental or hereditary evidence from twin studies Adv Neurol 200391 1337142 Tatton WG ChalmersrRedman R Brown D Tatton N Apoptosis in Parkinson s disease signals for neuronal degmdation Ann Neuro1200353Supp1 3S61770 Jenner P Oxidative stress in Parkinson s disease Ann Neurol 200353Supp1 3S26736 Orth M Schapim AH Mitochondrial involvement in Parkinson s disease Neurochem Int 2002405337541 McGeer PL McGeer EG In ammation and neurodegeneration in Parkinson s disease Parkinsonism Relat Disord 200410Supp1 1S377 Beal MF Excitotoxicity and nitric oxide in Parkinson s disease pathogenesis Ann Neurol 199844Supp1 131107SII4 McNaught KSP Olanow CW Halliwell Isacson O Jenner P Failure of the ubiquitinrproteasome system in Parkinson s dis ease Nat Rev Neurosci 200125897594 Petrucelli L Dawson TM Mechanism of neurodegenemtive dis ease role of the ubiquitin proteasome system Ann Med 2004 363157320 Pickart CM Mechanisms underlying ubiquitination Annu Rev Biochem 2001705037533 Pickart CM Cohen RE Proteasomes and their kin proteases in the machine age Nat Rev Mol Cell Biol 200451777187 Goldberg AL Protein degmdation and protection against misr folded or damaged proteins Nature 20034268957899 Ciechanover A Proteolysis from the lysosome to ubiquitin and the proteasome Nat Rev Mol Cell Biol 2005679787 Saric T Graef CI Goldberg AL Pathway for degmdation of peptides genemted by proteasomes a key role for thimet olir Mavemem DLSmderS Val 21 N0 1 2005 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 CW OLANOW AND KSP MCNAUGHT gopeptidase and other metallopeptidases J Biol Chem 2004279 46723746732 Grune T Jung T Merker K Davies KJ Decreased proteolysis caused by protein aggregates inclusion bodies plaques lipofusr cin ceroid and aggresomes during oxidative stress aging and disease Int J Biochem Cell Biol 200436251972530 Holmberg CI Staniszewski KE Mensah KN Matouschek A Morimoto RI Inef cient degradation of truncated polyglutamine proteins by the proteasome EMBO J 200423430774318 Venkatraman P Wetzel R Tanaka M Nukina N Goldberg AL Eukaryotic proteasomes cannot digest polyglutamine sequences and release them during degradation of polyglutaminercontaining proteins Mol Cell 200414957104 Har1l FU HayerrHartl M Molecular chaperones in the cytosol from nascent chain to folded protein Science 200229518527 1858 Muchowski PJ Wacker JL Modulation of neurodegenemtion by molecular chaperones Nat Rev Neurosci 2005611722 McNaught KS Shashidhamn P Perl DP Jenner P Olanow CW Aggresomerrelated biogenesis of Lewy bodies Eur J Neurosci 200216213672148 Bence NF Sampat RM Kopito RR Impairment of the ubiquitini proteasome system by protein aggregation Science 2001292 155271555 Kopito RR Aggresomes inclusion bodies and protein aggregar tion Trends Cell Biol 2000105247530 Bennett EJ Bence NF Jayakumar R Kopito RR Global impair ment of the ubiquitiniproteasome system by nuclear or cytoplasr mic protein aggregates precedes inclusion body formation Mol Cell 2005173517365 Sherman MY Goldberg AL Cellular defenses against unfolded proteins a cell biologist thinks about neurodegenemtive diseases Neuron 20012915732 Yamamum Y Sobue I Ando K Iida M Yanagi T Pamlysis agitans of early onset with marked diurnal uctuation of sympr toms Neurology 1973232397244 Matsumine H Saito M ShimodarMatsubayashi S et a1 Locale ization of a gene for an autosomal recessive form of juvenile Parkinsonism to chromosome 6q252r27 Am J Hum Genet 1997 605887596 Kitada T Asakawa S Hattori N et al Mutations in the parkin gene cause autosomal recessive juvenile parkinsonism Nature 19983926057608 Mizuno Y Hattori N Mori H Suzuki T Tanaka K Parkin and Parkinson s disease Curr Opin Neurol 2001144777482 Lucking CB Durr A Bonifati V et al Association between earlyronset Parkinson s disease and mutations in the parkin gene French Parkinson s Disease Genetics Study Group N Engl J Med 2000342156071567 Mori H Kondo T Yokochi M et al Pathologic and biochemical studies ofjuvenile parkinsonism linked to chromosome 6q Neur rology 1998518907892 Foroud T Uniacke SK Liu L et al Heterozygosity for a mutation in the parkin gene leads to later onset Parkinson disease Neurolr ogy 2003607967801 Farrer M Chan P Chen R et al Lewy bodies and parkinsonism in families with parkin mutations Ann Neuro12001502937300 Horowitz JM Vernace VA Myers J et al Immunodetection of Parkin protein in vertebmte and invertebrate bmins a company tive study using speci c antibodies J Chem Neuroanat 200121 75793 Shimura H Hattori N Kubo S et al Familial Parkinson disease gene product parkin is a ubiquitinrprotein ligase Nat Genet 2000253027305 Shimura H Schlossmacher MG Hattori N et al Ubiquitination of a new form of alphalrsynuclein by parkin from human bmin implications for Parkinson s disease Science 20012932637269 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 UBI Q UI TIN PR 0 TEAS OME SYSTEM Imai Y Soda M Takahashi R Parkin suppresses unfolded protein stressrinduced cell death through its E3 ubiquitinrprotein ligase activity J Biol Chem 200027535661735664 Imai Y Soda M Inoue H Hattori N Mizuno Y Takahashi R An unfolded putative tmnsmembmne polypeptide which can lead to endoplasmic reticulum stress is a substmte of parkin Cell 2001 1058917902 Zhang Y Gao J Chung KK Huang H Dawson VL Dawson 39IM Parkin functions as an E2rdependent ubiquitiniprotein ligase and promotes the degmdation of the synaptic vesiclerassociated pro tein CDCrelrl Proc Natl Acad Sci U S A 200097133547 13359 Sakata E Yamaguchi Y Kurimoto E et al Parkin binds the an10 subunit of 26S proteasomes through its ubiquitinrlike domain ElVIBO Rep 200343017306 Imai Y Soda M Hatakeyama S et al CHIP is associated with Parkin a gene responsible for familial Parkinson s disease and enhances its ubiquitin ligase activity Mol Cell 200210557 67 Cyr DM Hohfeld J Patterson C Protein quality control Urboxi containing E3 ubiquitin ligasesjoin the fold Trends Biochem Sci 2002273687375 Shimura H Hattori N Kubo S et al Immunohistochemical and subcellular localization of Parkin protein absence of protein in autosomal recessive juvenile parkinsonism patients Ann Neurol 1999456687672 Yang Y Nishimura I Imai Y Takahashi R Lu B Parkin supr presses dopaminergic neuronrselective neurotoxicity induced by Paeer in Drosophila Neuron 2003379117924 Petrucelli L O Farrell C Lockhart PJ et al Parkin protects against the toxicity associated with mutant alpharsynuclein pror teasome dysfunction selectively affects catecholaminergic neur rons Neuron 200236100771019 Itier JM Ibanez P Mena MA et al Parkin gene inactivation alters behaviour and dopamine neurotmnsmission in the mouse Hum Mol Genet 200312227772291 Goldberg MS Fleming SM Palacino JJ et al Parkinrde cient mice exhibit nigrostriatal de cits but not loss of dopaminergic neurons J Biol Chem 200327843628743635 Von Coelln R Thomas B Savitt JM et al Loss of locus coerr uleus neurons and reduced startle in parkin null mice Proc Natl Acad Sci USA 200410110744710749 Perez FA Palmiter RD Parkinrde cient mice are not a robust model of parkinsonism Proc Natl Acad Sci U S A 2005102 217472179 Pesah Y Pham T Burgess H et al Drosophila parkin mutants have decreased mass and cell size and increased sensitivity to oxygen mdical stress Development 2004131218372194 Lincoln SJ Mamganore DM Lesnick TG et al Parkin variants in North American Parkinson s disease cases and controls Mov Disord 200318 1306713 1 1 Leroy E Boyer R Auburger G et al The ubiquitin pathway in Parkinson s disease Nature 19983954517452 Auberger G Kessler K Kang JrS Gispert S Stoltenburg G Bmak H Is the PARK5 I93M mutation a cause of Parkinson s disease with cognitive de cits and conical Lewy pathology Berlin Sixteenth International Conference on Parkinson s Dis ease and Related Disorers 2005 p PT042 Wintermeyer P Kruger R Kuhn W et al Mutation analysis and association studies of the UCHLl gene in German Parkinson s disease patients Neuroreport 200011207972082 Mamganore DM Lesnick TG Elbaz A et al UCHLl is a Parkinson s disease susceptibility gene Ann Neuron 200455 5127521 Healy DG AbourSleiman PM Casas JP et al UCI39ILrl is not a Parkinson s disease susceptibility gene Ann Neurol 200659 6277633 Solano SM Miller DW Augood SJ Young AB Penney JB Jr Expression of alpharsynuclein parkin and ubiquitin carboxyr 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 1819 terminal hydrolase L1 mRNA in human brain genes associated with familial Parkinson s disease Ann Neurol 2000472017210 Wilkinson KD Deshpande S Larsen CN Comparisons of neur ronal PGP 95 and nonrneuronal ubiquitin Crterminal hydror lases Biochem Soc Trans 1992206317637 Wilkinson KD Lee KM Deshpande S DuerksenrHughes P Boss JM Pohl J The neuronrspeci c protein PGP 95 is a ubiquitin carboxylrterminal hydrolase Science 19892466707673 Liu Y Fallon L Lashuel HA Liu Z Lansbury PT Jr The UCHrLl gene encodes two opposing enzymatic activities that affect alpharsynuclein degradation and Parkinson s disease susr ceptibility Cell 20021112097218 Nishikawa K Li H Kawamura R et al Altemtions of structure and hydrolase activity of parkinsonismrassociated human ubqu uitin carboxylrterminal hydrolase L1 variants Biochem Biophys Res Commun 20033041767183 Osaka H Wang YL Takada K et al Ubiquitin carboxyrterminal hydrolase L1 binds to and stabilizes monoubiquitin in neuron Hum Mol Genet 200312194571958 McNaught KSP Mytilineou C JnoBaptiste R et al Impairment of the ubiquitinrproteasome system causes dopaminergic cell death and inclusion body formation in ventml mesencephalic cultures J Neurochem 2002813017306 Saigoh K Wang YL Suh JG et al Intmgenic deletion in the gene encoding ubiquitin carboxyrterminal hydrolase in gad mice Nat Genet 19992347751 Golbe LI Di Iorio G Bonavita V Miller DC Duvoisin RC A large kindred with autosomal dominant Parkinson s disease Ann Neurol 1990272767282 Polymeropoulos MH Higgins JJ Golbe LI et al Mapping of a gene for Parkinson s disease to chromosome 4q217q23 Science 1996274119771199 Polymeropoulos MH Lavedan C Leroy E et al Mutation in the alpharsynuclein gene identi ed in families with Parkinson s dis ease Science 1997276204572047 Kruger R Kuhn W Muller T et al Ala30Pro mutation in the gene encoding alpharsynuclein in Parkinson s disease Nat Genet 1998181067108 Zarmnz JJ Alegre J Gomeersteban JC et al The new mutation E46K of alpharsynuclein causes Parkinson and Lewy body der mentia Ann Neurol 2004551647173 ChartierrHarlin MC Kachergus J Roumier C et al Alphar synuclein locus duplication as a cause of familial Parkinson s disease Lancet 2004364116771169 Ibanez P Bonnet AM Debarges B et al Causal relation between alpharsynuclein gene duplication and familial Parkinson s dis ease Lancet 2004364116971171 Singleton AB Farrer M Johnson J et al Alpharsynuclein locus triplication causes Parkinson s disease Science 2003302841 Miller DW Hague SM Clarimon J et al Alpharsynuclein in blood and bmin from familial Parkinson disease with SNCA locus triplication Neurology 200462183571838 Muenter MD Forno LS Hornykiewicz O et al Hereditary form of parkinsonism dementia Ann Neurol 1998437687781 Farrer M Kachergus J Forno L et al Comparison of kindreds with parkinsonism and alpharsynuclein genomic multiplications Ann Neurol 200455 1747179 Kotzbauer PT Giasson BI Kmvitz AV et al Fibrillization of alpharsynuclein and tau in familial Parkinson s disease caused by the A53T alpharsynuclein mutation Exp Neurol 20041872797 288 Duda JE Giasson BI Mabon ME et al Concurrence of alpha synuclein and tau brain pathology in the Contursi kindred Acta Neuropathol Berl 20021047711 Maroteaux L Campanelli JT Scheller RH Synuclein a neuron speci c protein localized to the nucleus and presynaptic nerve terminal J Neurosci 19888280472815 Jakes R Spillantini MG Goedert M Identi cation of two distinct synucleins from human bmin FEBS Lett 199434527732 Mavemem Dmarders Val 21 N0 1 2005 1820 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 MDV GoedertM Alpharsynuclein and neurodegenemtive diseases Nat Rev Neurosci 200124927501 Abeliovich A Schmitz Y Farinas I et al Mice lacking alphar synuclein display functional de cits in the nigrostriatal dopamine system Neuron 2000252397252 Chandra S Fornai F Kwon HB et al Doublerknockout mice for alpha and betarsynucleins effect on synaptic functions Proc Natl Acad Sci U S A 200410114966714971 Conway KA Harper JD Lansbury PT Accelerated in vitro bril formation by a mutant alpharsynuclein linked to earlyronset Parr kinson disease Nat Med 19984131871320 Weinreb PH Zhen W Poon AW Conway KA Lansbury PT Jr NACP a protein implicated in Alzheimer s disease and learning is natively unfolded Biochemistry 19963513709713715 Conway KA Lee SJ Rochet JC Ding TT Williamson RE Lansbury PT Jr Acceleration of oligomerization not brillizar tion is a shared property of both alpharsynuclein mutations linked to earlyronset Parkinson s disease implications for pathor genesis and therapy Proc Natl Acad Sci U S A 2000975717576 Li J Uversky VN Fink AL Effect of familial Parkinson s disease point mutations A30P and A53T on the structuml properties aggregation and brillation of human alpharsynuclein Biochemr istry 2001 40 1 160471 1613 Lashuel HA Petre BM Wall J et al Alpharsynuclein especially the Parkinson s diseaserassociated mutants forms porerlike any nular and tubular proto brils J Mol Biol 2002322108971102 Caughey B Lansbury PT Proto brils pores brils and neuror degeneration sepamting the responsible protein aggregates from the innocent bystanders Annu Rev Neurosci 2003262677298 Spillantini MG Goedert M The alpharsynucleinopathies Parlng son s disease dementia with Lewy bodies and multiple system atrophy Ann NY Acad Sci 200092016727 Bennett MC Bishop JF Leng Y Chock PB Chase TN Moumr dian MM Degmdation of alpharsynuclein by proteasome J Biol Chem 199927433855733858 Tofaris GK Lay eld R Spillantini MG Alpharsynuclein metabr olism and aggregation is linged to ubiqutinrindependent degmr dation by the proteasome FEBS Lett 200125504175 Tanaka Y Engelender S lgamshi S et al Inducible expression of mutant alpharsynuclein decreases proteasome activity and in creases sensitivity to mitochondriardependent apoptosis Hum Mol Genet 2001109197926 Stefanis L Larsen KE Rideout HJ Sulzer D Greene LA Exr pression of A53T mutant but not wildrtype alpharsynuclein in PC12 cells induces alterations of the ubiquitinrdependent degmr dation system loss of dopamine release and autophagic cell death J Neurosci 200121954979560 Snyder H Mensah K Theisler C Lee JM Matouschek A Wolor zin B Aggregated and monomeric alpharsynuclein bind to the S639 proteasomal protein and inhibit proteasomal function J Biol Chem 200327811753711759 Liu CW Corboy MJ DeMartino GN Thomas PJ Endoproteor lytic activity of the proteasome Science 2003299408 7411 Liu CW Giasson BI Lewis KA Lee VM Demartino GN Thomas PJ A precipitating role for truncated alpharsynuclein and the proteasome in alpharsynuclein aggregation implications for pathogenesis of Parkinson s disease J Biol Chem 2005280 22670722678 Lee M Hyun D Halliwell B Jenner P Effect of the overexpresr sion of wildrtype or mutant alpharsynuclein on cell susceptibility to insult J Neurochem 20017699871009 Feany MB Bender W A Drosophila model of Parkinson s disease Nature 20004043947398 Kirik D Annett LE Burger C Muzyczka N Mandel RJ Bj orkr lund A Nigrostriatal alpharsynucleinopathy induced by viml vecr torrmediated overexpression of human alpharsynuclein a new primate model of Parkinson s disease Proc Natl Acad Sci U S A 2003100288472889 8mm DLS UYdEYS Val 21 N0 1 2005 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 CW OLANOW AND KSP MCNAUGHT Fernagut PO Chesselet MF Alpharsynuclein and transgenic mouse models Neurobiol Dis 2004171237130 Lee HJ Khoshaghideh F Patel S Lee SJ Cleamnce of alpha synuclein oligomeric intermediates via the lysosomal degmdation pathway J Neurosci 200424188871896 Cuervo AM Stefanis L Fredenburg R Lansbury PT Sulzer D Impaired degmdation of mutant alpharsynuclein by chaperoner mediated autophagy Science 2004305129271295 van Duijn CM Dekker MC Bonifati V et al Park7 a novel locus for autosomal recessive earlyronset parkinsonism on chromor some 1p36 Am J Hum Genet 2001696297634 Bonifati V Rizzu P van Baren MJ et al Mutations in the DJrl gene associated with autosomal recessive earlyronset parkinsonr ism Science 20032992567259 Bonifati V Oostra BA Heutink P Linking DJrl to neurodegenr emtion offers novel insights for understanding the pathogenesis of Parkinson s disease J Mol Med 2004821637174 Nagakubo D Taira T Kitaum H et al DJrl a novel oncogene which tmnsforms mouse NlH3T3 cells in coopemtion with ras Biochem Biophys Res Commun 19972315097513 Shang H Lang D JeanrMarc B Kaelianang A Localization of DJrl mRNA in the mouse bmin Neurosci Lett 20043672737 277 Bandopadhyay R Kingsbury AE Cookson MR et al The ex pression of DJrl PARK7 in normal human CNS and idiopathic Parkinson s disease Bmin 20041274207430 Yokota T SugaWam K Ito K Takahashi R Ariga H Mizusawa H Down regulation of DJrl enhances cell death by oxidative stress ER stress and proteasome inhibition Biochem Biophys Res Commun 2003312134271348 Taim T Saito Y Niki T lguchirAriga SM Takahashi K Ariga H DJrl has a role in antioxidative stress to prevent cell death EMBO Rep 200452137218 AbourSleiman PM Healy DG Quinn N Lees AJ Wood NW The role of pathogenic DJrl mutations in Parkinson s disease Ann Neurol 2003542837286 Lee SJ Kim SJ Kile et al Crystal structures of human DJrl and Escherichia coli Hsp31 which share an evolutionarily con served domain J Biol Chem 200327844552744559 Wilson MA St Amour CV Collins JL Ringe D Petsko GA The 18rA resolution crystal structure of YDR533Cp from Sankara myces cerevisiae a member of the DJylThiJprl superfamily Proc Natl Acad Sci U S A 2004101153171536 Moore DJ Zhang L Troncoso J et al Association of DJrl and parkin mediated by pathogenic DJrl mutations and oxidative stress Hum Mol Genet 20051471784 Olzmann JA Brown K Wilkinson KD et al Familial Parlng son s diseaserassociated L166P mutation disrupts DJrl protein folding and function J Biol Chem 2004279850678515 Moore DJ Zhang L Dawson TM Dawson VL A missense mutation L166P in DJ7 1 linked to familial Parkinson s disease confers reduced protein stability and impairs homoroligomerizar tion J Neurochem 200387155871567 Shendelman S Jonason A Martinat C Leete T Abeliovich A DJrl is a redoxrdependent molecular chaperone that inhibits alpharsynuclein aggregate formation PLoS Biol 20042E362 Goldberg MS Pisani A Haburcak M et al Nigrostriatal dopar minergic de cits and hypokinesia caused by inactivation of the familial parkinsonismrlinked gene DJrl Neuron 2005454897 496 Valente EM Bentivoglio AR Dixon PH et al Localization of a novel locus for autosomal recessive earlyronset parkinsonism PARK6 on human chromosome 1p357p36 Am J Hum Genet 2001688957900 Valente EM ancati F Fermris A et al PARK6rlinked parlng sonism occurs in seveml European families Ann Neurol 2002 51 14718 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 UBRQUYTHVJUQOIYZASCMIE SYSIEBI Valente EM AbourSleiman PM Caputo V et al Hereditary earlyronset Parkinson s disease caused by mutations in PlNKl Science 2004304115871160 Healy DG AbourSleiman PM Wood NW PINK PANK or PARK A clinicians guide to familial parkinsonism Lancet Neurol 200436527662 Rogaeva E Johnson J Lang AE et al Analysis of the PlNKl gene in a large cohort of cases with Parkinson disease Arch Neurol 200461189871904 Funayama M Hasegawa K Kowa H Saito M Tsuji S Obata F A new locus for Parkinson s disease PARK8 maps to chromor some 12p112rq131 Ann Neurol 2002512967301 Nichols WC Pankratz N Hernandez D et al Genetic screening for a single common LRRK2 mutation in familial Parkinson s disease Lancet 20053654107412 PaisanrRuiz C Jain S Evans EW et al Cloning of the gene containing mutations that cause PARK8rlinked Parkinson s dis ease Neuron 2004445957600 Zimprich A Biskup S Leitner P et al Mutations in LRRK2 cause autosomalrdominant parkinsonism with pleomorphic par thology Neuron 2004446017607 Di Fonzo A Rohe CF FerIeim J et al A frequent LRRK2 gene mutation associated with autosomal dominant Parkinson s dis ease Lancet 20053654127415 Gilks WP AbourSieiman PM Gandhi S et al A common LRRK2 mutation in idiopathic Parkinson s disease Lancet 2005 3654157416 Wszolek ZK Pfeiffer RF Tsuboi Y et al Autosomal dominant parkinsonism associated with variable synuclein and tau patholr ogy Neurology 200462161971622 Smith WW Pei Z Jiang H et al Leucinerrich repeat kinase 2 LRRK2 intemcts with parkin and mutant LRRK2 induces neur ronal degeneration Proc Natl Acad Sci U S A 2005102186767 18681 West AB Moore DJ Biskup S et al Parkinson s diseaserassor ciated mutations in leucinerrich repeat kinase 2 augment kinase activity Proc Natl Acad Sci U S A 200510216842716847 DiDonato J Mercurio F Rosette C et al Mapping of the inducr ible llrappaB phosphorylation sites that signal its ubiquitination and degmdation Mol Cell Biol 199616129571304 McNaught KS Belizaire R lsacson O Jenner P Olanow CW Altered proteasomal function in sporadic Parkinson s disease Exp Neurol 200317938745 McNaught KS Jenner P Proteasomal function is impaired in substantia nigm in Parkinson s disease Neurosci Lett 2001297 1917194 Tofaris GK Razzaq A Ghetti B Lilley K Spillantini MG Ubiquitination of alpharsynuclein in Lewy bodies is a pathology ical event not associated with impairment of proteasome function J Biol Chem 200327844405744411 Furukawa Y Vigouroux S Wong H et al Bmin proteasomal function in spomdic Parkinson s disease and related disorders Ann Neurol 2002517797782 Blandini F Sinforiani E Pacchetti C et al Peripheral proteasome and caspase activity in Parkinson s disease and Alzheimer s dis ease Neurology 2006665297534 Rideout HJ Larsen KE Sulzer D Stefanis L Proteasomal inhir bition leads to formation of ubiquitinalpharsynucleiniimmunor reactive inclusions in PC12 cells J Neurochem 2001788997 908 McNaught KSP Bjorklund LM Belizaire R Jenner P Olanow CW Proteasome inhibition causes nigral degenemtion with in clusion bodies in mts Neuroreport 200213143771441 Fomai F Lenzi P Gesi M et al Fine structure and biochemical mechanisms underlying nigrostriatal inclusions and cell death after proteasome inhibition J Neurosci 200323895578966 McNaught KSP Perl DP Brownell AL Olanow CW Systemic exposure to proteasome inhibitors causes a progressive model of Parkinson s disease Ann Neurol 2004561497162 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 1821 Kisselev AF Goldberg AL Proteasome inhibitors from research tools to drug candidates Chem Biol 200187397758 Fenteany G Schreiber SL Lactacystin proteasome function and cell fate J Biol Chem 1998273854578548 Sin N Kim KB Elofsson M et al Total synthesis of the potent proteasome inhibitor epoxomicin a useful tool for understanding proteasome biology Bioorg Med Chem Lett 19999228372288 Koguchi Y Kohno J Nishio M et al TMCy95A B C and D novel proteasome inhibitors produced by Apiospora montagnei Sacc TC 1093 taxonomy production isolation and biological activities J Antibiot Tokyo 2000531057109 Nam S Smith DM Dou QP Ester bondrcontaining tea polypher nols potently inhibit proteasome activity in vitro and in vivo J Biol Chem 200127613322713330 Kazi A Urbizu DA Kuhn DJ et al A natuml musaceas plant extract inhibits proteasome activity and induces apoptosis selecr tively in human tumor and transformed but not normal and nonrtransformed cells Int J Mol Med 2003128797887 Jana NR Dikshit P Goswami A Nukina N Inhibition of protear somal function by curcumin induces apoptosis through mitochonr drial pathway J Biol Chem 200427911680711685 Zhou Y Shie FS Piccardo P Montine TJ Zhang J Proteasomal inhibition induced by manganese ethylenerbisrdithiocarbamate relevance to Parkinson s disease Neuroscience 20041282817 291 Ensign JC Normand P Burden JP Yallop CA Physiology of some actinomycete genera Res Microbiol 19931446577660 Cross T Aquatic actinomycetes a critical survey of the occur rence growth and role of actinomycetes in aquatic habitats J Appl Bacteriol 1981503977423 Spillantini MG Schmidt ML Lee VM Trojanowski JQ Jakes R Goedert M Alpharsynuclein in Lewy bodies Nature 1997388 8397840 Spillantini MG Crowther RA Jakes R Hasegawa M Goedert M Alpharsynuclein in lamentous inclusions of Lewy bodies from Parkinson s disease and dementia with lewy bodies Proc Natl Acad Sci U S A 199895646976473 van Duinen SG Lammers GJ MaatrSchieman ML Roos RA Numerous and widespread alpharsynucleinrnegative Lewy bodies in an asymptomatic patient Acta Neuropathol Berl 199997 5337539 Olanow CW Perl DP DeMar1ino GN McNaught KS Lewa body formation is an aggresomerrelated process a hypothesis Lancet Neurol 20043496 7503 Rajan RS llling ME Bence NF Kopito RR Speci city in intmcellular protein aggregation and inclusion body formation Proc Natl Acad Sci U S A 20019813060713065 Johnston JA llling ME Kopito RR Cytoplasmic dyneindynactin mediates the assembly of aggresomes Cell Motil Cytoskeleton 20025326738 Johnston JA Ward CL Kopito RR Aggresomes a cellular response to misfolded proteins J Cell Biol 1998143188371898 Kawaguchi Y Kovacs JJ McLaurin A Vance JM lto A Yao TP The deacetylase HDAC6 regulates aggresome formation and cell viability in response to misfolded protein stress Cell 2003115 7277738 Armsate M Mitm S Schweitzer ES Segal MR Finkbeiner S Inclusion body formation reduces levels of mutant huntingtin and the risk of neuronal death Nature 20044318057810 Taylor JP Tanaka F Robitschek J et al Aggreso mes protect cells by enhancing the degmdation of toxic polyglutaminercontaining protein Hum Mol Genet 2003127497757 Cummings CJ Reinstein E Sun Y et al Mutation of the E6rAP ubiquitin ligase reduces nuclear inclusion frequency while accelr emting polyglutaminerinduced pathology in SCA1 mice Neuron 1999248797892 Keller JN Dimayuga E Chen Q Thorpe J Gee J Ding Q Autophagy proteasomes lipofuscin and oxidative stress in the aging bmin Int J Biochem Cell Biol 200436237672391 Mavemem DLS UYdEYS Val 21 N0 1 2005 1822 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 Keller JN Hanni KB Markesbery WR Possible involvement of proteasome inhibition in aging implications for oxidative stress Mech Ageing Dev 200011361770 Zeng BY Medhurst AD Jackson M Rose S Jenner P Protear somal activity in bmin differs between species and bmin regions and changes with age Mech Ageing Dev 20051267607766 Floor E Wetzel MG Increased protein oxidation in human subr stantia nigm pars compacta in comparison with basal ganglia and prefrontal cortex measured with an improved dinitrophenylhydrr azine assay J Neurochem 1998702687275 EHKhodor BF Kholodilov NG Yarygina O Burke RE The expression of mRNAs for the proteasome complex is developr mentally regulated in the mt mesencephalon Bmin Res Dev Bmin Res 200112947756 Conway KA Rochet JC Bieganski RM Lansbury PT Jr Kinetic stabilization of the alpharsynuclein proto bril by a dopamine alpharsynuclein adduct Science 2001294134671349 Cappai R Leck SL Tew DJ et al Dopamine promotes alphar synuclein aggregation into SDSrresistant soluble oligomers via a distinct folding pathway FASEB J 200519 137771379 Gibb WR Lees AJ The relevance of the Lewy body to the pathogenesis of idiopathic Parkinson s disease J Neurol Neuror surg Psychiatry 1988517457752 Aguilar RC Wendland B Ubiquitin not just for proteasomes anymore Curr Opin Cell Biol 2003151847190 Atlante A Bobba A Calissano P Passarella S Marra E The apoptosisnecrosis tmnsition in cerebellar granule cells depends on the mutual relationship of the antioxidant and the proteolytic systems which regulate ROS production and cytochrome c release en route to death J Neurochem 2003849607971 Jha N Kumar MJ Boonplueang R Andersen JK Glutathione decreases in dopaminergic PC12 cells interfere with the ubiquitin protein degmdation pathway relevance for Parkinson s disease J Neurochem 2002805557561 Hoglinger GU Carmrd G Michel PP et al Dysfunction of mitochondrial complex I and the proteasome interactions be tween two biochemical de cits in a cellular model of Parkinson s disease J Neurochem 200386129771307 Lee HJ Shin SY Choi C Lee YH Lee SJ Formation and removal of alpharsynuclein aggregates in cells exposed to mitor chondrial inhibitors J Biol Chem 20012727 Li Z Jansen M Pierre SR FigueiredorPereira ME Neurodegenr emtion linking ubiquitinproteasome pathway impairment with in ammation Int J Biochem Cell Biol 2003355477552 Jesenberger V Jentsch S Deadly encounter ubiquitin meets apoptosis Nat Rev Mol Cell Biol 200231127121 Kikuchi S Shinpo K Tsuji S et al Effect of proteasome inhibitor on cultured mesencephalic dopaminergic neurons Bmin Res 20039642287236 Rockwell P Yuan H Magnusson R FigueiredorPereim ME Proteasome inhibition in neuronal cells induces a proin ammar tory response manifested by upregulation of cyclooxygenaser2 its accumulation as ubiquitin conjugates and production of the prostaglandin PGE2 Arch Biochem Biophys 20003743257 333 Sitte N Merker K von Zglinicki T Grune T Protein oxidation and degradation during prolifemtive senescence of human MRCr5 broblasts Free Radic Biol Med 2000287017708 Okada K Wangpoengtrakul C Osawa T Toyokuni S Tanaka K Uchida K 4rhydroxyr2rnonenalrmediated impairment of intmcelr lular proteolysis during oxidative stress identi cation of protear somes as target molecules J Biol Chem 199927423787723793 Reinheckel T Sitte N Ullrich O Kuckelkom U Davies KJ Grune T Compamtive resistance of the 20S and 26S proteasome to oxidative stress Biochem J 1998335Pt 36377642 Mytilineou C McNaught KSP Shashidaran P JnoBaptiste R Parnandi A Olanow CW Inhibition of proteasome activity senr sitizes dopamine neurons to heat shock treatment and oxidative stress J Neuml Tmnsm 2004111123771251 Mavemem DLS UYdEYS Val 21 N0 1 2005 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 CW OLANOW AND KSP MCNAUGHT Bulteau AL Lundberg KC Humphries KM et al Oxidative modi cation and inactivation of the proteasome during coronary occlusionreperfusion J Biol Chem 199927630057730063 Ding Q Keller JN Proteasome inhibition in oxidative stress neurotoxicity implications for heat shock proteins J Neurochem 200177101071017 ShamotorNagai M Maruyama W Kato Y et al An inhibitor of mitochondrial complex I rotenone inactivates proteasome by oxidative modi cation and induces aggregation of oxidized pro teins in SHrSY5Y cells J Neurosci Res 2003745897597 Sullivan PG Dragicevic NB Deng J H et al Proteasome inhibir tion alters neural mitochondrial homeostasis and mitochondria turnover J Biol Chem 200427920699720707 Shashidhamn P Paris N Sandu D Karthikeyan L McNaught KSP Walker RH Olanow CW Overexpression of TorsinA in PC12 cells protects against toxicity J Neurochem 200488 10197 1025 Zourlidou A Payne Smith MD Latchman DS HSP27 but not HSP70 has a potent protective effect against alpharsynucleini induced cell death in mammalian neuronal cells J Neurochem 200488143971448 Klucken J Shin Y Masliah E Hyman BT McLean PJ Hsp70 reduces alpharsynuclein aggregation and toxicity J Biol Chem 200427925497725502 Lindersson E Beedholm R Hojrup P et al Proteasomal inhibir tion by alpharsynuclein laments and oligomers J Biol Chem 200427912924712934 Auluck PK Chan E Trojanowski JQ Lee V Bonini NM Chapr erone suppression of alpharsynuclein toxicity in a drosophila model of Parkinson s disease Science 20022958657868 Roe SM Prodromou C O Brien R Ladbury JE Piper PW Pearl LH Structural basis for inhibition of the Hsp90 molecular chapr erone by the antitumor antibiotics mdicicol and geldanamycin J Med Chem 1999422607266 Hargitai J Lewis H Boros I et al Bimoclomol a heat shock protein corinducer acts by the prolonged activation of heat shock factorrl Biochem Biophys Res Commun 20033076897695 Kieran D Kalmar B Dick JR RiddochrContreras J Burnstock G Greensmith L Treatment with arimoclomol a coinducer of heat shock proteins delays disease progression in ALS mice Nat Med 2004104027405 Zou J Guo Y Guettouche T Smith DF Voellmy R Repression of heat shock transcription factor HSF1 activation by HSP90 HSP90 complex that forms a stressrsensitive complex with HSF1 Cell 1998944717480 Sittler A Lurz R Lueder G et al Geldanamycin activates a heat shock response and inhibits huntingtin aggregation in a cell culture model of Huntington s disease Hum Mol Genet 200110 130771315 Whitesell L Mimnaugh EG De Costa B Myers CE Neckers LM Inhibition of heat shock protein HSP907pp60vrsrc heteror protein complex formation by benzoquinone ansamycins essenr tial role for stress proteins in oncogenic transformation Proc Natl Acad Sci U S A 199491832478328 Prodromou C Roe SM O Brien R Ladbury JE Piper PW Pearl LH Identi cation and structuml characterization of the ATP ADPrbinding site in the Hsp90 molecular chaperone Cell 1997 9065775 McLean PJ Klucken J Shin Y Hyman BT Geldanamycin inr duces Hsp70 and prevents alpharsynuclein aggregation and toxr icity in vitro Biochem Biophys Res Commun 20043216657 669 Auluck PK Bonini NM Pharmacological prevention of Parlng son disease in Drosophila Nat Med 20028118571186 Petrucelli L Dickson D Kehoe K et al CHlP and Hsp70 regulate tau ubiquitination degradation and aggregation Hum Mol Genet 2004137037714 Marinovic AC Zheng B Mitch WE Price SR Ubiquitin UbC expression in muscle cells is increased by glucocorticoids through 212 213 214 215 216 217 218 219 220 221 UBRQUYTHVJUQOIYZASCMIE SYSIEBI a mechanism involving Sp1 and MEKl J Biol Chem 2002277 16673716681 Wing SS Goldberg AL Glucocorticoids activate the A39I39Prubiqr uitini dependent proteolytic system in skeletal muscle during fasting Am J Physiol 19932646687676 Dardevet D Sornet C Taillandier D Savary I Attaix D Grizard J Sensitivity and protein turnover response to glucocom39coids are different in skeletal muscle from adult and old mts Lack of regulation of the ubiquitinrproteasome proteolytic pathway in aging J Clin Invest 199596211372119 Chrysis D Underwood LE Regulation of components of the ubiquitin system by insulinrljke growth factor I and growth horr mone in skeletal muscle of mts made catabolic with dexamethar sone Endocrinology 1999140563575641 Bodine SC Latres E Baumhueter S et al Identi cation of ubiquitin ligases required for skeletal muscle atrophy Science 2001294170471708 Du J Mitch WE Wang X Price SR Glucocom39coids induce proteasome C3 subunit expression in L6 muscle cells by opposing the suppression of its transcription by N39Frkappa B J Biol Chem 200027519661719666 Combaret L Taillandier D Dardevet D et al Glucocorticoids regulate mRNA levels for subunits of the 19 S regulatory comr plex of the 26 S proteasome in fastrtwitch skeletal muscles Biochem J 20043782397246 Tanaka M Machida Y Niu S et al Trehalose alleviates polyr glutaminermediated pathology in a mouse model of Huntington disease Nat Med 2004101487154 Singer MA Lindquist S Multiple effects of trehalose on protein folding in vitro and in vivo Mol Cell 199816397648 Willingham S Outeiro TF DeVit MJ Lindquist SL Muchowski PJ Yeast genes that enhance the toxicity of a mutant huntingtin fmgment or alpharsynuclein Science 2003302176971772 Masliah E Rockenstein E Adame A et al Effects of alpha synuclein immunization in a mouse model of Parkinson s disease Neuron 2005468577868 222 223 224 225 226 227 228 229 230 231 232 1823 Nair V McNaught K Sealfon S Olanow CW The p53 inhibitor Pi thrinralpha protects dopamine cells in vitro from proteasome inhibitionrinduced cell death New Orleans LA Ninth Internar tional Congress of Parkinson s Disease and Movement Disorders 2005 Thrower J S Hoffman L Rechsteiner M Pickart CM Recognition of the polyubiquitin proteolytic signal EMBO J 200019947102 Pickart CM Ubiquitin enters the new millennium Mol Cell 200184997504 Goldberg AL Cascio P Saric T Rock KL The importance of the proteasome and subsequent proteolytic steps in the genemtion of antigenic peptides Mol Immunol 2002391477164 Lam YA Lawson TG Velayutham M Zweier JL Pickart CM A proteasomal ATPase subunit recognizes the polyubiquitin degmr dation signal Nature 20024167637767 Glickman MH Rubin DM Coux O et al A subcomplex of the proteasome regulatory particle required for ubiquitinrconjugate degradation and related to the COP9rsignalosome and eIF3 Cell 1998946157623 Wilkinson KD Ubiquitinrdependent signaling the role of ubqu uitination in the response of cells to their environment J Nutr 1999129193371936 Aguilar RC Wendland B Ubiquitin not just for proteasomes anymore Curr Opin Cell Biol 2003151847190 Mumtani M Tansey W39P How the ubiquitinrproteasome system controls transcription Nat Rev Mol Cell Biol 200341927201 Grunblatt E Mandel S Jacoerirsch J et al Gene expression pro ling of parkinsonian substantia nigm pars compacta alter ations in ubiquitinrproteasome heat shock protein iron and oxir dative stress regulated proteins cell adhesioncellular matrix and vesicle tmf cking genes J Neural Tmnsm 2004111154371573 Adams I The proteasome a suitable antineoplastic target Nat Rev Cancer 20044349 7360 Mavemem Dmarders Val 21 N0 1 2005
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'