CSPα, a molecular co-chaperone essential for short and long-term synaptic maintenance

PERSPECTIVE published: 10 Feb ua y 2017 doi: 10.3389/ nins.2017.00039 F on ie s in Neu oscience | www. on ie sin.o g 1Feb ua y 2017 | Volume 11 | A icle 39 Edi ed by: Cin ia Rood eld , Andalusian Molecula Biology and Regene a i e Medicine Cen e (CABIMER) - CSIC, Spain Re iewed by: Janice E a A lee B aun, Uni e si y o Calga y, Canada Kon ad E ns Zinsmaie , Uni e si y o A izona, USA *Co espondence: Lucia Taba es [email p o ec ed] †P esen Add ess: Elena Lopez-O ega, Solomon H. Snyde Depa men o Neu oscience, Johns Hopkins Uni e si y School o Medicine, Bal imo e, MD, USA Special y sec ion: This a icle was submi ed o Neu odegene a ion, a sec ion o he jou nal F on ie s in Neu oscience Recei ed: 18 Decembe 2016 Accep ed: 19 Janua y 2017 Published: 10 Feb ua y 2017 Ci a ion: Lopez-O ega E, Ruiz R and Taba es L (2017) CSPα, a Molecula Co-chape one Essen ial o Sho and Long-Te m Synap ic Main enance. F on . Neu osci. 11:39. doi: 10.3389/ nins.2017.00039 CSPα, a Molecula Co-chape one Essen ial o Sho and Long-Te m Synap ic Main enance Elena Lopez-O ega1 †, Rocío Ruiz2and Lucia Taba es1* 1Depa men o Medical Physiology and Biophysics, School o Medicine, Uni e si y o Se ille, Se ille, Spain, 2Depa men o Biochemis y and Molecula Biology, School o Pha macy, Uni e si y o Se ille, Se ille, Spain Cys eine s ing p o ein α(CSPα) is a esicle p o ein loca ed in he p esynap ic e minal o mos synapses. CSPαis an essen ial molecula co-chape one ha acili a es he co ec olding o p o eins and he assembly o he exocy ic machine y. The absence o his p o ein leads o al e ed neu o ansmi e elease and neu odegene a ion in mul iple model sys ems, om lies o mice. In humans, CSPαmu a ions a e associa ed wi h he de elopmen o neu onal ce oid lipo uscinosis (NCL), a neu odegene a i e disease cha ac e ized by in acellula accumula ion o lysosomal ma e ial. He e, we e iew he physiological ole o CSPαand he pa hology esul ing om he homozygous dele ion o he gene o i s mu a ions. In addi ion, we in es iga e whe he long- e m mode a e educ ion o he p o ein p oduces mo o dys unc ion. We ound ha 1-yea -old CSPα he e ozygous mice display a educed abili y o sus ain mo o uni ec ui men du ing epe i i e s imula ion, which indica es ha physiological le els o CSPαa e equi ed o no mal neu omuscula esponses in mice and, likely, in humans. Keywo ds: cys eine s ing p o ein, co-chape one, mo o neu ons, synap ic ansmission, neu omuscula junc ion, CSPα PROTEIN DESCRIPTION Cys eine s ing p o ein α(CSPα) (Dnajc5) is a highly conse ed p o ein (Figu e 1A) ypically associa ed wi h he memb ane o synap ic esicles and sec e o y g anules (Zinsmaie e al., 1990). I con ains a DNA-J domain cha ac e is ic o Hsp40 co-chape ones. This domain in e ac s wi h he 70 kDa hea shock cogna e p o ein (Hsc70) (B aun e al., 1996) and egula es he e olding o clien p o eins (Hennessy e al., 2005). A linke egion connec s he DNA-J domain wi h he cys eine s ing domain. The cys eine s ing domain is app oxima ely 25-amino-acids long and con ains 13–15 cys eines, mos o hem palmi oyla ed. Palmi oyla ion is essen ial o a ge CSPα o synap ic esicles and o p omo e neu o ansmi e elease (A nold e al., 2004). CSPαalso con ains a C- e minal domain, he unc ion o which is no well-unde s ood. Lopez-O ega e al. CSPαand Synap ic Main enance FIGURE 1 | The lack/dec ease o CSPαinduces s uc u al and unc ional changes ha comp omise synap ic main enance. (A) Func ional domains o he CSPαp o ein. (B) Synap ic elease de ec s (le ) and ac ion o mo o ne e e minals wi h mul ilamella bodies and acuoles in elec on mic oscopy p o iles ( igh ) s. pos na al age in CSPαKO mice. G aphs summa ize nume ical alues in Ruiz e al. (2008, 2014) (le ) and in Fe nández-Chacon e al. (2004) ( igh ). (C) Two pa allel chape one pa hways p omo e e icien SNARE complex o ma ion and no mal neu o ansmission by egula ing SNAP25, h ough CSPα(pa hway I), and synap ob e in (VAMP2), h ough α-synuclein (pa hway II). The de ici in CSPαp oduces synap ic dys unc ion (Ruiz e al., 2008, 2014; Rozas e al., 2012), whose se e i y, age o onse , and ime cou se depend on he amoun o unc ional CSPαa ailable. α-synuclein o e exp ession, howe e , can a oid he synap ic pa hology p oduced by a de ec in pa hway I by inc easing he o ma ion o SNARE complexes (Sha ma e al., 2011, 2012a). (D) Hypo he ical model o how gene ic abla ion, gene mu a ions, o inc eased CSPαdeg ada ion induce a posi i e loop o neu o ansmi e (NT) elease de ici , accumula ion o mis olded synap ic p o eins, and neu odegene a ion. In humans, i emains unknown o wha ex en CSPαhaploinsu iciency, seques a ion o CSPαin agg ega es, and abe an palmi oyla ion o CSPαand o he p o eins con ibu e o ANCL. CSPαDEFICIENCY AND SYNAPTIC DYSFUNCTION CSPαis no essen ial o synap ogenesis, bu i is equi ed o no mal neu o ansmission and neu onal main enance in lies (Zinsmaie e al., 1994), wo ms (Kashyap e al., 2014), mice (Fe nández-Chacon e al., 2004), and humans (Nosko á e al., 2011). Dele ion o he CSPαgene in D osophila p oduces an emb yonic semile hal pheno ype, and lies ha su i e o adul hood p esen neu o ansmi e elease al e a ions and empe a u e-sensi i e pa alysis. Synap ic de ec s in CSPα-null (CSPαKO) mice s a ea ly a e bi h, and dea h occu s be o e 3 mon hs o age. Bo h mo o and senso y neu ons a e a ec ed by he lack o CSPα(Fe nández-Chacon e al., 2004; Schmi z e al., 2006). In mo o ne e e minals, he i s sign o unc ional al e a ion appea s a 2 weeks o age and consis s o epea ed bu s s o high- equency spon aneous elease (Ruiz e al., 2008) (Figu e 1B). Only 4 days la e , he e minal displays mul iple unc ional al e a ions such as educed quan um con en , low elease p obabili y, inc eased sho - e m acili a ion du ing epe i i e s imula ion, and educed calcium sensi i i y o he sec e o y machine y (Ruiz e al., 2008, 2014). In addi ion, he size o he eadily eleasable pool o synap ic esicles is dec eased (Rozas e al., 2012; Ruiz e al., 2014). CSPαAS A MOLECULAR CO-CHAPERONE CSPαin e ac s wi h se e al p o eins ha pa icipa e in exo- /endocy osis, including syn axin, synap o agmin, N- and P/Q- ype calcium channels, and dynamin 1 ( o a e iew see Bu goyne and Mo gan, 2015). The unc ional signi icance o many o hese in e ac ions is no well es ablished. Howe e , F on ie s in Neu oscience | www. on ie sin.o g 2Feb ua y 2017 | Volume 11 | A icle 39 Lopez-O ega e al. CSPαand Synap ic Main enance one o he bes -known unc ions o CSPαis i s ole as a co- chape one (Chambe lain and Bu goyne, 2000; Zinsmaie , 2010; Donnelie and B aun, 2014). CSPαin e ac s wi h Hsc70 and oge he e old clien p o eins such as SNAP25 (Sha ma e al., 2011, 2012a; Zhang e al., 2012). SNAP25 is equi ed o he assembly o he SNARE (soluble N-e hylmaleimide-sensi i e ac o a achmen ecep o ) complex, o med by synap ob e in, syn axin, and SNAP25, which in u n is essen ial o exocy osis and neu o ansmi e elease (Figu e 1C). In CSPαKO mice, bo h SNAP25 and SNARE complex le els a e educed by hal (Chand a e al., 2005). CSPαAND NEURODEGENERATION In CSPαKO mo o ne e e minals, hallma ks o degene a ion (i.e., acuoles and mul ilamella bodies) appea e y ea ly (Fe nández-Chacon e al., 2004), e en be o e he e oked elease de ec s become appa en (Figu e 1B, le g aphs). The degene a ion is mo e p ominen in cells wi h high elec ical ac i i y, such as mo o neu ons, pho o ecep o s, and GABAe gic neu ons (Fe nández-Chacon e al., 2004; Schmi z e al., 2006; Ga cía-Junco-Clemen e e al., 2010), sugges ing ha high synap ic ac i i y po en ia es degene a ion, which in u n may inc ease he elease de ici (Figu e 1D). A he molecula le el, i has been p oposed ha SNAP25 educ ion plays a majo ole in neu odegene a ion. This hypo hesis is ein o ced by he ac ha SNAP25 o e exp ession in CSPαKO mice p e en s neu odegene a ion (Sha ma e al., 2012a). Ne e heless, SNAP25 he e ozygous mice, wi h 50% o he p o ein, a e pheno ypically no mal and do no de elop neu odegene a ion (Washbou ne e al., 2002), indica ing ha solely educing unc ional SNAP25 is no su icien o p oduce he pa hology. On he o he hand, mis olded SNAP25 could ha e a dominan nega i e e ec o e he no mally olded p o ein copies, o ubiqui ina ed SNAP25 molecules could accumula e in he p o easome, in e e ing wi h i s no mal unc ion. Su p isingly, howe e , he ac ha pha macological inhibi ion o he p o easome inc eases SNAP25 and SNARE complex le els, and, hence, imp o es synap ic unc ion in CSPα- deple ed cells (Sha ma e al., 2012b), has challenged his las hypo hesis. Rema kably, neu odegene a ion in CSPαKO mice is p e en ed when SNARE complexes a e inc eased by he o e exp ession o α-synuclein (Sha ma e al., 2011, 2012a), in spi e o he ac ha SNAP25 le els a e no es o ed and, p esumably, he amoun o mis olded SNAP25 is no educed. O e exp ession o he mu a ed o m o α-synuclein A53T in CSPαKO mice es o es li e span and mo o unc ion as well as wild- ype (WT) α-synuclein (Chand a e al., 2005). On he o he hand, o e exp ession o A30P α-synuclein does no escue su i al, bu can ansi o ily amelio a e he elease de ici and he calcium sensi i i y de ec in mo o ne e e minals o CSPαKO mice (Ruiz e al., 2014). The pa ial e ec o A30P α-synuclein is likely due o i s limi ed abili y o inc ease he o ma ion o SNARE complexes. These indings sugges ha wo pa allel pa hways egula e SNARE complex o ma ion (Figu e 1C), and aise he ques ion o how he neu odegene a ion p og am is ac i a ed in he absence o CSPα. The molecula basis o he neu odegene a ion is unknown, bu a possibili y is ha neu odegene a ion is linked o he educed abili y o he synapse o o m SNARE complexes and, he e o e, o he misma ch be ween unc ional demands and e icien elease. CSPαDEFICIENCY IN HUMANS Neu onal Ce oid Lipo uscinosis (NCLs) cons i u e a he e ogeneous g oup o inhe i ed neu odegene a i e diso de s cha ac e ized by lysosomal accumula ion o au o luo escen ce oid-lipo uscin agg ega es in neu ons and o he cell ypes. The clinical symp oms o NCLs include seizu es, mo emen diso de s, cogni i e de e io a ion, and p og essi e demen ia, ollowed by a p ema u e dea h. The majo i y o NCL cases a ec child en, and only 10% o o al cases a e in adul s. In ecen yea s, wo mu a ions in he gene ha encodes CSPα,DNAJC5, ha e been linked o he de elopmen o adul - onse NCL (ANCL) (MIM #162350). These mu a ions consis o a poin mu a ion (p.L115R) and an in- ame codon dele ion (p.L1161), bo h a ec ing dileucine esidues loca ed in he cys eine s ing domain o CSPα(Nosko á e al., 2011). This domain is highly palmi oyla ed and media es he memb ane binding and in acellula a ge ing o CSPα. The e o e, mu a ions in his egion may explain he di use in acellula localiza ion o CSPαobse ed in he neu ons o ANCL pa ien s. Mo eo e , he mu a ed o ms o CSPαp esen an inc eased endency o sel -associa e, o ming de e gen - esis an agg ega es. These agg ega es in e e e wi h WT CSPαp o eins, educing he co- chape one unc ion o CSPαin neu ons (Nosko á e al., 2011; G ea es e al., 2012; Zhang and Chand a, 2014) (Figu e 1D), which is likely one o he main easons why he NCL-linked DNAJC5 gene mu a ions display an au osomal dominan (AD) inhe i ance pa e n. Addi ionally, a dominan e ec o mu a ed CSPαon he palmi oyla ion pa e n o lysosomal and synap ic p o eins has been sugges ed as a mechanism o he de elopmen o DNAJC5-linked ANCL (Hende son e al., 2016). LONG-TERM MODERATE CSPα DEFICIENCY ALTERS MOTOR RESPONSES In e es ingly, only homozygous CSPαKO mice p esen synap ic de ec s, while he e ozygous mu an mice appea pheno ypically no mal up o 3 mon hs o age (Fe nández-Chacon e al., 2004). Gi en he la e onse o AD-ANCL (a ound 30 yea s o age), we s udied he mo o unc ion o 1-yea -old CSPαhe e ozygous mice. Mo o pe o mance was i s assessed wi h Balance and G ip S eng h es s (Figu e 2A). The balance was measu ed by placing he mouse on a ho izon al pole suspended in he ai . The pole was o a ed manually a a cons an speed o one o a ion cycle pe second (Figu e 2A le ). The g ip s eng h es consis ed o suspending he mouse om he pole by i s o elimbs (Figu e 2A igh ). In bo h ials, he amoun o ime he mouse emained suspended om he pole (maximum 10 s) F on ie s in Neu oscience | www. on ie sin.o g 3Feb ua y 2017 | Volume 11 | A icle 39 Lopez-O ega e al. CSPαand Synap ic Main enance FIGURE 2 | The neu omuscula unc ion o 1-yea -old CSPαhe e ozygous mice is al e ed. (A,B) Balance and g ip s eng h es s show no signi ican di e ences be ween CSPαhe e ozygous (n=27) and WT mice (n=9). The plo illus a es he a e age alues ob ained in h ee eplica es/session o each geno ype (Mann-Whi ney U es ). (C) Rep esen a i e eco dings o CMAPs in a CSPα+/+mouse a e sup amaximal s imula ion o he scia ic ne e (1s and 15 h esponses a di e en s imula ion equencies). (D) Dep ession o he neu omuscula esponses (CMAP no malized ampli ude) is signi ican ly la ge in CSPα+/−(n=25) han in WT mice (n=7) du ing s imula ion ains a 20, 50, and 100 Hz. (E) Maximal dep ession o he neu omuscula esponse (no malized) a di e en s imula ion equencies in CSPα+/−(n=24–25) and WT mice (n=7) (Mann-Whi ney U es ). Ei he sex expe imen al mice (C57BL/6 backg ound) we e used. The mouse line was kindly dona ed by D . Südho . All expe imen s we e pe o med acco ding o he guidelines o he Eu opean Council Di ec i e o he Ca e o Labo a o y Animals. The p o ocol was app o ed by he E hics Commi ee o Animal Expe imen a ion o he Jun a de Andalucía ( e . 23-11-2015-364). was measu ed. Two sessions sepa a ed by 1 week we e pe o med o each es (Figu e 2B). Da a ob ained om he neu ological es s showed no signi ican di e ences be ween WT and CSPα he e ozygous mice, in ei he balance o g ip s eng h. Nex , he neu omuscula esponse o CSPαhe e ozygous mice was s udied using elec omyog aphy (EMG). E oked Compound Mo o Ac ion Po en ials (CMAPs) we e eco ded om he igh la e al gas ocnemius o anes he ized mice. S imula ion needle elec odes we e placed a he scia ic no ch and he head o he ibula (Ruiz e al., 2005). The ac i e eco ding elec ode was placed in he medial egion o he eco ded muscle. The e e ence elec ode was inse ed a he base o he i h oo phalanx. The g ound elec ode was loca ed a he base o he ail. B ie sup amaximal s imula ion pulses we e applied a 10 Hz (2 s), 20 Hz (1 s), 50 Hz (1 s), and 100 Hz (0.5 s). Rep esen a i e eco dings o CMAPs egis e ed du ing he ains a e shown in Figu e 2C. The s udy e ealed enhanced dep ession wi h s imula ions be ween 20 and 100 Hz in CSPαhe e ozygous mice compa ed o WT li e ma es (Figu e 2D). The mean maximal dep ession was 5% (20 Hz), 12% (50 Hz), and 25% (100 Hz) lowe in CSPαhe e ozygous han in WT mice, while no signi ican di e ence was obse ed a 10 Hz (Figu e 2E). Rema kably, he dep ession in he EMG eco dings was simila o ha seen in 3-week-old CSPαKO mice (Fe nández-Chacon e al., 2004), a pheno ype no obse ed in CSPα+/−mice up o 3 mon h o age. These esul s indica e ha , o e ime, a mode a e educ ion o CSPαexp ession al e s he abili y o he neu omuscula sys em o espond no mally o s imula ion. FUTURE DIRECTIONS The mul iple unc ions o CSPα ange om ac ing as a chape one, pa icipa ing in he assembly and dissocia ion o mul i-p o ein complexes, and egula ing Ca2+sensi i i y o neu o ansmi e elease. The se e e unc ional and s uc u al changes ha ake place in he absence o CSPαin in e eb a e and e eb a e o ganism models con i m he impo ance o his p o ein in synapse main enance and neu o ansmi e elease. In humans, CSPαmu a ions a e associa ed wi h he de elopmen o AD-ANCL, synap ic degene a ion, and neu onal F on ie s in Neu oscience | www. on ie sin.o g 4Feb ua y 2017 | Volume 11 | A icle 39 Lopez-O ega e al. CSPαand Synap ic Main enance loss. The e o e, al hough bo h he educ ion o CSPαexp ession and he p esence o CSPαmu a ions a e pa hogenic o he synapse, he se e i y and ime cou se o he neu ological impai men s may a y om se e e, including p ema u e dea h, o mild, depending on he amoun o unc ional CSPαin each case. The mode a e dec ease in CSPαand SNARE complexes in neu ons o e ime could esul in mo o unc ion impai men and, in addi ion, in luence he e olu ion o common age- ela ed neu odegene a i e diso de s, such as Alzheime ’s and Pa kinson’s diseases. Fu u e challenges a e o iden i y pa ien s wi h educed le els o molecula chape ones (such as CSPα), deciphe he mechanisms esponsible o he molecula de ici , unde s and how he homeos asis o he synapse is al e ed, and de e mine o wha ex en he educ ion o he chape ones in luences he se e i y o associa ed neu odegene a i e diseases. AUTHOR CONTRIBUTIONS Expe imen s shown in Figu e 2 we e pe o med by EL. EL, RR, and LT concei ed and w o e he manusc ip . FUNDING This wo k was suppo ed by g an s om he Spanish Minis y o Science and Inno a ion (BFU2013–43763-P) and he Ta iana Pe ez de Guzman Founda ion o LT. RR was suppo ed by a con ac om he V Plan P opio o he Uni e si y o Se ille. ACKNOWLEDGMENTS We a e g a e ul o Ra ael Fe nández-Chacón o discussions and commen s on he manusc ip . REFERENCES A nold, C., Reisch, N., Leibold, C., Becke , S., P u e , K., Sau e , K., e al. (2004). S uc u e- unc ion analysis o he cys eine s ing p o ein in D osophila: cys eine s ing, linke and C e minus. J. Exp. 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The use, dis ibu ion o ep oduc ion in o he o ums is pe mi ed, p o ided he o iginal au ho (s) o licenso a e c edi ed and ha he o iginal publica ion in his jou nal is ci ed, in acco dance wi h accep ed academic p ac ice. No use, dis ibu ion o ep oduc ion is pe mi ed which does no comply wi h hese e ms. F on ie s in Neu oscience | www. on ie sin.o g 6Feb ua y 2017 | Volume 11 | A icle 39