2023年節(jié)選自nature的一片研究生英語面試翻譯的文章

SkiｎregｅneｒationandrepaｉｒｃéｄricBlａｎpaｉｎDiｆｆerenttyｐesofｓtｅmcｅllｍaintaiｎtheskin’sepidermｉsaｎｄcontribuｔetoitｓheａlinｇafterdamａge.Ｔｈeiｄentitｙofaｓtem-ｃｅlltyｐethatgivesrｉsｅtodiffｅrｅnｔｅpiｄermａｌ-ｃelｌlineagesｈasjｕstｂeenｒｅveａled.Sｋiｎactsasａnesｓｅntialｂaｒriｅr,proｔｅctingoｒgａnismsｆroｍｔｈｅirｅnｖｉroｎment.Ｉtiｓcomposedoｆｔｗoｐａrts：ｔheepiｄerｍis,thｅcellsｏｆwhichｆｏrmｔhebarｒiｅｒ;ａｎdthedeｒmis,wｈichproviｄｅssｕｐｐortandnｕtｒｉtionｔotｈeｅpidermiｓ.Ｔhｅepidermisａlsoproｄucｅsappendａges,inｃludingsweatglａndｓ,ａnｄhairfoｌliｃlesaｎdtheirassoｃiａt(yī)ｅｄsｅbacｅousgｌands.Thedｉffｅrentepiｄermalcompartmｅnｔsuｎdeｒgoｃonstaｎtcellｕlａrturｎoveｒtｏｒｅｐlaceｔｈedeadｏrｄamagｅdceｌls.Thiｓhomeostaticpｒoceｓsisthouｇhttoinｖｏｌｖeｓeveraｌtypｅsｏｆstｅｍｃｅlｌ，eaｃhlｏcateｄｉnasｐecｉficepidermalregionａnｄcｏnｔributiｎgｔoｔhemaｉnｔenanceofadiscｒetｅcompａrtｍentoｆtｈｅｓkiｎ1(Fig．1a).IｎapapeｒpublｉｓhedｉnＳcｉｅnｃｅ,Snippertｅtal.idｅnｔifythｅ“Lgr６”proteinastheｍarkeｒofprｏgenitorsｔhaｔｃandiffｅrenｔiateintodifferｅnｔcｅlｌlineagesＴhｅfirｓtｅvｉdｅncｅthaｔsｋinstemcｅllｓｃａnｄiffｅrentiatｅintoｉntｅrfolｌicｕlarｅpidermiｓ，ｓｅｂaｃｅousglaｎdandｈａiｒｆolliclelinｅageｓcamefrｏmｔrａnsplantaｔiｏnｏfbｕｌｇeｓtemcｅlls(3,4）—ａcellpopulatioｎlocaｔｅdattｈｅbaseofhairfollｉｃｌes．Furtherexperimentsrevｅａledthaｔ,duｒingbｏtheｍbryｏnicdｅveｌｏpmentaｎdnormａlａdultｓkinhomｅoｓtasiｓ,ｂｕlgｅstｅmceｌlsandtheirproｇenyｃontｒibuteｔohair－folｌｉcｌｅreｇeneratioｎbｕｔnottotｈemaiｎｔｅnａnceｏftheｉnterfolliculareｐiｄermis(4–6).Inｃonditｉｏnssｕchａswoｕｎding,howevｅｒ,bulgeｓteｍcellsraｐidlyｍiｇｒatetowaｒdsｔｈeｉntｅrｆollｉcｕlareｐiderｍistoｈeｌpwitｈtheraｐidregeｎeｒaｔiｏnｏfｔhewouｎdedｓkin（5,７，8).Laterfｉnｄingsalｓosｈｏweｄthatｓｅbａceousｇｌandcellsarｅmaiｎtainｅdbyｐrogｅnｉtorslocａｔedaｂovｅtｈebulgｅ,whｉcｈｅxpressｔheＢｌimp１pｒoｔｅiｎdurinｇmｏrphｏｇｅｎesis(９).Maｉnｔenanｃeoftheinｔeｒfoｌｌiculareｐiｄerｍis，mｅanwhile,involvesmanysｍａｌlunitsofprolｉfｅrａt(yī)iｏnscatteredｔhroughoutthisskｉnｌayeｒ，ｃａlledepidermalｐrolifeｒａt(yī)ivｅunｉts(10,1１）.Ｔheｉｎfundiｂｕlum—theｕpｐerpaｒtofthehairfｏlliｃle,whｉchiｎtｅrｆaceswiththeinteｒfｏlliｃuｌaｒｅpidermis—isthoｕｇhttobemainｔainedbｙprｏgeｎitorｓｌocaｔeｄinaｈaｉr-fｏllicleregionknownａstheｉsthｍuｓ；theseｃells，ｗhｉcheｘｐressthemaｒkerpｒoｔeｉnsMTS24andLrig1(ｒefｓ12–14),candiｆferenｔｉateintｏallｅpidermaｌｃellｌｉｎeagesａfｔｅrtransplantation(1３,14).Sniｐｐｅｒtetal.2setoutｔoideｎtifythｅ‘ｍother’oｆtheseepideｒmalsｔｅｍｃｅｌｌs.Thｅｙfinｄthat,durinｇskiｎfoｒｍatiｏninmice，thｅtｒanｓｍembｒａnｅｒeｃeptｏrLgｒ６isexｐresｓediｎｂoththｅhａirfｏllicleandｔheｉnterfolliｃｕlarepｉdermis.Inaduｌtanimalｓ，ｈowevｅr,Lgr6expressｉonｂｅcｏmesrestrictｅdtotｈeisthｍｕｓ,wheｒeａｂouｔone-thiｒdofLｇr6-maｒkｅｄcｅllsａlsoeｘｐｒessMＴS２4ａndａｆｅwco-ｅxpresｓBlimp1.TomoreprecisｅlｙdefinethｅdiｆferentｉaｔioｎpoｔentialofLgｒ6-eｘpreｓsｉnｇcells,thｅａuthorsuseｄgenｅticwiｚardｒytopeｒmaｎentｌylａbelLｇr6-ｅｘｐreｓsingcelｌｓandtheirpｒｏgeny.Asexｐecｔedｆrｏmｔhｅfirstｓetｏfresulｔs2,ａswellａspｒeviousdaｔa６,8，Lｇr6－expressingcellsｇavｅrisetoceｌｌsofboｔｈthehａirfｏｌliｃleandｔhｅseｂaｃeousgｌaｎｄｄｕriｎgembｒyonicｄevelopmeｎt.Mｏｒｅｏｖeｒ,somecellsoftheinｔeｒfollicularｅｐｉdermisｗerｅderivedfrｏｍＬgｒ6-expressingcellｓ（Fig.1b).Theａuｔhｏrｓ’ｌineａgetracingofaｄuｌtsｋinsｈowｓthａt(yī)Lgr６ｌabｅllinｇwaｓinitialｌyｒｅstrｉctedｍainlyｔothecellsｏftｈeisthmuｓregion,ｗｉthsomelabｅllingｏfｃeｌlｓiｎtheiｎterfolliculaｒepｉdermｉsandｏtherpaｒtsｏfthehairfollｉcles,albｅitatlowｅｒfreｑｕｅncy.Tｗomoｎｔhslatｅr，Ｌgr6pｒogeｎywerefouｎdmａinlyiｎtheisthmusandｓebaceｏusglanｄ，ｗithｓomeintheｉnterfｏlｌicuｌarepidermiｓ,ａndｍoreraｒelyelsｅｗhereintｈehairfolliｃlｅ．TｈeｓｅfindinｇsｓｕggestthaｔLgr６-exｐressingcellscontribuｔemostｌｙtotheｈomeoｓtａsisｏftheisthｍusreｇiｏnandthｅsｅbaceousgｌaｎd,whereasafewｍayhavetｈepotｅntialｔodifｆerenｔiatｅｉntootherepｉｄｅrmａllinｅａｇes．ItrｅmaｉｎsｕncｌearwｈeｔｈeｒasinｇlｅsuｂｐopulatｉｏｎwiｔhintheＬgr６－marｋeｄcelｌｓrｅｇｅnｅraｔesbｏｔhｔheｉｓｔhｍusａndsebaｃeousgｌaｎdｏｒｗhetｈerLｇr6ｉsexpｒessedｉnboththeprｅviｏuslyideｎｔifiｅｄ１2–１4iｓthmusprｏgｅnｉtｏrsexprｅsｓingLｒig１ａnｄMＴS24,aｎｄtheBlimp1-exｐressiｎgsebaceous-ｇlａndpｒogenｉｔｏrｓ(9).Snippertetaｌ.alｓofindthat,ｌikeistｈmussｔemcｅllｓ13,１４,Lgｒ6-ｅxpｒesｓinｇceｌlstｒansplanｔedinｔｏimmｕnodeｆiｃientmｉｃegiｖeriｓｅtoallepidermalｃｅlllineagｅs.Moｒeover，likebuｌgestｅmcｅlｌs,Ｌgr6－ｅxｐressingstemcelｌｓａreactivａt(yī)edｂywｏｕndiｎganｄmigｒateｔowardｓthｅepidermｉstoaidｗoundrｅｐair（Fig.1ｂ）.Thesｅｉntrｉｇuｉngｏbｓerｖationｓｓｕｇgesttｈａt(yī)atｌｅasttwｏｄifferｅnthair-folｌicｌesteｍ-cellｐｏpulationscaｎactｉvｅlyｃontribuｔetoｔheｒepａiｒｏfthｅｄａmagedｅｐｉｄｅｒmｉs.ThｅprｅseｎceｏfLgr６-derivedceｌｌsintheinｔerfolｌiｃuｌarepideｒmisdｕrｉngtissuｅhoｍeosｔａsisiｓｍoｒepｕｚzlｉng．Ａｃcordingtoprｅviouscell-lineageｔraｃinｇｏｆembｒyoｎicsｋin6,8，allcellｓofthemａt(yī)ｕrehaiｒｆolｌiclｅ,incｌuｄingthoseｏftheiｓthmｕｓreｇion,aｒｅdｅｒｉveｄｆｒｏｍcelｌsexprｅssiｎgtwｏotherprogenｉtormaｒkers，ShｈandSｏx9.Bycoｎtrast,theinterｆolliculａｒepideｒmisｉsnotlabelleｄｗiｔｈtheｓｅmａｒkｅrsunlessｗoundeｄ,suggｅstiｎglittlｅｏrｎoｃoｎtrｉbutｉonofhair-fｏｌlicｌｅｃｅllstothｅｍaintenanceoｆｔｈeiｎterfｏｌlｉcｕlarepidermｉs6,8.ThreescenarioscoｕldexpｌaiｎSnippｅrtａndcollｅagueｓ’obsｅrｖatiｏｎthatLgr6-ｄerivedcｅllsaｒepｒｅseｎtｉｎtheｉnterfoｌlｉｃulａreｐidermｉs.Fiｒst,soｍeｒａrｅLgr6-exprｅsｓiｎgisthｍuscellsmiｇhtoｒiｇinatefｒomapoｏlofｈair-follｉcleproｇｅniｔｏrsｄifferentfroｍthoｓeexｐｒessinｇSｈhanｄＳox9,andtheseｗouldthｅｎmigraｔｅｔotｈeｉnteｒfｏｌliｃｕlarepiｄｅrmistocｏntrｉbutetoitsmａinｔenaｎce.Ｓecond，Lｇr６ｍｉｇｈtbemorebｒｏadｌyｅxpressedｔhanShhorSox９,ｔhusmarkiｎｇａpoｐuｌaｔｉｏnofprogenitorstｈaｔｒeｓidesｉｎtｈeｉnterfｏllｉcularepidermis，ａndcoｎtributingｌocalｌyｔothｅdevelopmentandhomeosｔａsisofｃellｓtｈeｒｅ.Finally，micro-wｏundinｇorｓｔrｅｓstoｔheｅpiｄeｒmiｓmightcａusｅｍiｇrａt(yī)iｏnｏfcellsfrｏｍｔhefｏlliｃｌeintoｔheinterｆolliｃｕｌareｐiｄermiｓ.Tｈｉsstudy２ａｄｄsyetanotherｐieceｔothecomplexpuzzleofskｉnhomeosｔasis,cleａｒｌydemonstｒatingｔhａｔLｇｒ6-exprｅsｓiｎｇｐroｇｅnｉtorｓactivelycyｃｌetoｅnsurｅtｈerｅnewａloftheisｔhmusrｅgｉonandｔheｓeｂacｅousｇlａndｕｎｄerpｈｙｓｉoｌｏgicａｌcoｎditiｏｎs.Dｕrｉｎｇｗｏunding，boｔhbuｌgｅstｅｍcｅlls5,7,8andLgr6-expｒｅssｉｎgstemcｅlls2arｅactivelｙreｃｒｕitedtｏrｅpairｔheinｔｅrｆollｉｃuｌarｅｐideｒmis．Formostｓkｉnsteｍcelｌs，ｔｈenaｔuraｌtｕrnｏveｒofceｌｌssｅrvesseverａｌｐuｒpoｓes:toreplacethedｅａｄcelｌsthatａreｓhedfromthesｋinsurfａｃe（ｉｎｔerｆoｌlicularｅpideｒmaｌsteｍceｌlｓ)，toｆuelｈaiｒgrowth（bulgestemceｌlｓ）ortomａkｅoｉlcells（ｓｅbaｃeous-gｌandsｔemceｌls).ButLgr6-expressｉngcｅｌlsarec