Frog eggs rejuvenate human cells

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日期: 2003-07-16 今日/总浏览: 1/5791 O$ Y, c/ m' Q  U

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: R2 ]- T8 [+ e+ T; i$ @1 X! @. i+ V7 PImmaturefrogeggscanrejuvenateadulthumancells.MoleculesintheamphibiannucleuscoaxmaturehumanandmouseDNAbacktoanadaptable,stem-cell-likestate1.: ^& `+ K; K' n" Z
JohnGurdonandhiscolleaguesatCambridgeUniversity,UK,hopetoisolatethesubstancesresponsibleandusethemtoreprogrammeordinaryadultcells,fromskinorblood,say.Thiswouldyieldalimitlesssupplyofdonor-matchedstemcellswithwhichtorepairtissuedamagedindiseasessuchasParkinson'sandmultiplesclerosis.
: v" X3 R) v! u" D2 s. WManyresearchersarehopingtoconvertspecializedadultcellsintoamoreimmaturestate.Stemcellscanbederivedfromexcessearly-stagehumanembryosfromfertilitytreatments.Butthisapproachhasethicalandpracticallimitations-theEuropeanUnionlastweekruledthatonlyembryoscreatedbefore27June2002canbeusedforresearch.Adultstemcellsexist,buttheirpotentialisuncertain.
0 k% B5 T0 ^0 H9 j  Z! kGurdon'steaminjectedimmatureXenopusfrogeggswithnucleifromadultmouseorhumanwhitebloodcells.Twodayslater,thedefinitivemouseorhumanstem-cellmarker,amoleculecalledOct4RNA,appearedinthehybrid.RNAhelpstoconvertDNAtoproteins,sotheresulthintsthattheadultnucleiarestartingtobehaveinastem-cell-likeway.% E! \% V, Y, m% m5 F
Thisisthefirststepinreprogrammingcells,agreesdevelopmentalgeneticistWolfReikoftheBabrahamInstituteinCambridge,UK,beforeadding:Youmightstillrunintoproblemslateron.Somegenesmayremainintheiradultform,causingcellstodivideandbecomecancerous.
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; y: Y( e+ i3 o$ l, b: C3 M5 w8 iNuclearreaction+ G; I* y# J$ f, O6 z+ _. ~& x
ThetechniqueisdifferentfromtheprocessusedtocreateDollythesheep.TomakeDolly,researchersinjectedadultDNAintoanemptysheepeggandstimulatedittodevelop.Gurdon'sapproachleavestheegg'snucleusinplace.  r% O; A1 p2 b, E' _7 F
Whentheresearchersinjectedtheadultnucleiintofrogeggnucleii,ratherthanintothesurroundingcytoplasm,Oct4levelsshotupbyafactoroften.Thereprogrammingactivityisparticularlyconcentratedhere,saysGurdon.Moleculesinthefrognucleusmayberesponsiblefortheeggs'revitalizingabilities,hespeculates.
" u# {% ~3 e* H, W! [. DFrogeggsarelargeandeasytomanipulate,sayscellbiologistRudolfJaenischoftheWhiteheadInstituteinCambridge,Massachusetts.Theygiveyouausefultoolforfindingthegenesthatareinvolvedinreprogramming,hesays.
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) A+ x% S$ d9 g* F" U1 ~Byrne,J.A.,Simonsson,S.,Western,P.S.&Gurdon,J.B.Nucleiofadultmammaliansomaticcellsaredirectlyreprogrammedtooct-4stemcellsgeneexpressionbyamphibianoocytes.CurrentBiology,13,1206-1213,(2003).% C/ H8 z! Q6 x8 }% K- H) j+ E* J
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作者: HELEN R. PILCHER1 i) G/ `5 @, m4 j; v% A+ f7 ?
来源: Nature- _( b  J1 V+ m# m
发布者: 亦云