Stem Cell Self-Renewal Gene Identified

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日期: 2003-11-02 今日/总浏览: 1/416
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Brain stem cells from mice that contain the Bmi-1 gene (top) proliferate more readily than those without the gene (bottom).
7 I% D8 O1 m$ K# ?Oneofthemostperplexingquestionsinstemcellbiologyis“Whatmakesastemcellastemcell?”Researchersstudyingadultstemcellswouldliketoknowwhatdistinguishesastemcell,whichcanreplenishitselfindefinitely,fromaprogenitorcell,whichcanproliferateonlyalimitednumberoftimes.Now,researchersareonestepclosertounderstandingthedifference.
7 g7 F) V4 J: M4 O4 H: ^% @ResearchersattheUniversityofMichiganinAnnArborhaveidentifiedagenethatisrequiredfortheproliferationofthreetypesofadultstemcellsfrommice.Stemcellsfromthecentralnervoussystem,theperipheralnervoussystemandthebloodallrelyonagenecalledBmi-1torenewthemselves.However,thegeneisnotrequiredfortheproliferationofprogenitorcellsfromthesametissues.0 @% q% |6 A- T, V
“Thisisthefirstgeneidentifiedthatisconsistentlyrequiredbystemcellstoproliferate,butit'snotrequiredbyatleastsometypesofprogenitorcells,”saysSeanJ.Morrison,wholedtheresearch.“Weexpectedthattherewouldbegeneslikethis,butitwasreallyexcitingtofinallyfindone.”* M: \8 A7 S8 X* a$ s9 @
Researcherswouldliketoidentifythegenesthatdistinguishstemcellsfromprogenitorcellsbecausethetwoareoftenconfused.Stemcellsaremoredifficulttoisolatebecausetherearefarfeweroftheminthebody,buttheyareconsideredmoreusefulbecausetheyproliferateincultureandcanreplacemostofthecelltypesofagiventissue.  u# x4 V$ X4 D$ H- Z! x( t
PreviousstudiesbyMorrisonandMichigancolleagueMichaelF.ClarkeshowedthattheBmi-1geneisneededtomaintainstemcellsfromtheblood.Thenewstudy,reportedinNature,showsthatthegeneisalsorequiredbynervestemcellsfromthebrainandgut.Thenewstudyfurthershowsthatthegeneaffectstheprocessofproliferation,buthasnoeffectonhowlongacellsurvives.
. \  {1 y' i  s- d* [  |, i+ UMaartenvanLohuizenoftheNetherlandsCancerCenterinAmsterdamdiscoveredtheBmi-1geneincancercellsin1991andfoundthatitblockstwoproteinsthatnormallyinhibitcellproliferation.* |) U" E9 h! Q& \9 v
VanLohuizenalsofindsthatthegeneisneededfortherenewalofstemcells.Hisstudiesalsosuggestthatthegeneisactiveinsomecellsinthecerebellumthatdonotappeartobestemcells.. U$ a; a6 l9 U7 _3 [$ w
Interestingly,manycancercellsalsooverexpressthegene.Becausethegenemakescellsimmortal,itmayplayakeyroleincancerdevelopment.ResearchersstudyingbothcancerandstemcellsarekeenonfiguringoutwhichgenesareregulatedbyBmi-1.
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* d9 I# G- v2 O- z8 c作者: Nancy Touchette
; C( Y% h+ y4 {. f$ U8 b5 Y来源: Genome News Network
3 D9 v5 H8 Y* _发布者: 亦云