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).8 x& t3 T- P! `. R8 A, p0 X1 W
Oneofthemostperplexingquestionsinstemcellbiologyis“Whatmakesastemcellastemcell?”Researchersstudyingadultstemcellswouldliketoknowwhatdistinguishesastemcell,whichcanreplenishitselfindefinitely,fromaprogenitorcell,whichcanproliferateonlyalimitednumberoftimes.Now,researchersareonestepclosertounderstandingthedifference.% Y- \5 p9 [. Z4 K* Y. Y! ?. X: [9 M5 y
ResearchersattheUniversityofMichiganinAnnArborhaveidentifiedagenethatisrequiredfortheproliferationofthreetypesofadultstemcellsfrommice.Stemcellsfromthecentralnervoussystem,theperipheralnervoussystemandthebloodallrelyonagenecalledBmi-1torenewthemselves.However,thegeneisnotrequiredfortheproliferationofprogenitorcellsfromthesametissues.) }- s" `, [) x' P9 J
“Thisisthefirstgeneidentifiedthatisconsistentlyrequiredbystemcellstoproliferate,butit'snotrequiredbyatleastsometypesofprogenitorcells,”saysSeanJ.Morrison,wholedtheresearch.“Weexpectedthattherewouldbegeneslikethis,butitwasreallyexcitingtofinallyfindone.”! c6 x4 B8 v& M; J
Researcherswouldliketoidentifythegenesthatdistinguishstemcellsfromprogenitorcellsbecausethetwoareoftenconfused.Stemcellsaremoredifficulttoisolatebecausetherearefarfeweroftheminthebody,buttheyareconsideredmoreusefulbecausetheyproliferateincultureandcanreplacemostofthecelltypesofagiventissue.6 A% [# V& p# e6 `; c
PreviousstudiesbyMorrisonandMichigancolleagueMichaelF.ClarkeshowedthattheBmi-1geneisneededtomaintainstemcellsfromtheblood.Thenewstudy,reportedinNature,showsthatthegeneisalsorequiredbynervestemcellsfromthebrainandgut.Thenewstudyfurthershowsthatthegeneaffectstheprocessofproliferation,buthasnoeffectonhowlongacellsurvives.$ p3 M- _, R5 [7 M8 d- O5 }  x
MaartenvanLohuizenoftheNetherlandsCancerCenterinAmsterdamdiscoveredtheBmi-1geneincancercellsin1991andfoundthatitblockstwoproteinsthatnormallyinhibitcellproliferation.
# ?& l/ W9 u0 `! H7 `9 N0 n' }$ ZVanLohuizenalsofindsthatthegeneisneededfortherenewalofstemcells.Hisstudiesalsosuggestthatthegeneisactiveinsomecellsinthecerebellumthatdonotappeartobestemcells.: D( }9 T, g- w7 P
Interestingly,manycancercellsalsooverexpressthegene.Becausethegenemakescellsimmortal,itmayplayakeyroleincancerdevelopment.ResearchersstudyingbothcancerandstemcellsarekeenonfiguringoutwhichgenesareregulatedbyBmi-1.
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3 _. [1 F) ]8 O) n) `" ^2 K  v& a作者: Nancy Touchette* D2 n$ x7 E5 ]2 d" E! a) @3 {
来源: Genome News Network
3 n- R* N9 s$ t& x' s5 h9 b: w发布者: 亦云