学科分类
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57 个结果
  • 简介:γ-AminobutyricacidandGABAergicreceptorswerepreviouslyreportedtobedistributedinreproductivesystemsbesidesCNSandpredictedtoparticipateinthemodulationoftesticularfunction.γ-Aminobutyricacidtransporterwasimplicatedtobeinvolvedinthisprocess.However,thepotentialroleofγ-aminobutyrictransporterintestishasnotbeenexplored.Inthisstudy,weinvestigatedtheexistenceofmouseγ-aminobutyricacidtransportersubtypeI(mGAT1)intestis.Wild-typeandtransgenicmice,whichoverexpressingmGAT1inavarietyoftissues,especiallyintestis,wereprimarilystudiedtoapproachtheprofileofmGAT1intestis.MicewithoverexpressedmGAT1developnormallybutwithreducedmassandsizeoftestisascomparedwithwild-type.Testicularmorphologyoftransgenicmiceexhibitedovertabnormalitiesincludingfocaldamageofthespermatogenicepitheliumaccompaniedbycapillariesproliferationandincreaseddiameterofseminiferoustubuleslumen.Reducednumberofspermatidswasalsofoundinsomeseminiferoustubules.OurresultsclearlydemonstratethepresenceofGAT1inmousetestisandimplythatGAT1ispossiblyinvolvedintesticularfunction.

  • 标签: 睾丸形态 GAT1 过表达 GABA γ-氨基丁酸转运蛋白
  • 简介:免疫不全病毒类型1(HIV-1)Vpr导致房间死亡在哺乳动物并且分裂酵母房间,建议那Vpr可以影响个保存细胞过程。然而,导致Vpr酵母房间死亡是否在哺乳动物房间模仿调停Vprapoptosis,不清楚。我们最近识别了很多Vprsuppressors不仅在分裂酵母压制导致Vpr房间死亡,而且在哺乳动物房间堵住导致Vprapoptosis。这些调查结果建议在酵母导致Vpr房间死亡可以类似于些哺乳动物房间apoptotic过程。这研究目标为apoptosis未来研究开发并且验证个分裂酵母模型系统。类似于在哺乳动物房间导致Vprapoptosis,我们这里证明在分裂酵母Vpr支持phosphatidylserine外表表现并且导致线粒体hyperpolarization,导致mitochondrial膜潜力变化。而且,反应氧种类(ROS)Vpr扳机生产,显示象apoptotic样细胞死亡可能被ROS调停。有趣地,Vpr在可以为在分裂酵母测量象apoptotic样过程提供个简单标记线粒体导致唯词法变化。验证这可能性,我们测试了二Vprsuppressors(EF2和Hsp16)除了最新识别的Vprsuppressor(Skp1)在哺乳动物房间压制导致Vprapoptosis。所有三蛋白质废除了房间死亡由Vpr调停了并且在酵母房间恢复了正常mitochondrial形态学。在结论,在分裂酵母导致Vpr房间死亡类似于哺乳动物apoptotic过程。分裂酵母可以潜在地因此为Vpr和另外proapoptotic代理人导致象apoptotic样过程未来学习被用作个简单模型有机体。

  • 标签: HIV-1 VPR 细胞死亡 线粒体 模型有机体
  • 简介:ASK1(ARABIDOPSIS象SKP1样)蛋白质招募ubiquitinligase建筑群指向SCF(Skp1-Cullin-F盒子蛋白质)个批评部件为由26Sproteosome降级蛋白质。为了调查蛋白质,那被调停ASK1解朊作用小径在Arabidopsis花影响,我们用二维电气泳动(2-DE)比较了Arabidopsis野类型和ask1异种花芽proteomes。有在与野类型花相比ask1异种花更高或更低丰富十个蛋白质点被切除并且使分析遭到了步集体spectrometry(MS)。结果证明他们涉及相片形态发生,生理节奏摆动,翻译以后过程,压力反应和房间扩大或延伸蛋白质,建议那些过程在ask1异种被影响。基因也是的这些抄本层次基于Affymetrix基因芯片比较了微数组数据。没有重要差别为大多数基因被观察,建议有在ask1异种累积提高层次蛋白质能条调停ASK1解朊作用小径调整候选人目标。阐明这些结果帮助在Arabidopsis发展过程并且也ASK1多种功能表明关于基因功能学习蛋白质层次重要性和必要性。

  • 标签: 蛋白质 水解途径 电位 生物研究
  • 简介:Activehost-pathogeninteractionstakeplaceduringinfectionofhumanimmunodeficiencyvirustype1(HIV-1).Outcomesoftheseinteractionsdeterminetheefficiencyofviralinfectionandsubsequentdiseaseprogression.HIV-infectedcellsrespondtoviralinvasionwithvariousdefensivestrategiessuchasinnate,cellularandhumoralimmuneantiviralmechanisms.Ontheotherhand,thevirushasalsodevelopedvariousoffensivetacticstosuppressthesehostcellularresponses.Amongmanyoftheviraloffensivestrategies,HIV-1viralauxiliaryproteins(Tat,Rev,Nef,Vif,VprandVpu)playimportantrolesinthehost-pathogeninteractionandthushavesignificantimpactsontheoutcomeofHIVinfection.OneofthebestexamplesistheinteractionofVifwithahostcytidinedeaminaseAPOBEC3G.AlthoughspecificrolesofotherauxiliaryproteinsarenotaswelldescribedasVif-APOBEC3Ginteraction,itisthegoalofthisbriefreviewtosummarizesomeofthepreliminaryfindingswiththehopetostimulatefurtherdiscussionandinvestigationinthisexhilaratingareaofresearch.

  • 标签: 爱滋病病毒-1 辅助蛋白 病毒感染 中国 病原体
  • 简介:真核细胞房间最惹人注目的形态特征各种各样围住膜分隔空间存在。包括细胞器和短暂运输中介,这些分隔空间不是静态。更确切地说,蛋白质和膜动态交换被需要维持细胞动态平衡。膜动员最戏剧例子之一在macroautophagy过程期间被看见。Macroautophagy为长寿蛋白质和细胞器降级主要细胞小径。响应环境暗示,例如饥饿或应力另外类型,房间生产唯膜结构,phagophore.Thephagophore扣押它形成个双膜cytosolic泡细胞质,anautophagosome。在结束之后,autophagosome与溶酶体熔化或在酵母个液泡,它交付水疗院放射激光与它货物,和产生大分子起毁坏内部autophagosome膜回来被释放进cytosol因为reuse.Autophagy因此正在骑车过程,允许房间熬过滋养限制时期;然而,它有个更宽生理角色,参予开发和老化,并且另外在对病原体侵略,癌症和某些neurodegenerative保护疾病。在许多情况中,autophagy角色通过autophagy相关蛋白质研究被识别,Atg6/Beclin1。这蛋白质类脂化合物kinase建筑群部分,并且最近研究建议它在协调autophagy并且在反对apoptosis细胞死亡过程thecytoprotective功能个中央作用。这里,我们总结我们Atg6/Beclin的当前知识1在在细胞不同模型有机体和它功能

  • 标签: 溶酶体 磷酸肌醇 蛋白质 液泡 酵母
  • 简介:ToexplorethemolecularmechanismofchromatinremodelinginvolvedintheregulationoftranscriptionalactivationofspecificgenesbyamyogenicregulatoryfactorMyogenin,weusedNIH3T3fibroblastswithastablyintegratedH1.1-GFPfusionproteintomonitorhistoneH1movementdirectlybyfluorescencerecov-eryafterphotobleaching(FRAP)inlivingcells.TheobservationfromFRAPexperimentswithmyogenintransfectedfibroblastsshowedthattheexchangerateofhistoneH1inchromatinwasobviouslyincreased,indicatingthatforcedexpressionofexogenousMyogenincaninducechromatinremodeling.Thehyper-acetylationofhistonesH3andH4frommyogenintransfectedfibroblastswasdetectedbytriton-acid-urea(TAU)/SDS(2-D)electrophoresisandWesternblotwithspecificantibodiesagainstacetylatedN-terminiofhistonesH3andH4.RT-PCRanalysisindicatedthatthenAChRa-subunitgenewasexpressedinthetrans-fectedfibroblasts.TheseresultssuggestthattheexpressionofexogenousMyogenincaninducechromatinremodelingandactivatethetranscriotionofMvogenin-targetedgeneinnon-musclecells.

  • 标签: 染色体 组蛋白 染色体改变 乙酰化
  • 简介:干扰素规章因素(IRF)3在病毒或细菌侵略期间为chemokines和cytokinestranscriptional正式就职批评。kinases坦克有约束力kinase(TBK)1并且IkappaBkinase(IKK)蔚罐头phosphorylateIRF3和玩C终端部分在IRF3激活重要角色。在这研究,我们显示出那另外个kinase,c-Jun-NH2-terminalkinase(JNK),它N终端丝氨酸上phosphorylatesIRF3173残余,和TAK1能经由JNK刺激IRF3phosphorylation。没有影响C终端phosphorylation,JNK特定禁止者SP600125禁止N终端phosphorylation。另外,lipopolysaccharide(LPS)上调停IRF3基因表情或polyinosinic-cytidylic酸(polyI:C)处理被SP600125严重地损害,以及为IRF3激活记者基因试金。进步证实TAK1击倒这些观察。有趣地,组成活跃IRF3(5D)能被SP600125禁止;JNK1罐头synergizeIRF3(5D)行动,然而并非S173A-IRF3(5D)变异。更重要地,polyI:没能戏剧性地导致变异S173A和SP600125phosphorylationC废除了被polyI刺激IRF3phosphorylation和dimerization:C。因此,这研究证明TAK1-JNK串联为IRF3功能被要求,除了TBK1/IKK蔚,揭开为激活mitogen蛋白质(地图)新机制调整天生免疫kinase。

  • 标签: 蛋白激酶 免疫反应 级联 天然 磷酸化 丝裂原活化
  • 简介:Inmacrophages,theaccumulationofcholesterylesterssynthesizedbytheactivatedacyl-coenzymeA:cholesterolacyltransferase-1(ACAT1)resultsinthefoamcellformation,ahallmarkofearlyatheroscleroticlesions.Inthisstudy,withthetreatmentofaglucocorticoidhormonedexamethasone(Dex),lipidstainingresultsclearlyshowedthelargeaccumulationoflipiddropletscontainingcholesterylestersinTHP-1-derivedmacrophagesexposedtolowerconcentrationoftheoxidizedlow-densitylipoprotein(ox-LDL).Morenotably,whentreatedtogetherwithspecificanti-ACATinhibitors,theabundantcholesterylesteraccumulationwasmarkedlydiminishedinTHP-l-derivedmacrophages,confirmingthatACATisthekeyenzymeresponsibleforintracellularcholesterylestersynthesis.RT-PCRandWesternblotresultsindicatedthatDexcausedup-regulationofhumanACAT1expressionatboththemRNAandproteinlevelsinTHP-1andTHP-1-derivedmacrophages.TheluciferaseactivityassaydemonstratedthatDexcouldenhancetheactivityofhumanACAT1geneP1promoter,amajorfactorleadingtotheACAT1activation,inacell-specificmanner.Furtherexperimentalevidencesshowedthataglucocorticoidresponseelement(GRE)locatedwithinhumanACAT1geneP1promotertoresponsetotheelevationofhumanACAT1geneexpressionbyDexcouldbefunctionallyboundwithglucocorticoidreceptor(GR)proteins.ThesedatasupportedthehypothesisthattheclinicaltreatmentwithDex,whichincreasedtheincidenceofatherosclerosis,mayinpartduetoenhancingtheACAT1expressiontopromotetheaccumulationofcholesterylestersduringthemacrophage-derivedfoamcellformation,anearlystageofatherosclerosis.

  • 标签: 巨噬细胞 地塞米松 泡沫细胞 人类 基因 表达
  • 简介:门高血压(PHT)gastropathy肝肝硬化经常复杂并发症,带之一从肝硬化死亡引起。Apoptosis广泛地被认为从坏死房间死亡房间死亡和个不同实体个活跃精力依赖者模式。胃mucosalapoptosis是否涉及PHTgastropathy,不清楚。通过cyclooxygenase(艇长)生产前列腺素(PG)被认为从损害和apoptosis在胃肠mucosa保护起个关键作用。然而,在PHTgastropathy艇长角色仍然不清楚地被理解。这研究目的调查(1)胃mucosalapoptosis是否涉及PHTgastropathy,(2)艇长downregulation贡献这apoptosis。在这研究,当mucosal增长在PHT老鼠被禁止时,我们证明胃mucosalapoptosis显著地被增加。胃mucosalCOX-1显著地在mRNA和蛋白质层次被压制,并且PGE2在PHT老鼠被减少。进步,PGE2处理在PHT老鼠压制了胃mucosalapoptosis。然而,胃mucosalCOX-2层次没在假冒操作老鼠和PHT老鼠之间不同。肿瘤坏死因素mucosal层次--(TNF-)并且船边交货ligand,然而并非TNF相关导致apoptosisligand,被增加,并且激活caspase-8和caspase-3层次在PHT老鼠upregulated。cytosol从线粒体细胞色素c版本没在PHT老鼠被观察。我们数据显示COX-1downregulation经由死亡涉及胃mucosalapoptosis调停信号类型--我在PHT老鼠房间死亡。

  • 标签: 细胞凋亡 胃粘膜 环氧 信号 死亡 大鼠
  • 简介:WereportedinthismanuscriptthatTGF-β1inducesapoptosisinAML12murinehepatocytes,whichisassociatedwiththeactivationofp38MAPKsignalingpathway.SB202190,aspecificinhibitorofp38MAPK,stronglyinhibitedtheTGF-β1-inducedapoptosisandPAI-1promoteractivity.TreatmentofcellswithTGF-β1activatesp38.Furthermore,over-expressionofdominantnegativemutantp38alsoreducedtheTGF-β1-inducedapoptosis.Thedataindicatethattheactivationofp38isinvolvedinTGF-β1-mediatedgeneexpressionandapoptosis.

  • 标签: 转化生长因子Β 细胞凋亡 P38 肝细胞 信号传导
  • 简介:兼容丑恶纸巾表面上花粉萌芽为植物授精必要步。这里,我们报导Arabidopsis变异bcl1由于花粉萌芽失败不育男性。我们证明bcl1异种等位基因不能被男配偶体播送,没有同型结合bcl1异种被获得。花粉发育阶段分析显示bcl1变化影响花粉萌芽然而并非花粉成熟。分子分析证明花粉萌芽失败被AtBECLIN1混乱引起。AtBECLIN1在成熟花粉主要被表示并且与重要相同编码蛋白质在酵母为autophagyandvacuolar蛋白质排序过程(VPS)要求Beclin1/Atg6/Vps30。我们也证明AtBECLIN1为正常被要求植物开发,和那与autophagy,VPS和glycosylphosphatidylinositolanchor系统有关基因,被AtBECLIN1缺乏影响。

  • 标签: 拟南芥 AtBECLIN1 花粉萌发 植物发育
  • 简介:MembersofBcl-2familyofproteinsareregulatorsofcelldeaththatcanbegroupedintosubfamiliesofprosurvivalandproapoptoticmolecules.Theyarecharacterizedbythepresenceofseveralconservedmotifs,knownastheBcl-2homology(BH)domains,designatedBH1,BH2,BH3andBH4.MutagenesisandstructuralstudiesrevealedthattheBHdomainsareimportantfunctionaldomainsthatarealsorequiredfordimerizationfunction.Recently,asubfamilyofproapoptoticmoleculesonlycontainsBH3motifhasbeenidentifiedsuggestingBH3domainalonemaybesufficientformediatingproapoptoticfunctionamong

  • 标签: 前凋亡蛋白 map-1 多bcl-2同源域 bax相关蛋白 特性
  • 简介:Peroxisome激活proliferator受体鲸鱼群妈(PPARγ)coactivator-1高山哈(PGC-1α)coactivates多重抄写因素并且调整几个代谢过程。Thecurrent学习在人上皮卵巢癌症房间在apoptosis正式就职调查了PGC-1α角色。在人卵巢和人卵巢上皮肿瘤之间PGC-1α信使rna水平被量RT-PCR检验。更少PGC-1α表示与正常卵巢相比在恶意肿瘤表面上皮被发现。在人上皮卵巢癌症房间线Ho-8910PGC-1αOverexpression通过Bcl-2和Bax表示协调规定导致了房间apoptosis。Microarray分析证实PGC-1α戏剧性地在Ho-8910房间影响了apoptosis相关基因。Mitochondrial功能试金证明apoptosis正式就职通过由细胞色素c.Furthermore版本终端阶段,导致apoptosis部分,然而并非完全,由PPARγantagonist(GW9662)堵住了PGC-1α-,并且由siRNAPPARγ表示抑制也在Ho-8910房间禁止了PGC-1α-inducedapoptosis。这些数据建议PGC-1α通过aPPARγ-依赖者小径施加了它效果。我们调查结果显示PGC-1α涉及apoptoticsignaltransduction小径,PGC-1αdown规定可以是在支持上皮卵巢癌症生长和前进个关键点。

  • 标签: 卵巢上皮癌细胞 PGC-1Α 诱导 细胞凋亡 PPARY
  • 简介:TRAF2isacriticaladaptormoleculeforTNFreceptorsininflammatoryandimmunesignaling.Uponreceptorengagement,TRAF2isrecruitedtoCD40andtranslocatestolipidraftsinaRINGfinger-dependentprocess,whichenablestheactivationofdownstreamkinases.TRAF1candisplaceTRAF2andCD40fromraftfractions,anditpromotestheabilityofTRAF2tosustainsignalactivation.ReplacementoftheRINGfingerofTRAF2witharaft-targetingsignalrestoresJNKactivationandassociationwiththecytoskeletalproteinFilamin,butnotNF-KBactivation.TRAF1-/-dendriticcellsshowattenuatedresponses

  • 标签: TRAF2细胞内定位 TRAF1调节 信号转导机制
  • 简介:Ionizingradiationisoneofthemosteffectivetoolsincancertherapy.Inapreviousstudy,wereportedthatproteintyrosinekinase(PTK)inhibitorsmodulatetheradiationresponsesinthehumanchronicmyelogenousleukemia(CML)celllineK562.Thereceptortyrosinekinaseinhibitor,genistein,delayedradiation-inducedcelldeath,whilenon-receptertyrosinekinaseinhibitor,herbimycinA(HMA)enhancesradiation-inducedapoptosis.Inthisstudy,wefocusedonthemodulationofradiation-inducedcelldeathbygenisteinandperformedPCR-selectsuppressionsubtractivehybridization(SSH)tounderstanditsmolecularmechanism.Weidentifiedhumanthymidinekinase1(TK1),whichiscellcycleregulatorygeneandconfirmedexpressionofTK1mRNAbyNorthernblotanalysis.ExpressionofTK1mRNAandTK1enzymaticactivitywereparallelintheirincreaseanddecrease.TK1isinvolvedinG1-Sphasetransitionofcellcycleprogression.Incellcycleanalysis,weshowedthatradiationinducedG2arrestinK562cellsbutitwasnotabletosustain.However,theadditionofgenisteintoirradiatedcellssustainedaprolongedG2arrestupto120h.Inaddition,theexpressionofcellcycle-relatedproteins,cyclinAandcyclinB1,providedtheevidencesofG1/SprogressionandG2-arrest,andtheirrelationshipwithTK1incellstreatedwithradiationandgenistein.TheseresultssuggestthattheactivationofTK1maybecriticaltomodulatetheradiation-inducedcelldeathandcellcycleprogressioninirradiatedK562cells.

  • 标签: 染料木素 胸腺嘧啶核苷激酶1 活化 辐射 细胞凋亡 K562
  • 简介:Wntsignalingplaysanimportantroleinembryogenesisandtumorgenesis.AlthoughthemechanismabouthowWntstransducetheirsignalingfromreceptorfrizzled(Fz)tocytosolhasnotbeenunderstood,dishevelled(Dvl)proteinwasconsideredastheintersectionofWntsignaltraffic.Inthisstudy,wecharacterizedthefunctionofthreedomains(DIX,PDZandDEP)ofDvl-1incanonicalWntsignaltransductionandDvl-1membranetranslocation.ItwasfoundbothDIXandDEPdomainweresufficienttoblockWnt-3a-inducedLEF-1transcriptionalactivityandfreecytosolβ-cateninaccumulation;whereasPDZdomainandafunctionalmutantformofDEPdomain(DEP-KM)hadnoeffectoncanonicalWntsignaling.Inaddition,whencotransfectedwithFz-7,DEPdomain,butnotDIX,PDZorDEP-KM,translocatedandco-localizedwithFz-7totheplasmamembrane,whichwassimilartoDvl-1.Furthermore,itwasDEPdomainthatcouldblockFz-7-inducedmembranetranslocationofDvl-1viaapossiblecompetitivemechanism.TheseresultsstronglysuggestthatDEPdomainisresponsibleforthemembranetranslocationofDvl-1proteinuponWntsignalstimulation.

  • 标签: 信号转导 膜易位 WNT 基因 蛋白质
  • 简介:Amajorproblemwhichispoorlyunderstoodinthemanagementofbladdercancerislowsensitivitytochemotherapyandhighrecurrenceaftertransurethralresection.Insulin-likegrowthfactor1receptor(IGF-1R)signalingplaysaveryimportantroleinprogression,invasionandmetastasisofbladdercancercells.Inthisstudy,weinvestigatedwhetherIGF-1Rwasinvolvedinthegrowthstimulatingactivityanddrugresistanceofbladdercancercells.Theresultsshowed:ThemRNAsofIGF-1,IGF-2andIGF-1Rwerestronglyexpressedinserum-freeculturedT24cellline,whereasnormalurothelialcellsdidnotexpressthesefactors/receptorsoronlyintracelevels;T24cellrespondedfarbettertogrowthstimulationbyIGF-1thandidnormalurothelialcells;blockageofIGF1Rbyantisenseoligodeoxynucleotide(ODN)significantlyinhibitedthegrowthofT24cellandenhancedsensitivityandapoptosisofT24cellstomitomycin(MMC).TheseresultssuggestedthatblockageofIGF-IRsignalingmightpotentiallycontributetothetreatmentofbladdercancercellswhichareinsensitivetochemotherapy.

  • 标签: 胰岛素生长因子-1受体 信号系统 抗药性 细胞凋亡 膀胱癌
  • 简介:神经干细胞(NSC)为胚胎大脑开发和神经发生组成细胞基础。这个过程被NSC壁龛包括邻居房间例如调整脉管并且glial房间。自从脉管并且glial房间分泌脉管endothelial生长因素(VEGF)和基本成纤维细胞生长因素(bFGF),我们用被区分开来与老鼠将近同类NSC估计了VEGF和bFGFonNSC增长效果胚胎干细胞。VEGF独自没有任何重要效果。当bFGF被增加时,然而,以种剂量依赖者方式VEGFstimulatedNSC增长,和这刺激被ZM323881禁止,aVEGF受体(Flk-1)特定禁止者。有趣地,ZM323881也当外长VEGF不在时禁止了细胞增殖,建议VEGFautocrine起在NSC增长个作用。NSC增长上VEGFstimulatory效果取决于bFGF,它由于Flk-1表示起来事实是可能经由ERK1/2.Collectively磷酸化由bFGF调整了,这研究可以提供卓见进微环境壁龛信号由调整NSC机制。

  • 标签: 神经干细胞 细胞增殖 神经发生 细胞生理学 纤维原细胞
  • 简介:LEF1/TCFs高活动性组调停包含盒子transcriptional因素在早胚胎开始和tumorigenesis.Beta-catenin期间发信号正规Wnt/beta-catenin在dorsalization期间与LEF1/TCFs和transactivatesLEF1/TCF-mediated抄写形成建筑群。尽管调停LEF抄写也在ventralization被含有,内在分子机制很好没被理解。用脊椎动物Xenopuslaevis模型系统,我们发现那Xom,它是有双角色oftranscriptionalventralizinghomeobox蛋白质激活和压抑,通过它N终端transactivation领域(男孩)通过它homeodomainandtransactivatesLEF1/TCF-mediated抄写与LEF1/TCF形成建筑群。我们数据表演缺乏N终端男孩那Xom自己没有通过腹基因,如此asBMP4和Xomtransactivate,但是保留能力压制背面的基因倡导者transcriptional激活例如Goosecoid倡导者,显示transactivation和压抑是Xom可分离函数。Xom与BMP4形成个积极援助环支持ventralization并且压制背面的基因表示,这被要求了。与LEF1/TCFsXomtransactivation个必要角色致在早胚胎开始期间,我们发现缺乏TAD主导否定Xom异种那表情失败援助BMP4和原因发信号灾难效果在gastrulation期间。我们数据建议Xom和LEF1/TCF-factors功能相互作用为腹房间命运决心和那LEF1/TCF必要因素可以作为集中个点工作调停在早胚胎开始期间Wnt/beta-catenin和BMP4/Xom小径发信号联合。

  • 标签: 脊椎动物 胚胎发生 腹侧细胞命运 Xom LEF1 TCFs