 上传我的文档
 下载
 收藏
该文档贡献者很忙，什么也没留下。
 下载此文档
Basic helix–loop–helix transcription factor
下载积分：4990
内容提示：Basic helix–loop–helix transcription factor
文档格式：PDF|
浏览次数：5|
上传日期： 00:01:07|
文档星级：
全文阅读已结束，如果下载本文需要使用
 4990 积分
下载此文档
该用户还上传了这些文档
Basic helix–loop–helix transcription factor
官方公共微信Basic helix-loop-helix transcription factors_文档下载
亿万文档 免费下载
当前位置： &
& Basic helix-loop-helix transcription factors
Basic helix-loop-helix transcription factors
reviewarticle
endocrinedifferentiationisalsoundercontroloftheNotchsignallingpathway.
DIABETES,OBESITYANDMETABOLISM
CommonOriginofEnteroendocrineCells
Thediscoveryofover15guthormonesproducedbyenteroendocrinecells,alongwithcharacterizationofeachcelltypeanditsorigins,becameatopicofconsiderableinterest.Itwasunclearwhethereachendocrinecelltypeexpressedoneormultiplehormones.Inaddition,littlewasknownabouttheprecursorcellsthatgaverisetoenteroendocrinecells.ClassicstudiesbyChengandLeblondfrom1974identi edself-renewingpropertiesofthefourepithelialcelltypesoftheintestine,includingenteroendocrinecells,andproposedthattheyarisefromcommonmultipotentialcellsintheintestinalcrypts[2].Continuousinfusionsoftritiatedthymidine rstlabelledcellsdeepinthecryptfollowedbymoredifferentiatedcellsupthecryptCvillusaxis,includingenterocytes,gobletcells,enteroendocrinecellsandPanethcells( gure1).Celllabellingkineticsindicatedthatenterocytes,gobletcellsandenteroendocrinecellsdifferentiatedascellsmigrateupthecryptCvillusaxisturningoverevery3C4days,whereasPanethcellsmigrateddownwardstothecryptbasewithamuchslowerturnoverofapproximately21days[2].Unlikemanyendocrinecellsindifferentglandsthatdifferentiateearlyinlifeandturnoverslowly,enteroendocrinecellsactivelyself-renewanddifferentiatethroughoutthelifeofananimalfromalargereservoirofstemcells.Asmatureenteroendocrinecells
tothetipsofthevilli,theypresumablyundergoapoptosisandareextrudedintothelumen[16].
Additionalevidenceforacommonmultipotentialenteroen-docrineprecursorcellincludedtheidenti cationofindividualcellsco-expressingmorethanonehormone.Inthesmallintestine,asubpopulationofsubstanceP-expressingcellsinvillico-expressedserotoninandsecretin,whereasproliferatingsubstancePcellsinthecryptsdidnot,leadingtospecula-tionthatserotoninandsecretincellsarisefromsubstancePcells[17,18].Inthecolon,peptideYY,GLP-1,cholecystokininandneurotensinareco-expressedinL-typeenteroendocrinecells.Colonicserotonin-expressingcellsco-expresssubstancePbutnevertheprecedingfourhormones,leadingtothehypoth-esisthattherearetwomajorbranchesforenteroendocrinedifferentiationinthecolon[19].
Expressionofstablereportergenesintransgenicmiceprovidedfurtherindirectsupportfortheexistenceofmultipotentialenteroendocrineprogenitorcells.Expressionofahumangrowthhormonereporter(hGH)undercontroloftheL-FABPgeneshowedlabellingofmultiplelineagesofenteroendocrinecells[17].Celllineageablationstudiesinvolvingexpressionofatoxicgeneintransgenicmicefurtherestablishedrelationshipsbetweendifferententeroendocrinecelltypes.Expressionofherpessimplexvirus1thymidinekinase(HSVTK)insecretin-expressingcellsoftransgenicmicerenderedcellssusceptibletotheantiviraldrugganciclovir[20].TreatmentoftransgenicmicewiththedrugresultedindepletionofsecretincellsaswellasmostcellsexpressingCCKandLcellsexpressingpeptideYYandGLP-1.Inaddition,thenumbersofcellsexpressingserotonin,GIP,substancePandsomatostatinweresigni cantlyreducedaswell,revealingpreviouslyunappreciatedrelationshipsbetweenthesedifferentcelltypesandsecretincells.Theresultsfurthersuggestedthatmanycelllineagesmayexpresssecretinatlevelsbelowthedetectablelimitforimmunostaining[20].
CurrentModelofEnteroendocrineCellDifferentiation
Earlierstudiesonenteroendocrinecelldifferentiationwerehamperedbysigni cantlimitations.Mosthistochemicalstudiesandlabellingkineticswerelargelydescriptiveanddidnotidentifygenesrequiredforenteroendocrinecellstodifferentiate.Thepaucityofmarkersfortheprecursorcellswasasecondmajorlimitationforprogress.Sincethen,severalfactorshavecontributedtomajoradvancesinunderstandingenteroendocrinedifferentiation.Newlinesofknockouttransgenicmicehaveidenti edgenesthatarerequiredforenteroendocrinecellstodifferentiate.Increaseduseofrecombination-basedcelllineageanalysisalongwiththediscoveryofbettermarkersforintestinalstemcellshasfurtherenhancedidenti cationofcellsfromwhichtheenteroendocrinelineagearises.
Inmanydevelopmentalsystems,expressionofoneormorespeci ctranscriptionfactorssequentiallyactivateslineage-speci cgeneexpressionprogrammes.Differentiationmaybehighlydependentonthetimingandcontextoftranscriptionfactorexpression.Anumberofsignallingpathways,most
Figure1.DifferentiationandfunctionalanatomywithinthecryptCvillusunit.Rapidlycyclingcryptbasecolumnar(CBC)andslowingcycling+4LRCstemcellsgiverisetoallfourepitheliallineages.Enterocytes,gobletcellsandenteroendocrinecellsdifferentiateascellsexitthelowercryptandaproliferativetransit-amplifying(TA)zoneastheymigrateupthecryptCvillusaxis.SomeenteroendocrinecellsdifferentiatejustabovethecryptbasewithoutgoingthroughaTApopulation.Incontrast,PanethcellsmigratetothecryptbaseandbecomeintercalatedbetweenCBCstemcells.
Word文档免费下载： （下载1-8页，共8页）
A basic-helix-loop-helix (bHLH) is a protein structural motif that characterizes a family of transcription factors. The motif is characterized by two α...? Mouse (NMRI×129) Introduction The basic helix-loop-helix (bHLH) proteins are a large class of transcription factors that are important for differThis...and molecular characterization of R2R3-MYB and bHLH-MYC transcription factors...Basic helix-loop-helix TF Transcription factor Introduction Flavonoids are ...Chen JY (2013) Molecular characterization of cold-responsive basic helix-loop-helix transcription factors MabHLHs that interact with MaICE1 in banana fruit....Transcription factor SCL / Tal 是参与原血干细胞分化的基本的转录因子。 A basic helix-loop-helix transcription factor 小鼠SCL基因无效突变的纯合子引起死亡 ...PH4 of Petunia Is an R2R3 MYB Protein That Activates Vacuolar Acidification through Interactions with Basic-Helix-Loop-Helix Transcription Factors of the ...For example, the basic helix-loop-helix (bHLH) transcription factor MyoD can induce muscle-specific properties in fibroblasts but not hepatocytes 13,14; ...这段基序折叠成α螺旋结构,与碱性区域螺旋环螺旋 (basic-region helix-loop-helix,bHLH) 和 Myb (a family of transcription factors with Trp cluster motif) ...Hox, zinc-?nger and bHLH (basic helix-loop-helix) family transcription factors had been identi?ed as regulators of key cell fate decisions. The ...basic helix-loop-helix transcription factors in the ponerine ant, Harpegnathos saltator β -葡聚糖调控抗瘤免疫应答的新机制 介孔介晶氧化铈基稀土氧化物材料的...