简介:Atransientpostanaphaserepositioningofthecentrioleisfoundtocontrolthecompletionofcytokinesis.Usingagreenfluorescentprotein-calmodulinfusionproteinasalivingcellprobe,wehavepreviouslyfoundthatcalmodulinisassociatedwiththeinitiationandprogressionofcytokinesis.Inthisstudy,wefurtherstudiedtheeffectofcalmodulinontherepositioningofthecentrioleandsubsequentcellcycleprogression.Whenactivityofcalmodulinisinhibited,theregressionofthecentriolefromtheintercellularbridgetothecellcenterisblocked,andthusthecompletionofcelldivisionisrepressedandtwodaughtercellsarelinkedbylongercellbridgeinperturbedcells.W7treatmentduringcytokinesisalsoresultsinunfinishedcytokinesisandstoppedG1phase.Theseresultssuggestthatcalmodulinactivityisrequiredforcentriolerepositioningandcanaffectthecompletionofcytokinesisandcellcycleprogression.
简介:ProteinkinaseRAFisstrategicallylocatedinthe'Ras-MAP-kinasesignaltransductionpathway',aprinciplesystemwhichtransmitssignalsfromgrowthfactorreceptorstothenucleus,resultingincellproliferation.GrowthfactorresponsesaremediatedinpartbyactivationofRas,whichinturnactivatesRAFtophosphorylateMEK,itsdownstreamsubstrate.MEKactivatesMAPkinasetoinfluencenuclearevents.itisclear.however,thatanetworkofsignalsotherthanthosecarredbyRasplaysaroleinRAFregulation.Theseorthogonalinfluencesaremediatedbu:serine/threoninekinases,tyrosinekinases,andprotein-proteininteractions.AsafurthercomplicationtotheRAFnetwork,threeisoformsofRAFhavebeenestablishedwhichhavedivergentN-terminalregulatorydomains,Whereasthesedivergentregulatorydomainsimplicateisoform-specificfunctions,noclearevidenceorhypothesisfordistinctfunctionsforindividualisoformshasbeenpresented.Recently,'isoform-specificproteininteractions'havebeenidentifiedamongnumerousproteinsinteractingwithRAF,ThesestudiesmayservetodelineateindependentfunctionsforRAFisoforms.
简介:Expressionoftheadhesionmolecules,ICAM-1,VCAM-1,NCAM,CD44,CD49d(VLA-4,αchain),andCDlla(LFA-1,αchain)onmouseoocytes,andpre-andperi-implantationstageembryoswasexam-inedbyquantitativeindirectimmunoliuorescencemicroscopy.ICAM-1wasmoststronglyexpressedattheoocytestage,graduallydecliningalmosttoundetectablelevelsbytheexpandedblastocyststage.NCAM,alsoexpressedmaximallyontheoocyte,declinedtoundetectablelevelsbeyondthemorulastage.Ontheotherhand,CD44declinedfromhighestexpressionattheoocytestagetoshowasecondmaximumatthecompacted8-cell/morula.Thismoleculeexhibitedhighexpressionaroundcontactareasbetweentrophecto-dermandzonapellucidaduringblastocysthatching.CD49dwashighlyexpressedintheoocyte,remainedsignificantlyexpressedthroughoutandafterblastocysthatchingwasexpressedonthepolartrophecto-derm.LikeCD44,CD49ddeclinedtoundetectablelevelsattheblastocystoutgrowthstage.ExpressionofbothVCAM-1andCDllawasundetectablethroughout.ThediametricaltemporalexpressionpatternofICAM-1andNCAMcomparedtoCD44andCD49dsuggestthatdynamicchangesinexpressionofadhesionmoleculesmaybeimportantforinteractionoftheembryowiththematernalcellularenvironmentaswellasforcontinuingdevelopmentandsurvivaloftheearlyembryo.