BackgroundInformation | HumanGlialFibrillaryAcidicProteindelta(GFAP-delta)isaGFAPproteinisoformthatisencodedbyanalternativesplicevariantoftheGFAP-gene.Asaresult,GFAP-deltaproteindiffersfromthepredominantspliceform,GFAP-alpha,byitsC-terminalproteinsequence.GFAP-deltaproteinisnotexpressedbyallGFAPexpressingastrocytesbutspecificallybyasubpopulationlocatedinthesubpialzoneofthecerebralcortex,thesubgranularzoneofthehippocampusand,mostintensely,byaribbonofastrocytesfollowingtheependymallayerofthecerebralventricles.Therefore,atleastinthesubventricularzone(SVZ),GFAP-deltaspecificallymarksthepopulationofastrocytesthatcontaintheneuralstemcellsintheadulthumanbrain.Interestingly,theSVZastrocytesactivelyspliceGFAP-deltatranscripts,incontrasttoastrocytesadjacenttothislayer.DatashowsthatGFAP-deltaprotein,unlikeGFAP-alpha,isnotupregulatedinastrogliosis.DataindicatesadifferentfunctionalroleforGFAP-deltainastrocytephysiology.TransfectionstudiesshowedthatGFAP-deltaproteinexpressionhasanegativeeffectonGFAPfilamentformation,andthereforecouldbeimportantformodulatingintermediatefilamentcytoskeletalproperties,possIBLyfacilitatingastrocytemotility.FurtherstudiesonGFAP-deltaandthecellsthatexpressitareimportantforgaininginsightsintoitsfunctionduringdifferentiation,migrationandduringhealthanddisease(Roelofs,RF,etal.,Glia(2005)52:289-300.). |