Functional redundancy of two C. elegans homologs of the histone chaperone Asf1 in germline DNA replication

摘要

EukaryoticgenomescontaineitheroneortwogenesencodinghomologsofthehighlyconservedhistonechaperoneAsf1,however,littleisknownoftheireminvivo/emrolesinanimaldevelopment.UNC-85isoneofthetwoemCaenorhabditiselegans/emAsf1homologsandfunctionsinpost-embryonicreplicationinneuroblasts.AlthoughUNC-85isbroadlyexpressedinreplicatingcells,thespecificityofthemutantphenotypesuggestedpossibleredundancywiththesecondemC.elegans/emAsf1homolog,ASFL-1.Theemasfl-1/emmRNAisexpressedinthemeioticregionofthegermline,andmutantsineitherAsf1geneshavereducedbroodsizesandlowpenetrancedefectsingametogenesis.Theemasfl-1,unc-85/emdoublemutantsaresterile,displayingdefectsinoogenesisandspermatogenesis,andanalysisofDNAsynthesisrevealedthatDNAreplicationinthegermlineisblocked.Analysisofsomaticphenotypespreviouslyobservedinemunc-85/emmutantsrevealedthattheyareneitherobservedinemasfl-1/emmutants,norenhancedinthedoublemutants,withtheexceptionofenhancedmaletailabnormalitiesinthedoublemutants.TheseresultssuggestthatthetwoAsf1homologshavepartiallyoverlappingfunctionsinthegermline,whileUNC-85isprimarilyresponsibleforseveralAsf1functionsinsomaticcells,andismoregenerallyinvolvedinreplicationthroughoutdevelopment./p/div