The Role Of TTP During Mouse Oocyte Development

Tristetraprolin(TTP),a member of TIS11 family containing Cys-Cys-Cys-His(CCCH)tandem zinc finger,is the founding member of a family of proteins containing tandem CCCH zinc fingers and one of the best characterized RNA-binding proteins.TTP can bind to AU-rich elements(AREs)located in the 3’ untranslated regions(3’UTR)of mRNA,remove the poly(A)tail,playing an important role in posttranscriptional regulation.However,to date,the role of TTP in mammalian oocytes remains completely unknown.In the present study,we report the altered maturational progression and cytokinesis,upon specific knockdown of TTP in mouse oocytes.Furthermore,we used immunofluoresence,chromosome spread and confocal scanning technology to study the functions of TTP in cytoskeletal organization during mouse oocyte maturation.In addition,we established TTP conditional knockout mouse model to explore the role of TTP during mouse oocyte development.1 The role of TTP in mouse oocyte maturation in vitroIn present study,we first examined the distribution of TTP during mouse oocyte maturation by immunostaining.The results showed the presence of TTP in oocytes at different developmental stages.TTP accumulate in the nucleus at GV stage.Accompany with resumption of meiosis,TTP appears to be colocalized with the chromosome from pre-metaphase Ⅰ to metaphase Ⅱ stages.Next,to investigate the influence of TTP-deficiency on oocyte maturation,we microinjected TTP-specific siRNA into fully-grown oocytes,we observed the altered maturational progression and cytokinesis,the proportion of first polar body(Pb1)was decreased compared with control ones(P<0.05).Furthermore,by confocal scanning,we observed the failure to form cortical actin cap during meiosis of TTP-depleted ooytes.Loss of TTP in oocytes also results in disruption of meiotic spindle morphology and chromose alignment.In support of these findings,incidence of aneuploidy is accordingly increased when TTP is abated in oocytes.Our results suggest that TTP as a novel cytoskeletal regulator is required for spindle morphology/chromosome alignment and actin polymerization in oocytes.2 The effects of conditional knockout of TTP during mouse oocyte developmentIn order to further explore the role of TTP in vivo,we used TTP conditional knockout mouse(TTPf/f ZP3Cre+)generated by Cre-LoxP system.Our preliminary data showed that oocyte specific knockout TTP seemed to have little effects on the fertility of female mice.Our ongoing research is to construct TTPf/f VasaCre+ mice to further examine the effects of TTP on oocyte development in vivo.