ABSTRACT
Objective To observe the protein expression , subcelluar localization of activated Pak 1 and its relation-ship with chromosome separation during meiosis in mouse oocytes .Methods Western blot was applied to analyze the expression of activated Pak1 (phosphorylated Pak1 at Ser204, pPak1Ser204 ) at different stages of meiotic progres-sion in semi-quantitative manner;immunofluorescent staining was employed to detect the sub-cellular localization of pPak1Ser204 and its spatial-temporal correlation with spindle and microtubule organizing centers (MTOC) during oo-cyte meiosis.Results pPak1Ser204 expression was found upon germinal vesicle breakdown (GVBD) in mouse oo-cytes which increased along with the meiotic progression , reaching peak level at metaphase Ⅰ( MⅠ) , which re-mained up to meiosis Ⅱ(MⅡ).From pro-metaphase Ⅰ(pro-MⅠ) to MⅠand at MⅡstage, pPak1Ser204was co-localized with MTOC key components , pericentrin and γ-tubulin on spindle poles, pPak1Ser204 was also distributed on chromosomes;During anaphase Ⅰ(AⅠ) to telophase Ⅰ(TelⅠ) progression, pPak1Ser204 was detached from chromosomes and MTOC, and mainly concentrated on the cleavage furrow.Conclusions pPak1Ser204 is expressed upon meiotic resumption in oocytes .It is a MTOC-associated protein which may regulate chromosome separation through participating the formation and maintenance of spindle apparatus .