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MEK1/2 is a critical regulator of microtubule assembly and spindle organization during rat oocyte meiotic maturation
Author(s) -
Sun ShaoChen,
Xiong Bo,
Lu ShengSheng,
Sun QingYuan
Publication year - 2008
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.20891
Subject(s) - biology , oocyte , meiosis , microbiology and biotechnology , microtubule , regulator , genetics , embryo , gene
MEK (MAPK kinase) is an upstream protein kinase of MAPK in the MOS/MEK/MAPK/p90rsk signaling pathway. We previously reported the function and regulation of MAPK during rat oocyte maturation. In this study, we further investigated the localization and possible roles of MEK1/2. First, immunofluorescent staining revealed that p‐MEK1/2 was restricted to the germinal vesicle (GV). After germinal vesicle breakdown (GVBD), p‐MEK1/2 condensed in the vicinity of chromosomes and then translocated to the spindle poles at metaphase I, while spindle microtubules stained faintly. When the oocyte went through anaphase I and telophase I, p‐MEK1/2 disappeared from spindle poles and became associated with the midbody. By metaphase II, p‐MEK1/2 was again localized to the spindle poles. Second, p‐MEK1/2 was localized to the centers of cytoplasmic microtubule asters induced by taxol. Third, p‐MEK1/2 co‐localized with γ‐tubulin in microtubule‐organizing centers (MTOCs). Forth, treatment with U0126, a non‐competitive MEK1/2 inhibitor, did not affect germinal vesicle breakdown, but caused chromosome mis‐alignment in all MI oocytes examined and abnormal spindle organization as well as small cytoplasmic spindle‐like structure formation in MII oocytes. Finally, U0126 reduced the number of cytoplasmic asters induced by taxol. Our data suggest that MEK1/2 has regulatory functions in microtubule assembly and spindle organization during rat oocyte meiotic maturation. Mol. Reprod. Dev. 75: 1542–1548 © 2008 Wiley‐Liss, Inc.