MEK1/2 regulates microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte meiotic maturation.
It is well known that MAPK plays pivotal roles in oocyte maturation, but the function of MEK (MAPK kinase) remains unknown. We have studied the expression, subcellular localization and functional roles of MEK during meiotic maturation of mouse oocytes. Firstly, we found that MEK1/2 phoshorylation (p-MEK1/2, indicative of MEK activation) was low in GV (germinal vesicle) stage, increased 2h after GVBD (germinal vesicle breakdown), and reached the maximum at metaphase II. Secondly, we found that P-MEK1/2 was restricted in the GV prior to GVBD. In prometaphase I and metaphase I, P-MEK1/2 was mainly associated with the spindle, especially with the spindle poles. At anaphase I and telophase I, p-MEK1/2 became diffusely distributed in the region between the separating chromosomes, and then became associated with the midbody. The association of p-MEK1/2 with spindle poles was further confirmed by its colocalization with the centrosomal proteins, gamma-tubulin and NuMA. Thirdly, we have investigated the possible functional role of MEK1/2 activation by intravenous administration and intrabursal injection of a specific MEK inhibitor, U0126, and by microinjection of MEK siRNA into oocytes. All these manipulations cause disorganized spindle poles and spindle structure, misaligned chromosomes and larger than normal polar bodies. Our results suggest that MEK1/2 may function as a centrosomal protein and may have roles in microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte maturation.
Yu
Ling-Zhu
LZ
State Key Laboratory of Reproductive Biology, Institute of Zoology, Graduate School, Chinese Academy of Sciences, Beijing, China.
Xiong
Bo
B
Gao
Wen-Xue
WX
Wang
Chun-Min
CM
Zhong
Zhi-Sheng
ZS
Huo
Li-Jun
LJ
Wang
Qiang
Q
Hou
Yi
Y
Liu
Kui
K
Liu
X Johné
XJ
Schatten
Heide
H
Chen
Da-Yuan
DY
Sun
Qing-Yuan
QY
D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D005260:Female; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000235:genetics / Q000378:metabolism*; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D008813:Mice, Inbred ICR; D018613:Microscopy, Confocal; D008870:Microtubules / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D015739:Nocodazole / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009866:Oogenesis / Q000187:drug effects; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism*
D002070:Butadienes; D009570:Nitriles; C113580:U 0126; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D017239:Paclitaxel; D015739:Nocodazole