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Dev Biol. 2011 Nov 1;359(1):73-81. doi: 10.1016/j.ydbio.2011.08.021. Epub 2011 Sep 5.

Possible involvement of mitogen- and stress-activated protein kinase 1, MSK1, in metaphase-II arrest through phosphorylation of EMI2 in mouse oocytes.

Author information

1
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8572, Japan.
2
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8572, Japan. Electronic address: acroman@sakura.cc.tsukuba.ac.jp.

Abstract

Ovulated oocytes are arrested at the metaphase of second meiotic division. The metaphase-II arrest in Xenopus oocytes is regulated by RSKs located downstream of the Mos-MAPK pathway. In mice, other kinase(s) besides RSKs may be responsible for the metaphase-II arrest, because RSK1/RSK2/RSK3-triple knockout mice exhibit no obvious phenotype. Here, we show the subcellular localization and possible role of mitogen- and stress-activated kinase 1, MSK1 known as another downstream kinase of the Mos-MAPK pathway, in the mouse oocytes. Immunostaining analysis indicated that MSK1 is present in the germinal vesicle (GV) and cytoplasm of oocytes at the GV and metaphase-II stages, respectively. An active, phosphorylated form of MSK1 was predominantly localized to the metaphase-II spindle. The inhibition of the MSK1 activity failed to maintain the sister chromatid alignment within the metaphase-II plate. Importantly, MSK1 exhibited the ability to phosphorylate four Ser/Thr residues of meiotic cell-cycle regulator EMI2. The phosphorylation was required for up-regulation of the EMI2 activity in the oocytes. These results suggest that mouse MSK1 may play a key role in the metaphase-II arrest through phosphorylation of EMI2.

PMID:
21924255
DOI:
10.1016/j.ydbio.2011.08.021
[Indexed for MEDLINE]
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