title: Possible involvement of mitogen- and stress-activated protein kinase 1, MSK1, in metaphase-II arrest through phosphorylation of EMI2 in mouse oocytes.
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.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8572, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Miyagaki
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8572, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kanemori
authors.affiliation: 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.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Baba
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D044783:F-Box Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008677:Metaphase; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D017931:DNA Primers; C509434:Emi2 protein, mouse; D044783:F-Box Proteins; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C116919:mitogen and stress-activated protein kinase 1