title: The Mos-MAPK pathway regulates Diaphanous-related formin activity to drive cleavage furrow closure during polar body extrusion in starfish oocytes.
abstract: Maintenance of spindle attachment to the cortex and formation of the cleavage furrow around the protruded spindle are essential for polar body extrusion (PBE) during meiotic maturation of oocytes. Although spindle movement to the cortex has been well-studied, how the spindle is maintained at the cortex during PBE is unknown. Here, we show that activation of Diaphanous-related formin mediated by mitogen-activated protein kinase (MAPK) is required for tight spindle attachment to the cortex and cleavage furrow closure during PBE in starfish (Asterina pectinifera) oocytes. A. pectinifera Diaphanous-related formin (ApDia) had a distinct localization in immature oocytes and was localized to the cleavage furrow during PBE. Inhibition of the Mos-MAPK pathway or the actin nucleating activity of formin homology 2 domain prevented cleavage furrow closure and resulted in PBE failure. In MEK/MAPK-inhibited oocytes, activation of ApDia by relief of its intramolecular inhibition restored PBE. In summary, this study elucidates a link between the Mos-MAPK pathway and Diaphanous-related formins, that is responsible for maintaining tight spindle attachment to the cortex and cleavage furrow closure during PBE.
authors.affiliation: Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
authors.forename: Hasan
authors.initials: H
authors.lastname: Ucar
authors.forename: Kazunori
authors.initials: K
authors.lastname: Tachibana
authors.forename: Takeo
authors.initials: T
authors.lastname: Kishimoto
mesh_terms: D000818:Animals; D008540:Meiosis; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D059705:Polar Bodies / Q000166:cytology / Q000378:metabolism; D017231:Proto-Oncogene Proteins c-mos / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000235:genetics*; D013215:Starfish
chemical_list: D009419:Nerve Tissue Proteins; D017231:Proto-Oncogene Proteins c-mos; D020929:Mitogen-Activated Protein Kinase Kinases
keywords: Cleavage furrow; Diaphanous-related formin; Meiosis; Mos–MAPK; Polar body extrusion