title: Protein kinase B (PKB/Akt) is required for the completion of meiosis in mouse oocytes.
abstract: Akt, also known as protein kinase B, is implicated in many cellular processes. Akt is phosphorylated at two residues, Thr308 and Ser473. Thr308-phosphorylated Akt is present in pericentriolar materials, while localization of Ser473-phosphorylated Akt was similar to that of microtubules in metaphase oocytes. Spindles were shorter and aberrant in oocytes injected with Thr308- or Ser473-phosphorylated Akt antibodies. Specifically, Thr308- and Ser473-phosphorylated Akts function individually and are both necessary to assemble the metaphase II (MII) spindle. Moreover, the functions of Thr308- and Ser473-phosphorylated Akts differ in MII oocytes. Although oocytes exhibited second polar body (PB2) emission after the injection of a peptide for Thr308, the chromosomal alignment and microtubular organization were aberrant. In contrast, the injection of a peptide for Ser473 caused a failure of PB2 emission. These results suggest that Thr308- and Ser473-phosphorylated Akts are individually involved in fertilization to complete meiosis, including different roles (i.e., Ser473-phosphorylated Akts are involved in PB2 emission, whereas Thr308-phosphorylated Akts regulate the organization of microtubules).
authors.affiliation: Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan. hoshimi@bios.tohoku.ac.jp
authors.forename: Yumi
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Eimei
authors.initials: E
authors.lastname: Sato
mesh_terms: D000818:Animals; D005306:Fertilization / Q000502:physiology; D008540:Meiosis / Q000502:physiology*; D051379:Mice; D008870:Microtubules / Q000502:physiology; D009865:Oocytes / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D051057:Proto-Oncogene Proteins c-akt