Hoshino Yumi, Sato Eimei
Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
Dev Biol. 2008 Feb 1;314(1):215-23. doi: 10.1016/j.ydbio.2007.12.005. Epub 2007 Dec 15.
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).
Akt，也被称为蛋白激酶B，参与许多细胞过程。Akt在两个位点（Thr308和Ser473）被磷酸化。Thr308磷酸化的Akt存在于中心粒周围物质中，而Ser473磷酸化的Akt在中期卵母细胞中的定位与微管相似。在用Thr308或Ser473磷酸化的Akt抗体注射的卵母细胞中，纺锤体较短且异常。具体而言，Thr308和Ser473磷酸化的Akt分别发挥作用，且二者对于组装中期II（MII）纺锤体都是必需的。此外，Thr308和Ser473磷酸化的Akt在MII卵母细胞中的功能不同。尽管在注射针对Thr308的肽后卵母细胞出现了第二极体（PB2）排放，但染色体排列和微管组织异常。相反，注射针对Ser473的肽导致PB2排放失败。这些结果表明，Thr308和Ser473磷酸化的Akt分别参与受精以完成减数分裂，包括不同的作用（即Ser473磷酸化的Akt参与PB2排放，而Thr308磷酸化的Akt调节微管的组织）。
