PtdIns(3,4,5)P3 is constitutively synthesized and required for spindle translocation during meiosis in mouse oocytes
PtdIns(3,4,5)P3 is constitutively synthesized and required for spindle translocation during meiosis in mouse oocytes
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DOI：
10.1242/jcs.118042
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发表时间：
2013-02
影响因子：
4
通讯作者：
P. Zheng;B. Baibakov;Xi-hong Wang;J. Dean
中科院分区：
文献类型：
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作者：
P. Zheng;B. Baibakov;Xi-hong Wang;J. Dean
哺乳动物卵母细胞在排卵前完成第一次减数分裂并停滞在中期II。在这种明显的不对称细胞分裂过程中，减数分裂纺锤体从卵母细胞中心急剧移动到皮质，以促进其染色体内容物的一半分离到微小的第一极体中。最近的研究表明，丝状肌动蛋白（F-actin）在减数分裂纺锤体易位中起着重要作用。然而，对这些精心策划的运动负责的上游监管机构的身份仍然难以捉摸。利用荧光标记的探针和延时共聚焦显微镜，我们的文件，磷脂酰肌醇3，4，5-三磷酸[PtdIns（3，4，5）P3]组成合成的空间和时间动力学类似的F-肌动蛋白和形成蛋白2（Fmn 2）。磷脂酰肌醇3-激酶（PI 3 K）的特异性抑制剂LY 294002阻断PtdIns（3，4，5）P3的合成，破坏细胞质F-肌动蛋白的组织结构和减数分裂纺锤体向皮质的迁移。F-actin成核剂Fmn 2和Rho GTdR Cdc 42在介导PtdIns（3，4，5）P3对F-actin组装的影响中起作用。此外，PtdIns（3，4，5）P3的空间和时间动力学受到MATER或Filia（由母体效应基因编码的两种卵母细胞蛋白质）耗竭的损害。因此，PtdIns（3，4，5）P3在减数分裂成熟过程中合成，并在Cdc 42和Fmn 2的上游，但在MATER/Filia蛋白的下游起作用，以调节小鼠卵母细胞减数分裂过程中F-肌动蛋白的组织和纺锤体向皮质的移位。
Summary Prior to ovulation, mammalian oocytes complete their first meiotic division and arrest at metaphase II. During this marked asymmetric cell division, the meiotic spindle moves dramatically from the center of the oocyte to the cortex to facilitate segregation of half of its chromosomal content into the diminutive first polar body. Recent investigations have documented crucial roles for filamentous actin (F-actin) in meiotic spindle translocation. However, the identity of the upstream regulators responsible for these carefully orchestrated movements has remained elusive. Utilizing fluorescently tagged probes and time-lapse confocal microscopy, we document that phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] is constitutively synthesized with spatial and temporal dynamics similar to that of F-actin and Formin 2 (Fmn2). Blockage of PtdIns(3,4,5)P3 synthesis by LY294002, a specific inhibitor of phosphoinositide 3-kinase (PI3K), disrupts cytoplasmic F-actin organization and meiotic spindle migration to the cortex. F-actin nucleator Fmn2 and Rho GTPase Cdc42 play roles in mediating the effect of PtdIns(3,4,5)P3 on F-actin assembly. Moreover, the spatial and temporal dynamics of PtdIns(3,4,5)P3 is impaired by depletion of MATER or Filia, two oocyte proteins encoded by maternal effect genes. Thus, PtdIns(3,4,5)P3 is synthesized during meiotic maturation and acts upstream of Cdc42 and Fmn2, but downstream of MATER/Filia proteins to regulate the F-actin organization and spindle translocation to the cortex during mouse oocyte meiosis.