Johnson A D, Cork R J, Williams M A, Robinson K R, Smith L D
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
Cell Regul. 1990 Jun;1(7):543-54. doi: 10.1091/mbc.1.7.543.
Microinjection of H-ras(val12) protein into fully grown Xenopus oocytes has been shown to induce meiotic maturation. In the present study, mRNA encoding the mutant ras protein was injected into both fully grown (stage 6) and growing (stage 4) oocytes. The mRNA induced nuclear breakdown in stage 6 oocytes, as expected. However, the mRNA induced neither nuclear breakdown nor maturation promoting factor when injected into stage 4 oocytes. Instead, the response in stage 4 oocytes included an activation pulse of calcium, cortical granule breakdown, elevation of the vitelline envelope, and abortive cleavage furrows, all of which are characteristics of the activation response in mature eggs. In addition, the injected mRNA led to increased rates of endogenous protein synthesis and the migration of subcortical organelles into the oocyte interior. These observations are discussed relative to the suggestion that oncogenic ras protein leads to an increase in both diacylglycerol and inositol trisphosphate, which then regulate the various cytoplasmic events described.
已证明将H-ras（val12）蛋白显微注射到完全成熟的非洲爪蟾卵母细胞中可诱导减数分裂成熟。在本研究中，将编码突变型ras蛋白的mRNA注射到完全成熟（6期）和正在生长（4期）的卵母细胞中。正如预期的那样，该mRNA在6期卵母细胞中诱导了核破裂。然而，当将该mRNA注射到4期卵母细胞中时，既未诱导核破裂，也未诱导成熟促进因子。相反，4期卵母细胞中的反应包括钙的激活脉冲、皮质颗粒破裂、卵黄膜升高和不完全分裂沟，所有这些都是成熟卵激活反应的特征。此外，注射的mRNA导致内源性蛋白质合成速率增加以及皮质下细胞器向卵母细胞内部迁移。相对于致癌性ras蛋白导致二酰基甘油和肌醇三磷酸均增加，进而调节上述各种细胞质事件的观点，对这些观察结果进行了讨论。
