Translational Regulation During Meiosis in Starfish

9305407 Hille基因在卵母细胞和卵子中的表达受翻译调控。未成熟的卵母细胞储存非活性的mRNAs、翻译起始因子和核糖体，在卵母细胞成熟和胚胎发育的早期卵裂阶段使用。在激素刺激下，未成熟卵母细胞经历减数分裂，翻译率增加，翻译专一性从支持生长的mRNAs切换到经历快速细胞分裂的mRNAs。在许多动物中，包括哺乳动物、青蛙和海星，减数分裂和受精是协调的，发生在减数分裂II，在第一极体被挤出之后。希尔博士之前的研究重点是阐明在成熟过程中激活翻译装置的机制。她已经证明，在向海星卵母细胞添加成熟激素20分钟后，启动因子eIF-4E被磷酸化，同时转化率增加。她现在提议克隆海星eIF-4E，这样她就可以确定被磷酸化的氨基酸位置。有了克隆的底物，她将在一连串的减数分裂事件中向后移动，寻找使这一起始因子磷酸化的激酶。这项研究将有两个方面：与Steven Pelech博士合作提纯海星细胞质，测试eIF-4E激酶活性，并试图筛选表达文库，寻找使海星eIF-4E磷酸化的激酶。海星eIF-4E激酶的克隆引起了人们的普遍兴趣，因为在体内负责eIF-4E磷酸化的激酶对任何生物体都是未知的。这一建议是启动细胞生长和发育的信号转导途径的原型，并将增加我们对环境刺激后eIF-4E如何激活翻译的基本理解，以及我们对动物卵母细胞激素激活的一般理解。***

9305407 Hille Gene expression is regulated by translational control in oocytes and eggs. Immature oocytes store inactive mRNAs, translational initiation factors, and ribosomes, to be used during maturation of the oocyte and during the early cleavage stages of embryogenesis. On hormonal stimulation, immature oocytes undergo meiosis, translational rates increase, and the translational specificity switches from mRNAs that support growth to those that undergo rapid cell divisions. In many animals, including mammals, frogs, and starfish, meiosis and fertilization are coordinated with fertilization occurring in meiosis II, after the first polar body is extruded. Dr. Hille's previous research focused on elucidating mechanisms that activate the translational apparatus during maturation. She has shown that initiation factor eIF-4E is phosphorylated 20 minutes after addition of the maturation hormone to starfish oocytes, at the same time that the translation rate increases. She now proposes to clone starfish eIF-4E so she can determine the amino acid site that is phosphorylated. With the cloned substrate in hand, she will move backward in the cascade of meiotic events, searching for kinases that phosphorylate this initiation factor. This search will have two prongs: purifying starfish cytoplasm in collaboration with Dr. Steven Pelech and testing for eIF-4E kinase activity, and trying to screen expression libraries for a kinase that phosphorylates the starfish eIF-4E. The cloning of the starfish eIF-4E kinase is of general interest since the kinase responsible for phosphorylation of eIF-4E in vivo is not known for any organism. This proposal is a prototype of a signal transduction pathway that initiates growth and development of cells and will increase our basic understanding of how translation is activated through eIF-4E after environmental stimulation, and our general understanding of hormone activation of animal oocytes. ***