Intracelllar Signaling During the Meiotic Maturation of Starfish Oocytes: Are PKN and Rho activated?

动物卵母细胞在其生长过程中储存着减数分裂、受精和受精后卵子快速分裂所需的蛋白质和信使rna。卵母细胞生长后通常停留在减数分裂的前期，直到被成熟激素刺激，在减数分裂成熟过程中激活储存的成分。由于储存的蛋白质和信使RNA的可用性，在任何动物胚胎的减数分裂成熟过程中都不会发生新的信使RNA的转录。在减数分裂成熟过程中，许多复杂的生物学途径中的蛋白质被激活，包括成熟促进因子（MPF），它导致核膜的破坏和染色体的减数分裂减少；刺激蛋白质合成的蛋白质；以及招募储存的mrna所需的那些。这一建议涉及到刺激卵母细胞成熟的储存蛋白的激活。本实验室发现了一种蛋白激酶c样活性，它出现在MPF活性之前，也出现在蛋白质合成率增加之前，可能代表了成熟的海星卵母细胞中最早激活的酶之一。本实验室已克隆出一种蛋白激酶c相关酶，该酶是哺乳动物PKN基因的同源物，在海星卵母细胞中有丰富的转录本。其他实验室的实验表明，哺乳动物PKN在体外和体内由不饱和脂肪酸激活，而不是由蛋白激酶C家族的传统磷酸酯激活剂激活。本基金申请假设海星卵母细胞中早期蛋白激酶c相关活性是由于海星PKN。本研究旨在确定：PKN是否存在于未成熟卵母细胞中，在减数分裂成熟过程中何时被激活，PKN的功能及其激活机制。本研究获得的信息将扩大对卵母细胞成熟激活信号转导途径的认识，并将作为细胞分化信号转导途径的原型。这项研究正在研究在海星卵母细胞成熟过程中重要的储存蛋白的激活。这位研究者正在研究她实验室发现的一种酶，这种酶与一种已知的哺乳动物酶有相似之处，这种酶在信号转导途径中很重要。本研究将为研究卵母细胞发育的信号机制提供新的信息。＊＊＊

Abstract 9723231 Hille The animal ooctye during its growth stores proteins and messenger RNAs that are required for meiosis, fertilization and the rapid cleavages of the egg that follows fertilization. After growth oocytes are usually arrested in prophase I of meiosis until stimulated by a maturation hormone that activates the stored components in a process called meiotic maturation. Because of the availability of stored proteins and messenger RNA, no transcription of new messerger RNA occurs during meiotic maturation of any animal embryo. Proteins in many complex biological pathways are activated during meiotic maturation including the maturation promotion factor (MPF), which leads to the breakdown of the nuclear membrane and the meiotic reduction of chromosome; proteins that stimulate protein synthesis; and those that are required to recruit stored mRNAs. This proposal is concerned with the activation of stored proteins that stimulate oocyte maturation. This laboratory had identified a protein kinase C-like activity, which appears prior to MPF activity and prior to the increase in protein synthesis rates, and possibly represents one of the earliest enzymes activated in the maturing starfish oocyte. A protein kinase C-related enzyme that is a homologue of mammalian PKN gene and has abundant transcripts in starfish oocytes, has been cloned by this laboratory. Experiments by other laboratories suggest that mammalian PKN is activated by unsaturated fatty acids in vitro and by Rho in vivo, and not by the traditional phorbol ester activators of the protein kinase C family. This grant application hypothesizes that the early protein kinase C-related activity in the starfish ooctyes is due to starfish PKN. The research aims to determine: whether PKN is present in immature oocytes, when it is activated during meiotic maturation, the function of PKN, and the mechanisms for its activation. Information gained from this research will expand the knowled ge of signal transduction pathways for the activation of maturation in oocytes, and will serve as a prototype of a signal transduction pathway in differentiating cells. %%% This research is studying the activation of stored proteins that are important in the maturation of starfish oocytes. This investigator is looking at an enzyme identified in her laboratory, which has similarities to a known mammalian enzyme which is important in signal transduction pathways. This research will provide new information on the signaling mechanisms in oocyte development. ***