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. ***
