Mitotic cell cycle genes have been the focus of intense research as investigators attempt to unravel the links between the normal cell cycle and the development of cancer in humans. However, the regulation of meiosis by these and other cell cycle genes has been virtually ignored until recently. In yeast, most of the same genes required for regulating the mitotic cell cycle are required for meiosis, although their exact functions in meiosis remain largely unknown. Determining the roles of these genes in meiosis will improve the current understanding of the functions of their protein products in the mitotic cell cycle. In addition, studying the regulation of meiosis will improve the understanding of this """"""""other"""""""" cell division process, which has obvious links to human infertility and birth defects. This proposal is specifically directed at studying the meiotic roles of CDC7 and DBF4, two genes known to be required for the initiation of DNA replication in the mitotic cell cycle. Very little work has been done to characterize their roles in meiosis, leaving a gap in the knowledge of the regulation of meiosis in general, and of the function of these two gene products in the meiotic cell in particular. First, the meiotic phenotype of mutations in these two genes will be carefully analyzed for their abilities to undergo the major events of meiosis: premeiotic DNA replication, recombination, the two divisions, and asci formation. Temperature sensitive alleles of the CDC7 and DBF4 genes will be tested, as well as deletion alleles of these genes taking advantage of the bob1 suppressor mutation. Second, it is clear that the Cdc7 and Dbf4 proteins interact during GI/S of the mitotic cell cycle. This interaction will be examined in meiosis using high-copy suppression and coimmunoprecipitation experiments. Third, Cdc7 protein is expressed at constant levels during the mitotic cell cycle but Dbf4 is expressed only at GI/S. Expression of the Cdc7 and Dbf4 proteins will be examined throughout meiosis, and peaks of expression will be correlated with the major meiotic events. Fourth, a screen will be done to isolate high-copy suppressors of the cdc7-1 temperature sensitive mutation. By performing these experiments, the role of, and interaction between the CDC7 and DBF4 gene products will be elucidated. In addition, other proteins that interact with the Cdc7 protein during meiosis will be identified so that their relationships can be ultimately characterized as well.
