THE DISTINCT AND DEVELOPMENTALLY-REGULATED PATTERNS OF EXPRESSION OF MEMBERS OF THE MOUSE CDC25 GENE FAMILY SUGGEST DIFFERENTIAL FUNCTIONS DURING GAMETOGENESIS

Cdc25 genes encode protein threonine/tyrosine phosphatases that activa te cyclin-dependent kinases. A cDNA encoding the murine homologue of t he human Cdc25C gene was isolated in studies designed to identify thos e genes involved in regulating the mitotic and meiotic cell cycles of developing mouse germ cells. Northern blot and in situ hybridization a long with immunoblot analyses were performed to determine the patterns of expression of Cdc25C compared to those of a second Cdc25 family me mber, Cdc25B. Murine Cdc25C transcripts of 2.1 kb were detected in mid gestation embryos and in several adult tissues, including testis and o vary. The highest levels of Cdc25C transcripts were detected in the te stis, with low levels of the 2.1-kb transcript and abundant levels of a 1.9-kb transcript that was not detected in the other tissues examine d. In the testis, Cdc25C expression was localized in germ cells, speci fically in late pachytene-diplotene spermatocytes and round spermatids , whereas Cdc25B expression was most readily detected in the somatic c ells. In the ovary, Cdc25C expression was apparent in cumulus granulos a cells, whereas the expression of Cdc25B was detected in both growing oocytes and somatic cells, including the granulosa cells. These resul ts not only indicate that the expression of the murine Cdc25 genes is lineage- and developmental stage-specific in the mouse testis and ovar y but also suggest that the Cdc25 genes may have different functions i n the germinal and somatic compartments of the ovary and the testis, o nly some of which are involved in cellular proliferation. (C) 1995 Aca demic Press, Inc.