Gene Expression in Endocrine Tissues
(W489) GENE EXPRESSION DURING THE PERI-FOLLICULOGENIC PERIOD IN THE NEONATAL HAMSTER OVARY.
Bowser, Jessica1, Srikanthan, Sowmya1, Hendry, William1, May, Jeffrey1, 1 Wichita State University, Wichita, KS
ABSTRACT- Mammalian ovarian organogenesis is characterized temporally by oogonial mitosis, oogonial apoptosis, rescue of germ cells via interaction with somatic cells to form primordial follicles, and entrance into meiosis. Recent studies suggest that germ cells activity participate in this process via the production of local regulatory factors. Growth differentiation factor-9 (GDF-9), a novel transforming growth factor-b family member, has been shown to be expressed in ovaries of various species as a crucial factor in ovarian follicular development. Likewise, the transcription factor, germ cell nuclear factor (GCNF), an orphan member of the nuclear receptor family has introduced itself as possible candidate in the regulation and development of the early mammalian ovary. Current data has shown GCNF to suppress the expression of GDF-9 and Oct-4, a transcription factor restricted to stem cells including the germ cell line. Recently, our lab has become interested in the pattern of expression associated with GDF-9, GCNF, and Oct-4 as it pertains to ovarian organogenesis and follicle formation in the neonatal hamster ovary due to the ability to obtain ovaries at specific stages of follicular organization. Consensus oligonucleotide primer pairs spanning at least one intron for GDF-9, GCNF, and Oct4 were determined by analysis of the gene sequences for human, mouse, rat, bovine and pig for use in the hamster. mRNA for these factors in the hamster ovary were detected by RT/PCR using total RNA. mRNA for GDF-9, GCNF, and Oct-4 was detected at all days examined (days 1, 3, 5 and 6-9 post delivery, day 0). This time frame reflects periods of active oogonial mitosis (days 1 and 3), oogonial atresia (day 5), and primordial follicle formation (days 6-9). Reports have suggested that GCNF represses Oct-4 and GDF-9 in the oocyte and that GDF-9 is not expressed in primordial follicles. Our results suggest that GDF-9 is expressed in oogonia both prior to and during primordial follicle formation. Continuous expression of GDF-9 along with GCNF and Oct-4 likely reflects differential cellular expression of GDF-9/Oct-4 (oogonia/oocyte) and GCNF (somatic pre-granulosa cells). (Support: NIH Grant 1R15ES012182-01 to JVM).
KEY WORDS: ovary, neonatal, GDF-9, GCNF