Expression of growth differentiation factor 9 in the oocytes is essential for the development of primordial follicles in the hamster ovary.
Postnatal growth differentiation factor 9 (GDF-9) expression in the hamster oocytes precedes the formation of primordial follicles. We examined the functional significance of GDF-9 in primordial folliculogenesis in the hamster ovary using RNA interference knockdown of GDF-9 mRNA and protein expression. Fifteen-day-old fetal ovaries were cultured for 9 d with or without 1 ng FSH, 1 microl Metafectane, 100 nM control nontargeting small interfering RNA (siRNA), GDF-9 siRNA, or GDF-9 siRNA + FSH, and the development of primordial follicles examined. The efficiency of siRNA transfecting ovarian cells in the organ culture was tested by culturing ovaries with siGlo, a nontargeting control siRNA labeled with Cy3. More than 90% of cells in the ovary were siGlo positive, and neither the Metafectane nor the siRNA-induced cellular apoptosis. Control siRNA did not affect the basal levels of GDF-9 mRNA, but GDF-9 siRNA slightly but significantly reduced the level. FSH markedly up-regulated the levels of GDF-9 mRNA and protein, and the effect was completely suppressed by GDF-9 siRNA. However, GDF-9 siRNA did not affect the levels of bone morphogenetic protein receptor IA or beta-actin mRNA. GDF-9 siRNA alone also reduced GDF-9 protein expression. Concurrent with GDF-9 expression, FSH significantly augmented primordial follicle formation, but the effect was abolished by GDF-9 siRNA. These results suggest that endogenous GDF-9 plays an important role in somatic cell differentiation and the formation of primordial follicles. Furthermore, FSH, by virtue of regulating GDF-9 expression, modulates oocyte regulation of primordial follicles formation.
Wang
Cheng
C
Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, 68198-4515, USA.
Roy
Shyamal K
SK
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D006224:Cricetinae; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D055429:Growth Differentiation Factor 9; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D008297:Male; D008647:Mesocricetus; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D006080:Ovarian Follicle / Q000196:embryology* / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology
D055429:Growth Differentiation Factor 9; D036341:Intercellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D005640:Follicle Stimulating Hormone