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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Nutrition, Growth and Physiology » Research » Publications at this Location » Publication #313979
Title: Granulosa cell cycle regulation and steroidogenesis in a high androstenedione follicular microenvironment

Author
item ROMEREIM, SARAH - University Of Nebraska
item SUMMERS, ADAM - New Mexico State University
item POHLMEIER, BILL - University Of Nebraska
item MCFEE, RENEE - University Of Nebraska
item SPURI-GOMES, RENATA - University Of Nebraska
item KURZ, SCOTT - University Of Nebraska
item McNeel, Anthony
item Cushman, Robert - Bob
item DAVIS, SCOTT - Nebraska Medical Center
item WOOD, JENNIFER - University Of Nebraska
item CUPP, ANDREA - University Of Nebraska

Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/2015
Publication Date: 6/2/2015
Citation: Romereim, S., Summers, A.F., Pohlmeier, B.E., McFee, R.M., Spuri-Gomes, R., Kurz, S.G., McNeel, A.K., Cushman, R.A., Davis, J.S., Wood, J.R., Cupp, A.S. 2015. Granulosa cell cycle regulation and steroidogenesis in a high androstenedione follicular microenvironment [abstract]. Society for the Study of Reproduction Annual Meeting. p. 245.

Interpretive Summary:

Technical Abstract: Anovulatory infertility (either chronic or sporadic anovulation) affects up to 40% of infertile women. In fact, sporadic anovulation in humans may often go undetected. Recent literature has reported that 8-13% of normally menstruating women (250 total, two reproductive cycles) exhibit sporadic anovulation. To gain a greater understanding of anovulation, our lab has described a naturally-occurring bovine model system which includes a subpopulation of cows with a 17% reduction in calving rate (P < 0.07) and endocrine profiles that are similar to women with chronic or sporadic anovulation. These cows exhibit excess androstenedione (A4) accumulation in their follicular fluid (10%; >30 fold higher) and lack an increase in estrogen production of similar magnitude (only 2 to 4 fold higher). Our objective was to gain a mechanistic understanding of the causes and consequences of this high-androgen follicular microenvironment. To explore avenues of investigation to explain this phenotype, our lab performed microarray analysis on the granulosa cells from control Low A4 (n=4, follicular A4 <20 ng/mL) and High A4 (n=5, follicular A4 > 40 ng/mL) cows. Overall, there were 1229 genes upregulated and 255 downregulated in High A4 granulosa compared to Low A4. With Ingenuity Pathway Analysis, we found that granulosa cells from the High A4 population exhibit a strong inhibition of the cell cycle, especially G1/S checkpoint proteins (e.g. cyclins and cyclin-dependent kinases), regulators of chromosome alignment and segregation (e.g. kinesins and related molecules), and other cell cycle regulators. Further investigation into the proliferation status of granulosa in High A4 follicles has utilized qRT-PCR, immunohistochemistry, and a fluorescent cell cycle reporter. There was also a striking increase in CYP17A1 mRNA expression and a moderate increase in lipid intake (membrane transporters) and lipid metabolite breakdown (UGT family), suggesting differential steroidogenesis between the High A4 and Low A4 granulosa. Subsequent exploration of this mechanism involved ELISA/radioimmunoassay detection of the steroidogenic capacity of isolated High and Low A4 granulosa and immunofluorescent localization of steroidogenic enzymes. This research provides an improved understanding of the bovine follicular microenvironment that can contribute to anovulatory infertility, thus offering a more solid foundational knowledge for further exploration into potential therapeutic or diagnostic targets for anovulatory infertility in both cattle and humans.