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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 #302951
Title: Granulosa cell gene expression profiling in cows with divergent follicular fluid concentrations of androgens

Author
item SUMMERS, A - University Of Nebraska
item POHLMEIER, WILLIAM - University Of Nebraska
item SARGENT, K - University Of Nebraska
item KURZ, S - University Of Nebraska
item MCFEE, R - University Of Nebraska
item McNeel, Anthony
item Cushman, Robert - Bob
item WOOD, J - 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: 7/1/2014
Publication Date: 7/19/2014
Citation: Summers, A., Pohlmeier, W., Sargent, K., Kurz, S., McFee, R., McNeel, A.K., Cushman, R.A., Wood, J., Cupp, A. 2014. Granulosa cell gene expression profiling in cows with divergent follicular fluid concentrations of androgens [abstract]. In: Society for the Study of Reproduction, 47th Annual Meeting, 19-23 July 2014, Grand Rapids, MI. Abstract 22.

Interpretive Summary:

Technical Abstract: Inefficiencies in reproduction result in significant production costs for beef producers in the United States. In the UNL cow-calf herd, two sub-populations of cows have been identified with divergent levels of follicular androstenedione (A4). Furthermore, High A4 cows (A4 > 40ng/ml) have a 10 percentage point reduction in calving rate compared to Low A4 cows (A4 < 20ng/ml) suggesting that androgen excess is a causative factor in High A4 cow subfertility. The objective of the current study was to link altered steroidogenesis in the dominant follicle of High A4 cows to molecular changes in the somatic cells of the follicle. To asses additional alterations in the follicular steroid environment of High A4 cows, HPLC MS/MS was conducted using fluid collected from the dominant follicle of High (n = 7) and Low A4 (n = 7) cows. As expected, follicular fluid (ff) A4 was significantly higher in High vs Low A4 cows (12926 nM vs. 8.1 nM; P < 0.05). Likewise ff concentration of other androgens including DHEA (92.6 nM vs. 15.3 nM; P < 0.05) and testosterone (106.5 nM vs. 3.5 nM; P < 0.05) were significantly higher in High A4 cows. While estradiol and estrone were significantly increased in High A4 ff, the fold change in estrogens between the two groups of cows (2.6-3.9 fold increase) were not as large as the fold change in androgens (6.0-157.8 fold increase). To identify differences in granulosa cell transcript levels between High and Low A4 cows, granulosa mRNA (High A4, n = 5; Low A4, n = 5) was examined using the Affymetrix GeneChip Bovine Genome Array. Principle component analysis and hierarchical clustering revealed global differences in the transcript profile of High and Low A4 granulosa cells. Furthermore, the National Institute of Aging Array Analysis Tool, identified approximately 1,200 genes that were differentially expressed (P-value < 0.05 and FDR < 0.05) between High and Low A4 granulosa cells. Ingenuity Pathway Analysis identified a number of expected transcriptional regulators as upstream activators including: Androgen, CCAAT/enhancer-binding protein alpha (CEBPA) and beta (CEBPB). Interestingly, hepatocyte nuclear factor 1 homeobox A (HNF1) was also listed as an upstream activator which potentially regulates 38 transcripts in the dataset. Further, a number of potential upstream inhibitors were identified including: miR-181a (inhibitor of activin receptor) which may affect granulosa cell proliferation, MYC which is predicted to inhibit transcription in atretic follicles, and activating transcription factor 4 (ATF4) which is expressed during cellular stress and is upregulated by retinoic acid (RA). Interestingly, Retinoate Biosynthesis was one of the top canonical pathways activated in the array analysis. Furthermore, we have previously shown that in vitro treatment of human theca cells with all trans RA increased DHEA synthesis as well as CYP17, CYP11, and StAR mRNA abundance. Taken together, these data suggest that granulosa cells from High compared to Low A4 cows may have impaired proliferation, altered retinoic acid signaling, and increased cellular stress. Elucidating the mechanisms of how excess androgen affects granulosa and theca cell function may provide insight into potential problems causing subfertility in these cows and may present new means for improving reproductive performance in beef cattle. Supported by AFRI grant no. 2013-67015-20965 from USDA-NIFA.