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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #420607
Research Project: Improving Lifetime Productivity in Swine using Systems Biology and Precision Management Approaches

Location: Livestock Bio-Systems

Title: Gonadotropin-releasing hormone II and its receptor act through theca cells of porcine preovulatory follicles to influence follicular developement in vitro

Author
item ROSS, CAITLIN - University Of Nebraska
item DESAULNIERS, AMY - University Of Nebraska
item Lents, Clay
item WHITE, BRETT - University Of Nebraska

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 12/5/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Pigs are the only mammalian livestock species that produce the second form of gonadotropin-releasing hormone (GnRH-II) and its specific receptor (GnRHR-II). Therefore, we utilized our transgenic swine line with ubiquitous knockdown (KD) of GnRHR-II (GnRHR-II KD) to elucidate how the GnRH-II/GnRHR-II system regulates female reproduction. Compared with littermate control females during the follicular phase of the estrous cycle, GnRHR-II gilts: 1) secreted 20% less serum 17ß-estradiol (especially during peak production just prior to estrus) despite similar circulating concentrations of gonadotropins; 2) possessed 10% larger preovulatory follicles; 3) ovulated 16% fewer follicles despite similar preovulatory follicle numbers; 4) exhibited similar numbers of granulosa cells (GC), which were 5% smaller; 5) displayed 10% fewer theca cells (TC), which were 15% larger; and 6) produced 40% less GnRHR-II protein within TC of preovulatory follicles. Therefore, the objective of this study was to evaluate the proteome of GC and TC from preovulatory follicles of GnRHR-II KD and littermate control gilts. Following collection of GC (n = 3 – 4 per line; follicular aspiration/centrifugation) and TC (n = 4 per line; manual dissection), protein was isolated and purified prior to mass spectrometry analysis. Proteins were quantified using Proteome Discoverer (Thermofisher, v2.4), and queried using Mascot (Matrix Science). Differentially expressed proteins (DEP) were significant at P = 0.05 following Benjamini-Hochberg adjustment, and tendencies were considered 0.05 < P = 0.10. There were 976 total proteins detected in GC samples and 2,047 total proteins identified in TC. The proteome of GC was similar (P > 0.10) between GnRHR-II KD and littermate control gilts. However, 14 DEP (P = 0.05) were detected in TC of GnRHR-II KD compared with TC of control follicles, whereas 196 proteins tended (P = 0.10) to differ. Of these 210 proteins, 199 were downregulated and 11 were upregulated in transgenic TC. All 14 of the DEP (P = 0.05) were downregulated, and included proteins involved with transcription/translation machinery (LUC7L2, SNRPA, SNRPD2, SNRNP70, RPL5, RPL9, RPL15, RPL28, RPL30, RPS2, RPS23, RTCB), signal transduction (PPP2R5D), and microtubule-based movement (KIF5B). Further, the majority of these proteins have been implicated in reproductive processes such as follicular development and maturation, oogenesis, oocyte activation and maturation, and early embryogenesis. However, no differences were observed in protein abundance for any key steroidogenic proteins (StAR, CYP11A1, HSD3B, CYP17A1, HSD17B1, CYP19A1) in TC from transgenic versus control follicles. Together, these data strongly suggest that GnRH-II and its receptor are critical for porcine theca cell function, and identified target proteins could reveal crucial mechanisms regulating follicular development and reduced ovulation rates observed in GnRHR-II KD gilts.