EXPRESSION OF NR5A2 DURING THE LIFECYCLE OF THE BOVINE CORPUS LUTEUM

Open Access
Author:
Rogus, Amelia E
Area of Honors:
Animal Sciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Joy Lee Pate, Thesis Supervisor
  • Chad Daniel Dechow, Honors Advisor
Keywords:
  • NR5A2
  • Corpus Luteum
  • Bovine
  • miRNA
  • expression
  • luteolysis
  • fertility
Abstract:
Genetic selection for increased productivity in dairy cattle in the United States has unfortunately coincided with a decline in fertility among these animals. Decreased conception rates and prolonged calving intervals lead to significant economic losses for dairy farmers. Pregnancies in cattle are often lost during the period between fertilization and day 24 as a result of insufficient progesterone secretion from the corpus luteum (CL). Orphan nuclear receptor NR5A2 has been shown to be necessary for proper ovulation as well as CL formation and function, but its expression profile in the CL has yet to be described. Therefore, the goal of this study was to examine the abundance of NR5A2 in the CL during early cyclicity, early pregnancy, and luteal regression. Luteal NR5A2 mRNA abundance decreased by 8 hr after PGF2α injection (p<0.05) while NR5A2 protein tended to decrease by 0.5hr and decreased by 2 hours after PGF2α (p<0.05). NR5A2 mRNA increased between day 4 and day 6 of the estrous cycle (p<0.05) but protein abundance between these days was not different. During early pregnancy, luteal NR5A2 mRNA was lesser on days 20 and 23 compared to day 14 (p<0.05); none of these days differed from day 17. Protein abundance during early pregnancy did not change. Discrepancies between mRNA and protein abundance in each group give strong evidence to potential micro RNA (miRNA) regulation of NR5A2 translation. Further work can be done to investigate specific miRNA that target NR5A2 during these times in the CL lifecycle.