Temporal changes in the corpus luteum during early pregnancy reveal regulation of pathways that enhance steroidogenesis and suppress luteolytic mechanisms†

Abstract

Although rescue of the corpus luteum (CL) is required for pregnancy, luteal function during maternal recognition of pregnancy remains largely unexplored. CL were collected from pregnant cattle on days 14, 17, 20, and 23, to encompass the maternal recognition of pregnancy period. Next-generation sequencing was used to profile mRNA abundance during this time, while tandem mass spectrometry and nanostring technology were used to profile proteins and miRNA, respectively. A total of 1157 mRNA were differentially abundant, while 27 miRNA changed, and 29 proteins tended to change. mRNA that increased were regulators of interferon signaling and DNA repair, while those that decreased were associated with luteolytic processes, such as calcium signaling and matrix metallopeptidase (MMP) signaling, indicating inhibition of these processes. One of these, MMP12, was regulated by prostaglandin F2A in vitro. mRNA that were maximally abundant on day 20 were primarily associated with immune processes. Two of these, C-C motif chemokine ligand 1 and NFKB inhibitor alpha, were regulated by interferon tau in vitro. MiRNA that increased were predicted to inhibit phosphatidylinositol signaling, while those that decreased may be negative regulators of steroidogenesis. One protein that was greater on day 20 than on day 14 was aldehyde dehydrogenase 1 family member A1 (ALDH1A1), which synthesizes retinoic acid. Pharmacological inhibition of this enzyme, or of retinoic acid receptor signaling, led to suppression of progesterone production in vitro. Overall, these data indicate that there are changes in the CL of pregnancy that are important for continued luteal function.

Downregulated luteolytic pathways in the transcriptome of early pregnancy bovine corpus luteum are mimicked by interferon-tau in vitro

“…TGFB1 signaling is a pathway that was shown to be significantly enriched and repressed in the current study in P compared to NP cows, as well as in previous reports [ 15 , 28 ] (see Figs. 2 , 3 , and 6 ).…”

“…This conclusion is based on DEGs, IPA, and metascape canonical pathways, GSEA enrichment plots, along with molecular and cellular functions. Unlike previous publications, this study captured the transcriptome of early pregnancy CL exposed to IFNT and compared it to non-luteolytic cyclic CL, thus singling out the effects of IFNT [ 15 , 28 – 30 ].…”

“…Several transcriptomic studies of early pregnant ruminant CL have been conducted in recent years [ 15 , 28 – 30 ]. These studies reported genes and pathways that are specific for pregnancy.…”

“…However, despite the wealth of information provided, there was little overlap of the differentially expressed genes (DEGs) and the regulated pathways in these studies. Most probably due to the different reference group, which were cyclic, pregnant at different stages, or regressing CL [ 15 , 28 – 30 ]. Here we analyzed the transcriptome of day matched (day 18) CL of pregnant (P) and non-pregnant (NP) cows.…”

NR5A2 and potential regulatory miRNAs in the bovine CL during early pregnancy

“…Cows were slaughtered for CL collection on day 4, while CL from day 6 were collected via colpotomy. For CL of days 14, 17, 20, and 23 of pregnancy, luteal tissue samples were collected as described by Hughes et al (2020). For CL of days 17 of the estrous cycle and pregnancy, luteal tissue samples were collected as described by Hughes et al (2019).…”