Luteotropic and Luteolytic Factors Modulate the Expression of Nuclear Receptor Coregulators in Bovine Luteal Cells Independently of Histone Acetyltransferase and Histone Deacetylase Activities

SIMPLE SUMMARY: Proper functioning of the ovaries significantly affects the duration of the estrous cycle and the appropriate course of pregnancy in female livestock, including cattle. The determinant of these processes is progesterone (P4), which, on the genomic pathway, acts through nuclear receptors that, by attaching to the promoter of a target gene, activate its transcription. At the final stage of the activation of PGRs and other nuclear receptors are attached coregulators, elements that regulate receptor function. They are divided into coactivators and corepressors, and their attachment determines the activation or inhibition of transcription of the target gene activated by these receptors, respectively. Adequate levels and activities of coregulators are crucial for the function of nuclear receptors, including PGRs, and as a result, the course of the normal estrous cycle and maintenance of early pregnancy. Therefore, the results obtained may be helpful in better understanding the regulation and expression of coactivators and corepressors in the CL of cows and may contribute to reducing nuclear receptor dysfunction in PGRs. This may also have important practical significance, contributing to increasing the efficiency of breeding these animals by reducing the early embryonic lethality that results from abnormal functioning of the PGRs. ABSTRACT: The aims of this study were to examine the effect of luteotropic and luteolytic factors on the mRNA and protein expression of the coactivators HAT: histone acetyltransferase p300 (P300), cyclic adenosine monophosphate response element-binding protein (CREB), and steroid receptor coactivator-1 (SRC-1) and the corepressor: nuclear receptor corepressor-2 (NCOR-2) in bovine luteal cells on days 6–10 and 16–20. HAT and HDAC activities were also measured. The obtained results showed that luteotropic and luteolytic factors influence changes in the mRNA and protein levels of the coregulators of PGRs. However, they did not affect the activity of related HAT and HDAC, respectively. Therefore, it is possible that these factors, through changes in the expression of nuclear receptor coactivators and corepressors, may affect the functioning of the nuclear receptors, including PGRs, in the bovine CL.