The maintenance of myometrial quiescence and initiation of contractility, which lead to parturition at term and preterm, involve a shifting equilibrium between anti-inflammatory and proinflammatory signalling pathways. Progesterone (P4), acting through the progesterone receptor (PR), has an essential and multifaceted role in the maintenance of myometrial quiescence. This effect of P4-PR signalling is mediated, in part, by its anti-inflammatory actions and capacity to repress the expression of genes that encode proinflammatory cytokines, such as IL-1 and IL-6, and contraction-associated proteins, such as OXTR, GJA1 and PTGS2. By contrast, increased expression of genes that ultimately lead to parturition is mediated by enhanced inflammatory and estradiol-17β (E2) and estrogen receptor α signalling, which reduce PR function, thus further intensifying the inflammatory response. To obtain a more complete understanding of the molecular events that underlie the transition of the pregnant myometrium from a refractory to a contractile state, the roles of microRNAs, their targets, and their transcriptional and hormonal regulation have been investigated. This article reviews the actions of the miR-200 family and their P4-regulated targets-the transcription factors ZEB1, ZEB2 and STAT5B-in the pregnant myometrium, as well as the role of miR-199a-3p and miR-214 and their mutual target PTGS2. The central role of ZEB1 as the mediator of the opposing actions of P4 and E2 on myometrial contractility will be highlighted.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism