Progesterone Receptor Signaling in Uterine Myometrial Physiology and Preterm Birth

Myometrium holds the structural integrity for the uterus and generates force for parturition with its primary component, the smooth muscle cells. The progesterone receptor mediates progesterone-dependent signaling and connects to a network of pathways for regulation of contractility and inflammatory responses in myometrium. Dysfunctional progesterone signaling has been linked to pregnancy complications including preterm birth. In the present review, we summarize recent findings on modifiers and effectors of the progesterone receptor signaling. Discussions include novel conceptual discoveries and new development in legacy pathways such as the signal transducers NF-kappa B, ZEB, microRNA, and the unfolded protein response pathways. We also discuss the impact of progesterone receptor isoform composition and ligand accessibility in modification of the progesterone receptor genomic actions.