Ion Channels Critical for Uterine Contraction, Reproduction, and Adenomyosis

Project Summary Uterine smooth muscle cells (USMCs) generate uterine peristalsis that is crucial for menstruation, sperm and embryo transfer, and embryo implantation; dysfunction in uterine peristalsis is associated with adenomyosis, a uterine disease that affects millions of women with physical and mental distress. To date, the molecular basis of uterine peristalsis and its precise role in reproduction, and adenomyosis remain unclear. We recently discovered that the activation of L-type Ca2+ channels in USMCs generates intercellular Ca2+ waves that lead to uterine peristalsis. We also found in our published or preliminary studies: (1). Among the four α1 pore- forming subunits of the L-type channel, Cav1.2 and Cav1.3 are expressed in non-pregnant uteri and their levels are decreased in uteri at the peri-implantation stage. (2). Smooth muscle cell-specific Cav1.2 deletion disrupts Ca2+ waves and uterine peristalsis, causing infertility. (3). Intercellular Ca2+ waves and uterine peristalsis from tamoxifen-induced adenomyotic mice are altered, with a down regulation of Cav1.2. (4). Tamoxifen-induced adenomyotic mice show impaired embryo implantation. And (5). Myometrium from normal regions of uterine slices from patients with adenomyosis exhibits synchronized Ca2+ waves and robust shortening. In contrast, the myometrium around adenomyotic lesions from the same patients produces asynchronized Ca2+ waves with less shortening. These functional changes are associated with a decrease in Cav1.2 mRNA and an increase in Cav1.3 mRNA in the adenomyotic regions. Given these findings, we hypothesize that (1) in both mice and humans, Cav1.2 and Cav1.3 contribute to the L-type Ca2+ current in USMCs, (2) Cav1.2 and Cav1.3 play distinct roles in uterine peristalsis, uniquely influencing embryo implantation, and (3) Cav1.2 down-regulation underlies alterations in uterine peristalsis in adenomyosis and contributes to adenomyosis pathogenesis. To test these hypotheses, we will investigate the roles of Cav1.2 and Cav1.3 in Ca2+ signaling, uterine peristalsis, and embryo implantation using Cav1.3 knockout mice and smooth muscle cell-specific and inducible Cav1.2 knockout mice (Aim 1). We will also determine whether Cav1.2 down-regulation alters uterine peristalsis, leading to adenomyosis and the resultant impaired embryo implantation in mice (Aim 2). Finally, to translate our findings in mice to humans, we will use RNA interference to determine whether Cav1.2 and/or Cav1.3 comprise L-type Ca2+ channels in human USMCs, identify and quantify the signatures of L-type Ca2+ currents, Ca2+ signals, and uterine peristalsis in human adenomyotic USMCs, and uncover the underlying mechanisms for generating these signatures (Aim 3). This study is expected to provide a fundamental understanding of uterine peristalsis and its role in fertility, as well as deep insights into the mechanisms of adenomyosis pathogenesis. The outcome of this study may provide the basis for targeting the Cav1 family in USMCs for new treatments of gynecologic disorders.