Hand2os1 Regulates the Secretion of Progesterone in Mice Corpus Luteum

SIMPLE SUMMARY: The corpus luteum plays a key role in pregnancy maintenance and estrous cycle regulation by secreting progesterone. In this study, we investigate the expression and regulation of lncRNA Hand2os1 in the ovaries. We found Hand2os1 was specifically detected in luteal cells during the proestrus and estrus phases, and strongly expressed in the corpus luteum on day 4 and day 18 of pregnancy. Moreover, Hand2os1 regulates the secretion of progesterone in the mouse corpus luteum by affecting the key rate-limiting enzyme StAR, which suggests it may have an impact on the maintenance of pregnancy. ABSTRACT: The corpus luteum plays a key role in pregnancy maintenance and estrous cycle regulation by secreting progesterone. Hand2os1 is an lncRNA located upstream of Hand2, with which a bidirectional promoter is shared and is involved in the regulation of cardiac development and embryo implantation in mice. The aim of this study was to investigate the expression and regulation of Hand2os1 in the ovaries. Here, we used RNAscope to detect differential expression of Hand2os1 in the ovaries of cycling and pregnant mice. Hand2os1 was specifically detected in luteal cells during the proestrus and estrus phases, showing its highest expression in the corpus luteum at estrus. Additionally, Hand2os1 was strongly expressed in the corpus luteum on day 4 of pregnancy, but the positive signal progressively disappeared after day 8, was detected again on day 18, and gradually decreased after delivery. Hand2os1 significantly promoted the synthesis of progesterone and the expression of StAR and Cyp11a1. The decreased progesterone levels caused by Hand2os1 interference were rescued by the overexpression of StAR. Our findings suggest that Hand2os1 may regulate the secretion of progesterone in the mouse corpus luteum by affecting the key rate-limiting enzyme StAR, which may have an impact on the maintenance of pregnancy.