Cyclic changes of the expression of StAR mRNA and protein in human endometrium

Abstract

Steroidogenic acute regulatory protein (StAR) regulates the first committed step in the biosynthesis of steroids. Recently, several studies have demonstrated the expression of StAR in rhesus monkey or mouse endometrium (Yi-Xun Liu, 2005) and human endometriosis strome cell(H. Sunny Sun, 2003), Which thus implants StAR plays a critical role in the etiology of implantation in rhesus monkey or mouse, also responsible for endometriosis. However, the profile of StAR expression in human endometrium remains unknown. The aim of this study was to investigate the fully characterize StAR mRNA and protein in human endometrium during the menstrual cycle. Experimental study. StAR mRNA expression was quantified by real-time PCR in fresh endometrial tissue from fertility cycling women with normal ovulation, and protein expression was analyzed by immunohistochemistry and western blotting. StAR mRNA was significantly up-regulated beginning at LH day until to mid-secretory (MS) phases compared with proliferative phases during the menstrual cycle (fig 1). StAR protein was localized to glandular and luminal epithelium which was present in high levels throughout the menstrual cycle except during early- proliferative (EP) phase and late-secrete (LS) phase, when it was remarkably decreased (fig 2). This is the first study to demonstrated that StAR expression cyclical changes in human endometrium. These basic findings may provide a new insights in understanding mechanism of etiology relate to molecules of implantation and endometriosis in human. Fig 1: Cyclic changes of StAR mRNA expression by RT-PCR in human endometrium. Fig 2: Cyclic changes of the StAR protein expression by Western–blot in human endometrium.