Decreased Expression of MicroRNA 451 (MIR) Alters Cell Cycle Genes and Ptgs2 in the Eutopic Endometrium (EUE) in a Baboon Model of Induced Endometriosis.

Endometriosis is one of the most common gynecological disorders which are a cause of chronic pelvic pain and infertility. The molecular mechanisms associated with the pathophysiology of the endometriosis related infertility are poorly understood. Several mechanisms have been postulated and recently the involvement of miR's which regulate gene expression have been postulated to play a role in endometriosis. To identify miR's in the EUE of baboons that are altered following the induction of endometriosis and to validate their potential target genes at different stages of the disease. Total RNA from the EUE extracted from the same group of baboons (n=3) before and 3 months after the induction of endometriosis were analyzed on a 8x15K microRNA microarray (Agilent). The signal data were preprocessed by AgiMiRna and an empirical Bayes model was used to estimate the p-values. The potential mRNA targets of differentially expressed miR's were predicated using TargetScan 5.1. The present study was restricted to the analysis of the significantly down regulated miR-451 and its 3 targets CDKN2D (inhibits CDK4-cell cycle regulation), GATAD2B (encodes transcription repressor protein p66 beta-component of the MeCP1 complex) and PTGS2 (involved in prostaglandins synthesis-Inflammation) by qRT-PCR analysis at different time points of the disease. Induction of endometriosis leads to rapid and significant changes in the expression of several miRs (miR 451, 181a, 200a, 19b, 424, 21, 29c and 141). miR-451 was highly down regulated (p< 0.000036) at 3 months and qRT-PCR analysis for miR-451 confirmed the microarray data. Further, detailed analysis of miR-451 in additional baboons with endometriosis revealed a continuous decrease in expression at 1, 6, 9, and 15 m in both the EUE and in endometriotic lesions. The temporal decrease in miR-451 expression leads to significant increases in the expression of its targets CDKN2D, GATAD2B and PTGS2. Induction of endometriosis causes rapid changes in the expression of miRNAs 181a, 200a, 19b, 424, 21, 29c and 141in the baboon endometrium. These miRs, previously reported to be altered in women with endometriosis, further validates baboon model. This study also identified a previously unreported miR-451 whose significant down regulation is associated with increased expression of its predicted targets CDKN2D, GATAD2B and PTGS2. Present study demonstrated that altered cell cycle and inflammatory response might be due to altered expression of CDKN2D and GATAD2B mediated by miR-451 under endometriotic condition. Protein p66 beta, product of GATAD2B, is a component of MeCP1 (Methyl-CpG-binding protein) complex, this complex represses transcription by binding and remodeling the methylated nucleosomes. This study reveals crucial role of miR-451 in regulating the expression of genes involved in cell cycle, nucleosome remodeling and inflammation. These physiological responses are associated with endometriotic pathology. (U54-HD40093) (poster)