OBESITY IS ASSOCIATED WITH IMPAIRED EXPRESSION OF THE GLYCOSYLTRANSFERASE EOGT IN DECIDUALIZING ENDOMETRIUM

In pregnancy, resistance of endometrial decidual cells to stress signals is critical for the integrity of the feto-maternal interface and, by extension, survival of the conceptus. O-GlcNAcylation is an essential post-translational modification that links glucose sensing to downstream stress resistance. Unexpectedly, decidualization of primary endometrial stromal cells (EnSCs) was associated with a 60% reduction in O-GlcNAc modified proteins, reflecting down-regulation of the enzyme that adds O-GlcNAc to substrates (O-GlcNAc transferase, OGT) but not the enzyme that removes the modification (O-GlcNAcase, OGA). Notably, EOGT, an endoplasmic reticulum-specific O-GlcNAc transferase that modifies a limited number of secreted and membrane proteins, was markedly induced in differentiating EnSCs. Knockdown of EOGT perturbed a network of decidual genes involved in multiple cellular functions. The most responsive gene downregulated upon EOGT knockdown in decidualizing cells was ENHO, which encodes adropin, a metabolic hormone involved in energy homeostasis and glucose and fatty acid metabolism. Analysis of mid-luteal endometrial biopsies revealed an inverse correlation between endometrial EOGT and ENHO expression and body mass index. Taken together, our findings reveal that obesity impairs the EOGT-adropin axis in decidual cells, which in turn provides a new mechanism that links between metabolic disorders to adverse pregnancy outcome. Overall design: Endometrial mRNA profiles of paired control (siRNA-NT) and siRNA-EOGT, either undifferentiated or decidualized with 8-br-cAMP and MPA for 4 days were generated by deep sequencing, in triplicate using Illumina