A Role for Malignant Brain Tumor Domain-Containing Protein 1 in Human Endometrial Stromal Cell Decidualization

iTRAQ-based quantitative proteomics reveals dysregulation of fibronectin 1 contributes to impaired endometrial decidualization in recurrent implantation failure

Recurrent implantation failure (RIF) poses challenges to successful embryo implantation. In this study, we utilized isobaric tags for relative and absolute quantification (iTRAQ) to profile endometrial protein abundance in RIF patients. Through functional and pathway analyses, ECM-related proteins including fibronectin 1 (FN1), collagen type I alpha 2 chain (COL1A2), and integrin beta-1 (ITGB1) were revealed to be associated with RIF. Correlation analysis identified TGF-β1 as an upstream regulator of FN1. Knockdown experiments showed TGF-β1 downregulation could inhibit FN1 expression to inhibit decidualization markers. Our findings suggest a mechanistic link between TGF-β1/FN1 axis dysregulation and impaired decidualization observed in RIF. SIGNIFICANCE: Our study addresses the pressing issue of RIF, a significant obstacle in assisted reproductive technology. By employing isobaric tags for relative and absolute quantification (iTRAQ), we comprehensively analyzed endometrial protein abundance in RIF patients. Through functional and pathway enrichment analyses, we identified dysregulation in extracellular matrix (ECM)-related proteins, including FN1, COL1A2, and ITGB1, shedding light on their potential roles in implantation failure. Additionally, our correlation analysis revealed TGF-β1 as an upstream regulator of FN1, suggesting a novel regulatory axis involved in decidualization. Knockdown experiments further demonstrated the impact of TGF-β1 and FN1 on decidualization markers. This study contributes to a better understanding of the molecular mechanisms underlying RIF.

A GREB1-steroid receptor feedforward mechanism governs differential GREB1 action in endometrial function and endometriosis

Cellular responses to the steroid hormones, estrogen (E2), and progesterone (P4) are governed by their cognate receptor's transcriptional output. However, the feed-forward mechanisms that shape cell-type-specific transcriptional fulcrums for steroid receptors are unidentified. Herein, we found that a common feed-forward mechanism between GREB1 and steroid receptors regulates the differential effect of GREB1 on steroid hormones in a physiological or pathological context. In physiological (receptive) endometrium, GREB1 controls P4-responses in uterine stroma, affecting endometrial receptivity and decidualization, while not affecting E2-mediated epithelial proliferation. Of mechanism, progesterone-induced GREB1 physically interacts with the progesterone receptor, acting as a cofactor in a positive feedback mechanism to regulate P4-responsive genes. Conversely, in endometrial pathology (endometriosis), E2-induced GREB1 modulates E2-dependent gene expression to promote the growth of endometriotic lesions in mice. This differential action of GREB1 exerted by a common feed-forward mechanism with steroid receptors advances our understanding of mechanisms that underlie cell- and tissue-specific steroid hormone actions.