Regulation of DNA Methylation Through EBP1 Interaction with NLRP2 and NLRP7

Background/Objectives: Mutations in NACHT, LRR and PYD domain-containing protein 2 (NLRP2) and NLRP7 genes, members of the NOD-like receptor (NLR) family of innate immune sensors, result in recurrent miscarriages and reproductive wastage in women. These genes have been identified to be maternal effect genes in humans and mice regulating early embryo development. Previous research in vitro suggests that NLRP2 and NLRP7 regulate DNA methylation and/or immune signaling through inflammasome formation. However, the exact mechanisms underlying NLRP2 and NLRP7 function are not well defined. Methods: To determine the interacting proteins required for NLRP2/NLRP7-mediated regulation of DNA methylation, yeast 2-hybrid screens, coimmunoprecipitation, and FRET studies were performed and verified the ability of novel protein interactions to affect global DNA methylation by 5-methylcytosine-specific ELISA. Results: Various methodologies employed in this research demonstrate a novel protein interaction between human ErbB3-binding protein 1 (EBP1, also known as proliferation-associated protein 2G4 (PA2G4) and NLRP2 or NLRP7. In addition, NLRP2 and NLRP7 regulate EBP1 gene expression. Functionally, global DNA methylation levels appeared to decrease further when NLRP2 and NLRP7 were co-expressed with EBP1, although additional studies may need to confirm the significance of this effect. Conclusions: Since EBP1 is implicated in apoptosis, cell proliferation, DNA methylation, and differentiation, our discovery significantly advances our understanding of how mutations in NLRP2 or NLRP7 may contribute to reproductive wastage in women through EBP1.