Mechanism of BLIMP1/TRIM66/COX2 in human decidua participates in parturition

The mechanism underlying the initiation of parturition remains unclear. Cyclooxygenase 2 (COX2) and prostaglandins (PGs) in decidual membrane tissue play an important role in the "parturition cascade". With the advancement of gestation, the expression of the transcriptional suppressor B lymphocyte-induced maturation protein 1 (BLIMP1) in the decidual membrane gradually decreases. Through chromatin immunoprecipitation sequencing, we found that BLIMP1 has a binding site in the distal intergenic of PTGS2(COX2). Tripartite motif-containing protein 66 (TRIM66) is a chromatin-binding protein, that usually performs transcriptional regulatory functions by "reading" histone modification sites in chromatin. In this study, TRIM66 exhibit the same trend of expression as BLIMP1 in the decidua during gestation. Moreover, the co-immunoprecipitation assay revealed that TRIM66 combined with BLIMP1. This finding indicated that TRIM66 formed a transcription complex with BLIMP1, which coregulated the expression of COX2. In animal experiments, we injected si-Blimp1 adenoviruses, Blimp1 overexpression plasmid (Blimp1-OE) and Trim66 overexpression plasmid (Trim66-OE) through the tail vein of mice. The results showed that BLIMP1 and TRIM66 affected the initiation of parturition in mice. Therefore, the present evidence suggests that BLIMP1 and TRIM66 partially participate in the initiation of labor, which may provide a new perspective for exploring the mechanism of term labor.