The uterine expression of SEC63 gene is up-regulated at implantation sites in association with the decidualization during the early pregnancy in mice

Integrative genetic, genomic and transcriptomic analysis of heat shock protein and nuclear hormone receptor gene associations with spontaneous preterm birth

Heat shock proteins are involved in the response to stress including activation of the immune response. Elevated circulating heat shock proteins are associated with spontaneous preterm birth (SPTB). Intracellular heat shock proteins act as multifunctional molecular chaperones that regulate activity of nuclear hormone receptors. Since SPTB has a significant genetic predisposition, our objective was to identify genetic and transcriptomic evidence of heat shock proteins and nuclear hormone receptors that may affect risk for SPTB. We investigated all 97 genes encoding members of the heat shock protein families and all 49 genes encoding nuclear hormone receptors for their potential role in SPTB susceptibility. We used multiple genetic and genomic datasets including genome-wide association studies (GWASs), whole-exome sequencing (WES), and placental transcriptomics to identify SPTB predisposing factors from the mother, infant, and placenta. There were multiple associations of heat shock protein and nuclear hormone receptor genes with SPTB. Several orthogonal datasets supported roles for SEC63, HSPA1L, SACS, RORA, and AR in susceptibility to SPTB. We propose that suppression of specific heat shock proteins promotes maintenance of pregnancy, whereas activation of specific heat shock protein mediated signaling may disturb maternal–fetal tolerance and promote labor.

Gene UCHL1 expresses specifically in mouse uterine decidual cells in response to estrogen

UCHL1 is expressed specifically in the brain and gonads of almost all studied model organisms including Drosophila, zebrafish, amphibians, and mammals, suggesting a high degree of evolutionary conservation in its structure and function. Although UCHL1 has been involved in spermatogenesis in mice, its specific expression in mammal placenta remains elusive. Our previous work has revealed that UCHL1 is highly expressed in oocytes, and has been involved in mouse ovarian follicular development. Here, we further examined UCHL1 expression change in endometria during early natural pregnancy, with different stages of the estrous cycle and pseudopregnancy as control. The UCHL1 gene deletion model showed that UCHL1 protein is associated with endometrial development, and its deletion leads to infertility. Notably, we demonstrate evidence showing the distinct expression pattern of UCHL1: weak expression over the uterine endometria, strong expression in decidualized stromal cells at the implantation site with a peak at pregnancy D6, and a shift with primary decidualization to secondary decidualized zones. Using the delayed implantation, the delayed implantation activation, and the artificial decidualization models, we have demonstrated that strong expression of UCHL1 occurred in response to decidualization and estrogen stimulation. These observations suggest that during the early proliferation and differentiation of mouse uterine decidua, UCHL1 expression is up-regulated, and formed an unique intracellular distribution mode. Therefore, we proposed that UCHL1 is involved in decidualization, and possibly in response to estrogen regulation.