Estradiol-regulated proline-rich acid protein 1 is repressed by class I histone deacetylase and functions in peri-implantation mouse uterus

Secretory protein proline-rich acid protein 1 (PRAP1) is abundantly expressed in late pregnant uterus. However, regulation and function of PRAP1 in pregnant uterus is still elusive. We firstly reported differential expression of PRAP1 in peri-implantation uteri and its localization in endometrial epithelia. Expression of PRAP1 in uterus was induced by 17β-estradiol and its expression showed a negative correlation with that of class Ihistone deacetylases (HDACs) in isolated endometrial epithelia. PRAP1 was increased by HDACs inhibitor sodium butyrate treatment, while decreased significantly by estrogen receptor inhibitor ICI182,780 via up-regulating class IHDACs. Number of implanted embryos was decreased in mice immunized with pCR3.1-PRAP1 or injected with rabbit anti-PRAP1 antibody. DNA immunization or antibody injection could affect apoptosis and expression of cytokines (IL-4, IFN-γ). In conclusion, both 17β-estradiol and class IHDACs are involved in modulating PRAP1 expression in peri-implantation uteri. Preliminary functional research indicates that neutralizing PRAP1 protein causes reduction of implanted embryos.