Connective tissue growth factor gene expression in goat endometrium during estrous cycle and early pregnancy

Embryo implantation is crucial for a successful pregnancy. Although many essential molecular modulators and pathways have been identified, the precise mechanisms of the process in goat remain largely unknown. CCN2 is a connective tissue growth factor participating in many biological processes; however, its presence or function in goat uterus has not yet been reported. In this study, we determined the expression and regulation of CCN2 in goat uterus. CCN2 was not detected by in situ hybridization at ED0 (Day 0 of the estrous cycle), but at ED6 (metestrus), ED12 (dioestrus), and ED16 (proestrus), with high signals in luminal epithelium, superficial glands, and caruncula matrix. During early pregnancy, CCN2 was also detected in these locations on D0 and D6 (pre-receptive uterus). The signals significantly increased on D16 and D19 (receptive uterus), and remained at high levels on D25 and D30. Similarly, the RT-qPCR assays showed that the mRNA level of CCN2 was relatively low on D0 and D6, increased on D16, peaked on D19, and kept high thereafter. Moreover, CCN2 was up-regulated not only in ovariectomized ewes subcutaneously injected with 17β-estradiol and progesterone (separately or together), but also in cultured goat uterine epithelial cells treated with the two hormones or interferon tau (IFNτ). In conclusion, CCN2 expression may be induced by 17β-estradiol, progesterone, and IFNτ in the luminal epithelium of goat receptive uterus, suggesting that CCN2 is involved in goat embryo adhesion during early pregnancy.