CREB1 Is Involved in miR-134-5p-Mediated Endometrial Stromal Cell Proliferation, Apoptosis, and Autophagy

The successful establishment of endometrial receptivity is a key factor in ensuring the fertility of ewes and their economic benefits. Hu sheep have attracted attention due to their high fecundity and year-round estrus. In this study, we found that in the luteal phase, the uterine gland density, uterine coefficient, and number of uterine caruncles of high-fertility Hu sheep were higher than those of low-fertility Hu sheep. Thousands of differentially expressed genes were identified in the endometrium of Hu sheep with different fertility potential using RNA sequencing (RNA-Seq). Several genes involved in endometrial receptivity were screened using bioinformatics analysis. The qRT-PCR analysis further revealed the differential expression of cAMP reactive element binding protein-1 (CREB1) in the Hu sheep endometrium during the estrous cycle. Functionally, our results suggested that CREB1 significantly affected the expression level of endometrial receptivity marker genes, promoted cell proliferation by facilitating the transition from the G1 phase to the S phase, and inhibited cell apoptosis and autophagy. Moreover, we observed a negative linear correlation between miR-134-5p and CREB1 in the endometrium. In addition, CREB1 overexpression prevented the negative effect of miR-134-5p on endometrial stromal cell (ESC) growth. Taken together, these data indicated that CREB1 was regulated by miR-134-5p and may promote the establishment of uterine receptivity by regulating the function of ESCs. Moreover, this study provides new theoretical references for identifying candidate genes associated with fertility.

Automated summary

The successful establishment of endometrial receptivity is crucial for the fertility and economic benefits of ewes. In this study, high-fertility Hu sheep were found to have higher uterine gland density, uterine coefficient, and number of uterine caruncles compared to low-fertility Hu sheep during the luteal phase. RNA sequencing (RNA-Seq) analysis identified thousands of differentially expressed genes in the endometrium of Hu sheep with different fertility potential. One of these genes, CREB1, was found to be differentially expressed in the Hu sheep endometrium during the estrous cycle. Functional analysis revealed that CREB1 significantly influenced the expression level of endometrial receptivity marker genes, promoted cell proliferation, and inhibited cell apoptosis and autophagy. Additionally, there was a negative linear correlation between miR-134-5p and CREB1 in the endometrium, and overexpression of CREB1 counteracted the negative effect of miR-134-5p on endometrial stromal cell growth.