Liver receptor homologue-1 and steroidogenic factor-1 expression in cultured granulosa cells from patients with endometriosis: A preliminary study

Mutation -388 C>G of NR5A1 gene affects litter size and promoter activity in sheep

The Nuclear receptor superfamily 5, group A, member 1 (NR5A1) gene encodes a nuclear receptor that regulates the transcription of genes involved in steroidogenesis, follicular development and female fertility. Little, however, is known about the relationship of this gene with reproductive performance in sheep. In this study, the transcription initiation site of Hu sheep NR5A1 gene was located 193 nucleotides (i.e., at -193 nt) before the translational start site (ATG). The core promoter region of the NR5A1 gene ranged from -696 nt to -298 nt, and a C>G mutation at -388 nt was detected in this region. Association analysis indicated ewes with the GG genotype had greater litter size at the second and third parity than those with the CC genotype (P < 0.05). The results from the luciferase assay provided evidence that the -388 G allele increased luciferase activity compared with that of the -388 C allele. Furthermore, the -388 C>G mutation lost a CpG site and gained a novel binding site for the transcription factor, SP1, and results from an overexpression experiment and methylation analysis indicated transcription factor SP1 and methylation of the -388 C>G mutation were both involved in alteration of NR5A1 transcription activity. Results of the present study revealed that the -388 C>G mutation lost a CpG site and promoted NR5A1 gene expression, which completely superimposed positive effects on NR5A1 gene transcription activity by transcription factor SP1, resulting in a fecundity increase in Hu sheep.

miR-1275 controls granulosa cell apoptosis and estradiol synthesis by impairing LRH-1/CYP19A1 axis

miR-1275 is one of the microRNAs (miRNAs) that are differentially expressed during follicular atresia in pig ovaries, as identified by a miRNA microarray assay in our previous study [1]. However, its functions in follicular atresia remain unknown. In this study, we showed that miR-1275 promotes early apoptosis of porcine granulosa cells (pGCs) and the initiation of follicular atresia, and inhibits E2 release and expression of CYP19A1, the key gene in E2 production. Bioinformatics and luciferase reporter assays revealed that liver receptor homolog (LRH)-1, not CYP19A1, is a direct functional target of miR-1275. In vitro overexpression and knockdown experiments showed that LRH-1 significantly repressed apoptosis and induced E2 secretion and CYP19A1 expression in pGCs. LRH-1, whose expression was regulated by miR-1275, prevented apoptosis in pGCs. Furthermore, luciferase and chromatin immunoprecipitation assays demonstrated that LRH-1 protein bound to the CYP19A1 promoter and increased its activity. Our findings suggest that miR-1275 attenuates LRH-1 expression by directly binding to its 3'UTR. This prevents the interaction of LRH-1 protein with the CYP19A1 promoter, represses E2 synthesis, promotes pGC apoptosis, and initiates follicular atresia in porcine ovaries.