MicroRNA‑378d inhibits by targeting in vitamin D deficient ovarian granulosa cells.

Vitamin D (VD) is not only associated with bone growth and development, but is also closely associated with numerous other pathological conditions. The present study aimed to investigate the effect of microRNA (miRNA/miR)‑378d on ovarian granulosa cells by regulating the round spermatid basic protein 1 () in the absence of VD. The abnormal expression of miRNAs in ovarian tissues of the VD‑deficient mouse was analyzed using transcriptome sequencing. miR‑378d, glucose transporter 4 () and aromatase () expression levels were examined via reverse transcription‑quantitative (RT‑q)PCR and western blotting. The expression levels of , and were detected in transfected mouse ovarian granulosa cells. The targeting regulation between miR‑378d and was verified using double reporter gene assay and functional rescue experiments. Among the 672 miRNAs that were differentially expressed, cluster analysis revealed that 17 were significantly upregulated and 16 were significantly downregulated. Moreover, miR‑378d showed significant upregulation, which was further verified via RT‑qPCR. It was identified that the protein expression level of was significantly downregulated. Furthermore, mRNA expression was significantly decreased in the mimic group but markedly increased in the inhibitor group. By contrast, the mRNA expression levels of and did not demonstrate any significant difference. The western blotting results indicated that the protein expression levels of and were decreased and increased, respectively, while did not show any significant change. In addition, the double reporter gene experiments confirmed that was the target gene of miR‑378d. Collectively, the present results demonstrated that miR‑378d was abnormally overexpressed in the ovarian tissues of the VD‑deficient mice, and that miR‑378d could inhibit production by targeting , which may lead to insulin resistance.