NCBI Summary:
microRNAs (miRNAs) are short (20-24 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. miRNAs are transcribed by RNA polymerase II as part of capped and polyadenylated primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA and antisense miRNA star (miRNA*) products. The mature miRNA is incorporated into a RNA-induced silencing complex (RISC), which recognizes target mRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilization of the target mRNA. The RefSeq represents the predicted microRNA stem-loop. [provided by RefSeq, Sep 2009]
General function
RNA processing, RNA binding
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Follicle atresia
Comment
MiR-26a promotes apoptosis of porcine granulosa cells by targeting the 3β-hydroxysteroid-Δ24-reductase gene. Zhang X et al. (2019) Apoptosis of ovarian granulosa cells (GCs) affects mammalian follicular development and fecundity. This study aimed to explore the regulatory relationship between microRNA-26a (miR-26a) and the 3β-hydroxysteroid-Δ24-reductase gene (DHCR24) gene in porcine follicular granular cells (pGCs), and to provide empirical data for the development of methods to improve the reproductive capacity of pigs. The pGCs were transfected with miR-26a mimic, miR-26a inhibitor and DHCR24-siRNA in vitro. The cell apoptosis rate of pGCs was detected by the flow cytometry. The secretion levels of estradiol (E2) and progesterone (P) in pGCs were detected by Enzyme-linked immunosorbent assay (ELISA). Double luciferase validation system was used to detect the binding sites between miR-26a and DHCR24 3'-UTR region. Qualitative real-time PCR (qPCR) and Western blotting (WB) were used to verify the DHCR24 mRNA and protein expression in pGCs, respectively, after transfecting with miR-26a mimic and miR-26a inhibitor. Results showed that enhancement of miR-26a promoted apoptosis, and inhibited E2 and P secretion in pGCs. Meanwhile, inhibition of DHCR24 also upregulated the Caspase-3 expression, reduced the BCL-2 expression, promoted pGCs apoptosis, and inhibited E2 and P secretion in pGCs. There was the binding sites of miR-26a located within DHCR24 3'-UTR. Up-regulation of miR-26a inhibited DHCR24 mRNA and protein expression in pGCs. This study demonstrates that miR-26a can promote cell apoptosis and inhibit E2 and P secretion by inhibiting the expression of DHCR24 in pGCs.//////////////////