miR‐21, miR‐125b, and let‐7b contribute to the involution of atretic follicles and corpus lutea in Tibetan sheep ovaries

Abstract

Follicular granulosa cells (FGCs) are crucial for ovarian follicle functions, and miRNAs are differentially expressed at various stages of follicular developments. In this study, we confirmed that miR-21, miR-125b, and let-7b were located in FGCs/luteal cells by in situ hybridization experiments. Moreover, miR-21 and miR-125b expressions were upregulated in late corpus lutea (CL) and atretic follicles (AF); let-7b expression was increased in early AF. After transfected with inhibitor or mimic of miRNAs in FGCs, we found that FGCs apoptosis was decreased in the miR-21-mi group but increased in the miR-125b-mi group using flow cytometry. mRNA and protein expression levels were determined for apoptosis-related factors (e.g., Bcl-2 and Bax), the potential target genes of miRNAs (e.g., SMAD7, SP1, and STAT3), hormone receptors (e.g., FSHR and LHR), and genes related to hormone secretion (e.g., CYP19, CYP11, and 3βHSD). The protein levels of SMAD7 were decreased in the miR-21-mi group but opposite to SP1 and FSHR. In the let-7b-mi group, Bcl-2, SMAD7, and FSHR were suppressed but not Bax, CYP11, and 3βHSD. However, hormone secretion was not changed in the supernatant of transfected FGCs. This study provides information about ovarian miRNAs to improve the fertility in Tibetan sheep.

miR-423 sponged by lncRNA NORHA inhibits granulosa cell apoptosis

“…SMAD7 is an inhibitory SMAD protein in the TGF-β pathway, which is strongly related to mammalian ovarian functions including GC states (proliferation or apoptosis) and cycle, secretion of steroid hormones (e.g., E2, P4, and androgen), oocyte-GC communication, and folliculogenesis [ 22 , 41 – 44 ]. In Tibetan sheep, miR-21 and let-7b, two miRNAs involved in FA and GC apoptosis, have been found to suppress SMAD7 expression in GCs [ 45 ]. In addition to miR-423, SMAD7 is a functional target of other miRNAs related to FA and GC apoptosis, such as miR-92a [ 22 ], miR-181b [ 24 ], and miR-21–5p [ 44 ].…”

Characterization of MicroRNA expression profiles in the ovarian tissue of goats during the sexual maturity period

“…Fig. 8 Protein-protein interaction network and network analysis for core genes and miRNAs from ovarian tissues or germ cells of goats [50][51][52], sheep [53][54][55], cows [56,57], and humans [58,59]; however, a complete analysis of the transcriptome of intact ovaries during the sexual maturity period of goats, especially Jining Grey goats, has rarely been reported thus far. Our analysis of the four developmental stage libraries identified a total of 667 miRNAs; only 474 miRNAs were commonly expressed in all four stages (Fig.…”