Effects of MicroRNA-27a on Myogenin Expression and Akt/FoxO1 Signal Pathway during Porcine Myoblast Differentiation

miR-423-5p Regulates Skeletal Muscle Growth and Development by Negatively Inhibiting Target Gene SRF

The process of muscle growth directly affects the yield and quality of pork food products. Muscle fibers are created during the embryonic stage, grow following birth, and regenerate during adulthood; these are all considered to be phases of muscle development. A multilevel network of transcriptional, post-transcriptional, and pathway levels controls this process. An integrated toolbox of genetics and genomics as well as the use of genomics techniques has been used in the past to attempt to understand the molecular processes behind skeletal muscle growth and development in pigs under divergent selection processes. A class of endogenous noncoding RNAs have a major regulatory function in myogenesis. But the precise function of miRNA-423-5p in muscle development and the related molecular pathways remain largely unknown. Using target prediction software, initially, the potential target genes of miR-423-5p in the Guangxi Bama miniature pig line were identified using various selection criteria for skeletal muscle growth and development. The serum response factor (SRF) was found to be one of the potential target genes, and the two are negatively correlated, suggesting that there may be targeted interactions. In addition to being strongly expressed in swine skeletal muscle, miR-423-5p was also up-regulated during C2C12 cell development. Furthermore, real-time PCR analysis showed that the overexpression of miR-423-5p significantly reduced the expression of myogenin and the myogenic differentiation antigen (p < 0.05). Moreover, the results of the enzyme-linked immunosorbent assay (ELISA) demonstrated that the overexpression of miR-423-5p led to a significant reduction in SRF expression (p < 0.05). Furthermore, miR-423-5p down-regulated the luciferase activities of report vectors carrying the 3' UTR of porcine SRF, confirming that SRF is a target gene of miR-423-5p. Taken together, miR-423-5p's involvement in skeletal muscle differentiation may be through the regulation of SRF.

MiR-424-5p targets HSP90AA1 to facilitate proliferation and restrain differentiation in skeletal muscle development

MiR-424-5p was found to be a potential regulator in the proliferation, migration, and invasion of various cancer cells. However, the effects and functional mechanism of miR-424-5p in the process of myogenesis are still unclear. Previously, using microRNA (miRNA) sequencing and expression analysis, we discovered that miR-424-5p was expressed differentially in the different skeletal muscle growth periods of Xuhuai goats. We hypothesized that miR-424-5p might play an important role in skeletal muscle myogenesis. Then, we found that the proliferation ability of the mouse myoblast cell (C2C12 myoblast cell line) was significantly augmented, whereas the C2C12 differentiation was repressed after increasing the expression of miR-424-5p. Mechanistically, HSP90AA1 presented a close interrelation with miR-424-5p, which was predicted as a target gene in the progression of skeletal muscle myogenesis, using transcriptome sequencing, dual luciferase reporter gene detection, and qRT-PCR. The silencing of HSP90AA1 obviously increased C2C12 proliferation and diminished differentiation, which is consistent with the ability of miR-424-5p in C2C12. Altogether, our findings indicated the role of miR-424-5p as a novel potential regulator via HSP90AA1 during muscle myogenesis progression.

miR-27a-3p targets NR5A2 to regulate CYP19A1 expression and 17-β estradiol synthesis in ovine granulosa cells

Although 17-β estradiol (E2) synthesis is important in regulating female fertility, we know little regarding the molecular mechanism of miRNA-regulated ovine E2 synthesis. Here, our experiments with granulosa cells (GCs) from Hu sheep revealed miR-27a-3p involvement in E2 synthesis and its association with ovine litter size. First, we showed that miR-27a-3p of sheep and other mammals share a high nucleotide identity. Next, gain- and loss-of-function assays indicated that miR-27a-3p inhibits CYP19A1 expression and E2 synthesis in GCs. Moreover, we demonstrated that NR5A2 is a direct target of miR-27a-3p. Ovine miR-27a-3p suppresses E2 synthesis via the NR5A2 and CYP19A1 axes. We also identified four single nucleotide polymorphisms in the ovine miR-27a gene, and g.-13 G>A and g 0.24 T > G were significantly associated with the first and the second parity litter size, respectively (P < 0.05). In summary, our findings reveal that miR-27a-3p is a novel regulator of E2 synthesis and may predict litter size of Hu sheep, providing insight into mechanisms underlying granulosa cell function and female fertility.

Knockdown of CDR1as Decreases Differentiation of Goat Skeletal Muscle Satellite Cells via Upregulating miR-27a-3p to Inhibit ANGPT1

Myogenesis is a complex process controlled by several coding and non-coding RNAs (ncRNAs), such as circular RNAs (circRNAs) that are known to function as endogenous microRNAs (miRNAs) sponges. Cerebellar Degeneration-Related protein 1 antisense (CDR1as) is the most spotlighted circRNA that is known as an miR-7 sponge, which has bloomed circRNAs’ research in animal disease and physiology. Here, we screened for miRNAs and mRNA associated with CDR1as and further characterized their regulatory function during muscle differentiation. We found that a total of 43 miRNAs (including miR-107-3p, miR-125b-5p, miR-140-5p, miR-29a-3p, and miR-27a-3p upregulated) and 789 mRNAs (including ANGPT1, E2F2, CCN1, FGFR1, and MEF2C downregulated) were differentially expressed in goat skeletal muscle satellite cells (SMSCs). Further, knockdown of CDR1as and ANGPT1 inhibited SMSCs differentiation. miR-27a-3p was differentially upregulated after the knockdown of CDR1as in SMSCs. Overexpressed miR-27a-3p decreased SMSCs differentiation. Via RNAhybrid and luciferase, miR-27a-3p was identified to regulate ANGPT1. We discovered that miR-27a-3p has an inverse relationship with CDR1as and decreases the expression level of ANGPT1 during SMSCs differentiation. In summary, our study demonstrates that siCDR1as inhibits myoblast differentiation by downregulating ANGPT1 mRNA via miR-27a-3p in SMSCs.

A novel identified circ-ANKHD1 targets the miR-27a-3p/SFRP1 signaling pathway and modulates the apoptosis of granulosa cells

The specific expression profile and function of circular RNAs (circRNAs) in mammalian ovarian follicles, especially during the atresia process, are unclear. In this study, we verified and explored the expression and function of circ-ANKHD1 in granulosa cells. Our results showed that abundance of circ-ANKHD1 was significantly lower in the granulosa cells than that of ANKHD1. The expression of ANKHD1 was highest in the granulosa cells from follicles with a diameter of 5-6 mm and lowest in that with a diameter of 3-4 mm. Furthermore, the expression level of circ-ANKHD1 in the ovarian tissue of 1-day-old piglets was significantly higher than that of 17-month-old multiparous sows. The luciferase reporter assay showed the potential interaction between circ-ANKHD1 and miR-27a-3p/miR-142-5p. Furthermore, circ-ANKHD1 overexpression up-regulated SFRP1 expression, while miR-27a-3p overexpression suppressed SFRP1 expression in granulosa cells. Circ-ANKHD1 overexpression significantly decreased the cell apoptotic rates of the granulosa cells and repressed the cell population at G0/G1 and S phases but increased cell population at G2/M phase. Finally, circ-ANKHD1 overexpression increased the mRNA expression levels of Bcl-2 and cyclin D1 in the granulosa cells, while there are no effects on the mRNA expression levels of caspase-3, p53, Bax, and proliferating cell nuclear antigen. In conclusion, our study for the first time identified a novel circRNA, circ-ANKHD1 that may be associated with the biological functions of granulosa cells. Circ-ANKHD1 may promote the granulosa cell proliferation, but attenuate apoptosis, and these effects may be associated with modulation of miR-27a-3p/SFRP1.

Role of microRNAs in myogenesis and their effects on meat quality in pig - A review

The demand for food is increasing day by day because of the increasing global population. Therefore, meat, the easiest and largely available source of protein, needs to be produced in large amounts with good quality. The pork industry is a significant shareholder in fulfilling the global meat demands. Notably, myogenesis- development of muscles during embryogenesis- is a complex mechanism which culminates in meat production. But the molecular mechanisms which govern the myogenesis are less known. The involvement of miRNAs in myogenesis and meat quality, which depends on factors such as myofiber composition and intramuscular fat contents which determine the meat color, flavor, juiciness, and water holding capacity, are being extrapolated to increase both the quantity and quality of pork. Various kinds of microRNAs (miRNAs), miR-1, miR-21, miR22, miR-27, miR-34, miR-127, miR-133, miR-143, miR-155, miR-199, miR-206, miR-208, miR-378, and miR-432 play important roles in pig skeletal muscle development. Further, the quality of meat also depends upon myofiber which is developed through the expression of different kinds of miRNAs at different stages. This review will focus on the mechanism of myogenesis, the role of miRNAs in myogenesis, and meat quality with a focus on the pig.

Propofol Alleviates DNA Damage Induced by Oxygen Glucose Deprivation and Reperfusion via FoxO1 Nuclear Translocation in H9c2 Cells

Ischemia/reperfusion (I/R) injury induces irreversible oxidative stress damage to the cardiac myocytes. Many studies have revealed that propofol alleviates the important organelle-mediated injury from oxidative stress in vitro. However, it remains unclear whether propofol prevents I/R-induced DNA damage in cardiomyocytes. In our study, we established an oxygen glucose deprivation/reoxygenation (OGD/R) model in H9c2 cells and found that propofol decreased reactive oxygen species (ROS) levels and suppressed cell apoptosis induced by OGD/R in H9c2 cells. In addition, propofol significantly reduced the molecular marker of DNA damage and inhibited double-strand breaks of DNA damage induced by OGD/R in H9c2 cells in a dose-dependent manner. Furthermore, we investigated the molecular mechanisms and demonstrated that propofol inhibited forkhead box O 1 (FoxO1) phosphorylation and increased FoxO1 nuclear translocation through inhibition of protein kinase B (Akt) and adenosine 5’-monophosphate-activated protein kinase (AMPK) pathways. The protective effects of propofol against oxidative stress-induced DNA damage were reversed by silencing FoxO1. Taken together, our results suggest that oxidative stress aggravates DNA damage and apoptosis in H9C2 cells, which can be reversed by propofol via FoxO1 nuclear translocation.