Muscle development is closely related to meat quality and production. CircRNAs, with a closed-ring structure, have been identified as a key regulator of muscle development. However, the roles and mechanisms of circRNAs in myogenesis are largely unknown. Hence, in order to unravel the functions of circRNAs in myogenesis, the present study explored circRNA profiling in skeletal muscle between Mashen and Large White pigs. The results showed that a total of 362 circRNAs, which included circIGF1R, were differentially expressed between the two pig breeds. Functional assays showed that circIGF1R promoted myoblast differentiation of porcine skeletal muscle satellite cells (SMSCs), while it had no effect on cell proliferation. In consideration of circRNA acting as a miRNA sponge, dual-luciferase reporter and RIP assays were performed and the results showed that circIGF1R could bind miR-16. Furthermore, the rescue experiments showed that circIGF1R could counteract the inhibitory effect of miR-16 on cell myoblast differentiation. Thus, circIGF1R may regulate myogenesis by acting as a miR-16 sponge. In conclusion, this study successfully screened candidate circRNAs involved in the regulation of porcine myogenesis and demonstrated that circIGF1R promotes myoblast differentiation via miR-16, which lays a theoretical foundation for understanding the role and mechanism of circRNAs in regulating porcine myoblast differentiation.

Genetic improvement of pork quality is one of the hot topics in pig germplasm innovation. Backfat thickness and intramuscular fat content are important indexes of meat quality. MiRNAs are becoming recognized as a crucial regulator of adipose development. Therefore, it is crucial to understand how miR-23b regulates fat metabolism at the molecular level. In the present study, Oil Red O staining, and Western blot were used to evaluate the effect of miR-23b on the differentiation of porcine preadipocytes. Dual-luciferase reporter gene assay, pulldown, and RIP were used to reveal the mechanism of miR-23b regulating cell differentiation. The findings demonstrated that miR-23b promotes the expression of adipogenic factors and increases the content of lipid droplets, thus promoting the differentiation of preadipocytes. Further research found that miR-23b can directly bind to the 3’UTR of SESN3 to regulate adipogenic differentiation. In addition, it was speculated that miR-23b controls cell differentiation by positively regulating the expression of ACSL4 in other ways. Here, we demonstrate that miR-23b promotes the differentiation of porcine preadipocytes by targeting SESN3 and promoting the expression of ACSL4. The present study is meaningful to the improvement of pork quality and the development of animal husbandry.

Feed fermentation enhances feed nutrition and animal health, but its impact on the gut microbiota of young pigs remains unclear. This study aimed to evaluate the effects of a probiotic fermented feed, which includes Lactobacillus plantarum, Pediococcus pentosaceus, Bacillus subtilis, and Bacillus coagulans, on the growth performance, meat quality, and intestinal microbiota of growing pigs. We randomly assigned 24 Duroc × Landrace × Landrace pigs to two groups: a control (Ctrl) group and the fermented liquid feed (FLF) group, with three replicate pens per group and four pigs per pen. Results indicated that the FLF group experienced a significant decrease in anti-nutritional factors like α-conglycinin and β-conglycinin. In addition, the average daily gain of pigs in the FLF group increased significantly, while the feed conversion ratio and shear force decreased. HE staining showed that the FLF group had notably enhanced villus height in the jejunum and ileum. 16S rRNA sequencing revealed a marked increase in the relative abundance of certain microbes in the FLF group, which were predominantly associated with carbohydrate and amino acid metabolism. These results indicated that compound probiotic FLF can elevate feed quality, enhance the growth performance of growing pigs, and ameliorate the structure of the gut microbiota.

Obesity and its associated metabolic disease do serious harm to human health. The transcriptional cascade network with transcription factors as the core is the focus of current research on adipogenesis and its mechanism. Previous studies have found that HMG domain protein 20A (HMG20A) is highly expressed in the early stage of adipogenic differentiation of porcine intramuscular fat (IMF), which may be involved in regulating adipogenesis. In this study, HMG20A was found to play a key negative regulatory role in adipogenesis. Gain- and loss-of-function studies revealed that HMG20A inhibited the differentiation of SVF cells and C3H10T1/2 cells into mature adipocytes. RNA-seq was used to screen differentially expressed genes after HMG20A knockdown. qRT-PCR and ChIP-PCR confirmed that MEF2C was the real target of HMG20A, and HMG20A played a negative regulatory role through MEF2C. HMG20A binding protein LSD1 was found to alleviate the inhibitory effect of HMG20A on adipogenesis. Further studies showed that HMG20A could cooperate with LSD1 to increase the H3K4me2 of the MEF2C promoter and then increase the expression of MEF2C. Collectively, these findings highlight a role for HMG20A-dependent transcriptional and epigenetic regulation in adipogenesis.

Circular RNA (circRNA) has a significant impact on the maturation of skeletal muscle, although their precise functions within this framework remain largely uncharted. This study presents an investigation of the regulatory effect of circAGGF1 on myogenesis in myoblasts, including the potential molecular mechanisms involved. It is revealed that circAGGF1 facilitates the differentiation of myoblasts into other states while simultaneously enhancing the manifestation of type I muscle fibers. In vivo investigations with mice revealed the promotion of skeletal muscle expansion and maturation by circAGGF1, bolstering its regenerative capacity. Mechanistically, circAGGF1 interacts with miR-199a-3p by acting as a sponge, promoting the subsequent expression of Fgf7. Furthermore, rescue experiments indicated a counteraction of the myogenesis induced by circAGGF1 overexpression by miR-199a-3p. To summarize, this research highlights the role played by circAGGF1 in the development of skeletal muscle, providing a valuable resource for enhancing our understanding of skeletal muscle biology.