Short-chain fatty acids (SCFAs), particularly acetate, propionate and butyrate, are mainly produced by anaerobic fermentation of gut microbes. SCFAs play an important role in regulating energy metabolism and energy supply, as well as maintaining the homeostasis of the intestinal environment. In recent years, many studies have shown that SCFAs demonstrate physiologically beneficial effects, and the signalling pathways related to SCFA production, absorption, metabolism, and intestinal effects have been discovered. Two major signalling pathways concerning SCFAs, G-protein-coupled receptors (GPRCs) and histone deacetylases (HDACs), are well recognized. In this review, we summarize the recent advances concerning the biological properties of SCFAs and the signalling pathways in inflammation and glucose and lipid metabolism.

Adipogenesis is a complex biological process and the main cause of obesity. Recently, microRNAs (miRNAs), a class of small endogenous non-coding RNAs, have been proven to play an important role in adipogenesis by the post-transcriptional regulation of target genes. In this current study, we observed an increment of miR-152 expression during the process of 3T3-L1 cell audiogenic differentiation. A functional analysis indicated that the overexpression of miR-152 inhibited pre-adipocyte proliferation and suppressed the expression of some cell cycle-related genes. Moreover, the overexpression of miR-152 promoted lipid accumulation in 3T3-L1 preadipocytes accompanied by increase of the expression of some pro-audiogenic genes. Additionally, a dual-luciferase reporter assay demonstrated lipoprotein lipase (LPL) was a direct target gene of miR-152 during preadipocyte differentiation. Further analysis showed that miR-152 was positively correlated with adipogenesis and intramuscular fat formation in vivo. Taken together, our findings suggest that miR-152 could suppress 3T3-L1 preadipocyte proliferation, whereas it could promote 3T3-L1 preadipocyte differentiation by negatively regulating LPL. The findings indicate that miR-152 might have a therapeutic significance for obesity and obesity-related metabolic syndrome.

Effective, targeted therapy for chronic liver disease nonalcoholic steatohepatitis (NASH) is imminent. MicroRNAs (miRNAs) are a potential therapeutic target, and natural products that regulate miRNA expression may be a safe and effective treatment strategy for liver disease. Here, we investigated the functional role of miR-451 and the therapeutic effects of genistein in the NASH mouse model. MiR-451 was downregulated in various types of liver inflammation, and subsequent experiments showed that miR-451 regulates liver inflammation via IL1β. Genistein is a phytoestrogen with anti-inflammatory and anti-oxidant effects. Interestingly, we found that the anti-inflammatory effects of genistein were related to miR-451 and was partially antagonized by the miR-451 inhibitor. MiR-451 overexpression or genistein treatment inhibited IL1β expression and inflammation. Taken together, this study shows that miR-451 has a protective effect on hepatic inflammation, and genistein can be used as a natural promoter of miR-451 to ameliorate NASH.

Skeletal muscle is the most abundant and a highly plastic tissue of the mammals, especially when it comes to regenerate after trauma, but there is limited information about the mechanism of muscle repair and its regeneration. In the present study, we found that miR‐204 is downregulated after skeletal muscle injury. In vitro experiments showed that over‐expression of miR‐204 by transfecting with miR‐204 mimics suppressed C2C12 cell proliferation, migration, and blocked subsequent differentiation, whereas inhibition of miR‐204 by transfecting with miR‐204 inhibitor showed the converse effects. Furthermore, through the dual luciferase reporter system, we demonstrated that miR‐204 can target the 3’UTR regions of Pax7, IGF1, and Mef2c and inhibit their expression. Taken together, our results suggest that Pax7, IGF1, and Mef2c are the target genes of miR‐204 in the process of myoblasts proliferation, cell migration, and differentiation, respectively, and may contribute to mouse skeletal muscle regeneration. Our results may provide new ideas and references for the skeletal muscle study and may also provide therapeutic strategies of skeletal muscle injury.

MiRNA is a small non-coding RNA, which plays an important role in diverse biological processes. In the present study, we explore the effect of ssc-miR-451 on porcine adipose development and meat quality. We observed that ssc-miR-451 was downregulated during porcine primary adipocyte differentiation. Overexpression of ssc-miR-451 inhibited adipogenic differentiation, while inhibition of ssc-miR-451 promoted adipogenic differentiation. The dual luciferase reporter system indicated Acetyl-CoA carboxylase alpha (ACACA) as a target gene of ssc-miR-451. Correlation analysis negatively correlated miR-451 expression with intramuscular fat content (IMF) and positively correlated ACACA expression with IMF. Further analysis of fatty acid composition revealed that pigs with high expression of ssc-miR-451 had higher monounsaturated fatty acid (MUFA) and lower polyunsaturated fatty acid (PUFA). Taken together, our study suggests that ssc-miR-451 regulates lipid deposition and fatty acid composition by targeting ACACA, and ssc-miR-451 may serve as a potential genetic marker to improve pork quality.

Gene transcripts or mRNAs and long noncoding RNAs (lncRNAs) are differentially expressed during porcine skeletal muscle development. However, only a few studies have been conducted on skeletal muscle transcriptome in pigs based on timepoints according to the growth curve for porcine. Here, we investigated gene expression in Qingyu pigs at three different growth stages: the inflection point with the maximum growth rate (MGI), the inflection point of the gradually increasing stage to the rapidly increasing stage (GRI), and the inflection point of the rapidly increasing stage to the slowly increasing stage (RSI). Subsequently, we explored gene expression profiles during muscle development at the MGI, GRI and RSI stages by Ribo-Zero RNA sequencing. Qingyu pigs reached the MGI, GRI and RSI stages at 156.40, 23.82 and 288.97 days of age with 51.73, 3.14 and 107.03 kg body weight, respectively. A total of 14,530 mRNAs and 11,970 lncRNAs were identified at the three stages, and 645, 323 differentially expressed genes (DEGs) and 696, 760 differentially expressed lncRNAs (DELs) were identified in the GRI vs. MGI, and RSI vs. MGI, comparisons. Functional enrichment analysis revealed that genes involved in immune system development and energy metabolism (mainly relate to amino acid, carbohydrate and lipid) were enriched at the GRI and MGI stages, respectively, whereas genes involved in lipid metabolism were enriched at the RSI stage. We further characterized G1430, an abundant lncRNA. The full-length sequence (316 nt) of lncRNA G1430 was determined by rapid amplification of cDNA ends (RACE). Subcellular distribution analysis by quantitative real-time PCR (qRT-PCR) revealed that G1430 is a cytoplasmic lncRNA. Binding site prediction and dual luciferase assay showed that lncRNA G1430 directly binds to microRNA 133a (miR-133a). Our findings provide the basis for further investigation of the regulatory mechanisms and molecular genetics of muscle development in pigs.