The SIRT1 epigenetic regulator is involved in hepatic lipid homoeostasis. However, the role of SIRT1 in regulating intramuscular fat deposition as well as the pathways and potential epigenetic targets involved remain unknown. Herein, we investigate SIRT1 function, its genome-wide epigenetic target profile, and transcriptomic changes under SIRT1 overexpression during yak intramuscular preadipocytes differentiation. To this end, we analysed the relationship between SIRT1 and intramuscular fat content as well as lipid metabolism-related genes in longissimus dorsi tissue. We found that SIRT1 expression negatively correlates with intramuscular fat content as well as with the expression of genes related to lipid synthesis, while positively correlating with that of fatty acid oxidation-involved genes. SIRT1 overexpression in intramuscular preadipocytes significantly reduced adipose differentiation marker expression, intracellular triacylglycerol content, and lipid deposition. Chromatin immunoprecipitation coupled with high-throughput sequencing of H3K4ac (a known direct target of SIRT1) and high-throughput mRNA sequencing results revealed that SIRT1 may regulate intramuscular fat deposition via three potential new transcription factors (NRF1, NKX3.1, and EGR1) and four genes (MAPK1, RXRA, AGPAT1, and HADH) implicated in protein processing within the endoplasmic reticulum pathway and the MAPK signalling pathway in yaks. Our study provides novel insights into the role of SIRT1 in regulating yak intramuscular fat deposition and may help clarify the mechanistic determinants of yak meat characteristics.

Due to its prominent secretory activity, adipose tissue (AT) is now considered a major player in the crosstalk between organs, especially with skeletal muscle. In which, exosomes are effective carriers for the intercellular material transfer of a wide range of molecules that can influence a series of physiological and pathological processes in recipient cells. Considering their underlying roles, the regulatory mechanisms of adipose-secreted exosomes and their cellular crosstalk with skeletal muscle have received great attention in the field. In this review, we describe what is currently known of adipose-secreted exosomes, as well as their applications in skeletal muscle pathophysiology.

The yak (Bos grunniens) has exceptional hypoxia resilience, making it an ideal model for studying high-altitude adaptation. Here, we investigated the effects of oxygen concentration on yak cardiac fibroblast proliferation and the underlying molecular regulatory pathways using RNA sequencing (RNA-seq) and metabolic analyses. Decreased oxygen levels significantly inhibited cardiac fibroblast proliferation and activity. Intriguingly, while the mitochondrial DNA (mtDNA) content remained stable, we observed coordinated upregulation of mtDNA-encoded oxidative phosphorylation components. Live-cell metabolic assessment further demonstrated that hypoxia led to mitochondrial respiratory inhibition and enhanced glycolysis. RNA-seq analysis identified key hypoxia adaptation genes, including glycolysis regulators (e.g., HK2, TPI1), and hypoxia-inducible factor 1-alpha (HIF-1α), with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses highlighting their involvement in metabolic regulation. The protein–protein interaction network identified three consensus hub genes across five topological algorithms (CCNA2, PLK1, and TP53) that may be involved in hypoxia adaptation. These findings highlight the importance of metabolic reprogramming underlying yak adaptation to hypoxia, providing valuable molecular insights into the mechanisms underlying high-altitude survival.

Methionine is an amino acid necessary for the growth and development of all animals. Glutathione produced during methionine metabolism can reduce damage to cells caused by oxidative stress. Supplementing restricted amino acids in animals by scientific means will be beneficial to protein synthesis, which will affect the growth and development of animals and will bring huge economic benefits when applied to actual production and life. In this study, we collected three muscle tissues from 24 male Maiwa yaks, which were fattened for three months with different methionine concentrations in their diet. RNA-seq was performed to obtain expression reads. A total of 1116 editing sites were identified by at least two software; the editing site types were mainly T-to-C and A-to-G mutations. We found two significant RNA editing sites presenting high-risk editing types. One was located on the MSRA gene that regulates the reduction of methionine, and the other can make changes to the properties of encoded proteins. This provides further understanding of the mechanism of yak muscle tissue and regulation of gene expression after the addition of methionine to daily rations.

Skeletal myogenesis is an extremely complex process that mononuclear myoblasts undergo proliferation, differentiation, and fusion to form multinucleated contractile muscle fibers, involving a balance between synthesis and degradation metabolism. Skeletal muscle requires an effective mechanism to balance rapid proliferation by degrading supernumerary or damaged organelles/proteins, or by activating cellular signals to regulate subsequent muscle differentiation. In recent years, three important cellular processes—apoptosis, ubiquitin–proteasome system (UPS), and autophagy—have received extensive attention in skeletal myogenesis. The UPS supports the early differentiation process and initiates apoptosis, and the increase in apoptosis activates autophagy to clear damaged organelles and proteins, which in turn inhibits apoptosis, preventing excessive cell death and maintaining cellular stability. The coordination among apoptosis, UPS, and autophagy is more intricate, as they interact through a dynamic balancing mechanism, determining the balance between cell death and survival, and enabling proper muscle differentiation. Here, we explore the molecular signals that mediate apoptosis, UPS, and autophagy, with a focus on analyzing their interrelationship in skeletal myogenesis. Studying the regulatory mechanisms of these molecules will help in understanding the role of cell death in skeletal muscle development, especially how they affect muscle cell differentiation, providing new insights into mammalian skeletal myogenesis.