The Role of the MYL4 Gene in Porcine Muscle Development and Its Molecular Regulatory Mechanisms.

Simple Summary: Muscle growth is essential for the economic sustainability of the swine industry. Gaining a deeper understanding of pig muscle development is crucial for improving both the quantity and quality of pork production. This study employed RNA-seq technology to conduct a transcriptomic analysis of the longissimus dorsi muscle (LD) in three different pig breeds with varying body sizes and growth rates: Tibetan pigs (TP), Wujin pigs (WJ), and large white pigs (LW). Significant differences in gene expression were observed among the different breeds. We identified that myosin light chain 4 (MYL4) plays a role in influencing muscle growth. Experimental validation confirmed that MYL4 promotes skeletal muscle cell proliferation and inhibits degradation. These findings reveal the molecular mechanisms that control muscle growth and provide valuable insights for improving pig breeding practices, ultimately enhancing the efficiency and quality of meat production. Muscle growth stands as a pivotal economic trait within pig production, governed by a complex interplay of multiple genes, each playing a role in its quantitative manifestation. Understanding the intricate regulatory mechanisms of porcine muscle development is crucial for enhancing both pork yield and quality. This study used the GSE99749 dataset downloaded from the GEO database, conducting a detailed analysis of the RNA-seq results from the longissimus dorsi muscle (LD) of Tibetan pigs (TP), Wujin pigs (WJ) and large white pigs (LW) at 60 days of gestation, representing diverse body sizes and growth rates. Comparative analyses between TPvsWJ and TPvsLW, along with differential gene expression (DEG) analysis, functional enrichment analysis, and protein–protein interaction (PPI) network analysis, revealed 1048 and 1157 significantly differentially expressed genes (p < 0.001) in TPvsWJ and TPvsLW, respectively. With stricter screening criteria, 37 DEGs were found to overlap between the 2 groups. PPI analysis identified MYL5, MYL4, and ACTC1 as the three core genes. This article focuses on exploring the MYL4 gene. Molecular-level experimental validation, through overexpression and interference of the MYL4 gene combined with EDU staining experiments, demonstrated that overexpression of MYL4 significantly promoted the proliferation of porcine skeletal muscle satellite cells (PSMSC), while interference with MYL4 inhibited their proliferation. Furthermore, by examining the effects of overexpressing and interfering with the MYL4 gene on the muscle hypertrophy marker Fst gene and the muscle degradation marker FOXO3 gene, the pivotal role of the MYL4 gene in promoting muscle growth and preventing muscle degradation was further confirmed. These findings offer a new perspective on the molecular mechanisms behind porcine muscle growth and development, furnishing valuable data and insights for muscle biology research. [ABSTRACT FROM AUTHOR]