Porcine Skeletal Muscle-Specific lncRNA-ssc.37456 Regulates Myoblast Proliferation and Differentiation.

Long-chain non-coding RNAs (lncRNAs) play important regulatory roles in the growth and development of skeletal muscle, but systematic identification and functional studies of lncRNAs related to porcine skeletal muscle development remain limited. Based on a previously constructed panoramic map of porcine skeletal muscle lncRNAs, lncRNA-ssc.37456 was identified as differentially expressed in porcine skeletal muscle before and after birth. Its function and potential mechanisms were investigated using a porcine skeletal muscle regeneration model, a primary skeletal muscle cell differentiation model, and knockdown and overexpression experiments in vitro. lncRNA-ssc.37456 was upregulated on day 7 of regeneration, with expression positively correlated with the muscle differentiation marker MYHC and negatively correlated with the proliferation marker PAX7. During differentiation of porcine primary myoblasts, expression continuously increased, peaking on day 4. Knockdown of lncRNA-ssc.37456 by small interfering RNA (siRNA) significantly increased cell proliferation, upregulated mRNA and protein levels of proliferation-related genes KI67 and PCNA, and increased the proportion of EdU-positive cells. Conversely, expression of differentiation-related genes MYOG and MYHC decreased, and immunofluorescence analysis revealed reduced myotube formation and differentiation index. Overexpression of lncRNA-ssc.37456 promoted differentiation and inhibited proliferation, showing effects opposite to those observed in knockdown experiments. Nucleocytoplasmic fractionation indicated predominant cytoplasmic localization, suggesting potential function through a ceRNA mechanism. An interaction network with miRNAs was constructed based on the miRDB database, indicating a potential miRNA "sponge" regulatory mechanism. These results indicate that lncRNA-ssc.37456 participates in porcine skeletal muscle development by regulating the transition of muscle cells from proliferation to differentiation, providing molecular insights and potential targets for muscle biology research and the molecular breeding of growth traits.