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

## TL;DR

A long non-coding RNA called ssc.37456 regulates muscle cell growth and maturation in pigs, offering potential for improving meat production through breeding.

## Contribution

The study identifies and functionally characterizes a novel lncRNA, ssc.37456, involved in porcine muscle development.

## Key findings

- Knockdown of ssc.37456 increases myoblast proliferation but impairs differentiation.
- Overexpression of ssc.37456 promotes muscle cell maturation and inhibits proliferation.
- The lncRNA is cytoplasmic and may act as a miRNA sponge to regulate gene expression.

## Abstract

The long non-coding RNA ssc.37456 exhibits dynamic expression changes during pig skeletal muscle development. Knockdown of ssc.37456 in a pig muscle injury model and in primary muscle cells increased cell proliferation but impaired myofiber formation, whereas overexpression suppressed proliferation and promoted muscle maturation. Subcellular localization analysis indicated that ssc.37456 is predominantly cytoplasmic, suggesting potential interactions with small regulatory RNAs to modulate gene expression. These results identify ssc.37456 as a regulator of pig muscle growth and indicate its potential utility for improving growth performance and meat production through molecular breeding.

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.