Wang Kaiming, Liu Caihong, Yi Lei, Liufu Sui, Chen Wenwu, Liu Xiaolin, Chen Bohe, Xu Xin, Liu Jingwen, Liu Xibing, Yin Yulong, Ma Haiming
College of Animal Science and Technology, Hunan Agricultural University, Changsha, 410128, China.
Yuelushan Laboratory, Changsha, 410128, China.
BMC Genomics. 2025 Jul 31;26(1):709. doi: 10.1186/s12864-025-11897-z.
Skeletal muscle is the largest tissue in mammals, and it plays a crucial role in metabolism and homeostasis. Skeletal muscle development and regeneration consist of a series of carefully regulated changes in gene expression. Leiomodin2 (LMOD2) gene is specifically expressed in the heart and skeletal muscle. But the physiological functions and mechanisms of LMOD2 on skeletal muscle development are unknown.
In this study, we examined the expression levels of the LMOD2 in porcine tissues and C2C12 cells. LMOD2 is mainly expressed in the heart, followed by skeletal muscle. The expression level of LMOD2 gradually decreased with skeletal muscle growth, but increased after injury. LMOD2 expression levels increased gradually with C2C12 cells proliferation and differentiation. In terms of function, the muscle fiber types were altered after LMOD2 was knocked out in C2C12 cells, MyHC-I and MyHC-2b were inhibited, whereas MyHC-2a and MyHC-2x were promoted. LMOD2 knockout has different effects on LMOD family, LMOD1 expression level was promoted, while LMOD3 was inhibited. Loss of LMOD2 suppressed cell viability and PAX7 protein expression. At the transcriptome level, proliferation-related genes and muscle contraction-related genes were respectively inhibited after LMOD2 knockout. In terms of molecular networks, a series of experiments have shown that MyoG is a transcription factor for LMOD2, while miR-335-3p can negatively regulate LMOD2 expression. We screened ACTC1 as a candidate interacting protein for LMOD2 using protein prediction software and RNA-seq, and Co-IP experiments confirmed the relationship between LMOD2 and ACTC1. In vivo, Lentivirus-mediated LMOD2 knockdown reduces muscle mass. LMOD2 knockdown inhibited MyHC-I mRNA expression, but had no effect on MyHC-2b. The protein expression of MyHC-I, MyHC-2x, and MyHC-2b was suppressed after LMOD2 knockdown.
Collectively, our data indicates that LMOD2 knockout inhibits myoblast proliferation and alters muscle fiber types. MyoG is a transcription factor for LMOD2, while miR-335-3p can negatively regulate LMOD2 expression. Moreover, LMOD2 and ACTC1 interact to regulate myogenic differentiation. Our study provides a new target for skeletal muscle development.
骨骼肌是哺乳动物中最大的组织，在新陈代谢和体内平衡中发挥着关键作用。骨骼肌的发育和再生包括一系列基因表达的精细调控变化。雷奥莫定2（LMOD2）基因在心脏和骨骼肌中特异性表达。但LMOD2在骨骼肌发育中的生理功能及机制尚不清楚。
在本研究中，我们检测了LMOD2在猪组织和C2C12细胞中的表达水平。LMOD2主要在心脏中表达，其次是骨骼肌。LMOD2的表达水平随着骨骼肌生长逐渐降低，但在损伤后升高。随着C2C12细胞的增殖和分化，LMOD2表达水平逐渐升高。在功能方面，C2C12细胞中敲除LMOD2后肌纤维类型发生改变，MyHC-I和MyHC-2b受到抑制，而MyHC-2a和MyHC-2x受到促进。敲除LMOD2对LMOD家族有不同影响，LMOD1表达水平升高，而LMOD3受到抑制。LMOD2缺失抑制细胞活力和PAX7蛋白表达。在转录组水平，敲除LMOD2后增殖相关基因和肌肉收缩相关基因分别受到抑制。在分子网络方面，一系列实验表明MyoG是LMOD2的转录因子，而miR-335-3p可负调控LMOD2表达。我们使用蛋白质预测软件和RNA测序筛选出ACTC1作为LMOD2的候选相互作用蛋白，免疫共沉淀实验证实了LMOD2与ACTC1之间的关系。在体内，慢病毒介导的LMOD2敲低降低了肌肉质量。敲低LMOD2抑制MyHC-I mRNA表达，但对MyHC-2b无影响。敲低LMOD2后，MyHC-I、MyHC-2x和MyHC-2b的蛋白表达受到抑制。
总体而言，我们的数据表明敲除LMOD2会抑制成肌细胞增殖并改变肌纤维类型。MyoG是LMOD2的转录因子，而miR-335-3p可负调控LMOD2表达。此外，LMOD2与ACTC1相互作用以调节肌源性分化。我们的研究为骨骼肌发育提供了一个新靶点。
