Institute of Stem Cell and Regenerative Medicine, School of Medicine, Xiamen University, Xiamen 361100, China.
Shenzhen Research Institute of Xiamen University, Guangdong Province, 518000, P.R. China.
Theranostics. 2020 Sep 11;10(24):11159-11177. doi: 10.7150/thno.44389. eCollection 2020.
The adult skeletal muscle can self-repair efficiently following mechanical or pathological damage due to its remarkable regenerative capacity. However, regulatory mechanisms underlying muscle regeneration are complicated and have not been fully elucidated. Alternative splicing (AS) is a major mechanism responsible for post-transcriptional regulation. Many aberrant AS events have been identified in patients with muscular dystrophy which is accompanied by abnormal muscle regeneration. However, little is known about the correlation between AS and muscle regeneration. It has been reported that RNA binding motif protein 24 (Rbm24), a tissue-specific splicing factor, is involved in embryo myogenesis while the role of Rbm24 in adult myogenesis (also called muscle regeneration) is poorly understood. To investigate the role of Rbm24 in adult skeletal muscle, we generated Rbm24 conditional knockout mice and satellite cell-specific knockout mice. Furthermore, a cardiotoxin (CTX)-induced injury model was utilized to assess the effects of Rbm24 on skeletal muscle regeneration. Genome-wide RNA-Seq was performed to identify the changes in AS following loss of Rbm24. Rbm24 knockout mice displayed abnormal regeneration 4 months after tamoxifen treatment. Using RNA-Seq, we found that Rbm24 regulated a complex network of AS events involved in multiple biological processes, including myogenesis, muscle regeneration and muscle hypertrophy. Moreover, using a CTX-induced injury model, we showed that loss of Rbm24 in skeletal muscle resulted in myogenic fusion and differentiation defects and significantly delayed muscle regeneration. Furthermore, satellite cell-specific Rbm24 knockout mice recapitulated the defects in regeneration seen in the global Rbm24 knockout mice. Importantly, we demonstrated that Rbm24 regulated AS of Mef2d, Naca, Rock2 and Lrrfip1 which are essential for myogenic differentiation and muscle regeneration. The present study demonstrated that Rbm24 regulates dynamic changes in AS and is essential for adult skeletal muscle regeneration.
成人骨骼肌具有显著的再生能力，能够在机械或病理损伤后有效地自我修复。然而，肌肉再生的调控机制很复杂，尚未完全阐明。可变剪接（AS）是负责转录后调控的主要机制。许多肌营养不良症患者中存在异常的 AS 事件，这些事件伴随着异常的肌肉再生。然而，关于 AS 与肌肉再生之间的相关性知之甚少。据报道，RNA 结合基序蛋白 24（Rbm24）是一种组织特异性剪接因子，参与胚胎肌发生，而 Rbm24 在成体肌发生（也称为肌肉再生）中的作用知之甚少。为了研究 Rbm24 在成人骨骼肌中的作用，我们生成了 Rbm24 条件性敲除小鼠和卫星细胞特异性敲除小鼠。此外，还利用心脏毒素（CTX）诱导的损伤模型来评估 Rbm24 对骨骼肌再生的影响。进行了全基因组 RNA-Seq 以鉴定 Rbm24 缺失后 AS 的变化。在他莫昔芬处理 4 个月后，Rbm24 敲除小鼠表现出异常的再生。通过 RNA-Seq，我们发现 Rbm24 调节了涉及多个生物学过程的 AS 事件的复杂网络，包括肌发生、肌肉再生和肌肉肥大。此外，使用 CTX 诱导的损伤模型，我们表明 Rbm24 在骨骼肌中的缺失导致成肌融合和分化缺陷，并显著延迟肌肉再生。此外，Rbm24 特异性敲除的卫星细胞在骨骼肌中 recapitulated 在全局 Rbm24 敲除小鼠中观察到的再生缺陷。重要的是，我们证明 Rbm24 调节了 Mef2d、Naca、Rock2 和 Lrrfip1 的 AS，这些基因对于肌发生分化和肌肉再生至关重要。本研究表明，Rbm24 调节 AS 的动态变化，是成人骨骼肌再生所必需的。
