Ji et al. <b>FUS-mediated inhibition of myogenesis elicited by suppressing TNNT1 production</b>_Supplementary materials

Myogenesis is a highly orchestrated process whereby muscle precursor cells, myoblasts, develop into muscle fibers to form skeletal muscle during embryogenesis and regenerate adult muscle. Here, we studied the RNA-binding protein FUS (fused in sarcoma), which has been implicated in muscular and neuromuscular pathologies but is poorly characterized in myogenesis. Given that FUS levels declined in human and mouse models of skeletal myogenesis, and that silencing FUS enhanced myogenesis, we hypothesized that FUS might be a repressor of myogenic differentiation. Interestingly, overexpression of FUS delayed myogenesis, accompanied by slower production of muscle differentiation markers. To identify the mechanisms through which FUS inhibits myogenesis, we uncovered RNA targets of FUS by ribonucleoprotein immunoprecipitation (RIP) followed by RNA-sequencing (RNA-seq) analysis. Stringent selection of the bound transcripts uncovered <i>Tnnt1</i> mRNA, encoding troponin T (TNNT1), as a major effector of FUS influence on myogenesis. We found that in myoblasts, FUS sequestered <i>Tnnt1</i> mRNA in the nucleus, preventing TNNT1 expression; however, reduction of FUS during myogenesis or by silencing FUS released <i>Tnnt1</i> mRNA for export to the cytoplasm, enabling TNNT1 translation and promoting myogenesis. We propose that FUS inhibits myogenesis by suppressing TNNT1 expression through a mechanism of nuclear <i>Tnnt1</i> mRNA retention.

肌发生（Myogenesis）是一类高度程序化的生物学过程：在胚胎发育阶段，肌肉前体细胞即成肌细胞（myoblasts）分化为肌纤维，进而形成骨骼肌，同时该过程也参与成体肌肉的再生修复。本研究聚焦于RNA结合蛋白（RNA-binding protein）FUS（肉瘤融合蛋白，fused in sarcoma）：该蛋白已被证实与肌肉疾病及神经肌肉病变相关，但在肌发生过程中的功能机制尚未得到充分阐释。鉴于在人类和小鼠骨骼肌肌发生模型中，FUS的表达水平呈下降趋势，且敲低FUS可促进肌发生，我们推测FUS可能作为肌源性分化的负调控因子。有趣的是，过表达FUS则会延缓肌发生进程，同时伴随肌肉分化标志物的合成速率显著降低。为阐明FUS抑制肌发生的具体分子机制，我们通过核糖核蛋白免疫沉淀（ribonucleoprotein immunoprecipitation, RIP）联合RNA测序（RNA-sequencing, RNA-seq）分析，筛选得到了FUS的RNA靶标。通过对结合转录本的严格筛选，我们发现编码肌钙蛋白T（troponin T, TNNT1）的Tnnt1 mRNA是FUS调控肌发生的核心效应分子。我们发现，在成肌细胞中，FUS会将Tnnt1 mRNA滞留于细胞核内，从而阻断TNNT1的表达；而在肌发生过程中降低FUS的表达水平，或是通过敲低FUS，则可释放Tnnt1 mRNA使其转运至细胞质，进而启动TNNT1的翻译并促进肌发生。我们提出，FUS通过将Tnnt1 mRNA滞留于细胞核内的机制，抑制TNNT1的表达，进而发挥肌发生负调控功能。

搜集汇总

背景与挑战

背景概述

该数据集是研究FUS蛋白抑制肌肉生成机制的补充材料，包含7个CSV文件，提供了FUS RIP测序、差异表达基因、实验试剂等原始数据。研究揭示FUS通过核滞留Tnnt1 mRNA来抑制TNNT1表达，从而延缓肌肉生成过程，为理解肌肉发育和疾病提供了分子机制依据。