ALDH1A1 and ALDH1A3 paralogues of aldehyde dehydrogenase 1 (ALDH1) control myogenic differentiation of skeletal muscle satellite cells (SC) by formation of retinoic acid (RA) and subsequent cell cycle adjustments. The respective relevance of each paralogue for myogenic differentiation and the mechanistic interaction of each paralogue within RA-dependent and RA-independent pathways remain elusive.

We analysed the impact of ALDH1A1 and ALDH1A3 activity on myogenesis of murine C2C12 myoblasts. Both paralogues are pivotal factors in myogenic differentiation, since CRISPR/Cas9-edited single paralogue knock-out impaired serum withdrawal-induced myogenic differentiation, while successive recombinant re-expression of ALDH1A1 or ALDH1A3, respectively, in the corresponding ALDH1 paralogue single knock-out cell lines, recovered the differentiation potential. Loss of differentiation in single knock-out cell lines was restored by treatment with RA-analogue TTNPB, while RA-receptor antagonization by AGN 193109 inhibited differentiation of wildtype cell lines, supporting the idea that RA-dependent pathway is pivotal for myogenic differentiation which is accomplished by both paralogues.

However, overexpression of ALDH1-paralogues or disulfiram-mediated inhibition of ALDH1 enzymatic activity not only increased ALDH1A1 and ALDH1A3 protein levels but also induced subsequent differentiation of C2C12 myoblasts independently from serum withdrawal, indicating that ALDH1-dependent myogenic differentiation relies on different cellular conditions. Remarkably, ALDH1-paralogue knock-out impaired the autophagic flux, namely autophagosome cargo protein p62 formation and LC3B-I to LC3B-II conversion, demonstrating that ALDH1-paralogues interact with autophagy in myogenesis. Together, ALDH1 paralogues play a crucial role in myogenesis by orchestration of complex RA-dependent and RA-independent pathways.

乙醛脱氢酶 1 (ALDH1) 的 ALDH1A1 和 ALDH1A3 旁系同源物通过视黄酸 (RA) 的形成和随后的细胞周期调整来控制骨骼肌卫星细胞 (SC) 的生肌分化。每个旁系同源物与肌源性分化的各自相关性以及每个旁系同源物在 RA 依赖性和 RA 独立途径中的机制相互作用仍然难以捉摸。

我们分析了 ALDH1A1 和 ALDH1A3 活性对小鼠 C2C12 成肌细胞的肌生成的影响。两种旁系同源物都是肌原性分化的关键因素，因为 CRISPR/Cas9 编辑的单旁系同源物敲除损害了血清撤药诱导的肌原性分化，而在相应的 ALDH1 旁系同源物单敲除中，分别连续重组重新表达 ALDH1A1 或 ALDH1A3细胞系，恢复了分化潜能。RA 类似物 TTNPB 处理可恢复单敲除细胞系中分化的丧失，而 AGN 193109 拮抗 RA 受体则抑制野生型细胞系的分化，这支持了 RA 依赖性途径对于肌源性分化至关重要的观点。由两位旁白完成。

然而，ALDH1 旁系同源物的过度表达或双硫仑介导的 ALDH1 酶活性抑制不仅增加了 ALDH1A1 和 ALDH1A3 蛋白水平，而且还诱导了 C2C12 成肌细胞的后续分化，与血清撤除无关，表明 ALDH1 依赖性肌原性分化依赖于不同的细胞条件。值得注意的是，ALDH1-旁系同源物敲除损害了自噬流，即自噬体货物蛋白 p62 的形成和 LC3B-I 到 LC3B-II 的转换，这表明 ALDH1-旁系同源物与肌发生中的自噬相互作用。ALDH1 旁系同源物通过协调复杂的 RA 依赖性和 RA 独立途径，在肌生成中发挥着至关重要的作用。