Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, UK.
Development. 2012 Apr;139(7):1270-5. doi: 10.1242/dev.077875. Epub 2012 Feb 22.
Muscle is an established paradigm for analysing the cell differentiation programs that underpin the production of specialised tissues during development. These programs are controlled by key transcription factors, and a well-studied regulator of muscle gene expression is the conserved transcription factor Mef2. In vivo, Mef2 is essential for the development of the Drosophila larval musculature: Mef2-null embryos have no differentiated somatic muscle. By contrast, a similar phenotype has not been seen in analyses of the function of Mef2 genes in other examples of myogenesis. These include using conditional mutant mice, using morpholinos in zebrafish and using hypomorphic mutants in Drosophila adult development. However, we show here that Mef2 is absolutely required for a diverse range of Drosophila adult muscle types. These include the dorso-longitudinal muscles (DLMs), the largest flight muscles, which are produced by tissue remodelling. Furthermore, we demonstrate that Mef2 has temporally separable functions in this remodelling and in muscle maintenance. Drosophila adult muscles are multi-fibre and physiologically diverse, in common with vertebrate skeletal muscles, but in contrast to Drosophila larval muscles. These results therefore establish the importance of Mef2 in multiple roles in examples of myogenesis that have parallels in vertebrates and are distinct from that occurring in Drosophila embryogenesis.
肌肉是分析细胞分化程序的既定范例，这些程序是专门组织在发育过程中的产生的基础。这些程序由关键转录因子控制，肌肉基因表达的一个研究得很好的调节剂是保守的转录因子 Mef2。在体内，Mef2 对于果蝇幼虫肌肉的发育是必不可少的：Mef2 缺失的胚胎没有分化的体壁肌肉。相比之下，在对 Mef2 基因在其他肌发生实例中的功能进行分析时，并没有观察到类似的表型。这些包括使用条件性突变小鼠、在斑马鱼中使用 morpholinos 以及在果蝇成体发育中使用功能减弱的突变体。然而，我们在这里表明，Mef2 对于广泛的果蝇成体肌肉类型是绝对必需的。这些包括背纵肌（DLMs），这是最大的飞行肌肉，是通过组织重塑产生的。此外，我们证明 Mef2 在这种重塑和肌肉维持中有时间上可分离的功能。果蝇成体肌肉是多纤维的，具有生理多样性，与脊椎动物的骨骼肌相同，但与果蝇幼虫肌肉不同。因此，这些结果确立了 Mef2 在与脊椎动物有相似之处的肌发生实例中的多种作用中的重要性，并且与发生在果蝇胚胎发生中的作用不同。
