Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
Department of Biology, San Diego State University, San Diego, CA 92182, USA.
Development. 2019 Apr 4;146(7):dev164129. doi: 10.1242/dev.164129.
Serum response factor (SRF) has an established role in controlling actin homeostasis in mammalian cells, yet its role in non-vertebrate muscle development has remained enigmatic. Here, we demonstrate that the single SRF ortholog, termed Blistered (Bs), is expressed in all adult muscles, but Bs is required for muscle organization only in the adult indirect flight muscles. Bs is a direct activator of the flight muscle actin gene , via a conserved promoter-proximal binding site. However, Bs only activates expression in the context of the flight muscle regulatory program provided by the Pbx and Meis orthologs Extradenticle and Homothorax, and appears to function in a similar manner to mammalian SRF in muscle maturation. These studies place Bs in a regulatory framework where it functions to sustain the flight muscle phenotype in Our studies uncover an evolutionarily ancient role for SRF in regulating muscle actin expression, and provide a model for how SRF might function to sustain muscle fate downstream of pioneer factors.
血清反应因子（SRF）在控制哺乳动物细胞中的肌动蛋白动态平衡方面具有既定的作用，但它在非脊椎动物肌肉发育中的作用仍然是个谜。在这里，我们证明了单一的 SRF 直系同源物，称为起泡（Bs），在所有成年肌肉中都有表达，但 Bs 仅在成年间接飞行肌肉中对肌肉组织的形成是必需的。Bs 是飞行肌肌动蛋白基因的直接激活剂，通过保守的启动子近端结合位点。然而，Bs 仅在由 Pbx 和 Meis 直系同源物 Extradenticle 和 Homothorax 提供的飞行肌调节程序的背景下激活 的表达，并且似乎在肌肉成熟过程中以类似于哺乳动物 SRF 的方式发挥作用。这些研究将 Bs 置于一个调节框架中，在这个框架中，它在维持 中的飞行肌肉表型方面发挥作用。我们的研究揭示了 SRF 在调节肌肉肌动蛋白表达方面的古老进化作用，并为 SRF 如何在先驱因子下游维持肌肉命运提供了一个模型。
