Nose A, Isshiki T, Takeichi M
National Institute for Basic Biology, Okazaki, Japan.
Development. 1998 Jan;125(2):215-23. doi: 10.1242/dev.125.2.215.
The somatic musculature in the abdominal hemisegments of Drosophila consists of 30 uniquely identifiable muscle fibers. Previous studies have suggested that the muscle diversity originates in a special class of myoblasts, called muscle founders, that are formed by the division of muscle progenitors. However, the mechanisms that locate and specify the muscle progenitors/founders are largely unknown. In this study, we first used a novel marker, rP298-LacZ, to chart the development of muscle progenitors/founders during the formation of distinct groups of mature muscles. We then determined the function of the muscle segment homeobox (msh) gene in myogenesis. msh encodes a homeobox-containing protein, vertebrate homologues of which are known as Msxs. We show that msh is expressed in the dorsal and lateral domains of muscle progenitors and is required for the specification of the progenitor cells. Ectopic expression of msh in the entire mesoderm inhibits the proper development of the normally msh-negative muscle progenitors in the dorsolateral domain. These results suggest that msh plays a role in regional specification of muscle progenitors/founders.
果蝇腹部半体节中的体壁肌肉组织由30条独特可识别的肌纤维组成。先前的研究表明，肌肉多样性起源于一类特殊的成肌细胞，称为肌肉始祖细胞，它们由肌肉祖细胞分裂形成。然而，定位和确定肌肉祖细胞/始祖细胞的机制在很大程度上尚不清楚。在本研究中，我们首先使用一种新型标记rP298-LacZ，来描绘在不同成熟肌肉群形成过程中肌肉祖细胞/始祖细胞的发育情况。然后我们确定了肌肉节段同源框（msh）基因在肌生成中的功能。msh编码一种含同源框的蛋白质，其脊椎动物同源物被称为Msxs。我们发现msh在肌肉祖细胞的背侧和外侧区域表达，并且是祖细胞特化所必需的。msh在整个中胚层中的异位表达会抑制背外侧区域中正常msh阴性的肌肉祖细胞的正常发育。这些结果表明，msh在肌肉祖细胞/始祖细胞的区域特化中发挥作用。
