Hughes S M, Koishi K, Rudnicki M, Maggs A M
MRC Muscle and Cell Motility Unit, Randall Institute, King's College London, UK.
Mech Dev. 1997 Jan;61(1-2):151-63. doi: 10.1016/s0925-4773(96)00631-4.
MyoD is a muscle-specific transcription factor involved in commitment of cells to myogenesis. MyoD mRNA levels differ between fast and slow muscles, suggesting that MyoD may regulate aspects of fibre type. Here we show that detectable MyoD protein becomes restricted during development to the nuclei of the fastest classes of fibres in fast muscles. myoDm1 mice, in which the myoD gene has been disrupted, show subtle shifts in fibre type of fast muscles toward a slower character, suggesting that MyoD is involved in the maintenance of the fast IIB/IIX fibre type. In contrast, slow muscle shifts to a faster phenotype in myoDm1. Moreover, MD6.0-lacZ transgenic mice with the myoD promoter driving lacZ, show highest beta-galactosidase activity in the fastest fibres of fast muscles, but also express low levels in slow fibres of slow, but not fast, muscles, suggesting distinct regulation of gene expression in slow fibres of fast and slow muscles.
肌分化抗原（MyoD）是一种肌肉特异性转录因子，参与细胞向肌生成的定向分化。快肌和慢肌中的MyoD mRNA水平有所不同，这表明MyoD可能调节纤维类型的某些方面。在此我们表明，在发育过程中，可检测到的MyoD蛋白在快肌中仅限于最快类型的纤维细胞核。myoDm1小鼠的myoD基因已被破坏，其快肌的纤维类型向较慢特征发生细微转变，这表明MyoD参与快速IIB/IIX纤维类型的维持。相比之下，myoDm1小鼠的慢肌转变为更快的表型。此外，由myoD启动子驱动lacZ的MD6.0-lacZ转基因小鼠，在快肌的最快纤维中显示出最高的β-半乳糖苷酶活性，但在慢肌（而非快肌）的慢纤维中也有低水平表达，这表明快肌和慢肌的慢纤维中基因表达存在不同调控。
