Inactivation of MyoD in mice leads to up-regulation of the myogenic HLH gene Myf-5 and results in apparently normal muscle development

• Published in: Cell Vol. 71; no. 3; pp. 383 - 390
• Main Authors: Rudnicki, Michael A., Braun, Thomas, Hinuma, Shuji, Jaenisch, Rudolf
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 30.10.1992; Cell Press
• Subjects: Animals; Biological and medical sciences; Cell differentiation, maturation, development, hematopoiesis; Cell physiology; Cells, Cultured; DNA-Binding Proteins; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Mice; Molecular and cellular biology; Muscle Proteins - genetics; Muscle Proteins - physiology; Muscles - anatomy & histology; Muscles - embryology; Mutagenesis, Site-Directed; MyoD Protein; Myogenic Regulatory Factor 5; Phenotype; RNA, Messenger - analysis; Stem Cells; Trans-Activators; Up-Regulation; Vertebrata; Regulation(control); Mammalia; Mouse; Rodentia; Histology; Transcription factor; Striated muscle; Myogenesis
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/0092-8674(92)90508-A

The myogenic basic HLH transcription factor family of genes, composed of MyoD, myogenin, Myf-5, and Myf-6, are thought to regulate skeletal muscle differentiation. To understand the role of MyoD in myogenesis, we have introduced a null mutation of MyoD into the germline of mice. Surprisingly, mice lacking MyoD are viable and fertile. Histological examination of skeletal muscle failed to reveal any morphological abnormalities in these mice. Furthermore, Northern analysis revealed normal levels of skeletal muscle-specific mRNAs. Significantly, Myf-5 mRNA levels are elevated in postnatal mutant mice. Normally, Myf-5 expression becomes markedly reduced at day 12 of gestation when MyoD mRNA first appears. This suggests that Myf-5 expression is repressed by MyoD. Our results indicate that MyoD is dispensable for skeletal muscle development in mice, revealing some degree of functional redundancy in the control of the skeletal myogenic developmental program.