Muscle homeodomain protein MHox inhibits ternary complex formation at the c-fos serum response element.
The Serum Response Element in the c-fos promoter is the target of growth factor-regulated signal transduction pathways. The ternary complex of Serum Response Element-binding protein Serum Response Factor and its accessory protein Ternary Complex Factor are important for transcriptional stimulation of the c-fos promoter in fibroblasts. However, this promoter is repressed in differentiating muscle cells. We discovered that MHox, a muscle homeodomain protein, was capable of inhibiting formation of the ternary complex by direct physical interaction between MHox and Serum Response Factor accessory protein-1 (SAP-1), one member of the Ternary Complex Factor family of proteins. Furthermore, exogenous MHox protein inhibited serum-inducibility of a Serum Response Element-dependent reporter gene in permeabilized fibroblasts. Taken together, these results imply that MHox is involved in blocking mitogenic signals during myogenesis.
Ma
J T
JT
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China.
Ng
S Y
SY
D016475:3T3 Cells; D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D026362:Serum Response Factor
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009124:Muscle Proteins; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D026362:Serum Response Factor; C072545:p62TCF protein, human; C489525:p62TCF protein, mouse