Necdin interacts with the Msx2 homeodomain protein via MAGE-D1 to promote myogenic differentiation of C2C12 cells.
Necdin is a potent growth suppressor that is expressed predominantly in postmitotic cells such as neurons and skeletal muscle cells. Necdin shows a significant homology to MAGE (melanoma antigen) family proteins, all of which contain a large homology domain. MAGE-D1 (NRAGE, Dlxin-1) interacts with the Dlx/Msx family homeodomain proteins via an interspersed hexapeptide repeat domain distinct from the homology domain. Here we report that necdin associates with the Msx homeodomain proteins via MAGE-D1 to modulate their function. In vitro binding and co-immunoprecipitation analyses revealed that MAGE-D1 directly interacted with necdin via the homology domain and Msx1 (or Msx2) via the repeat domain. A ternary complex of necdin, MAGE-D1, and Msx2 was formed in vitro, and an endogenous complex containing these three proteins was detected in differentiating embryonal carcinoma cells. Co-expression of necdin and MAGE-D1 released Msx-dependent transcriptional repression. C2C12 myoblast cells that were stably transfected with Msx2 cDNA showed a marked reduction in myogenic differentiation, and co-expression of necdin and MAGE-D1 canceled the Msx2-dependent repression. These results suggest that necdin and MAGE-D1 cooperate to modulate the function of Dlx/Msx homeodomain proteins in cellular differentiation.
Division of Regulation of Macromolecular Functions, Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
Takaaki
T
Kuwajima
Hideo
H
Taniura
Isao
I
Nishimura
Kazuaki
K
Yoshikawa
D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D017353:Gene Deletion; D005822:Genetic Vectors; D018398:Homeodomain Proteins; D015151:Immunoblotting; D007150:Immunohistochemistry; D051379:Mice; D008813:Mice, Inbred ICR; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009474:Neurons / Q000378:metabolism; D009687:Nuclear Proteins / Q000502:physiology*; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014018:Tissue Distribution; D014158:Transcription, Genetic
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C084119:MSX2 protein; C486541:Maged1 protein, mouse; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C069766:necdin