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J Biol Chem. 2004 Sep 24;279(39):40484-93. Epub 2004 Jul 21.

Necdin interacts with the Msx2 homeodomain protein via MAGE-D1 to promote myogenic differentiation of C2C12 cells.

Author information

1
Division of Regulation of Macromolecular Functions, Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.

Abstract

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.

PMID:
15272023
DOI:
10.1074/jbc.M404143200
[Indexed for MEDLINE]
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