Necdin, a postmitotic neuron-specific growth suppressor, interacts with viral transforming proteins and cellular transcription factor E2F1.
Necdin is a nuclear protein expressed in virtually all postmitotic neurons, and ectopic expression of this protein strongly suppresses the proliferation of NIH3T3 cells. Simian virus 40 large T antigen targets both p53 and the retinoblastoma protein (Rb) for cellular transformation. By analogy with the interactions of the large T antigen with these nuclear growth suppressors, we examined the ability of necdin to bind to the large T antigen. Necdin was co-immunoprecipitated with the large T antigen from the nuclear extract of necdin cDNA-transfected COS-1 cells. Yeast two-hybrid and in vitro binding analyses revealed that necdin bound to an amino-terminal region of the large T antigen, which encompasses the Rb-binding domain. Moreover, necdin bound to adenovirus E1A, another viral oncoprotein that forms a specific complex with Rb. We then examined the ability of necdin to bind to the transcription factor E2F1, a cellular Rb-binding factor involved in cell-cycle progression. Intriguingly, necdin, like Rb, bound to a carboxyl-terminal domain of E2F1, and repressed E2F-dependent transactivation in vivo. In addition, necdin suppressed the colony formation of Rb-deficient SAOS-2 osteosarcoma cells. These results suggest that necdin is a postmitotic neuron-specific growth suppressor that is functionally similar to Rb.
Taniura
H
H
Division of Regulation of Macromolecular Functions, Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565, Japan.
Taniguchi
N
N
Hara
M
M
Yoshikawa
K
K
D016475:3T3 Cells; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D019556:COS Cells; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002455:Cell Division; D002472:Cell Transformation, Viral; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D016160:Retinoblastoma Protein / Q000378:metabolism; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*
D000952:Antigens, Polyomavirus Transforming; C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493754:E2f1 protein, mouse; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D016160:Retinoblastoma Protein; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D014764:Viral Proteins; C069766:necdin