Id2 is a retinoblastoma protein target and mediates signalling by Myc oncoproteins.
In mammalian cells, Id proteins coordinate proliferation and differentiation. Id2 is a dominant-negative antagonist of basic helix-loop-helix transcription factors and proteins of the retinoblastoma (Rb) family. Here we show that Id2-Rb double knockout embryos survive to term with minimal or no defects in neurogenesis and haematopoiesis, but they die at birth from severe reduction of muscle tissue. In neuroblastoma, an embryonal tumour derived from the neural crest, Id2 is overexpressed in cells carrying extra copies of the N-myc gene. In these cells, Id2 is in molar excess of the active form of Rb. The overexpression of Id2 results from transcriptional activation by oncoproteins of the Myc family. Cell-cycle progression induced by Myc oncoproteins requires inactivation of Rb by Id2. Thus, a dual connection links Id2 and Rb: during normal cell-cycle, Rb prohibits the action of Id2 on its natural targets, but oncogenic activation of the Myc-Id2 transcriptional pathway overrides the tumour-suppressor function of Rb.
Lasorella
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Department of Neurology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Noseda
M
M
Beyna
M
M
Yokota
Y
Y
Iavarone
A
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D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000378:metabolism; D005314:Embryonic and Fetal Development; D005260:Female; D005786:Gene Expression Regulation; D006410:Hematopoiesis; D006801:Humans; D051797:Inhibitor of Differentiation Protein 2; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000196:embryology / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins; D012175:Retinoblastoma / Q000235:genetics / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C497450:ID2 protein, human; C497452:Idb2 protein, mouse; D051797:Inhibitor of Differentiation Protein 2; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; D016160:Retinoblastoma Protein; D014157:Transcription Factors