Regulation of Id1 and its association with basic helix-loop-helix proteins during nerve growth factor-induced differentiation of PC12 cells.
Cell differentiation in the nervous system is dictated by specific patterns of gene expression. We have investigated the role of helix-loop-helix (HLH) proteins during differentiation of PC12 pheochromocytoma cells in response to nerve growth factor. Gel mobility shift assays using PC12 cell nuclear extracts demonstrated that active basic HLH complexes exist throughout differentiation. Addition of exogeneous Id1 protein, a negative regulator of basic HLH proteins, disrupted specific complexes formed by PC12 cell nuclear extracts on a CANNTG consensus oligonucleotide. To identify possible novel basic HLH proteins in these complexes, a glutathione S-transferase-Id1 fusion protein was used to screen a PC12 cell cDNA expression library. A single clone representing the rat E2-2 gene was identified. Sequential immunoprecipitations with antibodies to each HLH protein revealed an association between Id1 and E2-2 that could be detected in both untreated and nerve growth factor-treated PC12 cell lysates. These experiments define a new HLH interaction between Id1 and E2-2 in neuronal cells and suggest that neuronal differentiation may be regulated by HLH proteins in a distinctive manner.
Einarson
M B
MB
Molecular Biology Program, Cornell University Graduate School of Medical Sciences, New York, New York, USA.
Chao
M V
MV
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002454:Cell Differentiation; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015723:Gene Library; D018257:Helix-Loop-Helix Motifs; D051798:Inhibitor of Differentiation Protein 1; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009474:Neurons / Q000502:physiology*; D016716:PC12 Cells; D011233:Precipitin Tests; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D000073940:Transcription Factor 4; D014157:Transcription Factors
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C497454:ID1 protein, rat; D051798:Inhibitor of Differentiation Protein 1; D009414:Nerve Growth Factors; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C491192:Tcf4 protein, rat; D015534:Trans-Activators; D000073940:Transcription Factor 4; D014157:Transcription Factors