title: Induction of apoptosis by the c-Myc helix-loop-helix/leucine zipper domain in mouse 3T3-L1 fibroblasts.
abstract: The cellular proto-oncogene c-myc is involved in cell proliferation and transformation but is also implicated in the induction of programmed cell death (apoptosis). The c-Myc protein is a transcriptional activator with a carboxyl-terminal basic region/helix-loop-helix (HLH)/leucine zipper (LZ) domain. It forms heterodimers with the HLH/LZ protein Max and transactivates gene expression after binding DNA E-box elements. We have studied the phenotype of dominant-negative mutants of c-Myc and Max in microinjection experiments. Max mutants with a deleted or mutated basic region inhibited DNA synthesis in serum-stimulated 3T3-L1 mouse fibroblasts. In contrast, mutants of c-Myc expressing only the basic region/HLH/LZ or HLH/LZ domains rapidly induced apoptosis at low and high serum levels. Co-expression of the HLH/LZ domains of c-Myc and Max failed to do so. We suggest that the c-Myc HLH/LZ domain induces apoptosis by specific interaction with cellular factors different to Max.
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D001769:Blood; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005799:Genes, Dominant; D018257:Helix-Loop-Helix Motifs / Q000235:genetics*; D016350:Leucine Zippers / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D014157:Transcription Factors
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C067850:Myc associated factor X; D009838:Oligodeoxyribonucleotides; D016271:Proto-Oncogene Proteins c-myc; D014157:Transcription Factors; C068422:Max protein, mouse; D004247:DNA