title: An N-Myc truncation analogous to c-Myc-S induces cell proliferation independently of transactivation but dependent on Myc homology box II.
abstract: Myc promotes both normal cell proliferation and oncogenic transformation through the activation and repression of target genes. The c-Myc-S protein is a truncated form of c-Myc that is produced in some cells from translation initiation at an internal AUG codon. We report that c-Myc-S and a similar truncated form of N-MycWT can fully rescue the proliferation defect in myc-null fibroblasts, but rescue is dependent on the highly conserved Myc homology box II (MBII). Global gene expression studies show that the N-Myc equivalent of c-Myc-S is defective for virtually all transcriptional activation of Myc target genes but remains active for the majority of transcriptional repression. Repression by Myc-S is dependent on MBII, but it does not bind to several known nuclear cofactors. These data suggest that repression by Myc involves recruitment of a novel MBII-dependent cofactor.
authors: Department of Pharmacology and Toxicology, Dartmouth Medical School, Norris Cotton Cancer Center, Lebanon, NH 03756, USA.
authors: V H
authors: VH
authors: Cowling
authors: M D
authors: MD
authors: Cole
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D049109:Cell Proliferation; D017124:Conserved Sequence; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051379:Mice; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation / Q000235:genetics*
chemical_list: D016271:Proto-Oncogene Proteins c-myc