title: Ubiquitin-Proteasome-mediated degradation of Id1 is modulated by MyoD.
abstract: Degradation of many short-lived cellular proteins such as the transcription factor MyoD occurs via the ubiquitin-proteasome pathway. MyoD, similar to many rapidly degraded regulatory factors, interacts with several high affinity binding partners, including members of the Id (inhibitors of DNA binding) family. Following transfection to HeLa cells, Id1 is localized to the nucleus and rapidly (t(1/2) approximately 1 h) degraded via the ubiquitin-proteasome system. Mutagenesis of lysine residues within the putative nuclear localization region (amino acids 68-82) directs Id1(NLS) to the cytoplasm yet confers an increased rate of degradation (t(1/2) approximately 0.5 h). Id1 in which all lysine residues were mutagenized to alanine (lysineless Id1) was also rapidly degraded (t(1/2) approximately 0.6 h). Addition of a Myc(6) tag to the N terminus of lysine-less Id1 markedly stabilized Id1 (t(1/2) > 10 h) and suggests degradation via the N terminus-dependent pathway. Co-transfection of MyoD with Id1 or Id1(NLS) increases Id1 or Id1(NLS) within the nucleus and markedly reduces the rate of Id1 or Id1(NLS) degradation. These results thus demonstrate that in vivo MyoD modulates the rate of Id1 degradation and suggest a dynamic interplay of these factors.
authors.affiliation: Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine and St. Louis Children's Hospital, Missouri 63110, USA.
authors.forename: Julie S
authors.initials: JS
authors.lastname: Trausch-Azar
authors.forename: Jody
authors.initials: J
authors.lastname: Lingbeck
authors.forename: Aaron
authors.initials: A
authors.lastname: Ciechanover
authors.forename: Alan L
authors.initials: AL
authors.lastname: Schwartz
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1; D008239:Lysine / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009097:Multienzyme Complexes / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017570:MyoD Protein / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1; D009097:Multienzyme Complexes; D017570:MyoD Protein; D012097:Repressor Proteins; D014157:Transcription Factors; D025801:Ubiquitin; D004247:DNA; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D008239:Lysine