Identification of domains responsible for ubiquitin-dependent degradation of dMyc by glycogen synthase kinase 3beta and casein kinase 1 kinases.
In the present study, we report that ubiquitin-mediated degradation of dMyc, the Drosophila homologue of the human c-myc proto-oncogene, is regulated in vitro and in vivo by members of the casein kinase 1 (CK1) family and by glycogen synthase kinase 3beta (GSK3beta). Using Drosophila S2 cells, we demonstrate that CK1alpha promotes dMyc ubiquitination and degradation with a mechanism similar to the one mediated by GSK3beta in vertebrates. Mutation of ck1alpha or -epsilon or sgg/gsk3beta in Drosophila wing imaginal discs results in the accumulation of dMyc protein, suggesting a physiological role for these kinases in vivo. Analysis of the dMyc amino acid sequence reveals the presence of conserved domains containing potential phosphorylation sites for mitogen kinases, GSK3beta, and members of the CK1 family. We demonstrate that mutations of specific residues within these phosphorylation domains regulate dMyc protein stability and confer resistance to degradation by CK1alpha and GSK3beta kinases. Expression of the dMyc mutants in the compound eye of the adult fly results in a visible defect that is attributed to the effect of dMyc on growth, cell death, and inhibition of ommatidial differentiation.
Department of Biology, City College of the City University of New York, 138th at Convent Ave., New York, NY 10031, USA.
Margherita
M
Galletti
Sara
S
Riccardo
Federica
F
Parisi
Carlina
C
Lora
Mahesh Kumar
MK
Saqcena
Leinny
L
Rivas
Bonnie
B
Wong
Alexis
A
Serra
Florenci
F
Serras
Daniela
D
Grifoni
PierGiuseppe
P
Pelicci
Jin
J
Jiang
Paola
P
Bellosta
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D048149:Casein Kinase 1 epsilon / Q000235:genetics / Q000378:metabolism*; D048128:Casein Kinase Ialpha / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000254:growth & development / Q000378:metabolism; D017344:Genes, Insect; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D000090063:Proto-Oncogene Mas; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D014921:Wings, Animal / Q000254:growth & development / Q000378:metabolism; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C000715470:MAS1 protein, human; C102284:Myc protein, Drosophila; D000090063:Proto-Oncogene Mas; D011994:Recombinant Proteins; D014157:Transcription Factors; D025801:Ubiquitin; D051155:Wnt1 Protein; C074622:wg protein, Drosophila; D048149:Casein Kinase 1 epsilon; D048128:Casein Kinase Ialpha; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C080335:Sgg protein, Drosophila; D038362:Glycogen Synthase Kinase 3