Abstract
The function of transcription factors can be critically regulated by SUMOylation. c-Maf, the cellular counterpart of v-maf oncogene, is a potent transactivator of the IL-4 gene in Th2 cells. We found in a yeast two-hybrid screen that c-Maf can interact with Ubc9 and PIAS1, two key enzymes of the SUMOylation pathway. In this study, we report that c-Maf co-localized with these two SUMO (small ubiquitin-like modifier) ligases in the nucleus and that c-Maf can be SUMOylated in vitro and also in primary Th2 cells. We also demonstrated that lysine-33 is the dominant, if not the only, SUMO acceptor site of c-Maf. SUMOylation of c-Maf attenuated its transcriptional activity. Reciprocally, a SUMOylation resistant c-Maf was more potent than WT-c-Maf in driving IL-4 production in c-Maf-deficient Th2 cells. Furthermore, we showed that ablation of the SUMO site did not alter the subcellular localization or the stability of c-Maf protein but instead enhanced its recruitment to the Il4-promoter. We conclude that SUMOylation at lysine-33 is a functionally critical post-translational modification event of c-Maf in Th cells.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Cell Line
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Cells, Cultured / metabolism
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Humans
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Interleukin-4 / biosynthesis*
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Interleukin-4 / genetics
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Kidney
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Lysine / chemistry
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Mice
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Molecular Sequence Data
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Protein Inhibitors of Activated STAT / chemistry
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Protein Inhibitors of Activated STAT / isolation & purification
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Protein Inhibitors of Activated STAT / physiology*
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Protein Interaction Mapping
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Protein Processing, Post-Translational*
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Proto-Oncogene Proteins c-maf / chemistry
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Proto-Oncogene Proteins c-maf / physiology*
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Recombinant Fusion Proteins / physiology
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Sequence Alignment
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Sequence Homology, Amino Acid
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Small Ubiquitin-Related Modifier Proteins / chemistry
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Small Ubiquitin-Related Modifier Proteins / genetics
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Small Ubiquitin-Related Modifier Proteins / isolation & purification
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Small Ubiquitin-Related Modifier Proteins / physiology*
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Th2 Cells / metabolism*
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Transcription, Genetic
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Two-Hybrid System Techniques
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Ubiquitin-Conjugating Enzymes / chemistry
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Ubiquitin-Conjugating Enzymes / physiology*
Substances
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IL4 protein, human
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MAF protein, human
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Maf protein, mouse
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PIAS1 protein, human
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Pias1 protein, mouse
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Protein Inhibitors of Activated STAT
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Proto-Oncogene Proteins c-maf
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Recombinant Fusion Proteins
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Small Ubiquitin-Related Modifier Proteins
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Interleukin-4
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Ubiquitin-Conjugating Enzymes
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ubiquitin-conjugating enzyme UBC9
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Lysine