title: Function of the C. elegans T-box factor TBX-2 depends on SUMOylation.
abstract: T-box transcription factors are critical developmental regulators in all multi-cellular organisms, and altered T-box factor activity is associated with a variety of human congenital diseases and cancers. Despite the biological significance of T-box factors, their mechanism of action is not well understood. Here we examine whether SUMOylation affects the function of the C. elegans Tbx2 sub-family T-box factor TBX-2. We have previously shown that TBX-2 interacts with the E2 SUMO-conjugating enzyme UBC-9, and that loss of TBX-2 or UBC-9 produces identical defects in ABa-derived pharyngeal muscle development. We now show that TBX-2 is SUMOylated in mammalian cell assays, and that both UBC-9 interaction and SUMOylation depends on two SUMO consensus sites located in the T-box DNA binding domain and near the TBX-2 C-terminus, respectively. In co-transfection assays, a TBX-2:GAL4 fusion protein represses expression of a 5xGal4:tk:luciferase construct. However, this activity does not require SUMOylation, indicating SUMO is not generally required for TBX-2 repressor activity. In C. elegans, reducing SUMOylation enhances the phenotype of a temperature-sensitive tbx-2 mutant and results in ectopic expression of a gene normally repressed by TBX-2, demonstrating that SUMOylation is important for TBX-2 function in vivo. Finally, we show mammalian orthologs of TBX-2, Tbx2, and Tbx3, can also be SUMOylated, suggesting SUMOylation may be a conserved mechanism controlling T-box factor activity.
authors.affiliation: Department of Biological Sciences, Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, IL, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Huber
authors.forename: Tanya
authors.initials: T
authors.lastname: Crum
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Clary
authors.forename: Tom
authors.initials: T
authors.lastname: Ronan
authors.forename: Adelaide V
authors.initials: AV
authors.lastname: Packard
authors.forename: Peter G
authors.initials: PG
authors.lastname: Okkema
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002522:Chlorocebus aethiops; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D058207:Sumoylation; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D029742:Caenorhabditis elegans Proteins; C097348:T-Box Domain Protein 2; D020825:T-Box Domain Proteins; C484504:TBX-2 protein, C elegans; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9