Function of the C. elegans T-box factor TBX-2 depends on interaction with the UNC-37/Groucho corepressor.
T-box transcription factors are important regulators of development in all animals, and altered expression of T-box factors has been identified in an increasing number of diseases and cancers. Despite these important roles, the mechanism of T-box factor activity is not well understood. We have previously shown that the Caenorhabditis elegans Tbx2 subfamily member TBX-2 functions as a transcriptional repressor to specify ABa-derived pharyngeal muscle, and that this function depends on SUMOylation. Here we show that TBX-2 function also depends on interaction with the Groucho-family corepressor UNC-37. TBX-2 interacts with UNC-37 in yeast two-hybrid assays via a highly conserved engrailed homology 1 (eh1) motif located near the TBX-2 C-terminus. Reducing unc-37 phenocopies tbx-2 mutants, resulting in a specific loss of anterior ABa-derived pharyngeal muscles and derepression of the tbx-2 promoter. Moreover, double mutants containing hypomorphic alleles of unc-37 and tbx-2 exhibit enhanced phenotypes, providing strong genetic evidence that unc-37 and tbx-2 share common functions in vivo. To test whether interaction with UNC-37 is necessary for TBX-2 activity, we developed a transgene rescue assay using a tbx-2 containing fosmid and found that mutating the tbx-2 eh1 motif reduced rescue of a tbx-2 null mutant. These results indicate that TBX-2 function in vivo depends on interaction with UNC-37. As many T-box factors contain eh1 motifs, we suggest that interaction with Groucho-family corepressors is a common mechanism contributing to their activity.
Department of Biological Sciences, Molecular, Cellular & Developmental Biology Research Group, University of Illinois at Chicago, Chicago, IL, USA.
Paul
P
Huber
Department of Biological Sciences, Molecular, Cellular & Developmental Biology Research Group, University of Illinois at Chicago, Chicago, IL, USA.
Tanya
T
Crum
Department of Biological Sciences, Molecular, Cellular & Developmental Biology Research Group, University of Illinois at Chicago, Chicago, IL, USA. Electronic address: okkema@uic.edu.
Peter G
PG
Okkema
D000595:Amino Acid Sequence; D000818:Animals; D001934:Branchial Region / Q000196:embryology; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D055785:Gene Knockdown Techniques; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D012097:Repressor Proteins; C484504:TBX-2 protein, C elegans; D014157:Transcription Factors; C106184:unc-37 protein, C elegans
Gro/TLE; Groucho; Pharyngeal muscle; T-box; Transcriptional repression