title: The T-box factor TBX-2 and the SUMO conjugating enzyme UBC-9 are required for ABa-derived pharyngeal muscle in C. elegans.
abstract: The C. elegans pharynx is produced from the embryonic blastomeres ABa and MS. Pharyngeal fate in the ABa lineage is specified by the combined activities of GLP-1/Notch-mediated signals and the TBX-37 and TBX-38 T-box transcription factors. Here, we show another T-box factor TBX-2 also functions in ABa-derived pharyngeal development. tbx-2 mutants arrest as L1 larvae lacking most or all ABa-derived pharyngeal muscles. In comparison, tbx-2 mutants retain ABa-derived marginal cells and pharyngeal muscles derived from MS. A tbx-2Colon, two colonsgfp translational fusion is expressed in a dynamic pattern in C. elegans embryos beginning near the 100-cell stage. Early expression is limited to a small number of cells, which likely include the ABa-derived pharyngeal precursors, while later expression is observed in body wall muscles and a subset of pharyngeal neurons. TBX-2 contains 2 consensus sumoylation sites, and it interacts in a yeast two-hybrid assay with the UBC-9 and GEI-17 components of the C. elegans SUMO-conjugating pathway. ubc-9(RNAi) has been previously shown to cause variable embryonic and larval arrest, and we find that, like tbx-2 mutants, ubc-9(RNAi) animals lack ABa-derived pharyngeal muscles. ubc-9(RNAi) also alters the subnuclear distribution of TBX-2::GFP fusion protein, suggesting that UBC-9 and TBX-2 interact in C. elegans. Together, these results indicate that TBX-2 and SUMO-conjugating enzymes are necessary for ABa-derived pharyngeal muscle, and we hypothesize that TBX-2 function requires sumoylation. Sumoylation is increasingly recognized as an important mechanism controlling activity of many nuclear factors, and these results provide the first evidence that T-box factor activity may require sumoylation.
authors.affiliation: Department of Biological Sciences (MC567), University of Illinois at Chicago, 900 S. Ashland Avenue, Chicago, IL 60607, USA.
authors.forename: Sinchita
authors.initials: S
authors.lastname: Roy Chowdhuri
authors.forename: Tanya
authors.initials: T
authors.lastname: Crum
authors.forename: Alison
authors.initials: A
authors.lastname: Woollard
authors.forename: Sobia
authors.initials: S
authors.lastname: Aslam
authors.forename: Peter G
authors.initials: PG
authors.lastname: Okkema
mesh_terms: D000818:Animals; D001665:Binding Sites; D001757:Blastomeres / Q000166:cytology / Q000502:physiology; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism / Q000502:physiology*; D019070:Cell Lineage; D004627:Embryonic Induction; D010609:Pharyngeal Muscles / Q000166:cytology / Q000196:embryology; D034741:RNA, Small Interfering / Q000494:pharmacology; D020825:T-Box Domain Proteins / Q000378:metabolism / Q000502:physiology*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D034741:RNA, Small Interfering; C097348:T-Box Domain Protein 2; D020825:T-Box Domain Proteins; D044763:Ubiquitin-Conjugating Enzymes