Function of the C. elegans T-box factor TBX-2 depends on SUMOylation
journal contributionposted on 2015-09-21, 00:00 authored by Paul Huber, Tanya Crum, Lynn M. Clary, Tom Ronan, Adelaide V. Packard, Peter G. Okkema
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.
This project was supported by NIH grant 5R01GM82865 (P.G.O.), a UIC LASURI Award (A.V.P.), and State of Illinois funding to the Laboratory for Molecular Biology. Some nematode strains used in this work were provided by the Caenorhabditis Genetics Center, which is funded by the NIH National Center for Research Resources (NCRR).
Publisher StatementPost print version of article may differ from published version. The final publication is available at springerlink.com; DOI: 10.1007/s00018-013-1336-y