title: An RNAi-based dimorphic genetic screen identified the double bromodomain protein BET-1 as a sumo-dependent attenuator of RAS-mediated signalling.
abstract: Attenuation of RAS/RAF/MAPK signalling is essential to prevent hyperactivation of this oncogenic pathway. In C. elegans, the sumoylation pathway and a combination of histone tail modifications regulate gene expression to attenuate the LET-60 (RAS) signalling pathway. We hypothesised that a number of chromatin regulators are likely to depend on sumoylation to attenuate the pathway. To reveal these, we designed an RNAi-based dimorphic genetic screen that selects candidates based on their ability to act as enhancers of a sumo mutant phenotype, such interactions would suggest that the candidates may be physically associated with sumoylation. We found 16 enhancers, one of which BET-1, is a conserved double bromodomain containing protein. We further characterised BET-1 and showed that it can physically associate with SMO-1 and UBC-9, and that it can be sumoylated in vitro within the second bromodomain at lysine 252. Previous work has shown that BET-1 can bind acetyl-lysines on histone tails to influence gene expression. In conclusion, our screening approach has identified BET-1 as a Sumo-dependent attenuator of LET-60-mediated signalling and our characterisation suggests that BET-1 can be sumoylated.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, Greater Manchester, United Kingdom.
authors.forename: Fiona
authors.initials: F
authors.lastname: Gee
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, Greater Manchester, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Fisher
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, Greater Manchester, United Kingdom.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Klemstein
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, Greater Manchester, United Kingdom.
authors.forename: Gino B
authors.initials: GB
authors.lastname: Poulin
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D058207:Sumoylation / Q000502:physiology*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C548500:BET-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D009687:Nuclear Proteins; D025842:SUMO-1 Protein; C066646:let-60 protein, C elegans; D018631:ras Proteins