title: Understanding the role of the Q338H MUTYH variant in oxidative damage repair.
abstract: The MUTYH DNA-glycosylase is indirectly engaged in the repair of the miscoding 7,8-dihydro-8-oxo-2'-deoxyguanine (8-oxodG) lesion by removing adenine erroneously incorporated opposite the oxidized purine. Inherited biallelic mutations in the MUTYH gene are responsible for a recessive syndrome, the MUTYH-associated polyposis (MAP), which confers an increased risk of colorectal cancer. In this study, we functionally characterized the Q338H variant using recombinant proteins, as well as cell-based assays. This is a common variant among human colorectal cancer genes, which is generally considered, unrelated to the MAP phenotype but recently indicated as a low-penetrance allele. We demonstrate that the Q338H variant retains a wild-type DNA-glycosylase activity in vitro, but it shows a reduced ability to interact with the replication sensor RAD9:RAD1:HUS1 (9-1-1) complex. In comparison with Mutyh(-)(/)(-) mouse embryo fibroblasts expressing a wild-type MUTYH cDNA, the expression of Q338H variant was associated with increased levels of DNA 8-oxodG, hypersensitivity to oxidant and accumulation of the population in the S phase of the cell cycle. Thus, an inefficient interaction of MUTYH with the 9-1-1 complex leads to a repair-defective phenotype, indicating that a proper communication between MUTYH enzymatic function and the S phase checkpoint is needed for effective repair of oxidative damage.
authors: Department of Environment and Primary Prevention, Istituto Superiore di Sanità, 00161 Roma, Italy.
authors: Eleonora
authors: E
authors: Turco
authors: Ilenia
authors: I
authors: Ventura
authors: Anna
authors: A
authors: Minoprio
authors: Maria Teresa
authors: MT
authors: Russo
authors: Paola
authors: P
authors: Torreri
authors: Paolo
authors: P
authors: Degan
authors: Sara
authors: S
authors: Molatore
authors: Guglielmina Nadia
authors: GN
authors: Ranzani
authors: Margherita
authors: M
authors: Bignami
authors: Filomena
authors: F
authors: Mazzei
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002478:Cells, Cultured; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004260:DNA Repair; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D018384:Oxidative Stress; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D011994:Recombinant Proteins; C069930:rad9 protein; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase