TY - JOUR
T1 - Loss of MUTYH function in human cells leads to accumulation of oxidative damage and genetic instability
AU - Ruggieri, V.
AU - Pin, E.
AU - Russo, M. T.
AU - Barone, F.
AU - Degan, P.
AU - Sanchez, M.
AU - Quaia, M.
AU - Minoprio, A.
AU - Turco, E.
AU - Mazzei, F.
AU - Viel, A.
AU - Bignami, M.
PY - 2013/9/19
Y1 - 2013/9/19
N2 - The DNA glycosylase MUTYH (mutY homolog (Escherichia coli)) counteracts the mutagenic effects of 8-oxo-7,8-dihydroguanine (8-oxodG) by removing adenine (A) misincorporated opposite the oxidized purine. Biallelic germline mutations in MUTYH cause the autosomal recessive MUTYH-associated adenomatous polyposis (MAP). Here we designed new tools to investigate the biochemical defects and biological consequences associated with different MUTYH mutations in human cells. To identify phenotype(s) associated with MUTYH mutations, lymphoblastoid cell lines (LCLs) were derived from seven MAP patients harboring missense as well as truncating mutations in MUTYH. These included homozygous p.Arg245His, p.Gly264TrpfsX7 or compound heterozygous variants (p.Gly396Asp/Arg245Cys, p.Gly396Asp/Tyr179Cys, p.Gly396Asp/Glu410GlyfsX43, p.Gly264TrpfsX7/Ala385ProfsX23 and p.Gly264TrpfsX7/Glu480del). DNA glycosylase assays of MAP LCL extracts confirmed that all these variants were defective in removing A from an 8-oxoG:A DNA substrate, but retained wild-type OGG1 activity. As a consequence of this defect, MAP LCLs accumulated DNA 8-oxodG in their genome and exhibited a fourfold increase in spontaneous mutagenesis at the PIG-A gene compared with LCLs from healthy donors. They were also hypermutable by KBrO 3 - a source of DNA 8-oxodG - indicating that the relatively modest spontaneous mutator phenotype associated with MUTYH loss can be significantly enhanced by conditions of oxidative stress. These observations identify accumulation of DNA 8-oxodG and a mutator phenotype as likely contributors to the pathogenesis of MUTYH variants.
AB - The DNA glycosylase MUTYH (mutY homolog (Escherichia coli)) counteracts the mutagenic effects of 8-oxo-7,8-dihydroguanine (8-oxodG) by removing adenine (A) misincorporated opposite the oxidized purine. Biallelic germline mutations in MUTYH cause the autosomal recessive MUTYH-associated adenomatous polyposis (MAP). Here we designed new tools to investigate the biochemical defects and biological consequences associated with different MUTYH mutations in human cells. To identify phenotype(s) associated with MUTYH mutations, lymphoblastoid cell lines (LCLs) were derived from seven MAP patients harboring missense as well as truncating mutations in MUTYH. These included homozygous p.Arg245His, p.Gly264TrpfsX7 or compound heterozygous variants (p.Gly396Asp/Arg245Cys, p.Gly396Asp/Tyr179Cys, p.Gly396Asp/Glu410GlyfsX43, p.Gly264TrpfsX7/Ala385ProfsX23 and p.Gly264TrpfsX7/Glu480del). DNA glycosylase assays of MAP LCL extracts confirmed that all these variants were defective in removing A from an 8-oxoG:A DNA substrate, but retained wild-type OGG1 activity. As a consequence of this defect, MAP LCLs accumulated DNA 8-oxodG in their genome and exhibited a fourfold increase in spontaneous mutagenesis at the PIG-A gene compared with LCLs from healthy donors. They were also hypermutable by KBrO 3 - a source of DNA 8-oxodG - indicating that the relatively modest spontaneous mutator phenotype associated with MUTYH loss can be significantly enhanced by conditions of oxidative stress. These observations identify accumulation of DNA 8-oxodG and a mutator phenotype as likely contributors to the pathogenesis of MUTYH variants.
KW - 8-oxodG
KW - DNA glycosylase activity
KW - MUTYH variants
KW - MUTYH-associated polyposis
KW - PIG-A
UR - http://www.scopus.com/inward/record.url?scp=84884588531&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84884588531&partnerID=8YFLogxK
U2 - 10.1038/onc.2012.479
DO - 10.1038/onc.2012.479
M3 - Article
C2 - 23108399
AN - SCOPUS:84884588531
SN - 0950-9232
VL - 32
SP - 4500
EP - 4508
JO - Oncogene
JF - Oncogene
IS - 38
ER -