title: Function of high-mobility group A proteins in the DNA damage signaling for the induction of apoptosis.
abstract: O(6)-Methylguanine produced in DNA can pair with thymine during DNA replication, thus leading to a G-to-A transition mutation. To prevent such outcomes, cells harboring O(6)-methylguanine-containing mispair undergo apoptosis that requires the function of mismatch repair (MMR) protein complex. To identify the genes involved in the induction of apoptosis, we performed gene-trap mutagenesis and isolated a clone of mouse cells exhibiting an increased resistance to the killing effect of an alkylating agent, N-methyl-N-nitrosourea (MNU). The mutant carries an insertion in the Hmga2 gene, which belongs to a gene family encoding the high-mobility group A non-histone chromatin proteins. To elucidate the function of HMGA proteins in the apoptosis pathway, we introduced siRNAs for HMGA1 and/or HMGA2 into human HeLa MR cells defective in O(6)-methylguanine-DNA methyltransferase. HMGA1- and HMGA2-single knockdown cells showed an increased resistance to MNU, and HMGA1/HMGA2-double knockdown cells exhibited further increased tolerance compared to the control. The phosphorylation of ATR and CHK1, the appearance of a sub-G1 population, and caspase-9 activation were suppressed in the knockdown cells, although the formation of mismatch recognition complex was unaffected. These results suggest that HMGA family proteins function at the step following the damage recognition in the process of apoptosis triggered by O(6)-methylguanine.
authors.affiliation: Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Fujikane
authors.affiliation: Department of Molecular Biology, Biomolecular Engineering Research Institute, Suita, 565-0874, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Komori
authors.affiliation: Advanced Science Research Center, Fukuoka Dental College, Fukuoka, 814-0193, Japan.
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Sekiguchi
authors.affiliation: Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan.|Department of Molecular Biology, Biomolecular Engineering Research Institute, Suita, 565-0874, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Hidaka
mesh_terms: D000818:Animals; D017209:Apoptosis; D053453:Caspase 9 / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D016193:G1 Phase / Q000235:genetics; D024003:HMGA Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D018345:Mice, Knockout; D015398:Signal Transduction
chemical_list: D024003:HMGA Proteins; C506433:CASP9 protein, human; C506434:Casp9 protein, mouse; D053453:Caspase 9