DNA damage and repair William Kaufmann 31 325 LCCC 966 8209 william kaufmann pathology unc edu 1 The four R s of human DNA metabolism 2 Mechanism of cytotoxicity of topoI poisons 3 TopoII reactions DNA strand scission by topoII poisons Sites of alkylation of DNA 4 BP adduct on DNA An arrested replicon 5 Pathways of DNA repair O6 alkylguanine DNA alkyltransferase suicide protein transfers methyl group Base excision repair glycosylase AP endonuclease DNA polymerase ligase Nucleotide excision repair transcription coupled and global Cross link repair Fanconi s anemia genes and BRCA2 Double strand break repair Homologous recombination and non homologous end joining Heteroduplex and mismatch repair Post replication repair translesion synthesis by pol eta zeta iota or kappa Nucleotide excision repair 6 Pathways of repair of DNA double strand breaks Non homologous end joining DNA PK Ku70 80 XRCC1 DNA ligase IV immunoglobulin and TCR gene rearrangement Homologous recombination rad51 52 XRCC2 3 4 7 Crosslink repair requires Fanconi s anemia genes and BRCA2 Familial cancer syndromes Ataxia telangiectasia cell cycle checkpoint function DNA repair ATM NBS1 MRE 11 Fanconi s anemia DNA repair BRCA2 and 5 other genes HNPCC mismatch repair hMSH2 hMLH1 PMS2 hMSH6 Xeroderma pigmentosum nucleotide excision repair and post replication repair 8 XP genes Familial breast cancer I S and G2 checkpoint responses BRCA1 Li Fraumeni syndrome cell cycle checkpoint function and DNA repair P53 Chk2 Bloom s syndrome Werner syndrome RothmundThompson syndrome chromosomal instability Blm Wrn RecQ 8 9 Spindle assembly and polyploidization checkpoints NHF neo NHF E6 control colcemid P53 dependent G1 checkpoint function 10 ATM Nbs1 and Mre11 are required for the IRinduced S checkpoint NHF1 ATM 0 35 0 80 0 30 0 70 0 25 0 60 0 50 0 20 0 40 0 30 Normalized 3H CPM 0 15 0 10 0 20 0 05 0 10 0 00 0 00 0 10 20 Sham 30 0 10 1 5 Gy 20 Sham NBS1 30 1 5 Gy Mre11 0 70 0 60 0 60 0 50 0 50 0 40 0 40 0 30 0 30 0 20 0 20 0 10 0 10 0 00 0 00 0 10 20 Sham 30 0 10 Sham 1 5Gy 20 30 1 5 Gy Fraction Number ATR is an essential checkpoint kinase Ataxia telangiectasia and rad3 related ATR null embryos die at day 3 with severe chromosomal damage Expression of kinase inactive ATR overrides checkpoint responses to IR and UVC Cell Cycle Checkpoints M G1 S G1 Delay UV IR IR DNA Damage ATM p53 CHK2 ATM ATR Plk 1 p21 p53 p21 14 3 3 Crm1 Cyclin CDK s M G2 Delay DNA Damage ATR G2 CHK1 CDC25C Cyclin B1 CDC2 11 Passive and active inhibition of DNA replication by UVC Mechanisms and consequences of inhibition of DNA replication by UVC TT Block pol ATR Chk1 Replicon initiation TT DNA pol TT p53 NER p48 DNA dsb ATM G2 checkpoint UVC induced chromosomal aberrations 12 Evolution of DNA damage during the cell cycle 13
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