title: DNA polymerase eta reduces the gamma-H2AX response to psoralen interstrand crosslinks in human cells.
abstract: DNA interstrand crosslinks are processed by multiple mechanisms whose relationships to each other are unclear. Xeroderma pigmentosum-variant (XP-V) cells lacking DNA polymerase eta are sensitive to psoralen photoadducts created under conditions favoring crosslink formation, suggesting a role for translesion synthesis in crosslink repair. Because crosslinks can lead to double-strand breaks, we monitored phosphorylated H2AX (gamma-H2AX), which is typically generated near double-strand breaks but also in response to single-stranded DNA, following psoralen photoadduct formation in XP-V fibroblasts to assess whether polymerase eta is involved in processing crosslinks. In contrast to conditions favoring monoadducts, conditions favoring psoralen crosslinks induced gamma-H2AX levels in both XP-V and nucleotide excision repair-deficient XP-A cells relative to control repair-proficient cells; ectopic expression of polymerase eta in XP-V cells normalized the gamma-H2AX response. In response to psoralen crosslinking, gamma-H2AX as well as 53BP1 formed coincident foci that were more numerous and intense in XP-V and XP-A cells than in controls. Psoralen photoadducts induced gamma-H2AX throughout the cell cycle in XP-V cells. These results indicate that polymerase eta is important in responding to psoralen crosslinks, and are consistent with a model in which nucleotide excision repair and polymerase eta are involved in processing crosslinks and avoiding gamma-H2AX associated with double-strand breaks and single-stranded DNA in human cells.
authors: Department of Dermatology, University of California, San Francisco, and Dermatology Research Unit, San Francisco VA Medical Center 94121, USA.
authors: Seiki
authors: S
authors: Mogi
authors: Christina E
authors: CE
authors: Butcher
authors: Dennis H
authors: DH
authors: Oh
mesh_terms: D002453:Cell Cycle; D002461:Cell Line, Transformed; D018736:DNA Adducts / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D011564:Furocoumarins / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000378:metabolism; D000099270:Y-Family DNA Polymerases
chemical_list: D018736:DNA Adducts; D004259:DNA-Directed DNA Polymerase; D011564:Furocoumarins; D006657:Histones; C468783:H2AX protein, human; C056465:psoralen-DNA adduct; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases