title: Selective DNA damage responses in murine Xpa-/-, Xpc-/- and Csb-/- keratinocyte cultures.
abstract: Cellular DNA damage responses (DDRs) are induced by unrepaired DNA lesions and constitute a protective back-up system that prevents the expansion of damaged cells. These cellular signaling pathways trigger either growth arrest or cell death and are believed to be major components of an early anti-cancer barrier. Cultures of C57BL/6J keratinocytes with various defects in NER sub-pathways allowed us to follow the kinetics of DDRs in an isogenic background and in the proper (physiologically relevant) target cells, supplementing earlier studies in heterogenic human fibroblasts. In a series of well-controlled parallel experiments we have shown that, depending on the NER deficiency, murine keratinocytes elicited highly selective DDRs. After a dose of UV-B that did not affect wild-type keratinocytes, Xpa(-/-) keratinocytes (complete NER deficiency) showed a rapid depletion of DNA replicating S-phase cells, a transient increase in quiescent S-phase cells (not replicating DNA), followed by massive apoptosis. Csb(-/-) keratinocytes (TC-NER deficient) responded by a more sustained increase in QS-phase cells and appeared more resistant to UV-B induced apoptosis than Xpa(-/-). In irradiated Xpc(-/-) keratinocytes (GG-NER deficient) the loss of replicating S-phase cells was associated with a gradual build-up of both QS-phase cells and cells arrested in late-S phase, in complete absence of apoptosis. Our analysis complements and extends previous in vivo investigations and highlights both similarities and differences with earlier fibroblast studies. In vitro cultures of murine keratinocytes provide a new tool to unravel the molecular mechanisms of UV-induced cellular stress responses in great detail and in a physiologically relevant background. This will be essential to fully appreciate the implications of DDRs in tumor suppression and cancer prevention.
authors.affiliation: Department of Dermatology, Leiden University Medical Centre, Wassenaarseweg 72, 2333 AL Leiden, The Netherlands.
authors.forename: Gerdine J
authors.initials: GJ
authors.lastname: Stout
authors.forename: Marijke van
authors.initials: Mv
authors.lastname: Oosten
authors.forename: Fatima Z
authors.initials: FZ
authors.lastname: Acherrat
authors.forename: Jan de
authors.initials: Jd
authors.lastname: Wit
authors.forename: Wilbert P
authors.initials: WP
authors.lastname: Vermeij
authors.forename: Leon H F
authors.initials: LH
authors.lastname: Mullenders
authors.forename: Frank R de
authors.initials: FR
authors.lastname: Gruijl
authors.forename: Claude
authors.initials: C
authors.lastname: Backendorf
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects; D016923:Cell Death / Q000528:radiation effects; D002455:Cell Division / Q000528:radiation effects; D002478:Cells, Cultured; D004249:DNA Damage / Q000235:genetics* / Q000502:physiology; D004260:DNA Repair / Q000235:genetics* / Q000502:physiology; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D004261:DNA Replication / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D020022:Genetic Predisposition to Disease; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects; D051379:Mice; D000075223:Poly-ADP-Ribose Binding Proteins; D011836:Radiation Tolerance; D016196:S Phase / Q000235:genetics / Q000528:radiation effects; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects; D012878:Skin Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D014466:Ultraviolet Rays; D051760:Xeroderma Pigmentosum Group A Protein / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects
chemical_list: D004268:DNA-Binding Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D051760:Xeroderma Pigmentosum Group A Protein; C497315:Xpa protein, mouse; C501002:Xpc protein, mouse; C513075:Ercc6 protein, mouse; D045643:DNA Repair Enzymes