title: Nonhomologous end-joining promotes resistance to DNA damage in the absence of an ADP-ribosyltransferase that signals DNA single strand breaks.
abstract: ADP-ribosylation of proteins at DNA lesions by ADP-ribosyltransferases (ARTs) is an early response to DNA damage. The best defined role of ADP-ribosylation in the DNA damage response is in repair of single strand breaks (SSBs). Recently, we initiated a study of how ADP-ribosylation regulates DNA repair in Dictyostelium and found that two ARTs (Adprt1b and Adprt2) are required for tolerance of cells to SSBs, and a third ART (Adprt1a) promotes nonhomologous end-joining (NHEJ). Here we report that disruption of adprt2 results in accumulation of DNA damage throughout the cell cycle following exposure to agents that induce base damage and DNA SSBs. Although ADP-ribosylation is evident in adprt2(-) cells exposed to methylmethanesulfonate (MMS), disruption of adprt1a and adprt2 in combination abolishes this response and further sensitises cells to this agent, indicating that in the absence of Adprt2, Adprt1a signals MMS-induced DNA lesions to promote resistance of cells to DNA damage. As a consequence of defective signalling of SSBs by Adprt2, Adprt1a is required to assemble NHEJ factors in chromatin, and disruption of the NHEJ pathway in combination with adprt2 increases sensitivity of cells to MMS. Taken together, these data indicate overlapping functions of different ARTs in signalling DNA damage, and illustrate a critical requirement for NHEJ in maintaining cell viability in the absence of an effective SSB response.
authors.affiliation: Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
authors.forename: C Anne-Marie
authors.initials: CA
authors.lastname: Couto
authors.forename: Duen-Wei
authors.initials: DW
authors.lastname: Hsu
authors.forename: Regina
authors.initials: R
authors.lastname: Teo
authors.forename: Alina
authors.initials: A
authors.lastname: Rakhimova
authors.forename: Styliana
authors.initials: S
authors.lastname: Lempidaki
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Pears
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Lakin
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism*; D053904:DNA Breaks, Single-Stranded; D059766:DNA End-Joining Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D021902:Enterobacter aerogenes / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011065:Poly(ADP-ribose) Polymerases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D004268:DNA-Binding Proteins; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases
keywords: ADP-ribosyltransferases; Dictyostelium; Nonhomologous end-joining; PARPs