title: PCNA ubiquitination-independent activation of polymerase η during somatic hypermutation and DNA damage tolerance.
abstract: The generation of high affinity antibodies in B cells critically depends on translesion synthesis (TLS) polymerases that introduce mutations into immunoglobulin genes during somatic hypermutation (SHM). The majority of mutations at A/T base pairs during SHM require ubiquitination of PCNA at lysine 164 (PCNA-Ub), which activates TLS polymerases. By comparing the mutation spectra in B cells of WT, TLS polymerase η (Polη)-deficient, PCNA(K164R)-mutant, and PCNA(K164R);Polη double-mutant mice, we now find that most PCNA-Ub-independent A/T mutagenesis during SHM is mediated by Polη. In addition, upon exposure to various DNA damaging agents, PCNA(K164R) mutant cells display strongly impaired recruitment of TLS polymerases, reduced daughter strand maturation and hypersensitivity. Interestingly, compared to the single mutants, PCNA(K164R);Polη double-mutant cells are dramatically delayed in S phase progression and far more prone to cell death following UV exposure. Taken together, these data support the existence of PCNA ubiquitination-dependent and -independent activation pathways of Polη during SHM and DNA damage tolerance.
authors: Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands.
authors: Peter H L
authors: PH
authors: Krijger
authors: Paul C M
authors: PC
authors: van den Berk
authors: Niek
authors: N
authors: Wit
authors: Petra
authors: P
authors: Langerak
authors: Jacob G
authors: JG
authors: Jansen
authors: Claude-Agnès
authors: CA
authors: Reynaud
authors: Niels
authors: N
authors: de Wind
authors: Heinz
authors: H
authors: Jacobs
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004789:Enzyme Activation; D008239:Lysine / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D016296:Mutagenesis; D009154:Mutation; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D027041:Somatic Hypermutation, Immunoglobulin / Q000235:genetics*; D054875:Ubiquitination; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D004259:DNA-Directed DNA Polymerase; D008239:Lysine; D018809:Proliferating Cell Nuclear Antigen; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases