DNA damage tolerance pathway involving DNA polymerase ι and the tumor suppressor p53 regulates DNA replication fork progression

Abstract

DNA damage tolerance facilitates the progression of replication forks that have encountered obstacles on the template strands. It involves either translesion DNA synthesis initiated by proliferating cell nuclear antigen monoubiquitination or less well-characterized fork reversal and template switch mechanisms. Herein, we characterize a novel tolerance pathway requiring the tumor suppressor p53, the translesion polymerase ι (POLι), the ubiquitin ligase Rad5-related helicase-like transcription factor (HLTF), and the SWI/SNF catalytic subunit (SNF2) translocase zinc finger ran-binding domain containing 3 (ZRANB3). This novel p53 activity is lost in the exonucleasedeficient but transcriptionally active p53(H115N) mutant. Wild-type p53, but not p53(H115N), associates with POLι in vivo. Strikingly, the concerted action of p53 and POLι decelerates nascent DNA elongation and promotes HLTF/ZRANB3-dependent recombination during unperturbed DNA replication. Particularly after cross-linkerinduced replication stress, p53 and POLι also act together to promote meiotic recombination enzyme 11 (MRE11)-dependent accumulation of (phospho-)replication protein A (RPA)-coated ssDNA. These results implicate a direct role of p53 in the processing of replication forks encountering obstacles on the template strand. Our findings define an unprecedented function of p53 and POLι in the DNA damage response to endogenous or exogenous replication stress.T he tumor suppressor protein p53 has been called the guardianof-the-genome due to its ability to transactivate downstream targets transcriptionally, which prevents S-phase entrance before facilitating DNA repair or eliminating cells with severe DNA damage via apoptosis (1). Interestingly, p53 also encodes an intrinsic 3′-5′ exonuclease activity located within its central DNA-binding domain (2-4). The contribution of the exonuclease proficiency to p53's function has largely remained obscure. Exonucleases are involved in DNA replication, DNA repair, and recombination, increasing the fidelity or efficiency of these processes. The 3′-5′ exonuclease activity of DNA polymerases (POLs) catalyzes the correction of replication errors, thereby preventing genomic instability and cancer (5-7). The potential involvement of p53's exonuclease in DNA repair has been ascribed to transcription-independent functions in nucleotide excision repair and base excision repair, in homologous recombination (HR), and in mitochondrial processes (8-10).Regarding HR, in particular, reports indicate a dual role for p53. On the one hand, it has been reported that p53 down-regulates unscheduled and excessive HR in response to severe genotoxic stress, like formation of DNA double-strand breaks (DSBs) (8-10). This antirecombinogenic effect of p53 has been linked to the blockage of continued strand exchange by interactions with recombinase RAD51, RAD54, and nascent HR intermediates carrying specific mismatches (11, 12). On the other hand, p53 stimulates spontaneous HR during S-phase to overcome replication fork stalling and to pr...

Multiple Defects Sensitize p53-Deficient Head and Neck Cancer Cells to the WEE1 Kinase Inhibition

“…This novel observation can imply that on a cell-by-cell basis, gH2AX response to replication stress is actually dampened by the knockdown of p53, and/or that p53 facilitates fork progression under stress. A stimulatory role of p53 in stressed fork progression was found by some studies (41,42) but not others (43). Resistance to AZD1775-induced replication stress at a replication fork level likely involves a RAD18-TLS polymerase kappa-dependent tolerance pathway and a RAD51-dependent fork protection pathway (13).…”

Phosphorylation of ETS‐1 is a critical event in DNA polymerase iota‐induced invasion and metastasis of esophageal squamous cell carcinoma

“…(10,32) Some DNA damage repair is Erk1/2-dependent or accelerated by Erk1/2 activation. (33,34) It has also been reported that Pol ι can interact with p53, (35) which can activate Erk1/ 2. (36) Therefore, we hypothesize that Erk1/2 is activated by Pol ι via the DNA damage repair system.…”

p53 Specifically Binds Triplex DNA In Vitro and in Cells

“…It was shown that triplex-forming oligonucleotides are able to activate DNA recombination and DNA repair in addition to inducing genomic instability [77]. Intact p53 C-terminus is necessary for recognition of damaged DNA and recombination intermediates [2, 3, 7, 8, 63, 78, 79]. Triplex DNA may also elicit genetic instability by a roadblock to DNA replication and transcription elongation [80].…”

“…Triplex DNA may also elicit genetic instability by a roadblock to DNA replication and transcription elongation [80]. The DNA damage tolerance pathway and p53 regulates DNA replication fork progression according to a recent study [78]. It was shown, that the helical distortions and structural alternations induced by triplex formation may be recognized as “DNA damage” [80, 81].…”