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1.
Cell Res ; 29(10): 783-784, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31434995
2.
Genet Med ; 2018 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-30504929

RESUMO

PURPOSE: To enhance classification of variants of uncertain significance (VUS) in the DNA mismatch repair (MMR) genes in the cancer predisposition Lynch syndrome, we developed the cell-free in vitro MMR activity (CIMRA) assay. Here, we calibrate and validate the assay, enabling its integration with in silico and clinical data. METHODS: Two sets of previously classified MLH1 and MSH2 variants were selected from a curated MMR gene database, and their biochemical activity determined by the CIMRA assay. The assay was calibrated by regression analysis followed by symmetric cross-validation and Bayesian integration with in silico predictions of pathogenicity. CIMRA assay reproducibility was assessed in four laboratories. RESULTS: Concordance between the training runs met our prespecified validation criterion. The CIMRA assay alone correctly classified 65% of variants, with only 3% discordant classification. Bayesian integration with in silico predictions of pathogenicity increased the proportion of correctly classified variants to 87%, without changing the discordance rate. Interlaboratory results were highly reproducible. CONCLUSION: The CIMRA assay accurately predicts pathogenic and benign MMR gene variants. Quantitative combination of assay results with in silico analysis correctly classified the majority of variants. Using this calibration, CIMRA assay results can be integrated into the diagnostic algorithm for MMR gene variants.

3.
Clin Cancer Res ; 24(13): 3197-3203, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29559562

RESUMO

Purpose: Pathogenic POLE proofreading domain mutations are found in many malignancies where they are associated with ultramutation and favorable prognosis. The extent to which this prognosis depends on their sensitivity to adjuvant treatment is unknown, as is the optimal therapy for advanced-staged or recurrent POLE-mutant cancers.Experimental Design: We examined the recurrence-free survival of women with POLE-mutant and POLE-wild-type endometrial cancers (EC) in the observation arm of the randomized PORTEC-1 endometrial cancer trial (N = 245 patients with stage I endometrial cancer for analysis). Sensitivity to radiotherapy and selected chemotherapeutics was compared between Pole-mutant mouse-derived embryonic stem (mES) cells, generated using CRISPR-Cas9 (Pole mutations D275A/E275A, and cancer-associated P286R, S297F, V411L) and isogenic wild-type cell lines.Results: In the observation arm of the PORTEC-1 trial (N = 245), women with POLE-mutant endometrial cancers (N = 16) had an improved recurrence-free survival (10-year recurrence-free survival 100% vs. 80.1% for POLE-wild-type; HR, 0.143; 95% confidence interval, 0.001-0.996; P = 0.049). Pole mutations did not increase sensitivity to radiotherapy nor to chemotherapeutics in mES cells. In contrast, Pole-mutant cells displayed significantly increased sensitivity to cytarabine and fludarabine (IC50Pole P286R-mutant vs. wild-type: 0.05 vs. 0.17 µmol/L for cytarabine, 4.62 vs. 11.1 µmol/L for fludarabine; P < 0.001 for both comparisons).Conclusions: The favorable prognosis of POLE-mutant cancers cannot be explained by increased sensitivity to currently used adjuvant treatments. These results support studies exploring minimization of adjuvant therapy for early-stage POLE-mutant cancers, including endometrial and colorectal cancers. Conversely, POLE mutations result in hypersensitivity to nucleoside analogues, suggesting the use of these compounds as a potentially effective targeted treatment for advanced-stage POLE-mutant cancers. Clin Cancer Res; 24(13); 3197-203. ©2018 AACR.

4.
5.
Sci Rep ; 7(1): 12480, 2017 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-28970491

RESUMO

Nucleic acids, which constitute the genetic material of all organisms, are continuously exposed to endogenous and exogenous damaging agents, representing a significant challenge to genome stability and genome integrity over the life of a cell or organism. Unrepaired DNA lesions, such as single- and double-stranded DNA breaks (SSBs and DSBs), and single-stranded gaps can block progression of the DNA replication fork, causing replicative stress and/or cell cycle arrest. However, translesion synthesis (TLS) DNA polymerases, such as Rev1, have the ability to bypass some DNA lesions, which can circumvent the process leading to replication fork arrest and minimize replicative stress. Here, we show that Rev1-deficiency in mouse embryo fibroblasts or mouse liver tissue is associated with replicative stress and mitochondrial dysfunction. In addition, Rev1-deficiency is associated with high poly(ADP) ribose polymerase 1 (PARP1) activity, low endogenous NAD+, low expression of SIRT1 and PGC1α and low adenosine monophosphate (AMP)-activated kinase (AMPK) activity. We conclude that replication stress via Rev1-deficiency contributes to metabolic stress caused by compromized mitochondrial function via the PARP-NAD+-SIRT1-PGC1α axis.

6.
Blood ; 130(13): 1523-1534, 2017 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-28827409

RESUMO

Endogenous DNA damage is causally associated with the functional decline and transformation of stem cells that characterize aging. DNA lesions that have escaped DNA repair can induce replication stress and genomic breaks that induce senescence and apoptosis. It is not clear how stem and proliferating cells cope with accumulating endogenous DNA lesions and how these ultimately affect the physiology of cells and tissues. Here we have addressed these questions by investigating the hematopoietic system of mice deficient for Rev1, a core factor in DNA translesion synthesis (TLS), the postreplicative bypass of damaged nucleotides. Rev1 hematopoietic stem and progenitor cells displayed compromised proliferation, and replication stress that could be rescued with an antioxidant. The additional disruption of Xpc, essential for global-genome nucleotide excision repair (ggNER) of helix-distorting nucleotide lesions, resulted in the perinatal loss of hematopoietic stem cells, progressive loss of bone marrow, and fatal aplastic anemia between 3 and 4 months of age. This was associated with replication stress, genomic breaks, DNA damage signaling, senescence, and apoptosis in bone marrow. Surprisingly, the collapse of the Rev1Xpc bone marrow was associated with progressive mitochondrial dysfunction and consequent exacerbation of oxidative stress. These data reveal that, to protect its genomic and functional integrity, the hematopoietic system critically depends on the combined activities of repair and replication of helix-distorting oxidative nucleotide lesions by ggNER and Rev1-dependent TLS, respectively. The error-prone nature of TLS may provide mechanistic understanding of the accumulation of mutations in the hematopoietic system upon aging.


Assuntos
Dano ao DNA/genética , Reparo do DNA/genética , Sistema Hematopoético/fisiologia , Estresse Oxidativo , Animais , Apoptose , Medula Óssea/patologia , Proliferação de Células , Senescência Celular/genética , Genoma , Células-Tronco Hematopoéticas/patologia , Camundongos , Nucleotidiltransferases
7.
Hum Mutat ; 37(11): 1162-1179, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27435373

RESUMO

Monoallelic PMS2 germline mutations cause 5%-15% of Lynch syndrome, a midlife cancer predisposition, whereas biallelic PMS2 mutations cause approximately 60% of constitutional mismatch repair deficiency (CMMRD), a rare childhood cancer syndrome. Recently improved DNA- and RNA-based strategies are applied to overcome problematic PMS2 mutation analysis due to the presence of pseudogenes and frequent gene conversion events. Here, we determined PMS2 mutation detection yield and mutation spectrum in a nationwide cohort of 396 probands. Furthermore, we studied concordance between tumor IHC/MSI (immunohistochemistry/microsatellite instability) profile and mutation carrier state. Overall, we found 52 different pathogenic PMS2 variants explaining 121 Lynch syndrome and nine CMMRD patients. In vitro mismatch repair assays suggested pathogenicity for three missense variants. Ninety-one PMS2 mutation carriers (70%) showed isolated loss of PMS2 in their tumors, for 31 (24%) no or inconclusive IHC was available, and eight carriers (6%) showed discordant IHC (presence of PMS2 or loss of both MLH1 and PMS2). Ten cases with isolated PMS2 loss (10%; 10/97) harbored MLH1 mutations. We confirmed that recently improved mutation analysis provides a high yield of PMS2 mutations in patients with isolated loss of PMS2 expression. Application of universal tumor prescreening methods will however miss some PMS2 germline mutation carriers.


Assuntos
Neoplasias Encefálicas/genética , Neoplasias Colorretais Hereditárias sem Polipose/genética , Neoplasias Colorretais/genética , Análise Mutacional de DNA/métodos , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Síndromes Neoplásicas Hereditárias/genética , Neoplasias Encefálicas/metabolismo , Estudos de Coortes , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais Hereditárias sem Polipose/metabolismo , Predisposição Genética para Doença , Variação Genética , Mutação em Linhagem Germinativa , Humanos , Instabilidade de Microssatélites , Endonuclease PMS2 de Reparo de Erro de Pareamento/metabolismo , Síndromes Neoplásicas Hereditárias/metabolismo , Países Baixos
10.
Nucleic Acids Res ; 43(17): 8325-39, 2015 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-26187992

RESUMO

REV1 is a eukaryotic member of the Y-family of DNA polymerases involved in translesion DNA synthesis and genome mutagenesis. Recently, REV1 is also found to function in homologous recombination. However, it remains unclear how REV1 is recruited to the sites where homologous recombination is processed. Here, we report that loss of mammalian REV1 results in a specific defect in replication-associated gene conversion. We found that REV1 is targeted to laser-induced DNA damage stripes in a manner dependent on its ubiquitin-binding motifs, on RAD18, and on monoubiquitinated FANCD2 (FANCD2-mUb) that associates with REV1. Expression of a FANCD2-Ub chimeric protein in RAD18-depleted cells enhances REV1 assembly at laser-damaged sites, suggesting that FANCD2-mUb functions downstream of RAD18 to recruit REV1 to DNA breaks. Consistent with this suggestion we found that REV1 and FANCD2 are epistatic with respect to sensitivity to the double-strand break-inducer camptothecin. REV1 enrichment at DNA damage stripes also partially depends on BRCA1 and BRCA2, components of the FANCD2/BRCA supercomplex. Intriguingly, analogous to FANCD2-mUb and BRCA1/BRCA2, REV1 plays an unexpected role in protecting nascent replication tracts from degradation by stabilizing RAD51 filaments. Collectively these data suggest that REV1 plays multiple roles at stalled replication forks in response to replication stress.


Assuntos
Dano ao DNA , Replicação do DNA , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/fisiologia , Proteínas Nucleares/fisiologia , Nucleotidiltransferases/fisiologia , Camptotecina/toxicidade , Linhagem Celular , DNA/metabolismo , Proteínas de Ligação a DNA/fisiologia , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/metabolismo , Conversão Gênica , Humanos , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Nucleotidiltransferases/química , Nucleotidiltransferases/metabolismo , Domínios e Motivos de Interação entre Proteínas , Estresse Fisiológico/genética , Inibidores da Topoisomerase I/toxicidade , Ubiquitina-Proteína Ligases
12.
Nat Commun ; 6: 7199, 2015 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-26068067

RESUMO

Möbius syndrome (MBS) is a neurological disorder that is characterized by paralysis of the facial nerves and variable other congenital anomalies. The aetiology of this syndrome has been enigmatic since the initial descriptions by von Graefe in 1880 and by Möbius in 1888, and it has been debated for decades whether MBS has a genetic or a non-genetic aetiology. Here, we report de novo mutations affecting two genes, PLXND1 and REV3L in MBS patients. PLXND1 and REV3L represent totally unrelated pathways involved in hindbrain development: neural migration and DNA translesion synthesis, essential for the replication of endogenously damaged DNA, respectively. Interestingly, analysis of Plxnd1 and Rev3l mutant mice shows that disruption of these separate pathways converge at the facial branchiomotor nucleus, affecting either motoneuron migration or proliferation. The finding that PLXND1 and REV3L mutations are responsible for a proportion of MBS patients suggests that de novo mutations in other genes might account for other MBS patients.


Assuntos
Moléculas de Adesão Celular Neuronais/genética , Proteínas de Ligação a DNA/genética , DNA Polimerase Dirigida por DNA/genética , Síndrome de Möbius/genética , Mutação , Animais , Dano ao DNA , Exoma , Heterozigoto , Humanos , Camundongos , Camundongos Mutantes
13.
J Cell Biol ; 209(1): 33-46, 2015 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-25869665

RESUMO

In addition to correcting mispaired nucleotides, DNA mismatch repair (MMR) proteins have been implicated in mutagenic, cell cycle, and apoptotic responses to agents that induce structurally aberrant nucleotide lesions. Here, we investigated the mechanistic basis for these responses by exposing cell lines with single or combined genetic defects in nucleotide excision repair (NER), postreplicative translesion synthesis (TLS), and MMR to low-dose ultraviolet light during S phase. Our data reveal that the MMR heterodimer Msh2/Msh6 mediates the excision of incorrect nucleotides that are incorporated by TLS opposite helix-distorting, noninstructive DNA photolesions. The resulting single-stranded DNA patches induce canonical Rpa-Atr-Chk1-mediated checkpoints and, in the next cell cycle, collapse to double-stranded DNA breaks that trigger apoptosis. In conclusion, a novel MMR-related DNA excision repair pathway controls TLS a posteriori, while initiating cellular responses to environmentally relevant densities of genotoxic lesions. These results may provide a rationale for the colorectal cancer tropism in Lynch syndrome, which is caused by inherited MMR gene defects.


Assuntos
Dano ao DNA , Reparo de Erro de Pareamento de DNA , Animais , Apoptose , Linhagem Celular , Proteínas de Ligação a DNA/fisiologia , Células-Tronco Embrionárias/fisiologia , Epistasia Genética , Humanos , Camundongos da Linhagem 129 , Proteína 2 Homóloga a MutS/fisiologia , Mutagênese
14.
DNA Repair (Amst) ; 29: 2017 Apr, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25655219

RESUMO

Most spontaneous and DNA damage-induced nucleotide substitutions in eukaryotes depend on translesion synthesis polymerases Rev1 and Pol ζ, the latter consisting of the catalytic subunit Rev3 and the accessory protein Rev7. Here we review the regulation, and the biochemical and cellular functions, of Rev1/Pol ζ-dependent translesion synthesis. These are correlated with phenotypes of mouse models with defects in Rev1, Rev3 or Rev7. The data indicate that Rev1/Pol ζ-mediated translesion synthesis is important for adaptive immunity while playing paradoxical roles in oncogenesis. On the other hand, by enabling the replication of endogenously damaged templates, Rev1/Pol ζ -dependent translesion synthesis protects stem cells, thereby preventing features of ageing. In conclusion, Rev1/Pol ζ-dependent translesion synthesis at DNA helix-distorting nucleotide lesions orchestrates pleiotropic responses that determine organismal fitness and disease.


Assuntos
Reparo do DNA/fisiologia , Replicação do DNA/fisiologia , DNA Polimerase Dirigida por DNA/metabolismo , Instabilidade Genômica , Mutagênese , Animais , DNA/metabolismo , Doença/genética , Proteínas Mad2/metabolismo , Camundongos , Nucleotidiltransferases/metabolismo
15.
Nucleic Acids Res ; 43(3): 1637-45, 2015 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-25589543

RESUMO

DNA-damage tolerance (DDT) via translesion DNA synthesis (TLS) or homology-dependent repair (HDR) functions to bypass DNA lesions encountered during replication, and is critical for maintaining genome stability. Here, we present piggyBlock, a new chromosomal assay that, using piggyBac transposition of DNA containing a known lesion, measures the division of labor between the two DDT pathways. We show that in the absence of DNA damage response, tolerance of the most common sunlight-induced DNA lesion, TT-CPD, is achieved by TLS in mouse embryo fibroblasts. Meanwhile, BP-G, a major smoke-induced DNA lesion, is bypassed primarily by HDR, providing the first evidence for this mechanism being the main tolerance pathway for a biologically important lesion in a mammalian genome. We also show that, far from being a last-resort strategy as it is sometimes portrayed, TLS operates alongside nucleotide excision repair, handling 40% of TT-CPDs in repair-proficient cells. Finally, DDT acts in mouse embryonic stem cells, exhibiting the same pattern­mutagenic TLS included­despite the risk of propagating mutations along all cell lineages. The new method highlights the importance of HDR, and provides an effective tool for studying DDT in mammalian cells.


Assuntos
Cromossomos , Dano ao DNA , Animais , Sequência de Bases , Células Cultivadas , Camundongos , Sondas de Oligonucleotídeos
16.
Nucleic Acids Res ; 43(1): 282-94, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25505145

RESUMO

Translesion synthesis (TLS) provides a highly conserved mechanism that enables DNA synthesis on a damaged template. TLS is performed by specialized DNA polymerases of which polymerase (Pol) κ is important for the cellular response to DNA damage induced by benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), ultraviolet (UV) light and the alkylating agent methyl methanesulfonate (MMS). As TLS polymerases are intrinsically error-prone, tight regulation of their activity is required. One level of control is provided by ubiquitination of the homotrimeric DNA clamp PCNA at lysine residue 164 (PCNA-Ub). We here show that Polκ can function independently of PCNA modification and that Polη can function as a backup during TLS of MMS-induced lesions. Compared to cell lines deficient for PCNA modification (Pcna(K164R)) or Polκ, double mutant cell lines display hypersensitivity to MMS but not to BPDE or UV-C. Double mutant cells also displayed delayed post-replicative TLS, accumulate higher levels of replication stress and delayed S-phase progression. Furthermore, we show that Polη and Polκ are redundant in the DNA damage bypass of MMS-induced DNA damage. Taken together, we provide evidence for PCNA-Ub-independent activation of Polκ and establish Polη as an important backup polymerase in the absence of Polκ in response to MMS-induced DNA damage.


Assuntos
Dano ao DNA , DNA Polimerase Dirigida por DNA/fisiologia , Antígeno Nuclear de Célula em Proliferação/metabolismo , Ubiquitinação , Animais , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Sobrevivência Celular , Células Cultivadas , Quinase 1 do Ponto de Checagem , Replicação do DNA , DNA Polimerase Dirigida por DNA/genética , Metanossulfonato de Metila/toxicidade , Camundongos Knockout , Mutação , Antígeno Nuclear de Célula em Proliferação/genética , Proteínas Quinases/metabolismo , Fase S
17.
Mol Carcinog ; 54(7): 513-22, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24302565

RESUMO

Variants that disrupt the translation initiation sequences in cancer predisposition genes are generally assumed to be deleterious. However, few studies have validated these assumptions with functional and clinical data. Two cancer syndrome gene variants likely to affect native translation initiation were identified by clinical genetic testing: MLH1:c.1A>G p.(Met1?) and BRCA2:c.67+3A>G. In vitro GFP-reporter assays were conducted to assess the consequences of translation initiation disruption on alternative downstream initiation codon usage. Analysis of MLH1:c.1A>G p.(Met1?) showed that translation was mostly initiated at an in-frame position 103 nucleotides downstream, but also at two ATG sequences downstream. The protein product encoded by the in-frame transcript initiating from position c.103 showed loss of in vitro mismatch repair activity comparable to known pathogenic mutations. BRCA2:c.67+3A>G was shown by mRNA analysis to result in an aberrantly spliced transcript deleting exon 2 and the consensus ATG site. In the absence of exon 2, translation initiated mostly at an out-of-frame ATG 323 nucleotides downstream, and to a lesser extent at an in-frame ATG 370 nucleotides downstream. Initiation from any of the downstream alternative sites tested in both genes would lead to loss of protein function, but further clinical data is required to confirm if these variants are associated with a high cancer risk. Importantly, our results highlight the need for caution in interpreting the functional and clinical consequences of variation that leads to disruption of the initiation codon, since translation may not necessarily occur from the first downstream alternative start site, or from a single alternative start site.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Processamento Alternativo , Proteína BRCA2/genética , Códon de Iniciação , Neoplasias/genética , Proteínas Nucleares/genética , Reparo de Erro de Pareamento de DNA , Éxons , Genes BRCA2 , Humanos , Proteína 1 Homóloga a MutL , Biossíntese de Proteínas , Isoformas de Proteínas/genética
18.
Mol Genet Genomic Med ; 2(4): 352-5, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25077178

RESUMO

In clinical genetic diagnostics, it is difficult to predict whether genetic mutations that do not greatly alter the primary sequence of the encoded protein causing unknown functional effects on cognate proteins lead to development of disease. Here, we report the clinical identification of c.2038 T>C missense mutation in exon 18 of the human MLH1 gene and biochemically characterization of the p.Cys680Arg mutant MLH1 protein to implicate it in the pathogenicity of the Lynch syndrome (LS). We show that the mutation is deficient in DNA mismatch repair and, therefore, contributing to LS in the carriers.

19.
Mol Cell ; 55(6): 807-817, 2014 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-25155611

RESUMO

Maternal metabolism provides essential nutrients to enable embryonic development. However, both mother and embryo produce reactive metabolites that can damage DNA. Here we discover how the embryo is protected from these genotoxins. Pregnant mice lacking Aldh2, a key enzyme that detoxifies reactive aldehydes, cannot support the development of embryos lacking the Fanconi anemia DNA repair pathway gene Fanca. Remarkably, transferring Aldh2(-/-)Fanca(-/-) embryos into wild-type mothers suppresses developmental defects and rescues embryonic lethality. These rescued neonates have severely depleted hematopoietic stem and progenitor cells, indicating that despite intact maternal aldehyde catabolism, fetal Aldh2 is essential for hematopoiesis. Hence, maternal and fetal aldehyde detoxification protects the developing embryo from DNA damage. Failure of this genome preservation mechanism might explain why birth defects and bone marrow failure occur in Fanconi anemia, and may have implications for fetal well-being in the many women in Southeast Asia that are genetically deficient in ALDH2.


Assuntos
Acetaldeído/metabolismo , Aldeído Desidrogenase/genética , Aldeído Desidrogenase/metabolismo , Embrião de Mamíferos/metabolismo , Etanol/toxicidade , Proteína do Grupo de Complementação A da Anemia de Fanconi/genética , Anemia de Fanconi/patologia , Acetaldeído/toxicidade , Aldeído-Desidrogenase Mitocondrial , Animais , Animais Recém-Nascidos , Dano ao DNA , Modelos Animais de Doenças , Embrião de Mamíferos/embriologia , Feminino , Genoma , Células-Tronco Hematopoéticas/metabolismo , Humanos , Isoenzimas/genética , Isoenzimas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Gravidez , Retinal Desidrogenase/genética , Retinal Desidrogenase/metabolismo
20.
Nucleic Acids Res ; 42(17): 11071-82, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25170086

RESUMO

Short-wave ultraviolet light induces both mildly helix-distorting cyclobutane pyrimidine dimers (CPDs) and severely distorting (6-4) pyrimidine pyrimidone photoproducts ((6-4)PPs). The only DNA polymerase (Pol) that is known to replicate efficiently across CPDs is Polη, a member of the Y family of translesion synthesis (TLS) DNA polymerases. Phenotypes of Polη deficiency are transient, suggesting redundancy with other DNA damage tolerance pathways. Here we performed a comprehensive analysis of the temporal requirements of Y-family Pols ι and κ as backups for Polη in (i) bypassing genomic CPD and (6-4)PP lesions in vivo, (ii) suppressing DNA damage signaling, (iii) maintaining cell cycle progression and (iv) promoting cell survival, by using mouse embryonic fibroblast lines with single and combined disruptions in these Pols. The contribution of Polι is restricted to TLS at a subset of the photolesions. Polκ plays a dominant role in rescuing stalled replication forks in Polη-deficient mouse embryonic fibroblasts, both at CPDs and (6-4)PPs. This dampens DNA damage signaling and cell cycle arrest, and results in increased survival. The role of relatively error-prone Pols ι and κ as backups for Polη contributes to the understanding of the mutator phenotype of xeroderma pigmentosum variant, a syndrome caused by Polη defects.


Assuntos
Dano ao DNA , DNA Polimerase Dirigida por DNA/fisiologia , Raios Ultravioleta/efeitos adversos , Animais , Ciclo Celular , Linhagem Celular , Quebras de DNA de Cadeia Dupla , Replicação do DNA , DNA Polimerase Dirigida por DNA/metabolismo , Fibroblastos/enzimologia , Fibroblastos/metabolismo , Genoma , Camundongos , Dímeros de Pirimidina/metabolismo
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