RESUMO
Lactylation is a lactate-induced post-translational modification best known for its roles in epigenetic regulation. Herein, we demonstrate that MRE11, a crucial homologous recombination (HR) protein, is lactylated at K673 by the CBP acetyltransferase in response to DNA damage and dependent on ATM phosphorylation of the latter. MRE11 lactylation promotes its binding to DNA, facilitating DNA end resection and HR. Inhibition of CBP or LDH downregulated MRE11 lactylation, impaired HR, and enhanced chemosensitivity of tumor cells in patient-derived xenograft and organoid models. A cell-penetrating peptide that specifically blocks MRE11 lactylation inhibited HR and sensitized cancer cells to cisplatin and PARPi. These findings unveil lactylation as a key regulator of HR, providing fresh insights into the ways in which cellular metabolism is linked to DSB repair. They also imply that the Warburg effect can confer chemoresistance through enhancing HR and suggest a potential therapeutic strategy of targeting MRE11 lactylation to mitigate the effects.
Assuntos
Proteínas de Ligação a DNA , Proteína Homóloga a MRE11 , Reparo de DNA por Recombinação , Humanos , DNA , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Proteínas de Ligação a DNA/metabolismo , Epigênese Genética , Recombinação Homóloga , Proteína Homóloga a MRE11/metabolismo , Ácido Láctico/metabolismoRESUMO
Non-small cell lung cancers (NSCLCs) harboring KEAP1 mutations are often resistant to immunotherapy. Here, we show that KEAP1 targets EMSY for ubiquitin-mediated degradation to regulate homologous recombination repair (HRR) and anti-tumor immunity. Loss of KEAP1 in NSCLC induces stabilization of EMSY, producing a BRCAness phenotype, i.e., HRR defects and sensitivity to PARP inhibitors. Defective HRR contributes to a high tumor mutational burden that, in turn, is expected to prompt an innate immune response. Notably, EMSY accumulation suppresses the type I interferon response and impairs innate immune signaling, fostering cancer immune evasion. Activation of the type I interferon response in the tumor microenvironment using a STING agonist results in the engagement of innate and adaptive immune signaling and impairs the growth of KEAP1-mutant tumors. Our results suggest that targeting PARP and STING pathways, individually or in combination, represents a therapeutic strategy in NSCLC patients harboring alterations in KEAP1.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/imunologia , Interferon Tipo I/metabolismo , Neoplasias Pulmonares/imunologia , Proteínas de Neoplasias/metabolismo , Proteínas Nucleares/metabolismo , Reparo de DNA por Recombinação/genética , Proteínas Repressoras/metabolismo , Evasão Tumoral/genética , Animais , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Feminino , Células HEK293 , Humanos , Imunidade Inata/genética , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Mutação , Proteínas de Neoplasias/genética , Proteínas Nucleares/genética , Proteínas Repressoras/genética , Transdução de Sinais/genética , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
End resection in homologous recombination (HR) and HR-mediated repair of DNA double-strand breaks (DSBs) removes several kilobases from 5' strands of DSBs, but 3' strands are exempted from degradation. The mechanism by which the 3' overhangs are protected has not been determined. Here, we established that the protection of 3' overhangs is achieved through the transient formation of RNA-DNA hybrids. The DNA strand in the hybrids is the 3' ssDNA overhang, while the RNA strand is newly synthesized. RNA polymerase III (RNAPIII) is responsible for synthesizing the RNA strand. Furthermore, RNAPIII is actively recruited to DSBs by the MRN complex. CtIP and MRN nuclease activity is required for initiating the RNAPIII-mediated RNA synthesis at DSBs. A reduced level of RNAPIII suppressed HR, and genetic loss > 30 bp increased at DSBs. Thus, RNAPIII is an essential HR factor, and the RNA-DNA hybrid is an essential repair intermediate for protecting the 3' overhangs in DSB repair.
Assuntos
RNA Polimerase III/metabolismo , Reparo de DNA por Recombinação , Ciclo Celular , Linhagem Celular Tumoral , Quebras de DNA de Cadeia Dupla , Endodesoxirribonucleases/genética , Células HEK293 , Humanos , Proteína Homóloga a MRE11/metabolismo , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Hibridização de Ácido Nucleico , RNA/químicaRESUMO
Cells confront DNA damage in every cell cycle. Among the most deleterious types of DNA damage are DNA double-strand breaks (DSBs), which can cause cell lethality if unrepaired or cancers if improperly repaired. In response to DNA DSBs, cells activate a complex DNA damage checkpoint (DDC) response that arrests the cell cycle, reprograms gene expression, and mobilizes DNA repair factors to prevent the inheritance of unrepaired and broken chromosomes. Here we examine the DDC, induced by DNA DSBs, in the budding yeast model system and in mammals.
Assuntos
Pontos de Checagem do Ciclo Celular/genética , Reparo do DNA por Junção de Extremidades , DNA/genética , Reparo de DNA por Recombinação , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Animais , Proteínas Mutadas de Ataxia Telangiectasia/química , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Quinase 1 do Ponto de Checagem/genética , Quinase 1 do Ponto de Checagem/metabolismo , Quinase do Ponto de Checagem 2/genética , Quinase do Ponto de Checagem 2/metabolismo , DNA/química , DNA/metabolismo , Quebras de DNA de Cadeia Dupla , Humanos , Modelos Moleculares , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Estrutura Secundária de Proteína , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
Mutations in the BRCA1 and BRCA2 genes predispose afflicted individuals to breast, ovarian, and other cancers. The BRCA-encoded products form complexes with other tumor suppressor proteins and with the recombinase enzyme RAD51 to mediate chromosome damage repair by homologous recombination and also to protect stressed DNA replication forks against spurious nucleolytic attrition. Understanding how the BRCA tumor suppressor network executes its biological functions would provide the foundation for developing targeted cancer therapeutics, but progress in this area has been greatly hampered by the challenge of obtaining purified BRCA complexes for mechanistic studies. In this article, we review how recent effort begins to overcome this technical challenge, leading to functional and structural insights into the biochemical attributes of these complexes and the multifaceted roles that they fulfill in genome maintenance. We also highlight the major mechanistic questions that remain.
Assuntos
Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Redes Reguladoras de Genes , Rad51 Recombinase/genética , Reparo de DNA por Recombinação , Proteínas Supressoras de Tumor/genética , Ubiquitina-Proteína Ligases/genética , Proteína BRCA1/química , Proteína BRCA1/metabolismo , Proteína BRCA2/química , Proteína BRCA2/metabolismo , Sítios de Ligação , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , DNA/química , DNA/genética , DNA/metabolismo , Quebras de DNA de Cadeia Dupla , Replicação do DNA , Feminino , Genoma Humano , Instabilidade Genômica , Humanos , Modelos Moleculares , Ligação Proteica , Estrutura Secundária de Proteína , Rad51 Recombinase/química , Rad51 Recombinase/metabolismo , Proteínas Supressoras de Tumor/química , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Genomic instability can be a hallmark of both human genetic disease and cancer. We identify a deleterious UBQLN4 mutation in families with an autosomal recessive syndrome reminiscent of genome instability disorders. UBQLN4 deficiency leads to increased sensitivity to genotoxic stress and delayed DNA double-strand break (DSB) repair. The proteasomal shuttle factor UBQLN4 is phosphorylated by ATM and interacts with ubiquitylated MRE11 to mediate early steps of homologous recombination-mediated DSB repair (HRR). Loss of UBQLN4 leads to chromatin retention of MRE11, promoting non-physiological HRR activity in vitro and in vivo. Conversely, UBQLN4 overexpression represses HRR and favors non-homologous end joining. Moreover, we find UBQLN4 overexpressed in aggressive tumors. In line with an HRR defect in these tumors, UBQLN4 overexpression is associated with PARP1 inhibitor sensitivity. UBQLN4 therefore curtails HRR activity through removal of MRE11 from damaged chromatin and thus offers a therapeutic window for PARP1 inhibitor treatment in UBQLN4-overexpressing tumors.
Assuntos
Proteínas de Transporte/genética , Proteínas Nucleares/genética , Proteínas de Transporte/metabolismo , Cromatina/metabolismo , DNA , Quebras de DNA de Cadeia Dupla , Dano ao DNA/genética , Reparo do DNA por Junção de Extremidades , Proteínas de Ligação a DNA/metabolismo , Feminino , Instabilidade Genômica , Mutação em Linhagem Germinativa , Recombinação Homóloga , Humanos , Proteína Homóloga a MRE11/genética , Proteína Homóloga a MRE11/metabolismo , Masculino , Neoplasias/genética , Neoplasias/metabolismo , Proteínas Nucleares/metabolismo , Cultura Primária de Células , Reparo de DNA por RecombinaçãoRESUMO
Given that genomic DNA exerts its function by being transcribed, it is critical for the maintenance of homeostasis that DNA damage, such as double-strand breaks (DSBs), within transcriptionally active regions undergoes accurate repair. However, it remains unclear how this is achieved. Here, we describe a mechanism for transcription-associated homologous recombination repair (TA-HRR) in human cells. The process is initiated by R-loops formed upon DSB induction. We identify Rad52, which is recruited to the DSB site in a DNA-RNA-hybrid-dependent manner, as playing pivotal roles in promoting XPG-mediated R-loop processing and initiating subsequent repair by HRR. Importantly, dysfunction of TA-HRR promotes DSB repair via non-homologous end joining, leading to a striking increase in genomic aberrations. Thus, our data suggest that the presence of R-loops around DSBs within transcriptionally active regions promotes accurate repair of DSBs via processing by Rad52 and XPG to protect genomic information in these critical regions from gene alterations.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Endonucleases/metabolismo , Proteínas Nucleares/metabolismo , Proteína Rad52 de Recombinação e Reparo de DNA/metabolismo , Reparo de DNA por Recombinação/fisiologia , Fatores de Transcrição/metabolismo , Linhagem Celular , DNA/genética , Quebras de DNA de Cadeia Dupla , Dano ao DNA , Reparo do DNA por Junção de Extremidades , Reparo do DNA , Proteínas de Ligação a DNA/fisiologia , Endonucleases/fisiologia , Recombinação Homóloga , Humanos , Proteínas Nucleares/genética , Proteínas Nucleares/fisiologia , RNA/genética , Proteína Rad52 de Recombinação e Reparo de DNA/genética , Fatores de Transcrição/fisiologiaRESUMO
The tumour suppressor breast cancer type 1 susceptibility protein (BRCA1) promotes DNA double-strand break (DSB) repair by homologous recombination and protects DNA replication forks from attrition. BRCA1 partners with BRCA1-associated RING domain protein 1 (BARD1) and other tumour suppressor proteins to mediate the initial nucleolytic resection of DNA lesions and the recruitment and regulation of the recombinase RAD51. The discovery of the opposing functions of BRCA1 and the p53-binding protein 1 (53BP1)-associated complex in DNA resection sheds light on how BRCA1 influences the choice of homologous recombination over non-homologous end joining and potentially other mutagenic pathways of DSB repair. Understanding the functional crosstalk between BRCA1-BARD1 and its cofactors and antagonists will illuminate the molecular basis of cancers that arise from a deficiency or misregulation of chromosome damage repair and replication fork maintenance. Such knowledge will also be valuable for understanding acquired tumour resistance to poly(ADP-ribose) polymerase (PARP) inhibitors and other therapeutics and for the development of new treatments. In this Review, we discuss recent advances in elucidating the mechanisms by which BRCA1-BARD1 functions in DNA repair, replication fork maintenance and tumour suppression, and its therapeutic relevance.
Assuntos
Proteína BRCA1/genética , Neoplasias da Mama/genética , Proteínas Supressoras de Tumor/genética , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética , Ubiquitina-Proteína Ligases/genética , Neoplasias da Mama/patologia , Reparo do DNA por Junção de Extremidades/genética , Replicação do DNA/genética , Feminino , Humanos , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Poli(ADP-Ribose) Polimerases/genética , Ligação Proteica/genética , Reparo de DNA por Recombinação/genéticaRESUMO
Maintenance of a minimal telomere length is essential to prevent cellular senescence. When critically short telomeres arise in the absence of telomerase, they can be repaired by homology-directed repair (HDR) to prevent premature senescence onset. It is unclear why specifically the shortest telomeres are targeted for HDR. We demonstrate that the non-coding RNA TERRA accumulates as HDR-promoting RNA-DNA hybrids (R-loops) preferentially at very short telomeres. The increased level of TERRA and R-loops, exclusively at short telomeres, is due to a local defect in RNA degradation by the Rat1 and RNase H2 nucleases, respectively. Consequently, the coordination of TERRA degradation with telomere replication is altered at shortened telomeres. R-loop persistence at short telomeres contributes to activation of the DNA damage response (DDR) and promotes recruitment of the Rad51 recombinase. Thus, the telomere length-dependent regulation of TERRA and TERRA R-loops is a critical determinant of the rate of replicative senescence.
Assuntos
Ciclo Celular , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Telômero/metabolismo , Senescência Celular , Dano ao DNA , Exorribonucleases/metabolismo , Hibridização de Ácido Nucleico , Reparo de DNA por Recombinação , Proteínas Repressoras/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Telômero/química , Proteínas de Ligação a Telômeros/metabolismoRESUMO
Tumor suppressor BRCA2 functions in homology-directed repair (HDR), the protection of stalled replication forks, and the suppression of replicative gaps, but their relative contributions to genome integrity and chemotherapy response are under scrutiny. Here, we report that mouse and human cells require a RAD51 filament stabilization motif in BRCA2 for fork protection and gap suppression but not HDR. In mice, the loss of fork protection/gap suppression does not compromise genome stability or shorten tumor latency. By contrast, HDR deficiency increases spontaneous and replication stress-induced chromosome aberrations and tumor predisposition. Unlike with HDR, fork protection/gap suppression defects are also observed in Brca2 heterozygous cells, likely due to reduced RAD51 stabilization at stalled forks/gaps. Gaps arise from PRIMPOL activity, which is associated with 5-hydroxymethyl-2'-deoxyuridine sensitivity due to the formation of SMUG1-generated abasic sites and is exacerbated by poly(ADP-ribose) polymerase (PARP) inhibition. However, HDR proficiency has the major role in mitigating sensitivity to chemotherapeutics, including PARP inhibitors.
Assuntos
Proteína BRCA2 , Replicação do DNA , Rad51 Recombinase , Animais , Humanos , Camundongos , Proteína BRCA2/metabolismo , Reparo do DNA , Instabilidade Genômica , Genômica , Rad51 Recombinase/genética , Rad51 Recombinase/metabolismo , Reparo de DNA por RecombinaçãoRESUMO
DNA repair is directly performed by hundreds of core factors and indirectly regulated by thousands of others. We massively expanded a CRISPR inhibition and Cas9-editing screening system to discover factors indirectly modulating homology-directed repair (HDR) in the context of â¼18,000 individual gene knockdowns. We focused on CCAR1, a poorly understood gene that we found the depletion of reduced both HDR and interstrand crosslink repair, phenocopying the loss of the Fanconi anemia pathway. CCAR1 loss abrogated FANCA protein without substantial reduction in the level of its mRNA or that of other FA genes. We instead found that CCAR1 prevents inclusion of a poison exon in FANCA. Transcriptomic analysis revealed that the CCAR1 splicing modulatory activity is not limited to FANCA, and it instead regulates widespread changes in alternative splicing that would damage coding sequences in mouse and human cells. CCAR1 therefore has an unanticipated function as a splicing fidelity factor.
Assuntos
Processamento Alternativo , Proteína do Grupo de Complementação A da Anemia de Fanconi , Humanos , Animais , Camundongos , Proteína do Grupo de Complementação A da Anemia de Fanconi/genética , Proteína do Grupo de Complementação A da Anemia de Fanconi/metabolismo , Reparo de DNA por Recombinação , Anemia de Fanconi/genética , Anemia de Fanconi/metabolismo , Células HEK293 , Éxons , Sistemas CRISPR-Cas , Reparo do DNA , Células HeLa , Dano ao DNARESUMO
The repair of DNA by homologous recombination is an essential, efficient, and high-fidelity process that mends DNA lesions formed during cellular metabolism; these lesions include double-stranded DNA breaks, daughter-strand gaps, and DNA cross-links. Genetic defects in the homologous recombination pathway undermine genomic integrity and cause the accumulation of gross chromosomal abnormalities-including rearrangements, deletions, and aneuploidy-that contribute to cancer formation. Recombination proceeds through the formation of joint DNA molecules-homologously paired but metastable DNA intermediates that are processed by several alternative subpathways-making recombination a versatile and robust mechanism to repair damaged chromosomes. Modern biophysical methods make it possible to visualize, probe, and manipulate the individual molecules participating in the intermediate steps of recombination, revealing new details about the mechanics of genetic recombination. We review and discuss the individual stages of homologous recombination, focusing on common pathways in bacteria, yeast, and humans, and place particular emphasis on the molecular mechanisms illuminated by single-molecule methods.
Assuntos
DNA/genética , Escherichia coli/genética , Recombinação Genética , Reparo de DNA por Recombinação , Saccharomyces cerevisiae/genética , Aberrações Cromossômicas , DNA/metabolismo , Dano ao DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/metabolismo , Escherichia coli/metabolismo , Exodesoxirribonuclease V/genética , Exodesoxirribonuclease V/metabolismo , Exodesoxirribonucleases/genética , Exodesoxirribonucleases/metabolismo , Regulação da Expressão Gênica , Instabilidade Genômica , Humanos , Proteína Rad52 de Recombinação e Reparo de DNA/genética , Proteína Rad52 de Recombinação e Reparo de DNA/metabolismo , RecQ Helicases/genética , RecQ Helicases/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Imagem Individual de MoléculaRESUMO
RNA-DNA hybrids are a major internal cause of DNA damage within cells, and their degradation by RNase H enzymes is important for maintaining genomic stability. Here, we identified an unexpected role for RNA-DNA hybrids and RNase H enzymes in DNA repair. Using a site-specific DNA double-strand break (DSB) system in Schizosaccharomyces pombe, we showed that RNA-DNA hybrids form as part of the homologous-recombination (HR)-mediated DSB repair process and that RNase H enzymes are essential for their degradation and efficient completion of DNA repair. Deleting RNase H stabilizes RNA-DNA hybrids around DSB sites and strongly impairs recruitment of the ssDNA-binding RPA complex. In contrast, overexpressing RNase H1 destabilizes these hybrids, leading to excessive strand resection and RPA recruitment and to severe loss of repeat regions around DSBs. Our study challenges the existing model of HR-mediated DSB repair and reveals a surprising role for RNA-DNA hybrids in maintaining genomic stability.
Assuntos
Instabilidade Genômica , Reparo de DNA por Recombinação , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , DNA/metabolismo , Dano ao DNA , Expressão Gênica , RNA/metabolismo , RNA Polimerase II/metabolismo , Ribonuclease H/genética , Ribonuclease H/metabolismo , Schizosaccharomyces/enzimologiaRESUMO
The tumor-suppressor breast cancer 1 (BRCA1) in complex with BRCA1-associated really interesting new gene (RING) domain 1 (BARD1) is a RING-type ubiquitin E3 ligase that modifies nucleosomal histone and other substrates. The importance of BRCA1-BARD1 E3 activity in tumor suppression remains highly controversial, mainly stemming from studying mutant ligase-deficient BRCA1-BARD1 species that we show here still retain significant ligase activity. Using full-length BRCA1-BARD1, we establish robust BRCA1-BARD1-mediated ubiquitylation with specificity, uncover multiple modes of activity modulation, and construct a truly ligase-null variant and a variant specifically impaired in targeting nucleosomal histones. Cells expressing either of these BRCA1-BARD1 separation-of-function alleles are hypersensitive to DNA-damaging agents. Furthermore, we demonstrate that BRCA1-BARD1 ligase is not only required for DNA resection during homology-directed repair (HDR) but also contributes to later stages for HDR completion. Altogether, our findings reveal crucial, previously unrecognized roles of BRCA1-BARD1 ligase activity in genome repair via HDR, settle prior controversies regarding BRCA1-BARD1 ligase functions, and catalyze new efforts to uncover substrates related to tumor suppression.
Assuntos
Neoplasias , Proteínas Supressoras de Tumor , Humanos , Proteínas Supressoras de Tumor/metabolismo , Proteína BRCA1/metabolismo , Ubiquitinação , Histonas/genética , Histonas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Reparo de DNA por Recombinação , DNA , Reparo do DNARESUMO
An important advance in cancer therapy has been the development of poly(ADP-ribose) polymerase (PARP) inhibitors for the treatment of homologous recombination (HR)-deficient cancers1-6. PARP inhibitors trap PARPs on DNA. The trapped PARPs are thought to block replisome progression, leading to formation of DNA double-strand breaks that require HR for repair7. Here we show that PARP1 functions together with TIMELESS and TIPIN to protect the replisome in early S phase from transcription-replication conflicts. Furthermore, the synthetic lethality of PARP inhibitors with HR deficiency is due to an inability to repair DNA damage caused by transcription-replication conflicts, rather than by trapped PARPs. Along these lines, inhibiting transcription elongation in early S phase rendered HR-deficient cells resistant to PARP inhibitors and depleting PARP1 by small-interfering RNA was synthetic lethal with HR deficiency. Thus, inhibiting PARP1 enzymatic activity may suffice for treatment efficacy in HR-deficient settings.
Assuntos
Replicação do DNA , Inibidores de Poli(ADP-Ribose) Polimerases , Poli(ADP-Ribose) Polimerases , Transcrição Gênica , Humanos , Quebras de DNA de Cadeia Dupla , Replicação do DNA/efeitos dos fármacos , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Poli(ADP-Ribose) Polimerases/metabolismo , Reparo de DNA por Recombinação , Fase S , Transcrição Gênica/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Poli(ADP-Ribose) Polimerase-1/metabolismoRESUMO
The Warburg effect is a hallmark of cancer that refers to the preference of cancer cells to metabolize glucose anaerobically rather than aerobically1,2. This results in substantial accumulation of lacate, the end product of anaerobic glycolysis, in cancer cells3. However, how cancer metabolism affects chemotherapy response and DNA repair in general remains incompletely understood. Here we report that lactate-driven lactylation of NBS1 promotes homologous recombination (HR)-mediated DNA repair. Lactylation of NBS1 at lysine 388 (K388) is essential for MRE11-RAD50-NBS1 (MRN) complex formation and the accumulation of HR repair proteins at the sites of DNA double-strand breaks. Furthermore, we identify TIP60 as the NBS1 lysine lactyltransferase and the 'writer' of NBS1 K388 lactylation, and HDAC3 as the NBS1 de-lactylase. High levels of NBS1 K388 lactylation predict poor patient outcome of neoadjuvant chemotherapy, and lactate reduction using either genetic depletion of lactate dehydrogenase A (LDHA) or stiripentol, a lactate dehydrogenase A inhibitor used clinically for anti-epileptic treatment, inhibited NBS1 K388 lactylation, decreased DNA repair efficacy and overcame resistance to chemotherapy. In summary, our work identifies NBS1 lactylation as a critical mechanism for genome stability that contributes to chemotherapy resistance and identifies inhibition of lactate production as a promising therapeutic cancer strategy.
Assuntos
Proteínas de Ciclo Celular , Resistencia a Medicamentos Antineoplásicos , Ácido Láctico , Proteínas Nucleares , Reparo de DNA por Recombinação , Animais , Feminino , Humanos , Masculino , Camundongos , Hidrolases Anidrido Ácido/metabolismo , Anaerobiose , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Quebras de DNA de Cadeia Dupla , Proteínas de Ligação a DNA/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Instabilidade Genômica , Ácido Láctico/metabolismo , Lisina/química , Lisina/metabolismo , Lisina Acetiltransferase 5/metabolismo , Lisina Acetiltransferase 5/genética , Proteína Homóloga a MRE11/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/genética , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Organoides , Glicólise , Terapia Neoadjuvante , L-Lactato Desidrogenase/antagonistas & inibidores , L-Lactato Desidrogenase/deficiência , L-Lactato Desidrogenase/genética , L-Lactato Desidrogenase/metabolismo , Anticonvulsivantes/farmacologiaRESUMO
Currently favored models for meiotic recombination posit that both noncrossover and crossover recombination are initiated by DNA double-strand breaks but form by different mechanisms: noncrossovers by synthesis-dependent strand annealing and crossovers by formation and resolution of double Holliday junctions centered around the break. This dual mechanism hypothesis predicts different hybrid DNA patterns in noncrossover and crossover recombinants. We show that these predictions are not upheld, by mapping with unprecedented resolution parental strand contributions to recombinants at a model locus. Instead, break repair in both noncrossovers and crossovers involves synthesis-dependent strand annealing, often with multiple rounds of strand invasion. Crossover-specific double Holliday junction formation occurs via processes involving branch migration as an integral feature, one that can be separated from repair of the break itself. These findings reveal meiotic recombination to be a highly dynamic process and prompt a new view of the relationship between crossover and noncrossover recombination.
Assuntos
Troca Genética , Quebras de DNA de Cadeia Dupla , DNA Cruciforme/genética , DNA Fúngico/genética , Meiose , Reparo de DNA por Recombinação , Saccharomyces cerevisiae/genética , Troca de Cromátide Irmã , DNA Cruciforme/metabolismo , DNA Fúngico/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Moldes GenéticosRESUMO
Homologous recombination (HR) is an essential DNA double-strand break (DSB) repair mechanism, which is frequently inactivated in cancer. During HR, RAD51 forms nucleoprotein filaments on RPA-coated, resected DNA and catalyzes strand invasion into homologous duplex DNA. How RAD51 displaces RPA and assembles into long HR-proficient filaments remains uncertain. Here, we employed single-molecule imaging to investigate the mechanism of nematode RAD-51 filament growth in the presence of BRC-2 (BRCA2) and RAD-51 paralogs, RFS-1/RIP-1. BRC-2 nucleates RAD-51 on RPA-coated DNA, whereas RFS-1/RIP-1 acts as a "chaperone" to promote 3' to 5' filament growth via highly dynamic engagement with 5' filament ends. Inhibiting ATPase or mutation in the RFS-1 Walker box leads to RFS-1/RIP-1 retention on RAD-51 filaments and hinders growth. The rfs-1 Walker box mutants display sensitivity to DNA damage and accumulate RAD-51 complexes non-functional for HR in vivo. Our work reveals the mechanism of RAD-51 nucleation and filament growth in the presence of recombination mediators.
Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Proteínas de Transporte/genética , DNA de Helmintos/genética , Proteínas de Ligação a DNA/genética , Rad51 Recombinase/genética , Reparo de DNA por Recombinação , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Transporte/metabolismo , Quebras de DNA de Cadeia Dupla , DNA de Helmintos/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Mutação , Ligação Proteica , Rad51 Recombinase/metabolismo , Proteína de Replicação A/genética , Proteína de Replicação A/metabolismo , Transdução de Sinais , Imagem Individual de MoléculaRESUMO
The Shieldin complex shields double-strand DNA breaks (DSBs) from nucleolytic resection. Curiously, the penultimate Shieldin component, SHLD1, is one of the least abundant mammalian proteins. Here, we report that the transcription factors THAP1, YY1, and HCF1 bind directly to the SHLD1 promoter, where they cooperatively maintain the low basal expression of SHLD1, thereby ensuring a proper balance between end protection and resection during DSB repair. The loss of THAP1-dependent SHLD1 expression confers cross-resistance to poly (ADP-ribose) polymerase (PARP) inhibitor and cisplatin in BRCA1-deficient cells and shorter progression-free survival in ovarian cancer patients. Moreover, the embryonic lethality and PARPi sensitivity of BRCA1-deficient mice is rescued by ablation of SHLD1. Our study uncovers a transcriptional network that directly controls DSB repair choice and suggests a potential link between DNA damage and pathogenic THAP1 mutations, found in patients with the neurodevelopmental movement disorder adult-onset torsion dystonia type 6.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Animais , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Proteínas de Ciclo Celular/genética , DNA/metabolismo , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Reparo do DNA por Junção de Extremidades/efeitos dos fármacos , Reparo do DNA/genética , Distonia/genética , Feminino , Fator C1 de Célula Hospedeira/metabolismo , Proteínas Mad2/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Poli(ADP-Ribose) Polimerase-1/metabolismo , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Reparo de DNA por Recombinação/efeitos dos fármacos , Proteínas de Ligação a Telômeros/metabolismo , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismo , Fator de Transcrição YY1/metabolismoRESUMO
BRCA1/2 mutant tumor cells display an elevated mutation burden, the etiology of which remains unclear. Here, we report that these cells accumulate ssDNA gaps and spontaneous mutations during unperturbed DNA replication due to repriming by the DNA primase-polymerase PRIMPOL. Gap accumulation requires the DNA glycosylase SMUG1 and is exacerbated by depletion of the translesion synthesis (TLS) factor RAD18 or inhibition of the error-prone TLS polymerase complex REV1-Polζ by the small molecule JH-RE-06. JH-RE-06 treatment of BRCA1/2-deficient cells results in reduced mutation rates and PRIMPOL- and SMUG1-dependent loss of viability. Through cellular and animal studies, we demonstrate that JH-RE-06 is preferentially toxic toward HR-deficient cancer cells. Furthermore, JH-RE-06 remains effective toward PARP inhibitor (PARPi)-resistant BRCA1 mutant cells and displays additive toxicity with crosslinking agents or PARPi. Collectively, these studies identify a protective and mutagenic role for REV1-Polζ in BRCA1/2 mutant cells and provide the rationale for using REV1-Polζ inhibitors to treat BRCA1/2 mutant tumors.