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1.
Nat Commun ; 15(1): 2862, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38580648

RESUMO

The DNA damage response (DDR) protein DNA Polymerase θ (Polθ) is synthetic lethal with homologous recombination (HR) factors and is therefore a promising drug target in BRCA1/2 mutant cancers. We discover an allosteric Polθ inhibitor (Polθi) class with 4-6 nM IC50 that selectively kills HR-deficient cells and acts synergistically with PARP inhibitors (PARPi) in multiple genetic backgrounds. X-ray crystallography and biochemistry reveal that Polθi selectively inhibits Polθ polymerase (Polθ-pol) in the closed conformation on B-form DNA/DNA via an induced fit mechanism. In contrast, Polθi fails to inhibit Polθ-pol catalytic activity on A-form DNA/RNA in which the enzyme binds in the open configuration. Remarkably, Polθi binding to the Polθ-pol:DNA/DNA closed complex traps the polymerase on DNA for more than forty minutes which elucidates the inhibitory mechanism of action. These data reveal a unique small-molecule DNA polymerase:DNA trapping mechanism that induces synthetic lethality in HR-deficient cells and potentiates the activity of PARPi.


Assuntos
Proteína BRCA1 , Inibidores de Poli(ADP-Ribose) Polimerases , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Proteína BRCA1/genética , Proteína BRCA2/genética , DNA/metabolismo , DNA Polimerase Dirigida por DNA/metabolismo , Reparo do DNA , Recombinação Homóloga
2.
J Extracell Vesicles ; 13(4): e12428, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38581089

RESUMO

It is well known that DNA damage can cause apoptosis. However, whether apoptosis and its metabolites contribute to DNA repair is largely unknown. In this study, we found that apoptosis-deficient Fasmut and Bim- /- mice show significantly elevated DNA damage and premature cellular senescence, along with a significantly reduced number of 16,000 g apoptotic vesicles (apoVs). Intravenous infusion of mesenchymal stromal cell (MSC)-derived 16,000 g apoVs rescued the DNA damage and premature senescence in Fasmut and Bim-/- mice. Moreover, a sublethal dose of radiation exposure caused more severe DNA damage, reduced survival rate, and loss of body weight in Fasmut mice than in wild-type mice, which can be recovered by the infusion of MSC-apoVs. Mechanistically, we showed that apoptosis can assemble multiple nuclear DNA repair enzymes, such as the full-length PARP1, into 16,000 g apoVs. These DNA repair components are directly transferred by 16,000 g apoVs to recipient cells, leading to the rescue of DNA damage and elimination of senescent cells. Finally, we showed that embryonic stem cell-derived 16,000 g apoVs have superior DNA repair capacity due to containing a high level of nuclear DNA repair enzymes to rescue lethal dose-irradiated mice. This study uncovers a previously unknown role of 16,000 g apoVs in safeguarding tissues from DNA damage and demonstrates a strategy for using stem cell-derived apoVs to ameliorate irradiation-induced DNA damage.


Assuntos
Vesículas Extracelulares , Animais , Camundongos , Senescência Celular , Dano ao DNA , Reparo do DNA , Enzimas Reparadoras do DNA
3.
Nat Commun ; 15(1): 2857, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38565848

RESUMO

PARP2 is a DNA-dependent ADP-ribosyl transferase (ARTs) enzyme with Poly(ADP-ribosyl)ation activity that is triggered by DNA breaks. It plays a role in the Base Excision Repair pathway, where it has overlapping functions with PARP1. However, additional roles for PARP2 have emerged in the response of cells to replication stress. In this study, we demonstrate that PARP2 promotes replication stress-induced telomere fragility and prevents telomere loss following chronic induction of oxidative DNA lesions and BLM helicase depletion. Telomere fragility results from the activity of the break-induced replication pathway (BIR). During this process, PARP2 promotes DNA end resection, strand invasion and BIR-dependent mitotic DNA synthesis by orchestrating POLD3 recruitment and activity. Our study has identified a role for PARP2 in the response to replication stress. This finding may lead to the development of therapeutic approaches that target DNA-dependent ART enzymes, particularly in cancer cells with high levels of replication stress.


Assuntos
Reparo do DNA , DNA , Poli(ADP-Ribose) Polimerase-1/genética , Poli(ADP-Ribose) Polimerase-1/metabolismo , DNA/metabolismo , Dano ao DNA , DNA Helicases/genética , DNA Helicases/metabolismo , Telômero/genética , Telômero/metabolismo
4.
Int J Hyperthermia ; 41(1): 2335201, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38583875

RESUMO

PURPOSE: Radiotherapy (RT) is the primary treatment for prostate cancer (PCa); however, the emergence of castration-resistant prostate cancer (CRPC) often leads to treatment failure and cancer-related deaths. In this study, we aimed to explore the use of microwave hyperthermia (MW-HT) to sensitize PCa to RT and investigate the underlying molecular mechanisms. METHODS: We developed a dedicated MW-HT heating setup, created an in vitro and in vivo MW-HT + RT treatment model for CRPC. We evaluated PC3 cell proliferation using CCK-8, colony experiments, DAPI staining, comet assay and ROS detection method. We also monitored nude mouse models of PCa during treatment, measured tumor weight, and calculated the tumor inhibition rate. Western blotting was used to detect DNA damage repair protein expression in PC3 cells and transplanted tumors. RESULTS: Compared to control, PC3 cell survival and clone formation rates decreased in RT + MW-HT group, demonstrating significant increase in apoptosis, ROS levels, and DNA damage. Lower tumor volumes and weights were observed in treatment groups. Ki-67 expression level was reduced in all treatment groups, with significant decrease in RT + MW-HT groups. The most significant apoptosis induction was confirmed in RT + MW-HT group by TUNEL staining. Protein expression levels of DNA-PKcs, ATM, ATR, and P53/P21 signaling pathways significantly decreased in RT + MW-HT groups. CONCLUSION: MW-HT + RT treatment significantly inhibited DNA damage repair by downregulating DNA-PKcs, ATM, ATR, and P53/P21 signaling pathways, leading to increased ROS levels, aggravate DNA damage, apoptosis, and necrosis in PC3 cells, a well-established model of CRPC.


Assuntos
Adenocarcinoma , Hipertermia Induzida , Neoplasias de Próstata Resistentes à Castração , Neoplasias da Próstata , Humanos , Masculino , Animais , Camundongos , Neoplasias de Próstata Resistentes à Castração/radioterapia , Neoplasias de Próstata Resistentes à Castração/metabolismo , Células PC-3 , Espécies Reativas de Oxigênio/metabolismo , Micro-Ondas , Proteína Supressora de Tumor p53/metabolismo , Hipertermia Induzida/métodos , Neoplasias da Próstata/radioterapia , Neoplasias da Próstata/metabolismo , Reparo do DNA , Apoptose , Estresse Oxidativo , Hipertermia , Adenocarcinoma/radioterapia , DNA/metabolismo , Linhagem Celular Tumoral , Proliferação de Células
5.
Nat Commun ; 15(1): 2890, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38570537

RESUMO

DNA double-strand breaks (DSBs) can be repaired by several pathways. In eukaryotes, DSB repair pathway choice occurs at the level of DNA end resection and is controlled by the cell cycle. Upon cell cycle-dependent activation, cyclin-dependent kinases (CDKs) phosphorylate resection proteins and thereby stimulate end resection and repair by homologous recombination (HR). However, inability of CDK phospho-mimetic mutants to bypass this cell cycle regulation, suggests that additional cell cycle regulators may be important. Here, we identify Dbf4-dependent kinase (DDK) as a second major cell cycle regulator of DNA end resection. Using inducible genetic and chemical inhibition of DDK in budding yeast and human cells, we show that end resection and HR require activation by DDK. Mechanistically, DDK phosphorylates at least two resection nucleases in budding yeast: the Mre11 activator Sae2, which promotes resection initiation, as well as the Dna2 nuclease, which promotes resection elongation. Notably, synthetic activation of DDK allows limited resection and HR in G1 cells, suggesting that DDK is a key component of DSB repair pathway selection.


Assuntos
Quebras de DNA de Cadeia Dupla , Proteínas de Saccharomyces cerevisiae , Humanos , Ciclo Celular , Recombinação Homóloga , Divisão Celular , Endonucleases/metabolismo , Quinases Ciclina-Dependentes/genética , Quinases Ciclina-Dependentes/metabolismo , DNA , Reparo do DNA , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
6.
BMC Cancer ; 24(1): 415, 2024 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-38575974

RESUMO

BACKGROUND: Genome stability is maintained by the DNA damage repair (DDR) system composed of multiple DNA repair pathways of hundreds of genes. Germline pathogenic variation (PV) in DDR genes damages function of the affected DDR genes, leading to genome instability and high risk of diseases, in particular, cancer. Knowing evolutionary origin of the PVs in human DDR genes is essential to understand the etiology of human diseases. However, answer to the issue remains largely elusive. In this study, we analyzed evolutionary origin for the PVs in human DDR genes. METHODS: We identified 169 DDR genes by referring to various databases and identified PVs in the DDR genes of modern humans from ClinVar database. We performed a phylogenetic analysis to analyze the conservation of human DDR PVs in 100 vertebrates through cross-species genomic data comparison using the phyloFit program of the PHAST package and visualized the results using the GraphPad Prism software and the ggplot module. We identified DDR PVs from over 5000 ancient humans developed a database to host the DDR PVs ( https://genemutation.fhs.um.edu.mo/dbDDR-AncientHumans ). Using the PV data, we performed a molecular archeological analysis to compare the DDR PVs between modern humans and ancient humans. We analyzed evolution selection of DDR genes across 20 vertebrates using the CodeML in PAML for phylogenetic analysis. RESULTS: Our phylogenic analysis ruled out cross-species conservation as the origin of human DDR PVs. Our archeological approach identified rich DDR PVs shared between modern and ancient humans, which were mostly dated within the last 5000 years. We also observed similar pattern of quantitative PV distribution between modern and ancient humans. We further detected a set of ATM, BRCA2 and CHEK2 PVs shared between human and Neanderthals. CONCLUSIONS: Our study reveals that human DDR PVs mostly arose in recent human history. We propose that human high cancer risk caused by DDR PVs can be a by-product of human evolution.


Assuntos
Reparo do DNA , Neoplasias , Humanos , Filogenia , Reparo do DNA/genética , Genes BRCA2 , Neoplasias/genética , Instabilidade Genômica , Dano ao DNA/genética , Predisposição Genética para Doença
7.
Cell Mol Life Sci ; 81(1): 173, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38597967

RESUMO

Heterozygous mutations in any of three major genes, BRCA1, BRCA2 and PALB2, are associated with high-risk hereditary breast cancer susceptibility frequently seen as familial disease clustering. PALB2 is a key interaction partner and regulator of several vital cellular activities of BRCA1 and BRCA2, and is thus required for DNA damage repair and alleviation of replicative and oxidative stress. Little is however known about how PALB2-deficiency affects cell function beyond that, especially in the three-dimensional setting, and also about its role during early steps of malignancy development. To answer these questions, we have generated biologically relevant MCF10A mammary epithelial cell lines with mutations that are comparable to certain clinically important PALB2 defects. We show in a non-cancerous background how both mono- and biallelically PALB2-mutated cells exhibit gross spontaneous DNA damage and mitotic aberrations. Furthermore, PALB2-deficiency disturbs three-dimensional spheroid morphology, increases the migrational capacity and invasiveness of the cells, and broadly alters their transcriptome profiles. TGFß signaling and KRT14 expression are enhanced in PALB2-mutated cells and their inhibition and knock down, respectively, lead to partial restoration of cell functions. KRT14-positive cells are also more abundant with DNA damage than KRT14-negative cells. The obtained results indicate comprehensive cellular changes upon PALB2 mutations, even in the presence of half dosage of wild type PALB2 and demonstrate how PALB2 mutations may predispose their carriers to malignancy.


Assuntos
Neoplasias , Transdução de Sinais , Humanos , Reparo do DNA , Células Epiteliais , Mama , Proteína do Grupo de Complementação N da Anemia de Fanconi/genética
8.
Sci Rep ; 14(1): 6702, 2024 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-38509102

RESUMO

DNA damage response (DDR) pathways are responsible for repairing endogenous or exogenous DNA damage to maintain the stability of the cellular genome, including homologous recombination repair (HRR) pathway, mismatch repair (MMR) pathway, etc. In ovarian cancer, current studies are focused on HRR genes, especially BRCA1/2, and the results show regional and population differences. To characterize germline mutations in DDR genes in ovarian cancer in Southwest China, 432 unselected ovarian cancer patients underwent multi-gene panel testing from October 2016 to October 2020. Overall, deleterious germline mutations in DDR genes were detected in 346 patients (80.1%), and in BRCA1/2 were detected in 126 patients (29.2%). The prevalence of deleterious germline mutations in BRCA2 is higher than in other studies (patients are mainly from Eastern China), and so is the mismatch repair genes. We identified three novel BRCA1/2 mutations, two of which probably deleterious (BRCA1 p.K1622* and BRCA2 p.L2987P). Furthermore, we pointed out that deleterious mutations of FNACD2 and RECQL4 are potential ovarian cancer susceptibility genes and may predispose carriers to ovarian cancer. In conclusion, our study highlights the necessity of comprehensive germline mutation detection of DNA damage response genes in ovarian cancer patients, which is conducive to patient management and genetic counseling.


Assuntos
Proteína BRCA1 , Neoplasias Ovarianas , Humanos , Feminino , Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias Ovarianas/epidemiologia , Neoplasias Ovarianas/genética , Mutação em Linhagem Germinativa , Reparo do DNA/genética , Células Germinativas , Predisposição Genética para Doença
9.
Nature ; 628(8006): 145-153, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38538785

RESUMO

As hippocampal neurons respond to diverse types of information1, a subset assembles into microcircuits representing a memory2. Those neurons typically undergo energy-intensive molecular adaptations, occasionally resulting in transient DNA damage3-5. Here we found discrete clusters of excitatory hippocampal CA1 neurons with persistent double-stranded DNA (dsDNA) breaks, nuclear envelope ruptures and perinuclear release of histone and dsDNA fragments hours after learning. Following these early events, some neurons acquired an inflammatory phenotype involving activation of TLR9 signalling and accumulation of centrosomal DNA damage repair complexes6. Neuron-specific knockdown of Tlr9 impaired memory while blunting contextual fear conditioning-induced changes of gene expression in specific clusters of excitatory CA1 neurons. Notably, TLR9 had an essential role in centrosome function, including DNA damage repair, ciliogenesis and build-up of perineuronal nets. We demonstrate a novel cascade of learning-induced molecular events in discrete neuronal clusters undergoing dsDNA damage and TLR9-mediated repair, resulting in their recruitment to memory circuits. With compromised TLR9 function, this fundamental memory mechanism becomes a gateway to genomic instability and cognitive impairments implicated in accelerated senescence, psychiatric disorders and neurodegenerative disorders. Maintaining the integrity of TLR9 inflammatory signalling thus emerges as a promising preventive strategy for neurocognitive deficits.


Assuntos
Região CA1 Hipocampal , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Inflamação , Memória , Receptor Toll-Like 9 , Animais , Feminino , Masculino , Camundongos , Envelhecimento/genética , Envelhecimento/patologia , Região CA1 Hipocampal/fisiologia , Centrossomo/metabolismo , Disfunção Cognitiva/genética , Condicionamento Clássico , Matriz Extracelular/metabolismo , Medo , Instabilidade Genômica/genética , Histonas/metabolismo , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Memória/fisiologia , Transtornos Mentais/genética , Doenças Neurodegenerativas/genética , Doenças Neuroinflamatórias/genética , Neurônios/metabolismo , Neurônios/patologia , Membrana Nuclear/patologia , Receptor Toll-Like 9/deficiência , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/imunologia , Receptor Toll-Like 9/metabolismo
10.
Cell Signal ; 118: 111151, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38522807

RESUMO

Chemoresistance poses a significant obstacle to the treatment of breast cancer patients. The increased capacity of DNA damage repair is one of the mechanisms underlying chemoresistance. Bioinformatic analyses showed that E2F8 was associated with cell cycle progression and homologous recombination (HR) repair of DNA double-strand breaks (DSBs) in breast cancer. E2F8 knockdown suppressed cell growth and attenuated HR repair. Accordingly, E2F8 knockdown sensitized cancer cells to Adriamycin and Cisplatin. Centromere protein L (CENPL) is a transcriptional target by E2F8. CENPL overexpression in E2F8-knockdowned cells recovered at least in part the effect of E2F8 on DNA damage repair and chemotherapy sensitivity. Consistently, CENPL knockdown impaired DNA damage repair and sensitized cancer cells to DNA-damaging drugs. These findings demonstrate that targeting E2F8-CENPL pathway is a potential approach to overcoming chemoresistance.


Assuntos
Neoplasias da Mama , Reparo de DNA por Recombinação , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Resistencia a Medicamentos Antineoplásicos/genética , Reparo do DNA , DNA , Proteínas Repressoras/genética , Proteínas Cromossômicas não Histona , Proteínas de Ciclo Celular/genética
11.
Acc Chem Res ; 57(7): 1019-1031, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38471078

RESUMO

ConspectusBase excision repair (BER) enzymes are genomic superheroes that stealthily and accurately identify and remove chemically modified DNA bases. DNA base modifications erode the informational content of DNA and underlie many disease phenotypes, most conspicuously, cancer. The "OG" of oxidative base damage, 8-oxo-7,8-dihydroguanine (OG), is particularly insidious due to its miscoding ability that leads to the formation of rare, pro-mutagenic OG:A mismatches. Thwarting mutagenesis relies on the capture of OG:A mismatches prior to DNA replication and removal of the mis-inserted adenine by MutY glycosylases to initiate BER. The threat of OG and the importance of its repair are underscored by the association between inherited dysfunctional variants of the MutY human homologue (MUTYH) and colorectal cancer, known as MUTYH-associated polyposis (MAP). Our functional studies of the two founder MUTYH variants revealed that both have compromised activity and a reduced affinity for OG:A mismatches. Indeed, these studies underscored the challenge of the recognition of OG:A mismatches that are only subtly structurally different than T:A base pairs. Since the original discovery of MAP, many MUTYH variants have been reported, with most considered to be "variants of uncertain significance." To reveal features associated with damage recognition and adenine excision by MutY and MUTYH, we have developed a multipronged chemical biology approach combining enzyme kinetics, X-ray crystallography, single-molecule visualization, and cellular repair assays. In this review, we highlight recent work in our laboratory where we defined MutY structure-activity relationship (SAR) studies using synthetic analogs of OG and A in cellular and in vitro assays. Our studies revealed the 2-amino group of OG as the key distinguishing feature of OG:A mismatches. Indeed, the unique position of the 2-amino group in the major groove of OGsyn:Aanti mismatches provides a means for its rapid detection among a large excess of highly abundant and structurally similar canonical base pairs. Furthermore, site-directed mutagenesis and structural analysis showed that a conserved C-terminal domain ß-hairpin "FSH'' loop is critical for OG recognition with the "His" serving as the lesion detector. Notably, MUTYH variants located within and near the FSH loop have been associated with different forms of cancer. Uncovering the role(s) of this loop in lesion recognition provided a detailed understanding of the search and repair process of MutY. Such insights are also useful to identify mutational hotspots and pathogenic variants, which may improve the ability of physicians to diagnose the likelihood of disease onset and prognosis. The critical importance of the "FSH" loop in lesion detection suggests that it may serve as a unique locus for targeting probes or inhibitors of MutY/MUTYH to provide new chemical biology tools and avenues for therapeutic development.


Assuntos
Neoplasias Colorretais , Reparo do DNA , Guanina/análogos & derivados , Humanos , Adenina/química , Escherichia coli/química , Dano ao DNA , DNA/genética , DNA/química , Hormônio Foliculoestimulante/genética
12.
Nature ; 628(8006): 212-220, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38509361

RESUMO

RAD51 is the central eukaryotic recombinase required for meiotic recombination and mitotic repair of double-strand DNA breaks (DSBs)1,2. However, the mechanism by which RAD51 functions at DSB sites in chromatin has remained elusive. Here we report the cryo-electron microscopy structures of human RAD51-nucleosome complexes, in which RAD51 forms ring and filament conformations. In the ring forms, the N-terminal lobe domains (NLDs) of RAD51 protomers are aligned on the outside of the RAD51 ring, and directly bind to the nucleosomal DNA. The nucleosomal linker DNA that contains the DSB site is recognized by the L1 and L2 loops-active centres that face the central hole of the RAD51 ring. In the filament form, the nucleosomal DNA is peeled by the RAD51 filament extension, and the NLDs of RAD51 protomers proximal to the nucleosome bind to the remaining nucleosomal DNA and histones. Mutations that affect nucleosome-binding residues of the RAD51 NLD decrease nucleosome binding, but barely affect DNA binding in vitro. Consistently, yeast Rad51 mutants with the corresponding mutations are substantially defective in DNA repair in vivo. These results reveal an unexpected function of the RAD51 NLD, and explain the mechanism by which RAD51 associates with nucleosomes, recognizes DSBs and forms the active filament in chromatin.


Assuntos
Microscopia Crioeletrônica , Quebras de DNA de Cadeia Dupla , Nucleossomos , Rad51 Recombinase , Proteínas de Saccharomyces cerevisiae , Humanos , DNA/química , DNA/metabolismo , DNA/ultraestrutura , Reparo do DNA/genética , Nucleossomos/química , Nucleossomos/metabolismo , Nucleossomos/ultraestrutura , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Rad51 Recombinase/química , Rad51 Recombinase/metabolismo , Rad51 Recombinase/ultraestrutura , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Mutação , Domínios Proteicos , Histonas/química , Histonas/metabolismo , Histonas/ultraestrutura , Ligação Proteica
13.
Chem Biol Interact ; 393: 110938, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38484825

RESUMO

Radiotherapy remains the preferred treatment option for cancer patients with the advantages of broad indications and significant therapeutic effects. However, ionizing radiation can also damage normal tissues. Unfortunately, there are few anti-radiation damage drugs available on the market for radiotherapy patients. Our previous study showed that rosamultin had antioxidant and hepatoprotective activities. However, its anti-radiation activity has not been evaluated. Irradiating small intestinal epithelial cells and mice with whole-body X-rays radiation were used to evaluate the in vitro and in vivo effects of rosamultin, respectively. Intragastric administration of rosamultin improved survival, limited leukocyte depletion, and reduced damage to the spleen and small intestine in irradiated mice. Rosamultin reversed the downregulation of the apoptotic protein BCL-2 and the upregulation of BAX in irradiated mouse small intestine tissue and in irradiation-induced small intestinal epithelial cells. DNA-PKcs antagonists reversed the promoting DNA repair effects of rosamulin. Detailed mechanistic studies revealed that rosamultin promoted Translin-associated protein X (TRAX) into the nucleus. Knockdown of TRAX reduced the protective effect of rosamultin against DNA damage. In addition, rosamultin reduced irradiation-induced oxidative stress through promoting Nrf2/HO-1 signaling pathway. To sum up, in vitro and in vivo experiments using genetic knockdown and pharmacological activation demonstrated that rosamultin exerts radioprotection via the TRAX/NHEJ and Nrf2/HO pathways.


Assuntos
Fator 2 Relacionado a NF-E2 , Lesões por Radiação , Triterpenos , Humanos , Camundongos , Animais , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Reparo do DNA , Dano ao DNA , Lesões por Radiação/tratamento farmacológico , Lesões por Radiação/prevenção & controle , DNA/metabolismo , Apoptose
14.
DNA Repair (Amst) ; 137: 103666, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38492429

RESUMO

Mitochondrial DNA (mtDNA) plays a key role in mitochondrial and cellular functions. mtDNA is maintained by active DNA turnover and base excision repair (BER). In BER, one of the toxic repair intermediates is 5'-deoxyribose phosphate (5'dRp). Human mitochondrial DNA polymerase γ has weak dRp lyase activities, and another known dRp lyase in the nucleus, human DNA polymerase ß, can also localize to mitochondria in certain cell and tissue types. Nonetheless, whether additional proteins have the ability to remove 5'dRp in mitochondria remains unknown. Our prior work on the AP lyase activity of mitochondrial transcription factor A (TFAM) has prompted us to examine its ability to remove 5'dRp residues in vitro. TFAM is the primary DNA-packaging factor in human mitochondria and interacts with mitochondrial DNA extensively. Our data demonstrate that TFAM has the dRp lyase activity with different DNA substrates. Under single-turnover conditions, TFAM removes 5'dRp residues at a rate comparable to that of DNA polymerase (pol) ß, albeit slower than that of pol λ. Among the three proteins examined, pol λ shows the highest single-turnover rates in dRp lyase reactions. The catalytic effect of TFAM is facilitated by lysine residues of TFAM via Schiff base chemistry, as evidenced by the observation of dRp-lysine adducts in mass spectrometry experiments. The catalytic effect of TFAM observed here is analogous to the AP lyase activity of TFAM reported previously. Together, these results suggest a potential role of TFAM in preventing the accumulation of toxic DNA repair intermediates.


Assuntos
DNA Polimerase beta , Liases , Fósforo-Oxigênio Liases , Humanos , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Liases/metabolismo , Lisina , DNA Polimerase beta/metabolismo , Reparo do DNA , DNA Polimerase gama/metabolismo , DNA Mitocondrial/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição , Proteínas Mitocondriais/metabolismo
15.
Artigo em Inglês | MEDLINE | ID: mdl-38432774

RESUMO

The ultraviolet (UV) component of sunlight can damage DNA. Although most solar UV is absorbed by the ozone layer, wavelengths > 300 nm (UVA and UVB bands) can reach the Earth's surface. It is essential to understand the genotoxic effects of UV light, particularly in natural environments. Caulobacter crescentus, a bacterium widely employed as a model for cell cycle studies, was selected for this study. Strains proficient and deficient in DNA repair (uvrA-) were used to concurrently investigate three genotoxic endpoints: cytotoxicity, SOS induction, and gene mutation, using colony-formation, the SOS chromotest, and RifR mutagenesis, respectively. Our findings underscore the distinct impacts of individual UV bands and the full spectrum of sunlight itself in C. crescentus. UVC light was highly genotoxic, especially for the repair-deficient strain. A UVB dose equivalent to 20 min sunlight exposure also affected the cells. UVA exposure caused a significant response only at high doses, likely due to activation of photorepair. Exposure to solar irradiation resulted in reduced levels of SOS induction, possibly due to decreased cell survival. However, mutagenicity is increased, particularly in uvrA- deficient cells.


Assuntos
Caulobacter crescentus , Raios Ultravioleta , Raios Ultravioleta/efeitos adversos , Caulobacter crescentus/genética , Dano ao DNA , Reparo do DNA , Mutação
16.
J Cancer Res Ther ; 20(1): 126-132, 2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38554309

RESUMO

BACKGROUND: The Ccr4-Not complex (CNOT complex in mammals) is a unique and highly conserved complex with numerous cellular functions. Until now, there has been relatively little known about the importance of the CNOT complex subunits in the DNA damage response (DDR) in mammalian cells. CNOT4 is a subunit of the complex with E3 ubiquitin ligase activity that interacts transiently with the CNOT1 subunit. Here, we attempt to investigate the role of human CNOT4 subunit in the DDR in human cells. MATERIAL AND METHODS: In this study, cell viability in the absence of CNOT4 was assessed using a Cell Titer-Glo Luminescence assay up to 4 days post siRNA transfection. In a further experiment, CNOT4-depleted HeLa cells were exposed to 3Gy ionizing radiation (IR). Ataxia telangiectasia-mutated (ATM) and ATM Rad3-related (ATR) signaling pathways were then investigated by western blotting for phosphorylated substrates. In addition, foci formation of histone 2A family member X (γH2AX), replication protein A (RPA), TP53 binding protein 1 (53BP1), and DNA repair protein RAD51 homolog 1 was also determined by immunofluorescence microscopy comparing control and CNOT4-depleted HeLa cells 0, 8, and 24 h post IR treatment. RESULTS: Our results from cell viability assays showed a significant reduction of cell growth activity at 24 (P value 0.02) and 48 h (P value 0.002) post siRNA. Western blot analysis showed slightly reduced or slightly delayed DDR signaling in CNOT4-depleted HeLa cells after IR. More significantly, we observed increased formation of γH2AX, RPA, 53BP1, and RAD51 foci after IR in CNOT4-depleted cells compared with the control cells. CONCLUSION: We conclude that depletion of CNOT4 affects various aspects of the cellular response to DNA damage.


Assuntos
Proteínas de Ciclo Celular , Radiação Ionizante , Animais , Humanos , Células HeLa , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Dano ao DNA , Reparo do DNA , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Fosforilação , Mamíferos/genética , Mamíferos/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
Anticancer Res ; 44(4): 1353-1364, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38538001

RESUMO

Ataxia-telangiectasia mutated (ATM) is a pivotal protein with versatile kinase activity that responds to DNA damage. While its well-established role as a DNA repair protein is widely recognized, the understanding of its noncanonical functions in ovarian cancer remains limited. Numerous studies have investigated the potential of targeting ATM for ovarian cancer treatment. In addition to its involvement in homologous recombination repair (HRR), an increasing body of research suggests that ATM plays a role in cellular metabolism and adaptive immunity. This review focuses on the current evidence and provides a perspective on how targeting ATM in ovarian cancer can address HRR-deficient genotypes, influence macropinocytosis, and enhance immune checkpoint blockade (ICB) therapy. It underscores the diverse avenues through which targeting ATM is a potential tailored treatment for ovarian cancer.


Assuntos
Proteínas Mutadas de Ataxia Telangiectasia , Neoplasias Ovarianas , Feminino , Humanos , Imunidade Adaptativa , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Proteínas de Ciclo Celular/metabolismo , Dano ao DNA , Reparo do DNA , Proteínas de Ligação a DNA/genética , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Supressoras de Tumor/metabolismo
18.
Nat Commun ; 15(1): 2599, 2024 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-38521768

RESUMO

The effectiveness of poly (ADP-ribose) polymerase inhibitors (PARPi) in creating single-stranded DNA gaps and inducing sensitivity requires the FANCJ DNA helicase. Yet, how FANCJ relates to PARP1 inhibition or trapping, which contribute to PARPi toxicity, remains unclear. Here, we find PARPi effectiveness hinges on S-phase PARP1 activity, which is reduced in FANCJ deficient cells as G-quadruplexes sequester PARP1 and MSH2. Additionally, loss of the FANCJ-MLH1 interaction diminishes PARP1 activity; however, depleting MSH2 reinstates PARPi sensitivity and gaps. Indicating sequestered and trapped PARP1 are distinct, FANCJ loss increases PARPi resistance in cells susceptible to PARP1 trapping. However, with BRCA1 deficiency, the loss of FANCJ mirrors PARP1 loss or inhibition, with the detrimental commonality being loss of S-phase PARP1 activity. These insights underline the crucial role of PARP1 activity during DNA replication in BRCA1 deficient cells and emphasize the importance of understanding drug mechanisms for enhancing therapeutic response.


Assuntos
DNA Helicases , Replicação do DNA , Proteína 2 Homóloga a MutS/genética , Linhagem Celular Tumoral , Poli(ADP-Ribose) Polimerase-1/metabolismo , DNA Helicases/genética , Fase S , Reparo do DNA
19.
Front Immunol ; 15: 1324531, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38464523

RESUMO

Parvoviruses are a group of non-enveloped DNA viruses that have a broad spectrum of natural infections, making them important in public health. NS1 is the largest and most complex non-structural protein in the parvovirus genome, which is indispensable in the life cycle of parvovirus and is closely related to viral replication, induction of host cell apoptosis, cycle arrest, DNA damage response (DDR), and other processes. Parvovirus activates and utilizes the DDR pathway to promote viral replication through NS1, thereby increasing pathogenicity to the host cells. Here, we review the latest progress of parvovirus in regulating host cell DDR during the parvovirus lifecycle and discuss the potential of cellular consequences of regulating the DDR pathway, targeting to provide the theoretical basis for further elucidation of the pathogenesis of parvovirus and development of new antiviral drugs.


Assuntos
Infecções por Parvoviridae , Parvovirus B19 Humano , Parvovirus , Humanos , Parvovirus/genética , Replicação Viral , Parvovirus B19 Humano/genética , Reparo do DNA
20.
Bioorg Med Chem ; 103: 117662, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38493730

RESUMO

Inhibition of the low fidelity DNA polymerase Theta (Polθ) is emerging as an attractive, synthetic-lethal antitumor strategy in BRCA-deficient tumors. Here we report the AI-enabled development of 3-hydroxymethyl-azetidine derivatives as a novel class of Polθ inhibitors featuring central scaffolding rings. Structure-based drug design first identified A7 as a lead compound, which was further optimized to the more potent derivative B3 and the metabolically stable deuterated compound C1. C1 exhibited significant antiproliferative properties in DNA repair-compromised cells and demonstrated favorable pharmacokinetics, showcasing that 3-hydroxymethyl-azetidine is an effective bio-isostere of pyrrolidin-3-ol and emphasizing the potential of AI in medicinal chemistry for precise molecular modifications.


Assuntos
Azetidinas , Neoplasias , Humanos , Reparo do DNA , Azetidinas/química
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