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Molecular Cell Jun 2022Faithful DNA replication is critical for the maintenance of genomic integrity. Although DNA replication machinery is highly accurate, the process of DNA replication is... (Review)
Review
Faithful DNA replication is critical for the maintenance of genomic integrity. Although DNA replication machinery is highly accurate, the process of DNA replication is constantly challenged by DNA damage and other intrinsic and extrinsic stresses throughout the genome. A variety of cellular stresses interfering with DNA replication, which are collectively termed replication stress, pose a threat to genomic stability in both normal and cancer cells. To cope with replication stress and maintain genomic stability, cells have evolved a complex network of cellular responses to alleviate and tolerate replication problems. This review will focus on the major sources of replication stress, the impacts of replication stress in cells, and the assays to detect replication stress, offering an overview of the hallmarks of DNA replication stress.
Topics: Ataxia Telangiectasia Mutated Proteins; DNA Damage; DNA Repair; DNA Replication; Genomic Instability; Humans
PubMed: 35714587
DOI: 10.1016/j.molcel.2022.05.004 -
Autophagy Aug 2021ATM (ataxia telangiectasia mutated) protein is found associated with multiple organelles including synaptic vesicles, endosomes and lysosomes, often in cooperation with...
ATM (ataxia telangiectasia mutated) protein is found associated with multiple organelles including synaptic vesicles, endosomes and lysosomes, often in cooperation with ATR (ataxia telangiectasia and Rad3 related). Mutation of the gene results in ataxia-telangiectasia (A-T), an autosomal recessive disorder with defects in multiple organs including the nervous system. Precisely how ATM deficiency leads to the complex phenotypes of A-T, however, remains elusive. Here, we reported that part of the connection may lie in autophagy and lysosomal abnormalities. We found that ATM was degraded through the autophagy pathway, while ATR was processed by the proteasome. Autophagy and lysosomal trafficking were both abnormal in neurons and the deficits impacted cellular functions such as synapse maintenance, neuronal survival and glucose uptake. Upregulated autophagic flux was observed in lysosomes, associated with a more acidic pH. Significantly, we found that the ATP6V1A (ATPase, H+ transporting, lysosomal V1 subunit A) proton pump was an ATM kinase target. In neurons, lysosomes showed enhanced retrograde transport and accumulated in the perinuclear regions. We attributed this change to an unexpected physical interaction between ATM and the retrograde transport motor protein, dynein. As a consequence, SLC2A4/GLUT4 (solute carrier family 4 [facilitated glucose transporter], member 4) translocation to the plasma membrane was inhibited and trafficking to the lysosomes was increased, leading to impaired glucose uptake capacity. Together, these data underscored the involvement of ATM in a variety of neuronal vesicular trafficking processes, offering new and therapeutically useful insights into the pathogenesis of A-T. 3-MA: 3-methyladenine; A-T: ataxia-telangiectasia; ALG2: asparagine-linked glycosylation 2 (alpha-1,3-mannosyltransferase); AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; ATG5: autophagy related 5; ATM: ataxia telangiectasia mutated; ATP6V1A: ATPase, H+ transporting, lysosomal V1 subunit A; ATR: ataxia-telangiectasia and Rad3 related; BFA1: bafilomycin A; CC3: cleaved-CASP3; CGN: cerebellar granule neuron; CLQ: chloroquine; CN: neocortical neuron; CTSB: cathepsin B; CTSD: cathepsin D; DYNLL1: the light chain1 of dynein; EIF4EBP1/4E-BP1: eukaryotic translation initiation factor 4E binding protein 1; Etop: etoposide; FBS: fetal bovine serum; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HBS: HEPES-buffered saline; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; HOMER1: homer protein homolog 1; KU: KU-60019; LAMP1: lysosomal-associated membrane protein 1; LC3B-II: LC3-phosphatidylethanolamine conjugate; Lyso: lysosome; LysopH-GFP: lysopHluorin-GFP; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MAP2: microtubule associated protein 2; MAPK14: mitogen-activated protein kinase 14; MAPK8/JNK1: mitogen-activated protein kinase 8; MCOLN1/TRPML1: mucolipin 1; OSBPL1A: oxysterol binding protein like 1A; PIKK: phosphatidylinositol 3 kinase related kinase; Rapa: rapamycin; RILP: rab interacting lysosomal protein; ROS: reactive oxygen species; SEM: standard error of mean; SLC2A4/GLUT4: solute carrier family 2 (facilitated glucose transporter), member 4; TSC2/tuberin: TSC complex subunit 2; ULK1: unc-51 like kinase 1; UPS: ubiquitin-proteasome system; VE: VE-822; WCL: whole-cell lysate; WT: wild type.
Topics: Adaptor Proteins, Signal Transducing; Animals; Ataxia Telangiectasia Mutated Proteins; Autophagosomes; Autophagy; Humans; Lysosomes; Mice; Phagocytosis; Ubiquitin
PubMed: 32757690
DOI: 10.1080/15548627.2020.1805860 -
The Journal of Clinical Investigation Feb 2021Novel approaches are needed to boost the efficacy of immune checkpoint blockade (ICB) therapy. Ataxia telangiectasia mutated (ATM) protein plays a central role in...
Novel approaches are needed to boost the efficacy of immune checkpoint blockade (ICB) therapy. Ataxia telangiectasia mutated (ATM) protein plays a central role in sensing DNA double-stranded breaks (DSBs) and coordinating their repair. Recent data indicated that ATM might be a promising target to enhance ICB therapy. However, the molecular mechanism involved has not been clearly elucidated. Here, we show that ATM inhibition could potentiate ICB therapy by promoting cytoplasmic leakage of mitochondrial DNA (mtDNA) and activation of the cGAS/STING pathway. We show that genetic depletion of ATM in murine cancer cells delayed tumor growth in syngeneic mouse hosts in a T cell-dependent manner. Furthermore, chemical inhibition of ATM potentiated anti-PD-1 therapy of mouse tumors. ATM inhibition potently activated the cGAS/STING pathway and enhanced lymphocyte infiltration into the tumor microenvironment by downregulating mitochondrial transcription factor A (TFAM), which led to mtDNA leakage into the cytoplasm. Moreover, our analysis of data from a large patient cohort indicated that ATM mutations, especially nonsense mutations, predicted for clinical benefits of ICB therapy. Our study therefore provides strong evidence that ATM may serve as both a therapeutic target and a biomarker to enable ICB therapy.
Topics: Animals; Ataxia Telangiectasia Mutated Proteins; Cell Line, Tumor; Codon, Nonsense; DNA, Mitochondrial; Humans; Immune Checkpoint Inhibitors; Immunotherapy; Membrane Proteins; Mice; Neoplasm Proteins; Neoplasms, Experimental; Nucleotidyltransferases; Signal Transduction
PubMed: 33290271
DOI: 10.1172/JCI139333 -
Pediatrics and Neonatology Sep 2022
Topics: Ataxia Telangiectasia; Humans
PubMed: 35431147
DOI: 10.1016/j.pedneo.2022.01.004 -
Human Reproduction Update Jan 2020Oocyte aging has significant clinical consequences, and yet no treatment exists to address the age-related decline in oocyte quality. The lack of progress in the... (Review)
Review
BACKGROUND
Oocyte aging has significant clinical consequences, and yet no treatment exists to address the age-related decline in oocyte quality. The lack of progress in the treatment of oocyte aging is due to the fact that the underlying molecular mechanisms are not sufficiently understood. BRCA1 and 2 are involved in homologous DNA recombination and play essential roles in ataxia telangiectasia mutated (ATM)-mediated DNA double-strand break (DSB) repair. A growing body of laboratory, translational and clinical evidence has emerged within the past decade indicating a role for BRCA function and ATM-mediated DNA DSB repair in ovarian aging.
OBJECTIVE AND RATIONALE
Although there are several competing or complementary theories, given the growing evidence tying BRCA function and ATM-mediated DNA DSB repair mechanisms in general to ovarian aging, we performed this review encompassing basic, translational and clinical work to assess the current state of knowledge on the topic. A clear understanding of the mechanisms underlying oocyte aging may result in targeted treatments to preserve ovarian reserve and improve oocyte quality.
SEARCH METHODS
We searched for published articles in the PubMed database containing key words, BRCA, BRCA1, BRCA2, Mutations, Fertility, Ovarian Reserve, Infertility, Mechanisms of Ovarian Aging, Oocyte or Oocyte DNA Repair, in the English-language literature until May 2019. We did not include abstracts or conference proceedings, with the exception of our own.
OUTCOMES
Laboratory studies provided robust and reproducible evidence that BRCA1 function and ATM-mediated DNA DSB repair, in general, weakens with age in oocytes of multiple species including human. In both women with BRCA mutations and BRCA-mutant mice, primordial follicle numbers are reduced and there is accelerated accumulation of DNA DSBs in oocytes. In general, women with BRCA1 mutations have lower ovarian reserves and experience earlier menopause. Laboratory evidence also supports critical role for BRCA1 and other ATM-mediated DNA DSB repair pathway members in meiotic function. When laboratory, translational and clinical evidence is considered together, BRCA-related ATM-mediated DNA DSB repair function emerges as a likely regulator of ovarian aging. Moreover, DNA damage and repair appear to be key features in chemotherapy-induced ovarian aging.
WIDER IMPLICATIONS
The existing data suggest that the BRCA-related ATM-mediated DNA repair pathway is a strong candidate to be a regulator of oocyte aging, and the age-related decline of this pathway likely impairs oocyte health. This knowledge may create an opportunity to develop targeted treatments to reverse or prevent physiological or chemotherapy-induced oocyte aging. On the immediate practical side, women with BRCA or similar mutations may need to be specially counselled for fertility preservation.
Topics: Aging; Animals; Ataxia Telangiectasia; BRCA1 Protein; BRCA2 Protein; DNA Breaks, Double-Stranded; DNA Repair; Female; Fertility; Fertility Preservation; Humans; Mice; Oocytes; Ovarian Follicle; Ovarian Reserve; Ovary
PubMed: 31822904
DOI: 10.1093/humupd/dmz043 -
Cancer Cell Apr 2021Small cell neuroendocrine cancers (SCNCs) are recalcitrant cancers arising from diverse primary sites that lack effective treatments. Using chemical genetic screens, we...
Small cell neuroendocrine cancers (SCNCs) are recalcitrant cancers arising from diverse primary sites that lack effective treatments. Using chemical genetic screens, we identified inhibition of ataxia telangiectasia and rad3 related (ATR), the primary activator of the replication stress response, and topoisomerase I (TOP1), nuclear enzyme that suppresses genomic instability, as synergistically cytotoxic in small cell lung cancer (SCLC). In a proof-of-concept study, we combined M6620 (berzosertib), first-in-class ATR inhibitor, and TOP1 inhibitor topotecan in patients with relapsed SCNCs. Objective response rate among patients with SCLC was 36% (9/25), achieving the primary efficacy endpoint. Durable tumor regressions were observed in patients with platinum-resistant SCNCs, typically fatal within weeks of recurrence. SCNCs with high neuroendocrine differentiation, characterized by enhanced replication stress, were more likely to respond. These findings highlight replication stress as a potentially transformative vulnerability of SCNCs, paving the way for rational patient selection in these cancers, now treated as a single disease.
Topics: Aged; Antineoplastic Agents; Ataxia Telangiectasia Mutated Proteins; DNA Replication; DNA Topoisomerases, Type I; Genomic Instability; Humans; Isoxazoles; Lung Neoplasms; Middle Aged; Neoplasm Recurrence, Local; Protein Kinase Inhibitors; Pyrazines; Signal Transduction; Small Cell Lung Carcinoma
PubMed: 33848478
DOI: 10.1016/j.ccell.2021.02.014 -
Nature Jul 2023Splice-switching antisense oligonucleotides (ASOs) could be used to treat a subset of individuals with genetic diseases, but the systematic identification of such...
Splice-switching antisense oligonucleotides (ASOs) could be used to treat a subset of individuals with genetic diseases, but the systematic identification of such individuals remains a challenge. Here we performed whole-genome sequencing analyses to characterize genetic variation in 235 individuals (from 209 families) with ataxia-telangiectasia, a severely debilitating and life-threatening recessive genetic disorder, yielding a complete molecular diagnosis in almost all individuals. We developed a predictive taxonomy to assess the amenability of each individual to splice-switching ASO intervention; 9% and 6% of the individuals had variants that were 'probably' or 'possibly' amenable to ASO splice modulation, respectively. Most amenable variants were in deep intronic regions that are inaccessible to exon-targeted sequencing. We developed ASOs that successfully rescued mis-splicing and ATM cellular signalling in patient fibroblasts for two recurrent variants. In a pilot clinical study, one of these ASOs was used to treat a child who had been diagnosed with ataxia-telangiectasia soon after birth, and showed good tolerability without serious adverse events for three years. Our study provides a framework for the prospective identification of individuals with genetic diseases who might benefit from a therapeutic approach involving splice-switching ASOs.
Topics: Child; Humans; Ataxia Telangiectasia; Oligonucleotides, Antisense; Prospective Studies; RNA Splicing; Whole Genome Sequencing; Introns; Exons; Precision Medicine; Pilot Projects
PubMed: 37438524
DOI: 10.1038/s41586-023-06277-0 -
Ageing Research Reviews Aug 2022Ataxia-telangiectasia (A-T) is caused by absence of the catalytic activity of ATM, a protein kinase that plays a central role in the DNA damage response, many branches... (Review)
Review
Ataxia-telangiectasia (A-T) is caused by absence of the catalytic activity of ATM, a protein kinase that plays a central role in the DNA damage response, many branches of cellular metabolism, redox and mitochondrial homeostasis, and cell cycle regulation. A-T is a complex disorder characterized mainly by progressive cerebellar degeneration, immunodeficiency, radiation sensitivity, genome instability, and predisposition to cancer. It is increasingly recognized that the premature aging component of A-T is an important driver of this disease, and A-T is therefore an attractive model to study the aging process. This review outlines the current state of knowledge pertaining to the molecular and cellular signatures of aging in A-T and proposes how these new insights can guide novel therapeutic approaches for A-T.
Topics: Aging; Aging, Premature; Ataxia Telangiectasia; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; DNA Damage; Genomic Instability; Humans
PubMed: 35644374
DOI: 10.1016/j.arr.2022.101653