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Toufektchan E, Dananberg A, Striepen J, Hickling JH, Shim A, Chen Y, Nichols A, Duran Paez MA, Mohr L, Bakhoum SF, Maciejowski J. Intratumoral TREX1 Induction Promotes Immune Evasion by Limiting Type I IFN. Cancer Immunol Res 2024; 12:673-686. [PMID: 38408184 PMCID: PMC11148545 DOI: 10.1158/2326-6066.cir-23-1093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/06/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024]
Abstract
Chromosomal instability is a hallmark of human cancer that is associated with aggressive disease characteristics. Chromosome mis-segregations help fuel natural selection, but they risk provoking a cGAS-STING immune response through the accumulation of cytosolic DNA. The mechanisms of how tumors benefit from chromosomal instability while mitigating associated risks, such as enhanced immune surveillance, are poorly understood. Here, we identify cGAS-STING-dependent upregulation of the nuclease TREX1 as an adaptive, negative feedback mechanism that promotes immune evasion through digestion of cytosolic DNA. TREX1 loss diminishes tumor growth, prolongs survival of host animals, increases tumor immune infiltration, and potentiates response to immune checkpoint blockade selectively in tumors capable of mounting a type I IFN response downstream of STING. Together, these data demonstrate that TREX1 induction shields chromosomally unstable tumors from immune surveillance by dampening type I IFN production and suggest that TREX1 inhibitors might be used to selectively target tumors that have retained the inherent ability to mount an IFN response downstream of STING. See related article by Lim et al., p. 663.
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Chauvin SD, Ando S, Holley JA, Sugie A, Zhao FR, Poddar S, Kato R, Miner CA, Nitta Y, Krishnamurthy SR, Saito R, Ning Y, Hatano Y, Kitahara S, Koide S, Stinson WA, Fu J, Surve N, Kumble L, Qian W, Polishchuk O, Andhey PS, Chiang C, Liu G, Colombeau L, Rodriguez R, Manel N, Kakita A, Artyomov MN, Schultz DC, Coates PT, Roberson EDO, Belkaid Y, Greenberg RA, Cherry S, Gack MU, Hardy T, Onodera O, Kato T, Miner JJ. Inherited C-terminal TREX1 variants disrupt homology-directed repair to cause senescence and DNA damage phenotypes in Drosophila, mice, and humans. Nat Commun 2024; 15:4696. [PMID: 38824133 PMCID: PMC11144269 DOI: 10.1038/s41467-024-49066-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 05/22/2024] [Indexed: 06/03/2024] Open
Abstract
Age-related microangiopathy, also known as small vessel disease (SVD), causes damage to the brain, retina, liver, and kidney. Based on the DNA damage theory of aging, we reasoned that genomic instability may underlie an SVD caused by dominant C-terminal variants in TREX1, the most abundant 3'-5' DNA exonuclease in mammals. C-terminal TREX1 variants cause an adult-onset SVD known as retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S). In RVCL, an aberrant, C-terminally truncated TREX1 mislocalizes to the nucleus due to deletion of its ER-anchoring domain. Since RVCL pathology mimics that of radiation injury, we reasoned that nuclear TREX1 would cause DNA damage. Here, we show that RVCL-associated TREX1 variants trigger DNA damage in humans, mice, and Drosophila, and that cells expressing RVCL mutant TREX1 are more vulnerable to DNA damage induced by chemotherapy and cytokines that up-regulate TREX1, leading to depletion of TREX1-high cells in RVCL mice. RVCL-associated TREX1 mutants inhibit homology-directed repair (HDR), causing DNA deletions and vulnerablility to PARP inhibitors. In women with RVCL, we observe early-onset breast cancer, similar to patients with BRCA1/2 variants. Our results provide a mechanistic basis linking aberrant TREX1 activity to the DNA damage theory of aging, premature senescence, and microvascular disease.
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Shi W, Xu G, Gao Y, Yang H, Liu T, Zhao J, Li H, Wei Z, Hou X, Chen Y, Wen J, Li C, Zhao J, Zhang P, Wang Z, Xiao X, Bai Z. Compound Danshen Dripping Pill effectively alleviates cGAS-STING-triggered diseases by disrupting STING-TBK1 interaction. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2024; 128:155404. [PMID: 38507852 DOI: 10.1016/j.phymed.2024.155404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/13/2024] [Accepted: 01/31/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon (IFN) genes (STING) pathway is critical in the innate immune system and can be mobilized by cytosolic DNA. The various inflammatory and autoimmune diseases progression is highly correlated with aberrant cGAS-STING pathway activation. While some cGAS-STING pathway inhibitor were identified, there are no drugs that can be applied to the clinic. Compound Danshen Dripping Pill (CDDP) has been successfully used in clinic around the world, but the most common application is limited to cardiovascular disease. Therefore, the purpose of the present investigation was to examine whether CDDP inhibits the cGAS-STING pathway and could be used as a therapeutic agent for multiple cGAS-STING-triggered diseases. METHODS BMDMs, THP1 cells or Trex1-/- BMDMs were stimulated with various cGAS-STING-agonists after pretreatment with CDDP to detect the function of CDDP on IFN-β and ISGs productionn. Next, we detect the influence on IRF3 and P65 nuclear translocation, STING oligomerization and STING-TBK1-IRF3 complex formation of CDDP. Additionally, the DMXAA-mediated activation mice model of cGAS-STING pathway was used to study the effects of CDDP. Trex1-/- mice model and HFD-mediated obesity model were established to clarify the efficacy of CDDP on inflammatory and autoimmune diseases. RESULTS CDDP efficacy suppressed the IRF3 phosphorylation or the generation of IFN-β, ISGs, IL-6 and TNF-α. Mechanistically, CDDP did not influence the STING oligomerization and IRF3-TBK1 and STING-IRF3 interaction, but remarkably eliminated the STING-TBK1 interaction, ultimately blocking the downstream responses. In addition, we also clarified that CDDP could suppress cGAS-STING pathway activation triggered by DMXAA, in vivo. Consistently, CDDP could alleviate multi-organ inflammatory responses in Trex1-/- mice model and attenuate the inflammatory disorders, incleding obesity-induced insulin resistance. CONCLUSION CDDP is a specifically cGAS-STING pathway inhibitor. Furthermore, we provide novel mechanism for CDDP and discovered a clinical agent for the therapy of cGAS-STING-triggered inflammatory and autoimmune diseases.
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Wang WW, Yi GS, Zhou H, Zhao YX, Wang QS, He JH, Yu F, Xiao X, Liu XP. The structure of the archaeal nuclease RecJ2 implicates its catalytic mechanism and inability to interact with GINS. J Biol Chem 2024; 300:107379. [PMID: 38762184 PMCID: PMC11193018 DOI: 10.1016/j.jbc.2024.107379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 05/06/2024] [Accepted: 05/08/2024] [Indexed: 05/20/2024] Open
Abstract
Bacterial RecJ exhibits 5'→3' exonuclease activity that is specific to ssDNA; however, archaeal RecJs show 5' or 3' exonuclease activity. The hyperthermophilic archaea Methanocaldococcus jannaschii encodes the 5'-exonuclease MjRecJ1 and the 3'-exonuclease MjRecJ2. In addition to nuclease activity, archaeal RecJ interacts with GINS, a structural subcomplex of the replicative DNA helicase complex. However, MjRecJ1 and MjRecJ2 do not interact with MjGINS. Here, we report the structural basis for the inability of the MjRecJ2 homologous dimer to interact with MjGINS and its efficient 3' hydrolysis polarity for short dinucleotides. Based on the crystal structure of MjRecJ2, we propose that the interaction surface of the MjRecJ2 dimer overlaps the potential interaction surface for MjGINS and blocks the formation of the MjRecJ2-GINS complex. Exposing the interaction surface of the MjRecJ2 dimer restores its interaction with MjGINS. The cocrystal structures of MjRecJ2 with substrate dideoxynucleotides or product dCMP/CMP show that MjRecJ2 has a short substrate binding patch, which is perpendicular to the longer patch of bacterial RecJ. Our results provide new insights into the function and diversification of archaeal RecJ/Cdc45 proteins.
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Zheng Y, Zhao Y, Dong K, Miao L, Zhou X, Gong Y, Zhang L. A novel Mre11 protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 possesses 5'-3' exonuclease and endonuclease activities. Int J Biol Macromol 2024; 272:132654. [PMID: 38810854 DOI: 10.1016/j.ijbiomac.2024.132654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/21/2024] [Accepted: 05/23/2024] [Indexed: 05/31/2024]
Abstract
Mre11 is one of important proteins that are involved in DNA repair and recombination by processing DNA ends to produce 3'-single stranded DNA, thus providing a platform for other DNA repair and recombination proteins. In this work, we characterized the Mre11 protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 (Tba-Mre11) biochemically and dissected the roles of its four conserved residues, which is the first report on Mre11 proteins from Thermococcus. Tba-Mre11 possesses exonuclease activity for degrading ssDNA and dsDNA in the 5'-3' direction, which contrasts with other reported Mre11 homologs. Maximum degradation efficiency was observed with Mn2+ at 80 °C and at pH 7.5-9.5. In addition to possessing 5'-3' exonuclease activity, Tba-Mre11 has endonuclease activity that nicks plasmid DNA and circular ssDNA. Mutational data show that residues D10, D51 and N86 in Tba-Mre11 are essential for DNA degradation since almost no activity was observed for the D10A, D51A and N86A mutants. By comparison, residue D44 in Tba-Mre11 is not responsible for DNA degradation since the D44A mutant possessed the similar WT protein activity. Notably, the D44A mutant almost completely abolished the ability to bind DNA, suggesting that residue D44 is essential for binding DNA.
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Császár I, Kalmár T, Maróti Z, Ávéd J, Szederkényi E, Zombori J, Pankotai-Bodó G, Turkevi-Nagy S, Iványi B. Phenotypic and Genotypic Features of the FAN1 Mutation-Related Disease in a Large Hungarian Family. Int J Mol Sci 2024; 25:5907. [PMID: 38892095 PMCID: PMC11172681 DOI: 10.3390/ijms25115907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 05/23/2024] [Accepted: 05/26/2024] [Indexed: 06/21/2024] Open
Abstract
Pathogenic variants in the FAN1 gene lead to a systemic disease with karyomegalic interstitial nephritis (KIN) at the forefront clinically. The phenotypic-genotypic features of a FAN1 mutation-related disease involving five members of a Hungarian Caucasian family are presented. Each had adult-onset chronic kidney disease of unknown cause treated with renal replacement therapy and elevated liver enzymes. Short stature, emaciation, latte-colored skin, freckles, and a hawk-like nose in four patients, a limited intellect in two patients, and chronic restrictive lung disease in one patient completed the phenotype. Severe infections occurred in four patients. All five patients had ceased. Four patients underwent autopsy. KIN and extrarenal karyomegaly were observed histologically; the livers showed no specific abnormality. The genotyping using formalin-fixed tissue samples detected a hitherto undescribed homozygous FAN1 mutation (c.1673_1674insT/p.Met558lfs*4; exon 5) in three of these patients and a heterozygous FAN1 mutation in one patient. The reason for the heterozygosity is discussed. In addition, 56 family members consented to the screening for FAN1 mutation from which 17 individuals proved to be heterozygous carriers; a blood chemistry evaluation of their kidney and liver function did not find any abnormality. The clinical presentation of FAN1-related disease was multifaceted, and not yet described manifestations were observed besides kidney and liver disease. Mutation in this gene should be suspected in adults with small kidneys of unknown cause, elevated liver enzymes, and recurrent infections, even without a family history.
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Bugallo A, Sánchez M, Fernández-García M, Segurado M. S-phase checkpoint prevents leading strand degradation from strand-associated nicks at stalled replication forks. Nucleic Acids Res 2024; 52:5121-5137. [PMID: 38520409 PMCID: PMC11109941 DOI: 10.1093/nar/gkae192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 03/01/2024] [Accepted: 03/07/2024] [Indexed: 03/25/2024] Open
Abstract
The S-phase checkpoint is involved in coupling DNA unwinding with nascent strand synthesis and is critical to maintain replication fork stability in conditions of replicative stress. However, its role in the specific regulation of leading and lagging strands at stalled forks is unclear. By conditionally depleting RNaseH2 and analyzing polymerase usage genome-wide, we examine the enzymology of DNA replication during a single S-phase in the presence of replicative stress and show that there is a differential regulation of lagging and leading strands. In checkpoint proficient cells, lagging strand replication is down-regulated through an Elg1-dependent mechanism. Nevertheless, when checkpoint function is impaired we observe a defect specifically at the leading strand, which was partially dependent on Exo1 activity. Further, our genome-wide mapping of DNA single-strand breaks reveals that strand discontinuities highly accumulate at the leading strand in HU-treated cells, whose dynamics are affected by checkpoint function and Exo1 activity. Our data reveal an unexpected role of Exo1 at the leading strand and support a model of fork stabilization through prevention of unrestrained Exo1-dependent resection of leading strand-associated nicks after fork stalling.
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Shi H, Li L, Mu S, Gou S, Liu X, Chen F, Chen M, Jin Q, Lai L, Wang K. Exonuclease editor promotes precision of gene editing in mammalian cells. BMC Biol 2024; 22:119. [PMID: 38769511 PMCID: PMC11107001 DOI: 10.1186/s12915-024-01918-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 05/13/2024] [Indexed: 05/22/2024] Open
Abstract
BACKGROUND Many efforts have been made to improve the precision of Cas9-mediated gene editing through increasing knock-in efficiency and decreasing byproducts, which proved to be challenging. RESULTS Here, we have developed a human exonuclease 1-based genome-editing tool, referred to as exonuclease editor. When compared to Cas9, the exonuclease editor gave rise to increased HDR efficiency, reduced NHEJ repair frequency, and significantly elevated HDR/indel ratio. Robust gene editing precision of exonuclease editor was even superior to the fusion of Cas9 with E1B or DN1S, two previously reported precision-enhancing domains. Notably, exonuclease editor inhibited NHEJ at double strand breaks locally rather than globally, reducing indel frequency without compromising genome integrity. The replacement of Cas9 with single-strand DNA break-creating Cas9 nickase further increased the HDR/indel ratio by 453-fold than the original Cas9. In addition, exonuclease editor resulted in high microhomology-mediated end joining efficiency, allowing accurate and flexible deletion of targeted sequences with extended lengths with the aid of paired sgRNAs. Exonuclease editor was further used for correction of DMD patient-derived induced pluripotent stem cells, where 30.0% of colonies were repaired by HDR versus 11.1% in the control. CONCLUSIONS Therefore, the exonuclease editor system provides a versatile and safe genome editing tool with high precision and holds promise for therapeutic gene correction.
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Yang M, Gao L, Gao Y, Hao Z, Zhou X, Su G, Bai C, Wei Z, Liu X, Yang L, Li G. Inactivation of Myostatin Delays Senescence via TREX1-SASP in Bovine Skeletal Muscle Cells. Int J Mol Sci 2024; 25:5277. [PMID: 38791317 PMCID: PMC11120739 DOI: 10.3390/ijms25105277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/03/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
The myostatin (MSTN) gene also regulates the developmental balance of skeletal muscle after birth, and has long been linked to age-related muscle wasting. Many rodent studies have shown a correlation between MSTN and age-related diseases. It is unclear how MSTN and age-associated muscle loss in other animals are related. In this study, we utilized MSTN gene-edited bovine skeletal muscle cells to investigate the mechanisms relating to MSTN and muscle cell senescence. The expression of MSTN was higher in older individuals than in younger individuals. We obtained consecutively passaged senescent cells and performed senescence index assays and transcriptome sequencing. We found that senescence hallmarks and the senescence-associated secretory phenotype (SASP) were decreased in long-term-cultured myostatin inactivated (MT-KO) bovine skeletal muscle cells (bSMCs). Using cell signaling profiling, MSTN was shown to regulate the SASP, predominantly through the cycle GMP-AMP synthase-stimulator of antiviral genes (cGAS-STING) pathway. An in-depth investigation by chromatin immunoprecipitation (ChIP) analysis revealed that MSTN influenced three prime repair exonuclease 1 (TREX1) expression through the SMAD2/3 complex. The downregulation of MSTN contributed to the activation of the MSTN-SMAD2/3-TREX1 signaling axis, influencing the secretion of SASP, and consequently delaying the senescence of bSMCs. This study provided valuable new insight into the role of MSTN in cell senescence in large animals.
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Aithal R, Nangalia K, Spirek M, Chen D, Klein F, Krejci L. Physical interaction with Spo11 mediates the localisation of Mre11 to chromatin in meiosis and promotes its nuclease activity. Nucleic Acids Res 2024; 52:4328-4343. [PMID: 38407383 PMCID: PMC11077076 DOI: 10.1093/nar/gkae111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 01/19/2024] [Accepted: 02/06/2024] [Indexed: 02/27/2024] Open
Abstract
Meiotic recombination is of central importance for the proper segregation of homologous chromosomes, but also for creating genetic diversity. It is initiated by the formation of double-strand breaks (DSBs) in DNA catalysed by evolutionarily conserved Spo11, together with additional protein partners. Difficulties in purifying the Spo11 protein have limited the characterization of its biochemical properties and of its interactions with other DSB proteins. In this study, we have purified fragments of Spo11 and show for the first time that Spo11 can physically interact with Mre11 and modulates its DNA binding, bridging, and nuclease activities. The interaction of Mre11 with Spo11 requires its far C-terminal region, which is in line with the severe meiotic phenotypes of various mre11 mutations located at the C-terminus. Moreover, calibrated ChIP for Mre11 shows that Spo11 promotes Mre11 recruitment to chromatin, independent of DSB formation. A mutant deficient in Spo11 interaction severely reduces the association of Mre11 with meiotic chromatin. Consistent with the reduction of Mre11 foci in this mutant, it strongly impedes DSB formation, leading to spore death. Our data provide evidence that physical interaction between Spo11 and Mre11, together with end-bridging, promote normal recruitment of Mre11 to hotspots and DSB formation.
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Wang WX, Spiegelman D, Rao PK, Ford AL, Apte RS. Crizanlizumab for retinal vasculopathy with cerebral leukoencephalopathy in a phase II clinical study. J Clin Invest 2024; 134:e180916. [PMID: 38950286 PMCID: PMC11178534 DOI: 10.1172/jci180916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 05/01/2024] [Indexed: 07/03/2024] Open
Abstract
BackgroundRetinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a rare, autosomal dominant, universally fatal disease without effective treatment options. This study explores the safety and preliminary efficacy of crizanlizumab, a humanized monoclonal antibody against P-selectin approved for the prevention of sickle cell crises, in slowing retinal nonperfusion and preserving vision in patients with RVCL-S.METHODSEleven patients with RVCL-S with confirmed exonuclease 3 prime repair exonuclease 1 (TREX1) mutations received monthly crizanlizumab infusions over 2 years. The study measured the nonperfusion index within 3 retinal zones and the total retina with fluorescein angiography, visual acuity, intraocular pressure (IOP), and optical coherence tomography central subfield thickness (CST) at baseline, 1 year, and 2 years. A mixed repeated-measures analysis was performed to assess the progression rates and changes from baseline.RESULTSEleven participants received crizanlizumab infusions. All of the participants tolerated crizanlizumab well, with 8 of 11 (72.7%) reporting mild adverse effects such as nausea, fatigue, and gastrointestinal symptoms. The change in total retinal nonperfusion was 7.22% [4.47, 9.97] in year 1 and -0.69% [-4.06, 2.68] in year 2 (P < 0.001). In the mid periphery, the change in nonperfusion was 10.6% [5.1, 16.1] in year 1 and -0.68% [-3.98, 5.35] in year 2 (P < 0.01), demonstrating a reduction in progression of nonperfusion in the second year of treatment. Visual acuity, IOP, and CST remained stable.CONCLUSIONCrizanlizumab has an acceptable safety profile. These results show promising potential for examining crizanlizumab in larger studies of RVCL-S and similar small-vessel diseases and for using the retina as a biomarker for systemic disease.Trial registrationClinicalTrials.gov NCT04611880.FUNDINGThe Clayco Foundation; DeNardo Education and Research Foundation Grant; Jeffrey T. Fort Innovation Fund; Siteman Retina Research Fund; unrestricted grant from Research to Prevent Blindness Inc.; National Heart,Lung, and Blood Institute (NHLBI), NIH (R01HL129241); National Institute of Neurological Disorders and Stroke (NINDS), NIH (RF1NS116565).
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Tani T, Mathsyaraja H, Campisi M, Li ZH, Haratani K, Fahey CG, Ota K, Mahadevan NR, Shi Y, Saito S, Mizuno K, Thai TC, Sasaki N, Homme M, Yusuf CFB, Kashishian A, Panchal J, Wang M, Wolf BJ, Barbie TU, Paweletz CP, Gokhale PC, Liu D, Uppaluri R, Kitajima S, Cain J, Barbie DA. TREX1 Inactivation Unleashes Cancer Cell STING-Interferon Signaling and Promotes Antitumor Immunity. Cancer Discov 2024; 14:752-765. [PMID: 38227896 PMCID: PMC11062818 DOI: 10.1158/2159-8290.cd-23-0700] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 11/28/2023] [Accepted: 01/08/2024] [Indexed: 01/18/2024]
Abstract
A substantial fraction of cancers evade immune detection by silencing Stimulator of Interferon Genes (STING)-Interferon (IFN) signaling. Therapeutic reactivation of this program via STING agonists, epigenetic, or DNA-damaging therapies can restore antitumor immunity in multiple preclinical models. Here we show that adaptive induction of three prime exonuclease 1 (TREX1) restrains STING-dependent nucleic acid sensing in cancer cells via its catalytic function in degrading cytosolic DNA. Cancer cell TREX1 expression is coordinately induced with STING by autocrine IFN and downstream STAT1, preventing signal amplification. TREX1 inactivation in cancer cells thus unleashes STING-IFN signaling, recruiting T and natural killer (NK) cells, sensitizing to NK cell-derived IFNγ, and cooperating with programmed cell death protein 1 blockade in multiple mouse tumor models to enhance immunogenicity. Targeting TREX1 may represent a complementary strategy to induce cytosolic DNA and amplify cancer cell STING-IFN signaling as a means to sensitize tumors to immune checkpoint blockade (ICB) and/or cell therapies. SIGNIFICANCE STING-IFN signaling in cancer cells promotes tumor cell immunogenicity. Inactivation of the DNA exonuclease TREX1, which is adaptively upregulated to limit pathway activation in cancer cells, recruits immune effector cells and primes NK cell-mediated killing. Targeting TREX1 has substantial therapeutic potential to amplify cancer cell immunogenicity and overcome ICB resistance. This article is featured in Selected Articles from This Issue, p. 695.
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de Barcelos IP, Woidill S, Gavazzi F, Modesti NB, Sevagamoorthy A, Vanderver A, Adang L. Systematic analysis of genotype-phenotype variability in siblings with Aicardi Goutières Syndrome (AGS). Mol Genet Metab 2024; 142:108346. [PMID: 38368708 DOI: 10.1016/j.ymgme.2024.108346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/11/2023] [Accepted: 02/11/2024] [Indexed: 02/20/2024]
Abstract
OBJECTIVE Aicardi Goutières Syndrome (AGS) is a genetic interferonopathy associated with multisystemic heterogeneous disease and neurologic dysfunction. AGS includes a broad phenotypic spectrum which is only partially explained by genotype. To better characterize this variability, we will perform a systematic analysis of phenotypic variability in familial cases of AGS. METHODS Among thirteen families, twenty-six siblings diagnosed with AGS were identified from the Myelin Disorders and Biorepository Project (MDBP) at the Children's Hospital of Philadelphia. Data were collected on the age of onset, genotype, neurologic impairment, and systemic complications. Neurologic impairment was assessed by a disease-specific scale (AGS Severity Scale) at the last available clinical encounter (range: 0-11 representing severe - attenuated phenotypes). The concordance of clinical severity within sibling pairs was categorized based on the difference in AGS Scale (discordant defined as >2-unit difference). The severity classifications were compared between sibling sets and by genotype. RESULTS Five genotypes were represented: TREX1 (n = 4 subjects), RNASEH2B (n = 8), SAMHD1 (n = 8) ADAR1 (n = 4), and IFIH1 (n = 2). The older sibling was diagnosed later relative to the younger affected sibling (median age 7.32 years [IQR = 14.1] compared to 1.54 years [IQR = 10.3]). Common presenting neurologic symptoms were tone abnormalities (n = 10/26) and gross motor dysfunction (n = 9/26). Common early systemic complications included dysphagia and chilblains. The overall cohort median AGS severity score at the last encounter was 8, while subjects presenting with symptoms before one year had a median score of 5. The TREX1 cohort presented at the youngest age and with the most severe phenotype on average. AGS scores were discordant for 5 of 13 sibling pairs, most commonly in the SAMHD1 pairs. Microcephaly, feeding tube placement, seizures and earlier onset sibling were associated with lower AGS scores (respectively, Wilcoxon rank sum: p = 0.0001, p < 0.0001, p = 0.0426, and Wilcoxon signed rank: p = 0.0239). CONCLUSIONS In this systematic analysis of phenotypic variability in familial cases, we found discordance between siblings affected by AGS. Our results underscore the heterogeneity of AGS and suggest factors beyond AGS genotype may affect phenotype. Understanding the critical variables associated with disease onset and severity can guide future therapeutic interventions and clinical monitoring. This report reinforces the need for further studies to uncover potential factors to better understand this phenotypic variability, and consequently identify potential targets for interventions in attempt to change the natural history of the disease.
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Mathavarajah S, Thompson AW, Stoyek MR, Quinn TA, Roy S, Braasch I, Dellaire G. Suppressors of cGAS-STING are downregulated during fin-limb regeneration and aging in aquatic vertebrates. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:241-251. [PMID: 37877156 PMCID: PMC11043210 DOI: 10.1002/jez.b.23227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 09/19/2023] [Accepted: 10/03/2023] [Indexed: 10/26/2023]
Abstract
During the early stages of limb and fin regeneration in aquatic vertebrates (i.e., fishes and amphibians), blastema undergo transcriptional rewiring of innate immune signaling pathways to promote immune cell recruitment. In mammals, a fundamental component of innate immune signaling is the cytosolic DNA sensing pathway, cGAS-STING. However, to what extent the cGAS-STING pathway influences regeneration in aquatic anamniotes is unknown. In jawed vertebrates, negative regulation of cGAS-STING activity is accomplished by suppressors of cytosolic DNA such as Trex1, Pml, and PML-like exon 9 (Plex9) exonucleases. Here, we examine the expression of these suppressors of cGAS-STING, as well as inflammatory genes and cGAS activity during caudal fin and limb regeneration using the spotted gar (Lepisosteus oculatus) and axolotl (Ambystoma mexicanum) model species, and during age-related senescence in zebrafish (Danio rerio). In the regenerative blastema of wounded gar and axolotl, we observe increased inflammatory gene expression, including interferon genes and interleukins 6 and 8. We also observed a decrease in axolotl Trex1 and gar pml expression during the early phases of wound healing which correlates with a dramatic increase in cGAS activity. In contrast, the plex9.1 gene does not change in expression during wound healing in gar. However, we observed decreased expression of plex9.1 in the senescing cardiac tissue of aged zebrafish, where 2'3'-cGAMP levels are elevated. Finally, we demonstrate a similar pattern of Trex1, pml, and plex9.1 gene regulation across species in response to exogenous 2'3'-cGAMP. Thus, during the early stages of limb-fin regeneration, Pml, Trex1, and Plex9.1 exonucleases are downregulated, presumably to allow an evolutionarily ancient cGAS-STING activity to promote inflammation and the recruitment of immune cells.
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Mao EYC, Yen HY, Wu CC. Structural basis of how MGME1 processes DNA 5' ends to maintain mitochondrial genome integrity. Nucleic Acids Res 2024; 52:4067-4078. [PMID: 38471810 DOI: 10.1093/nar/gkae186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/29/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024] Open
Abstract
Mitochondrial genome maintenance exonuclease 1 (MGME1) helps to ensure mitochondrial DNA (mtDNA) integrity by serving as an ancillary 5'-exonuclease for DNA polymerase γ. Curiously, MGME1 exhibits unique bidirectionality in vitro, being capable of degrading DNA from either the 5' or 3' end. The structural basis of this bidirectionally and, particularly, how it processes DNA from the 5' end to assist in mtDNA maintenance remain unclear. Here, we present a crystal structure of human MGME1 in complex with a 5'-overhang DNA, revealing that MGME1 functions as a rigid DNA clamp equipped with a single-strand (ss)-selective arch, allowing it to slide on single-stranded DNA in either the 5'-to-3' or 3'-to-5' direction. Using a nuclease activity assay, we have dissected the structural basis of MGME1-derived DNA cleavage patterns in which the arch serves as a ruler to determine the cleavage site. We also reveal that MGME1 displays partial DNA-unwinding ability that helps it to better resolve 5'-DNA flaps, providing insights into MGME1-mediated 5'-end processing of nascent mtDNA. Our study builds on previously solved MGME1-DNA complex structures, finally providing the comprehensive functional mechanism of this bidirectional, ss-specific exonuclease.
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Audry J, Zhang H, Kerr C, Berkner KL, Runge K. Ccq1 restrains Mre11-mediated degradation to distinguish short telomeres from double-strand breaks. Nucleic Acids Res 2024; 52:3722-3739. [PMID: 38321948 PMCID: PMC11040153 DOI: 10.1093/nar/gkae044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 12/21/2023] [Accepted: 01/12/2024] [Indexed: 02/08/2024] Open
Abstract
Telomeres protect chromosome ends and are distinguished from DNA double-strand breaks (DSBs) by means of a specialized chromatin composed of DNA repeats bound by a multiprotein complex called shelterin. We investigated the role of telomere-associated proteins in establishing end-protection by studying viable mutants lacking these proteins. Mutants were studied using a Schizosaccharomyces pombe model system that induces cutting of a 'proto-telomere' bearing telomere repeats to rapidly form a new stable chromosomal end, in contrast to the rapid degradation of a control DSB. Cells lacking the telomere-associated proteins Taz1, Rap1, Poz1 or Rif1 formed a chromosome end that was stable. Surprisingly, cells lacking Ccq1, or impaired for recruiting Ccq1 to the telomere, converted the cleaved proto-telomere to a rapidly degraded DSB. Ccq1 recruits telomerase, establishes heterochromatin and affects DNA damage checkpoint activation; however, these functions were separable from protection of the new telomere by Ccq1. In cells lacking Ccq1, telomere degradation was greatly reduced by eliminating the nuclease activity of Mre11 (part of the Mre11-Rad50-Nbs1/Xrs2 DSB processing complex), and higher amounts of nuclease-deficient Mre11 associated with the new telomere. These results demonstrate a novel function for S. pombe Ccq1 to effect end-protection by restraining Mre11-dependent degradation of the DNA end.
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Kim KH, Hong EP, Lee Y, McLean ZL, Elezi E, Lee R, Kwak S, McAllister B, Massey TH, Lobanov S, Holmans P, Orth M, Ciosi M, Monckton DG, Long JD, Lucente D, Wheeler VC, MacDonald ME, Gusella JF, Lee JM. Posttranscriptional regulation of FAN1 by miR-124-3p at rs3512 underlies onset-delaying genetic modification in Huntington's disease. Proc Natl Acad Sci U S A 2024; 121:e2322924121. [PMID: 38607933 PMCID: PMC11032436 DOI: 10.1073/pnas.2322924121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/06/2024] [Indexed: 04/14/2024] Open
Abstract
Many Mendelian disorders, such as Huntington's disease (HD) and spinocerebellar ataxias, arise from expansions of CAG trinucleotide repeats. Despite the clear genetic causes, additional genetic factors may influence the rate of those monogenic disorders. Notably, genome-wide association studies discovered somewhat expected modifiers, particularly mismatch repair genes involved in the CAG repeat instability, impacting age at onset of HD. Strikingly, FAN1, previously unrelated to repeat instability, produced the strongest HD modification signals. Diverse FAN1 haplotypes independently modify HD, with rare genetic variants diminishing DNA binding or nuclease activity of the FAN1 protein, hastening HD onset. However, the mechanism behind the frequent and the most significant onset-delaying FAN1 haplotype lacking missense variations has remained elusive. Here, we illustrated that a microRNA acting on 3'-UTR (untranslated region) SNP rs3512, rather than transcriptional regulation, is responsible for the significant FAN1 expression quantitative trait loci signal and allelic imbalance in FAN1 messenger ribonucleic acid (mRNA), accounting for the most significant and frequent onset-delaying modifier haplotype in HD. Specifically, miR-124-3p selectively targets the reference allele at rs3512, diminishing the stability of FAN1 mRNA harboring that allele and consequently reducing its levels. Subsequent validation analyses, including the use of antagomir and 3'-UTR reporter vectors with swapped alleles, confirmed the specificity of miR-124-3p at rs3512. Together, these findings indicate that the alternative allele at rs3512 renders the FAN1 mRNA less susceptible to miR-124-3p-mediated posttranscriptional regulation, resulting in increased FAN1 levels and a subsequent delay in HD onset by mitigating CAG repeat instability.
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Bories C, Lejour T, Adolphe F, Kermasson L, Couvé S, Tanguy L, Luszczewska G, Watzky M, Poillerat V, Garnier P, Groisman R, Ferlicot S, Richard S, Saparbaev M, Revy P, Gad S, Renaud F. DCLRE1B/Apollo germline mutations associated with renal cell carcinoma impair telomere protection. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167107. [PMID: 38430974 DOI: 10.1016/j.bbadis.2024.167107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 02/14/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
Hereditary renal cell carcinoma (RCC) is caused by germline mutations in a subset of genes, including VHL, MET, FLCN, and FH. However, many familial RCC cases do not harbor mutations in the known predisposition genes. Using Whole Exome Sequencing, we identified two germline missense variants in the DCLRE1B/Apollo gene (ApolloN246I and ApolloY273H) in two unrelated families with several RCC cases. Apollo encodes an exonuclease involved in DNA Damage Response and Repair (DDRR) and telomere integrity. We characterized these two functions in the human renal epithelial cell line HKC8. The decrease or inhibition of Apollo expression sensitizes these cells to DNA interstrand crosslink damage (ICLs). HKC8 Apollo-/- cells appear defective in the DDRR and present an accumulation of telomere damage. Wild-type and mutated Apollo forms could interact with TRF2, a shelterin protein involved in telomere protection. However, only ApolloWT can rescue the telomere damage in HKC8 Apollo-/- cells. Our results strongly suggest that ApolloN246I and ApolloY273H are loss-of-function mutants that cause impaired telomere integrity and could lead to genomic instability. Altogether, our results suggest that mutations in Apollo could induce renal oncogenesis.
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Queiroz MAF, de Oliveira AQT, Moura TCF, Brito WRDS, Santana EGM, de Lima LLP, Lopes FT, Bichara CDA, Amoras EDSG, Ishak R, Vallinoto IMVC, Vallinoto ACR. The Expression Levels of TREX1 and IFN-α Are Associated with Immune Reconstitution in HIV-1-Infected Individuals. Viruses 2024; 16:499. [PMID: 38675842 PMCID: PMC11054413 DOI: 10.3390/v16040499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
TREX1 acts in the initial prevention of an autoimmune response, but it may contribute to the permissiveness of retrovirus infections. This study investigated the association between the levels of TREX1 gene expression with the polymorphisms TREX1 rs3135941 (T/C) and TREX1 rs3135945 (G/A), and the presence of antinuclear antibodies (ANA) in antiretroviral therapy (ART)-naïve individuals and after 1 year of treatment. Blood samples from 119 individuals with HIV-1 were subjected to genotyping of polymorphisms and quantification of TREX1 gene expression and HIV-1 viral load by qPCR. The concentration of IFN-α and the number of CD4+/CD8+ T lymphocytes were determined by ELISA and flow cytometry, respectively; ANA was investigated by immunofluorescence. A control group of 167 seronegative individuals was used for the comparison of genotypic frequencies. The frequency of the polymorphisms were not associated with HIV infection or with variations in the expression of TREX1 and IFN-α (p > 0.05). ART-naïve individuals exhibited higher TREX1 expression and lower IFN-α expression. After 1 year of ART, TREX1 levels were reduced, while IFN-α and CD4+ T lymphocytes were elevated (p < 0.05). Some individuals on ART presented ANA. These results suggest that ART-mediated restoration of immune competence is associated with a reduction in TREX1 expression, which may induce the development of ANA, regardless of the polymorphism investigated.
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Pizzul P, Casari E, Rinaldi C, Gnugnoli M, Mangiagalli M, Tisi R, Longhese MP. Rif2 interaction with Rad50 counteracts Tel1 functions in checkpoint signalling and DNA tethering by releasing Tel1 from MRX binding. Nucleic Acids Res 2024; 52:2355-2371. [PMID: 38180815 PMCID: PMC10954470 DOI: 10.1093/nar/gkad1246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/07/2024] Open
Abstract
The yeast Rif2 protein is known to inhibit Mre11 nuclease and the activation of Tel1 kinase through a short motif termed MIN, which binds the Rad50 subunit and simulates its ATPase activity in vitro. The mechanism by which Rif2 restrains Tel1 activation and the consequences of this inhibition at DNA double-strand breaks (DSBs) are poorly understood. In this study, we employed AlphaFold-Multimer modelling to pinpoint and validate the interaction surface between Rif2 MIN and Rad50. We also engineered the rif2-S6E mutation that enhances the inhibitory effect of Rif2 by increasing Rif2-Rad50 interaction. Unlike rif2Δ, the rif2-S6E mutation impairs hairpin cleavage. Furthermore, it diminishes Tel1 activation by inhibiting Tel1 binding to DSBs while leaving MRX association unchanged, indicating that Rif2 can directly inhibit Tel1 recruitment to DSBs. Additionally, Rif2S6E reduces Tel1-MRX interaction and increases stimulation of ATPase by Rad50, indicating that Rif2 binding to Rad50 induces an ADP-bound MRX conformation that is not suitable for Tel1 binding. The decreased Tel1 recruitment to DSBs in rif2-S6E cells impairs DSB end-tethering and this bridging defect is suppressed by expressing a Tel1 mutant variant that increases Tel1 persistence at DSBs, suggesting a direct role for Tel1 in the bridging of DSB ends.
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Mojumdar A, Granger C, Lunke M, Cobb JA. Loss of Dna2 fidelity results in decreased Exo1-mediated resection at DNA double-strand breaks. J Biol Chem 2024; 300:105708. [PMID: 38311177 PMCID: PMC10909748 DOI: 10.1016/j.jbc.2024.105708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/13/2024] [Accepted: 01/25/2024] [Indexed: 02/10/2024] Open
Abstract
A DNA double-strand break (DSB) is one of the most dangerous types of DNA damage that is repaired largely by homologous recombination or nonhomologous end-joining (NHEJ). The interplay of repair factors at the break directs which pathway is used, and a subset of these factors also function in more mutagenic alternative (alt) repair pathways. Resection is a key event in repair pathway choice and extensive resection, which is a hallmark of homologous recombination, and it is mediated by two nucleases, Exo1 and Dna2. We observed differences in resection and repair outcomes in cells harboring nuclease-dead dna2-1 compared with dna2Δ pif1-m2 that could be attributed to the level of Exo1 recovered at DSBs. Cells harboring dna2-1 showed reduced Exo1 localization, increased NHEJ, and a greater resection defect compared with cells where DNA2 was deleted. Both the resection defect and the increased rate of NHEJ in dna2-1 mutants were reversed upon deletion of KU70 or ectopic expression of Exo1. By contrast, when DNA2 was deleted, Exo1 and Ku70 recovery levels did not change; however, Nej1 increased as did the frequency of alt-end joining/microhomology-mediated end-joining repair. Our findings demonstrate that decreased Exo1 at DSBs contributed to the resection defect in cells expressing inactive Dna2 and highlight the complexity of understanding how functionally redundant factors are regulated in vivo to promote genome stability.
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Andronikou C, Burdova K, Dibitetto D, Lieftink C, Malzer E, Kuiken HJ, Gogola E, Ray Chaudhuri A, Beijersbergen RL, Hanzlikova H, Jonkers J, Rottenberg S. PARG-deficient tumor cells have an increased dependence on EXO1/FEN1-mediated DNA repair. EMBO J 2024; 43:1015-1042. [PMID: 38360994 PMCID: PMC10943112 DOI: 10.1038/s44318-024-00043-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 02/17/2024] Open
Abstract
Targeting poly(ADP-ribose) glycohydrolase (PARG) is currently explored as a therapeutic approach to treat various cancer types, but we have a poor understanding of the specific genetic vulnerabilities that would make cancer cells susceptible to such a tailored therapy. Moreover, the identification of such vulnerabilities is of interest for targeting BRCA2;p53-deficient tumors that have acquired resistance to poly(ADP-ribose) polymerase inhibitors (PARPi) through loss of PARG expression. Here, by performing whole-genome CRISPR/Cas9 drop-out screens, we identify various genes involved in DNA repair to be essential for the survival of PARG;BRCA2;p53-deficient cells. In particular, our findings reveal EXO1 and FEN1 as major synthetic lethal interactors of PARG loss. We provide evidence for compromised replication fork progression, DNA single-strand break repair, and Okazaki fragment processing in PARG;BRCA2;p53-deficient cells, alterations that exacerbate the effects of EXO1/FEN1 inhibition and become lethal in this context. Since this sensitivity is dependent on BRCA2 defects, we propose to target EXO1/FEN1 in PARPi-resistant tumors that have lost PARG activity. Moreover, EXO1/FEN1 targeting may be a useful strategy for enhancing the effect of PARG inhibitors in homologous recombination-deficient tumors.
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Goldberg G, Coelho L, Mo G, Adang LA, Patne M, Chen Z, Garcia-Bassets I, Mesci P, Muotri AR. TREX1 is required for microglial cholesterol homeostasis and oligodendrocyte terminal differentiation in human neural assembloids. Mol Psychiatry 2024; 29:566-579. [PMID: 38129659 PMCID: PMC11153041 DOI: 10.1038/s41380-023-02348-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023]
Abstract
Three Prime Repair Exonuclease 1 (TREX1) gene mutations have been associated with Aicardi-Goutières Syndrome (AGS) - a rare, severe pediatric autoimmune disorder that primarily affects the brain and has a poorly understood etiology. Microglia are brain-resident macrophages indispensable for brain development and implicated in multiple neuroinflammatory diseases. However, the role of TREX1 - a DNase that cleaves cytosolic nucleic acids, preventing viral- and autoimmune-related inflammatory responses - in microglia biology remains to be elucidated. Here, we leverage a model of human embryonic stem cell (hESC)-derived engineered microglia-like cells, bulk, and single-cell transcriptomics, optical and transmission electron microscopy, and three-month-old assembloids composed of microglia and oligodendrocyte-containing organoids to interrogate TREX1 functions in human microglia. Our analyses suggest that TREX1 influences cholesterol metabolism, leading to an active microglial morphology with increased phagocytosis in the absence of TREX1. Notably, regulating cholesterol metabolism with an HMG-CoA reductase inhibitor, FDA-approved atorvastatin, rescues these microglial phenotypes. Functionally, TREX1 in microglia is necessary for the transition from gliogenic intermediate progenitors known as pre-oligodendrocyte precursor cells (pre-OPCs) to precursors of the oligodendrocyte lineage known as OPCs, impairing oligodendrogenesis in favor of astrogliogenesis in human assembloids. Together, these results suggest routes for therapeutic intervention in pathologies such as AGS based on microglia-specific molecular and cellular mechanisms.
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van de Kooij B, Schreuder A, Pavani R, Garzero V, Uruci S, Wendel TJ, van Hoeck A, San Martin Alonso M, Everts M, Koerse D, Callen E, Boom J, Mei H, Cuppen E, Luijsterburg MS, van Vugt MATM, Nussenzweig A, van Attikum H, Noordermeer SM. EXO1 protects BRCA1-deficient cells against toxic DNA lesions. Mol Cell 2024; 84:659-674.e7. [PMID: 38266640 DOI: 10.1016/j.molcel.2023.12.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 10/14/2023] [Accepted: 12/22/2023] [Indexed: 01/26/2024]
Abstract
Inactivating mutations in the BRCA1 and BRCA2 genes impair DNA double-strand break (DSB) repair by homologous recombination (HR), leading to chromosomal instability and cancer. Importantly, BRCA1/2 deficiency also causes therapeutically targetable vulnerabilities. Here, we identify the dependency on the end resection factor EXO1 as a key vulnerability of BRCA1-deficient cells. EXO1 deficiency generates poly(ADP-ribose)-decorated DNA lesions during S phase that associate with unresolved DSBs and genomic instability in BRCA1-deficient but not in wild-type or BRCA2-deficient cells. Our data indicate that BRCA1/EXO1 double-deficient cells accumulate DSBs due to impaired repair by single-strand annealing (SSA) on top of their HR defect. In contrast, BRCA2-deficient cells retain SSA activity in the absence of EXO1 and hence tolerate EXO1 loss. Consistent with a dependency on EXO1-mediated SSA, we find that BRCA1-mutated tumors show elevated EXO1 expression and increased SSA-associated genomic scars compared with BRCA1-proficient tumors. Overall, our findings uncover EXO1 as a promising therapeutic target for BRCA1-deficient tumors.
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Zhang H, Ma J, Wu Z, Chen X, Qian Y, Chen W, Wang Z, Zhang Y, Zhu H, Huang X, Ji Q. BacPE: a versatile prime-editing platform in bacteria by inhibiting DNA exonucleases. Nat Commun 2024; 15:825. [PMID: 38280845 PMCID: PMC10821919 DOI: 10.1038/s41467-024-45114-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 01/16/2024] [Indexed: 01/29/2024] Open
Abstract
Prime editing allows precise installation of any single base substitution and small insertions and deletions without requiring homologous recombination or double-strand DNA breaks in eukaryotic cells. However, the applications in bacteria are hindered and the underlying mechanisms that impede efficient prime editing remain enigmatic. Here, we report the determination of vital cellular factors that affect prime editing in bacteria. Genetic screening of 129 Escherichia coli transposon mutants identified sbcB, a 3'→5' DNA exonuclease, as a key genetic determinant in impeding prime editing in E. coli, combinational deletions of which with two additional 3'→5' DNA exonucleases, xseA and exoX, drastically enhanced the prime editing efficiency by up to 100-fold. Efficient prime editing in wild-type E. coli can be achieved by simultaneously inhibiting the DNA exonucleases via CRISPRi. Our results pave the way for versatile applications of prime editing for bacterial genome engineering.
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