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1.
Sci Rep ; 14(1): 13074, 2024 06 06.
Article in English | MEDLINE | ID: mdl-38844784

ABSTRACT

While adaptive immune responses have been studied extensively in SLE (systemic lupus erythematosus), there is limited and contradictory evidence regarding the contribution of natural killer (NK) cells to disease pathogenesis. There is even less evidence about the role of NK cells in the more severe phenotype with juvenile-onset (J)SLE. In this study, analysis of the phenotype and function of NK cells in a large cohort of JSLE patients demonstrated that total NK cells, as well as perforin and granzyme A expressing NK cell populations, were significantly diminished in JSLE patients compared to age- and sex-matched healthy controls. The reduction in NK cell frequency was associated with increased disease activity, and transcriptomic analysis of NK populations from active and low disease activity JSLE patients versus healthy controls confirmed that disease activity was the main driver of differential NK cell gene expression. Pathway analysis of differentially expressed genes revealed an upregulation of interferon-α responses and a downregulation of exocytosis in active disease compared to healthy controls. Further gene set enrichment analysis also demonstrated an overrepresentation of the apoptosis pathway in active disease. This points to increased propensity for apoptosis as a potential factor contributing to NK cell deficiency in JSLE.


Subject(s)
Killer Cells, Natural , Lupus Erythematosus, Systemic , Humans , Killer Cells, Natural/immunology , Killer Cells, Natural/metabolism , Lupus Erythematosus, Systemic/genetics , Lupus Erythematosus, Systemic/immunology , Lupus Erythematosus, Systemic/pathology , Female , Male , Adolescent , Child , Phenotype , Granzymes/metabolism , Granzymes/genetics , Perforin/metabolism , Perforin/genetics , Apoptosis/genetics , Transcriptome , Gene Expression Profiling , Case-Control Studies
2.
Prenat Diagn ; 44(4): 465-479, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38441167

ABSTRACT

OBJECTIVES: In October 2020, rapid prenatal exome sequencing (pES) was introduced into routine National Health Service (NHS) care in England. This study aimed to explore parent experiences and their information and support needs from the perspective of parents offered pES and of health professionals involved in its delivery. METHODS: In this qualitative study, semi-structured interviews were conducted with 42 women and 6 male partners and 63 fetal medicine and genetic health professionals. Interviews were transcribed verbatim and analysed using thematic analysis. RESULTS: Overall views about pES were positive and parents were grateful to be offered the test. Highlighted benefits of pES included the value of the additional information for pregnancy management and planning for future pregnancies. An anxious wait for results was common, often associated with the need to make decisions near to 24 weeks in pregnancy when there are legal restrictions for late termination. Descriptions of dealing with uncertainty were also common, even when results had been returned. Many parents described pES results as informing decision-making around whether or not to terminate pregnancy. Some professionals were concerned that a non-informative result could be overly reassuring and highlighted that careful counselling was needed to ensure parents have a good understanding of what the result means for their pregnancy. Emotional support from professionals was valued; however, some parents felt that post-test support was lacking. CONCLUSION: Parents and professionals welcomed the introduction of pES. Results inform parents' decision-making around the termination of pregnancy. When there are no diagnostic findings or uncertain findings from pES, personalised counselling that considers scans and other tests are crucial. Directing parents to reliable online sources of information and providing emotional support throughout could improve their experiences of care.


Subject(s)
Parents , State Medicine , Pregnancy , Humans , Male , Female , Exome Sequencing , Parents/psychology , England , Counseling , Qualitative Research
3.
Front Oncol ; 13: 1277556, 2023.
Article in English | MEDLINE | ID: mdl-38125950

ABSTRACT

Introduction: The early identification of good responders to neoadjuvant chemotherapy (NACT) holds a significant potential in the optimal treatment of breast cancer. A recent Bayesian approach has been postulated to improve the accuracy of the intravoxel incoherent motion (IVIM) model for clinical translation. This study examined the prediction and early sensitivity of Bayesian IVIM to NACT response. Materials and methods: Seventeen female patients with breast cancer were scanned at baseline and 16 patients were scanned after Cycle 1. Tissue diffusion and perfusion from Bayesian IVIM were calculated at baseline with percentage change at Cycle 1 computed with reference to baseline. Cellular proliferative activity marker Ki-67 was obtained semi-quantitatively with percentage change at excision computed with reference to core biopsy. Results: The perfusion fraction showed a significant difference (p = 0.042) in percentage change between responder groups at Cycle 1, with a decrease in good responders [-7.98% (-19.47-1.73), n = 7] and an increase in poor responders [10.04% (5.09-28.93), n = 9]. There was a significant correlation between percentage change in perfusion fraction and percentage change in Ki-67 (p = 0.042). Tissue diffusion and pseudodiffusion showed no significant difference in percentage change between groups at Cycle 1, nor was there a significant correlation against percentage change in Ki-67. Perfusion fraction, tissue diffusion, and pseudodiffusion showed no significant difference between groups at baseline, nor was there a significant correlation against Ki-67 from core biopsy. Conclusion: The alteration in tumour perfusion fraction from the Bayesian IVIM model, in association with cellular proliferation, showed early sensitivity to good responders in NACT. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT03501394, identifier NCT03501394.

4.
Nucleic Acids Res ; 51(15): 8217-8236, 2023 08 25.
Article in English | MEDLINE | ID: mdl-37326024

ABSTRACT

AlphaFold2 and related computational tools have greatly aided studies of structural biology through their ability to accurately predict protein structures. In the present work, we explored AF2 structural models of the 17 canonical members of the human PARP protein family and supplemented this analysis with new experiments and an overview of recent published data. PARP proteins are typically involved in the modification of proteins and nucleic acids through mono or poly(ADP-ribosyl)ation, but this function can be modulated by the presence of various auxiliary protein domains. Our analysis provides a comprehensive view of the structured domains and long intrinsically disordered regions within human PARPs, offering a revised basis for understanding the function of these proteins. Among other functional insights, the study provides a model of PARP1 domain dynamics in the DNA-free and DNA-bound states and enhances the connection between ADP-ribosylation and RNA biology and between ADP-ribosylation and ubiquitin-like modifications by predicting putative RNA-binding domains and E2-related RWD domains in certain PARPs. In line with the bioinformatic analysis, we demonstrate for the first time PARP14's RNA-binding capability and RNA ADP-ribosylation activity in vitro. While our insights align with existing experimental data and are probably accurate, they need further validation through experiments.


Subject(s)
Poly(ADP-ribose) Polymerase Inhibitors , Poly(ADP-ribose) Polymerases , Humans , Poly(ADP-ribose) Polymerases/metabolism , Protein Domains , ADP-Ribosylation , RNA/metabolism
5.
Emerg Microbes Infect ; 12(1): 2204155, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37070526

ABSTRACT

Between January 2015 and October 2022, 38 patients with culture-confirmed melioidosis were identified in the Kowloon West (KW) Region, Hong Kong. Notably, 30 of them were clustered in the Sham Shui Po (SSP) district, which covers an estimated area of 2.5 km2. Between August and October 2022, 18 patients were identified in this district after heavy rainfall and typhoons. The sudden upsurge in cases prompted an environmental investigation, which involved collecting 20 air samples and 72 soil samples from residential areas near the patients. A viable isolate of Burkholderia pseudomallei was obtained from an air sample collected at a building site five days after a typhoon. B. pseudomallei DNA was also detected in 21 soil samples collected from the building site and adjacent gardening areas using full-length 16S rRNA gene sequencing, suggesting that B. psuedomallei is widely distributed in the soil environment surrounding the district. Core genome-multilocus sequence typing showed that the air sample isolate was phylogenetically clustered with the outbreak isolates in KW Region. Multispectral satellite imagery revealed a continuous reduction in vegetation region in SSP district by 162,255 m2 from 2016 to 2022, supporting the hypothesis of inhalation of aerosols from the contaminated soil as the transmission route of melioidosis during extreme weather events. This is because the bacteria in unvegetated soil are more easily spread by winds. In consistent with inhalational melioidosis, 24 (63.2%) patients had pneumonia. Clinicians should be aware of melioidosis during typhoon season and initiate appropriate investigation and treatment for patients with compatible symptoms.


Subject(s)
Burkholderia pseudomallei , Cyclonic Storms , Melioidosis , Humans , Melioidosis/diagnosis , Hong Kong , Seasons , RNA, Ribosomal, 16S , Respiratory Aerosols and Droplets , Disease Outbreaks , China
7.
Front Oncol ; 12: 908026, 2022.
Article in English | MEDLINE | ID: mdl-36387109

ABSTRACT

Background: While the efficacy of immune checkpoint inhibitors (ICIs) is increasingly recognized in advanced gastric cancer (aGC), overall survival (OS) has not been consistently improved across the different randomized controlled trials (RCTs). This meta-analysis aimed to quantify the efficacy and safety of ICI and explore potential predictive tumor tissue biomarkers in aGC. Methods: A random-effect pairwise meta-analysis was used to evaluate the primary outcome of OS. Sensitivity analysis was performed to investigate the effects of ICIs on PD-L1 status, TMB, MSI-H, and the Asian patient population. We extracted the OS Kaplan-Meier curves from the included trials to compare the effect of PD-L1 status on response to ICIs using DigitizeIt 2.5 and Guyot's algorithm. Results: A pairwise meta-analysis of seven RCTs included in this study showed that ICIs were more effective than the comparator in improving OS (pooled HR: 0.84). We demonstrated that PD-1 ICIs were additive when combined with the comparator arm (pooled HR: 0.79). A sensitivity analysis showed that PD-1 ICIs were associated with better OS outcomes in the Asian patient population as monotherapy (pooled HR: 0.66) or in combination with chemotherapy (pooled HR: 0.83). We demonstrated that tumors with PD-L1 ≥1 (P = 0.02) and PD-L1 ≥10 (P = 0.006) derived OS benefit from ICI monotherapy. Equally, MSI-H (P <0.00001) and TMB-high (P <0.0001) tumors derived favorable survival benefits from ICIs. Conclusions and relevance: The results of this meta-analysis suggest that ICIs result in improved OS outcomes in aGC. The benefits varied with different ethnicities, class of ICI, PD-L1 expression, MSI status, and TMB. Systematic Review Registration: https://www.crd.york.ac.uk/prospero, identifier (CRD42019137829).

9.
Front Public Health ; 10: 928107, 2022.
Article in English | MEDLINE | ID: mdl-35832284

ABSTRACT

Background: The COVID-19 pandemic is an unprecedented global public health crisis that continues to exert immense pressure on healthcare and related professional staff and services. The impact on staff wellbeing is likely to be influenced by a combination of modifiable and non-modifiable factors. Objectives: The aim of this study is to evaluate the effect of the COVID-19 pandemic on the self-reported wellbeing, resilience, and job satisfaction of National Health Service (NHS) and university staff working in the field of healthcare and medical research. Methods: We conducted a cross sectional survey of NHS and UK university staff throughout the COVID-19 pandemic between May-November 2020. The anonymous and voluntary survey was disseminated through social media platforms, and via e-mail to members of professional and medical bodies. The data was analyzed using descriptive and regression (R) statistics. Results: The enjoyment of work and satisfaction outside of work was significantly negatively impacted by the COVID-19 pandemic for all of staff groups independent of other variables. Furthermore, married women reporting significantly lower wellbeing than married men (P = 0.028). Additionally, the wellbeing of single females was significantly lower than both married women and men (P = 0.017 and P < 0.0001, respectively). Gender differences were also found in satisfaction outside of work, with women reporting higher satisfaction than men before the COVID-19 pandemic (P = 0.0002). Conclusion: Our study confirms that the enjoyment of work and general satisfaction of staff members has been significantly affected by the first wave of the COVID-19 pandemic. Interestingly, being married appears to be a protective factor for wellbeing and resilience but the effect may be reversed for life satisfaction outside work. Our survey highlights the critical need for further research to examine gender differences using a wider range of methods.


Subject(s)
COVID-19 , Pandemics , COVID-19/epidemiology , Cross-Sectional Studies , Female , Health Personnel , Humans , Job Satisfaction , Male , Marital Status , Sex Factors , State Medicine , United Kingdom/epidemiology
10.
Rheumatol Adv Pract ; 6(2): rkac031, 2022.
Article in English | MEDLINE | ID: mdl-35591904

ABSTRACT

Objectives: We report the results of a pilot young patient survey that targeted patients with JSLE and JDM, exploring well-being, resilience and general concern about the coronavirus disease 2019 (COVID-19) pandemic as well as self-assessment of disease activity. Methods: The survey was completed anonymously by patients who had been approached via the automatically generated hospital database between June and December 2020. In addition to disease characteristics, geographic location, education and employment level, we explored young patients' resilience, mood and feelings, mental well-being, self-assessed disease activity and general COVID-19 concerns using validated tools and visual analogue scales. Results: This pilot study found that self-perceived disease activity was the strongest predictor of COVID-19 concern, irrespective of gender, employment and education status or well-being and resilience. Generalized concerns regarding the COVID-19 pandemic were significantly higher in females, although their self-reported DASs were comparable to male respondents. Conclusion: Our findings highlight a gender bias in the generalized concern related to the COVID-19 pandemic, irrespective of the examined potential confounders. This suggests the need for further research around young patient self-reported outcomes outside hospital visits, especially in the context of gender differences and potential challenges of future pandemics.

11.
J Geriatr Oncol ; 13(5): 563-571, 2022 06.
Article in English | MEDLINE | ID: mdl-35078741

ABSTRACT

Breast cancer is the most common type of cancer affecting women worldwide and its risk increases with age. Compared with other breast cancer subtypes, triple negative breast cancer (TNBC) behaves more aggressively, with earlier relapses and poorer survival outcomes. Although the incidence of TNBC decreases with age, it still affects about 10% of older women with breast cancer. The management of TNBC in older patients is particularly challenging as chemotherapy is the main treatment choice in both early and advanced diseases and older patients are often prone to increased treatment-related toxicities. This review highlights the specific considerations in this vulnerable group of patients and summarizes the current evidence for TNBC management in older adults from early to late stage of disease.


Subject(s)
Triple Negative Breast Neoplasms , Aged , Female , Humans , Triple Negative Breast Neoplasms/drug therapy
12.
NIHR Open Res ; 2: 10, 2022.
Article in English | MEDLINE | ID: mdl-35935673

ABSTRACT

Background: Prenatal exome sequencing (ES) for the diagnosis of fetal anomalies was implemented nationally in England in October 2020 by the NHS Genomic Medicine Service (GMS). is the GMS is based around seven regional Genomic Laboratory Hubs (GLHs). Prenatal ES has the potential to significantly improve NHS prenatal diagnostic services by increasing genetic diagnoses and informing prenatal decision-making. Prenatal ES has not previously been offered routinely in a national healthcare system and there are gaps in knowledge and guidance. Methods: Our mixed-methods evaluation commenced in October 2020, aligning with the start date of the NHS prenatal ES service . Study design draws on a framework developed in previous studies of major system innovation. There are five interrelated workstreams. Workstream-1 will use interviews and surveys with professionals, non-participant observations and documentary analysis to produce in-depth case studies across all GLHs. Data collection at multiple time points will track changes over time. In Workstream-2 qualitative interviews with parents offered prenatal ES will explore experiences and establish information and support needs. Workstream-3 will analyse data from all prenatal ES tests for nine-months to establish service outcomes (e.g. diagnostic yield, referral rates, referral sources). Comparisons between GLHs will identify factors (individual or service-related) associated with any variation in outcomes. Workstream-4 will identify and analyse practical ethical problems. Requirements for an effective ethics framework for an optimal and equitable service will be determined. Workstream-5 will assess costs and cost-effectiveness of prenatal ES versus standard tests and evaluate costs of implementing an optimal prenatal ES care pathway. Integration of findings will determine key features of an optimal care pathway from a service delivery, parent and professional perspective. Discussion: The proposed formative and summative evaluation will inform the evolving prenatal ES service to ensure equity of access, high standards of care and benefits for parents across England.


BACKGROUND: Prenatal exome sequencing is a new test that is offered through the NHS Genomic Medicine Service. Prenatal exome sequencing is offered to pregnant women when ultrasound scans suggest that their baby may have a genetic condition that cannot be diagnosed using standard tests. If a genetic condition is diagnosed this can give parents important information about the outlook for their baby. It can also help with their decisions about whether to continue or end the pregnancy, pregnancy management, post-birth care and future pregnancies. STUDY METHODS: The aim of this study is to evaluate the prenatal exome sequencing service. To do this we will; 1. Study how prenatal exome sequencing is delivered across England using surveys and interviews with professionals.2. Interview parents to ask what they think of prenatal exome sequencing and how support and information could be improved3. Look at how many parents have prenatal exome sequencing and the test results. We will look carefully at who has access to the test and whether any particular groups are less likely to be offered testing.4. Conduct workshops with health professionals and parents to identify any practical or ethical problems that arise when prenatal exome sequencing is offered.5. Look at the cost of prenatal exome sequencing and compare it to the cost of other tests that are offered to diagnose genetic conditions in pregnancy.6. Gather our findings together to make recommendations for best practice. Patient and Public Involvement: A patient and public Involvement, engagement and participation (PPIEP) advisory group will work closely with the research team to design the study and develop study materials. They will also help us understand our findings to make sure the information and recommendations that come out of our research will be helpful to parents and the NHS.

14.
Rheumatol Adv Pract ; 5(3): rkab058, 2021.
Article in English | MEDLINE | ID: mdl-34541451

ABSTRACT

OBJECTIVES: This aim of this study was to gain a better understanding of how parents and carers feel about the effects and impact of the coronavirus disease 2019 (COVID-19) pandemic lockdown and how this impacted upon their child/young person with JDM. METHOD: We approached 139 participants from the JDM Cohort Biomarker Study (JDCBS), with specific consent to approach electronically for research studies. A secure electronic questionnaire with study introduction was sent to participants for their parents and carers around the UK to complete. It consisted of 20 questions about the impact of the pandemic on their child or young person's clinical care. Data were analysed quantitatively and qualitatively. RESULTS: There were 76 (55%) responses to the survey. More than 50% of participants were actively being treated for their JDM at the point of survey completion as recorded by their parent or carer. More than 40% attested to disrupted treatment owing to COVID-19. The biggest impact upon clinical care was cancellation of appointments, initiating virtual appointments and extension of time between blood tests. Parents and carers expressed their own feelings of worry, concern and anxiety, but also those of their child or young person. CONCLUSION: Families who have a child or young person with JDM have been affected by COVID-19. Qualitative comments highlight that it has been a very difficult time. Further investigation is required into this area and could be compared with research on the effects of COVID-19 on other patient groups with chronic disease.

15.
J Virol ; 95(12)2021 05 24.
Article in English | MEDLINE | ID: mdl-33827945

ABSTRACT

Immune memory represents the most efficient defense against invasion and transmission of infectious pathogens. In contrast to memory T and B cells, the roles of innate immunity in recall responses remain inconclusive. In this study, we identified a novel mouse spleen NK cell subset expressing NKp46 and NKG2A induced by intranasal influenza virus infection. These memory NK cells specifically recognize N-linked glycosylation sites on influenza hemagglutinin (HA) protein. Different from memory-like NK cells reported previously, these NKp46+ NKG2A+ memory NK cells exhibited HA-specific silence of cytotoxicity but increase of gamma interferon (IFN-γ) response against influenza virus-infected cells, which could be reversed by pifithrin-µ, a p53-heat shock protein 70 (HSP70) signaling inhibitor. During recall responses, splenic NKp46+ NKG2A+ NK cells were recruited to infected lung and modulated viral clearance of virus and CD8+ T cell distribution, resulting in improved clinical outcomes. This long-lived NK memory bridges innate and adaptive immune memory response and promotes the homeostasis of local environment during recall response.IMPORTANCE In this study, we demonstrate a novel hemagglutinin (HA)-specific NKp46+ NKG2A+ NK cell subset induced by influenza A virus infection. These memory NK cells show virus-specific decreased cytotoxicity and increased gamma interferon (IFN-γ) on reencountering the same influenza virus antigen. In addition, they modulate host recall responses and CD8 T cell distribution, thus bridging the innate immune and adaptive immune responses during influenza virus infection.


Subject(s)
Hemagglutinin Glycoproteins, Influenza Virus/immunology , Immunologic Memory , Influenza A Virus, H1N1 Subtype/immunology , Killer Cells, Natural/immunology , Orthomyxoviridae Infections/immunology , Adoptive Transfer , Animals , Antigens, Ly/analysis , Antigens, Ly/metabolism , Benzothiazoles/pharmacology , CD8-Positive T-Lymphocytes/immunology , Coculture Techniques , Cytotoxicity, Immunologic , Dendritic Cells/immunology , Influenza A Virus, H9N2 Subtype/immunology , Interferon-gamma/metabolism , Killer Cells, Natural/drug effects , Mice , Mice, Inbred C57BL , NK Cell Lectin-Like Receptor Subfamily C/analysis , Natural Cytotoxicity Triggering Receptor 1/analysis , Natural Cytotoxicity Triggering Receptor 1/metabolism , Spleen/cytology , Spleen/immunology , Toluene/analogs & derivatives , Toluene/pharmacology
17.
Nat Commun ; 10(1): 498, 2019 01 30.
Article in English | MEDLINE | ID: mdl-30700717

ABSTRACT

The mechanisms controlling CD4+ T cell switching from an effector to an anti-inflammatory (IL-10+) phenotype play an important role in the persistence of chronic inflammatory diseases. Here, we identify the cholesterol biosynthesis pathway as a key regulator of this process. Pathway analysis of cultured cytokine-producing human T cells reveals a significant association between IL-10 and cholesterol metabolism gene expression. Inhibition of the cholesterol biosynthesis pathway with atorvastatin or 25-hydroxycholesterol during switching from IFNγ+ to IL-10+ shows a specific block in immune resolution, defined as a significant decrease in IL-10 expression. Mechanistically, the master transcriptional regulator of IL10 in T cells, c-Maf, is significantly decreased by physiological levels of 25-hydroxycholesterol. Strikingly, progression to rheumatoid arthritis is associated with altered expression of cholesterol biosynthesis genes in synovial biopsies of predisposed individuals. Our data reveal a link between sterol metabolism and the regulation of the anti-inflammatory response in human CD4+ T cells.


Subject(s)
Cholesterol/biosynthesis , Interferon-gamma/metabolism , Interleukin-10/metabolism , Th1 Cells/metabolism , Atorvastatin/pharmacology , Humans , Hydroxycholesterols/pharmacology , Th1 Cells/drug effects
19.
Nat Commun ; 7: 11208, 2016 Apr 07.
Article in English | MEDLINE | ID: mdl-27052461

ABSTRACT

The production of megakaryocytes (MKs)--the precursors of blood platelets--from human pluripotent stem cells (hPSCs) offers exciting clinical opportunities for transfusion medicine. Here we describe an original approach for the large-scale generation of MKs in chemically defined conditions using a forward programming strategy relying on the concurrent exogenous expression of three transcription factors: GATA1, FLI1 and TAL1. The forward programmed MKs proliferate and differentiate in culture for several months with MK purity over 90% reaching up to 2 × 10(5) mature MKs per input hPSC. Functional platelets are generated throughout the culture allowing the prospective collection of several transfusion units from as few as 1 million starting hPSCs. The high cell purity and yield achieved by MK forward programming, combined with efficient cryopreservation and good manufacturing practice (GMP)-compatible culture, make this approach eminently suitable to both in vitro production of platelets for transfusion and basic research in MK and platelet biology.


Subject(s)
Basic Helix-Loop-Helix Transcription Factors/genetics , Cellular Reprogramming , GATA1 Transcription Factor/genetics , Megakaryocytes/cytology , Pluripotent Stem Cells/cytology , Proto-Oncogene Protein c-fli-1/genetics , Proto-Oncogene Proteins/genetics , Basic Helix-Loop-Helix Transcription Factors/metabolism , Blood Platelets/cytology , Blood Platelets/metabolism , Cell Culture Techniques , Cell Differentiation , Cell Proliferation , Cryopreservation/methods , GATA1 Transcription Factor/metabolism , Gene Expression Regulation , Genes, Reporter , Genetic Vectors , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Humans , Lentivirus/genetics , Megakaryocytes/metabolism , Microarray Analysis , Pluripotent Stem Cells/metabolism , Proto-Oncogene Protein c-fli-1/metabolism , Proto-Oncogene Proteins/metabolism , Signal Transduction , T-Cell Acute Lymphocytic Leukemia Protein 1 , Transduction, Genetic , Transgenes
20.
Mol Cell ; 60(5): 742-754, 2015 Dec 03.
Article in English | MEDLINE | ID: mdl-26626479

ABSTRACT

Poly(ADP-ribose)polymerase 1 (PARP-1) is a key eukaryotic stress sensor that responds in seconds to DNA single-strand breaks (SSBs), the most frequent genomic damage. A burst of poly(ADP-ribose) synthesis initiates DNA damage response, whereas PARP-1 inhibition kills BRCA-deficient tumor cells selectively, providing the first anti-cancer therapy based on synthetic lethality. However, the mechanism underlying PARP-1's function remained obscure; inherent dynamics of SSBs and PARP-1's multi-domain architecture hindered structural studies. Here we reveal the structural basis of SSB detection and how multi-domain folding underlies the allosteric switch that determines PARP-1's signaling response. Two flexibly linked N-terminal zinc fingers recognize the extreme deformability of SSBs and drive co-operative, stepwise self-assembly of remaining PARP-1 domains to control the activity of the C-terminal catalytic domain. Automodification in cis explains the subsequent release of monomeric PARP-1 from DNA, allowing repair and replication to proceed. Our results provide a molecular framework for understanding PARP inhibitor action and, more generally, allosteric control of dynamic, multi-domain proteins.


Subject(s)
DNA Breaks, Single-Stranded , DNA/metabolism , Poly(ADP-ribose) Polymerases/chemistry , Poly(ADP-ribose) Polymerases/metabolism , Catalytic Domain , Crystallography, X-Ray , DNA/chemistry , DNA Repair , Humans , Magnetic Resonance Spectroscopy , Models, Molecular , Nucleic Acid Conformation , Poly (ADP-Ribose) Polymerase-1 , Protein Folding , Zinc Fingers
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