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Leszczynska KB, Dzwigonska M, Estephan H, Moehlenbrink J, Bowler E, Giaccia AJ, Mieczkowski J, Kaminska B, Hammond EM. Hypoxia-mediated regulation of DDX5 through decreased chromatin accessibility and post-translational targeting restricts R-loop accumulation. Mol Oncol 2023. [PMID: 37013907 DOI: 10.1002/1878-0261.13431] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/03/2023] [Indexed: 04/05/2023] Open
Abstract
Local hypoxia occurs in most solid tumors and is associated with aggressive disease and therapy resistance. Widespread changes in gene expression play a critical role in the biological response to hypoxia. However, most research has focused on hypoxia-inducible genes as opposed to those which are decreased in hypoxia. We demonstrate that chromatin accessibility is decreased in hypoxia, predominantly at gene promoters and specific pathways are impacted including DNA repair, splicing and the R-loop interactome. One of the genes with decreased chromatin accessibility in hypoxia was DDX5, encoding the RNA helicase, DDX5, which showed reduced expression in various cancer cell lines in hypoxic conditions, tumor xenografts and in patient samples with hypoxic tumors. Most interestingly, we found that when DDX5 is rescued in hypoxia, replication stress and R-loop levels accumulate further, demonstrating that hypoxia-mediated repression of DDX5 restricts R-loop accumulation. Together these data support the hypothesis that a critical part of the biological response to hypoxia is the repression of multiple R-loop processing factors, however, as shown for DDX5, their role is specific and distinct.
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Affiliation(s)
- Katarzyna B Leszczynska
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford, OX3 7DQ, UK
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Monika Dzwigonska
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Hala Estephan
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford, OX3 7DQ, UK
| | - Jutta Moehlenbrink
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford, OX3 7DQ, UK
| | - Elizabeth Bowler
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford, OX3 7DQ, UK
| | - Amato J Giaccia
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford, OX3 7DQ, UK
| | - Jakub Mieczkowski
- 3P-Medicine Laboratory, Medical University of Gdansk, Gdansk, Poland
| | - Bozena Kaminska
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Ester M Hammond
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford, OX3 7DQ, UK
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Riddell V, Betteridge Z, Bowler E, Chinoy H, Gordon P, Wedderburn L, Bagby S, Mchugh N, Tansley S. P224 Anti-PARP1 as a novel autoantibody in myositis. Rheumatology (Oxford) 2022. [DOI: 10.1093/rheumatology/keac133.223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background/Aims
Idiopathic inflammatory myopathies (IIM) are multisystem diseases characterised by muscle inflammation. Over 60% of patients with IIM have a myositis-related autoantibody. Our laboratory specialises in autoantibody testing. We offer an extended spectrum autoantibody testing diagnostic service and have also screened over 3000 myositis patients enrolled in research studies for the presence of autoantibodies. We noticed a recurring pattern following K562 cell radio-immunoprecipitation that was present in several myositis patient sera and in a handful of samples that came to us via the diagnostic service. We set out to determine the antigenic target of this novel autoantibody.
Methods
We have previously screened 1319 serum/plasma samples from IIM patients enrolled in the UKMyoNet and 380 from patients with juvenile onset IIM enrolled in the JDCBS for autoantibodies by immunoprecipitation. Additional cohorts similarly investigated include >150 healthy control sera and >400 SLE patient sera. Patients with the novel autoantibody of interest were identified by a distinctive 120kDa band associated with a ‘smear’ on autoradiography following K562 cell immunoprecipitation and separation of autoantigens by SDS PAGE. ESI-QTOF mass spectrometry was used to identify the antigenic target in an example serum. Using a commercial anti-PARP1 antibody as a control, western blotting of K562 and PARP1 overexpressed cell lysate was used to confirm the antigenic target in remaining samples of interest. Indirect immunofluorescence was performed on HEp-2 cells according to manufacturers’ instructions.
Results
11 patient samples were identified as having the 120 complex ‘smear’ pattern of interest: six had been received via the diagnostic service and five were enrolled in UKMyoNet. Prevalence in the UKMyoNet cohort was 0.4%. Mass spectrometry identified PARP1 as the antigenic target. This was confirmed in all remaining samples by western blot. Table 1 shows available clinical data.
Conclusion
PARP1 is an autoantigen target in myositis patients in addition to those with other rheumatic diseases. Where data was available, patients with anti-PARP1 had features suggesting an anti-synthetase syndrome phenotype, but this may primarily relate to the other autoantibodies present. Further work is needed to determine the prevalence of anti-PARP1 in other cohorts and its clinical associations.
Disclosure
V. Riddell: Grants/research support; Bath Institute of Rheumatic Disease. Z. Betteridge: None. E. Bowler: None. H. Chinoy: None. P. Gordon: None. L. Wedderburn: None. S. Bagby: None. N. Mchugh: None. S. Tansley: None.
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Affiliation(s)
- Victoria Riddell
- Biology and Biochemistry, University of Bath, Bath, UNITED KINGDOM
| | - Zoe Betteridge
- Pharmacy and Pharmacology, University of Bath, Bath, UNITED KINGDOM
| | - Elizabeth Bowler
- Pharmacy and Pharmacology, University of Bath, Bath, UNITED KINGDOM
| | - Hector Chinoy
- Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UNITED KINGDOM
| | - Patrick Gordon
- NHS Foundation Trust, King's College London, London, UNITED KINGDOM
| | - Lucy Wedderburn
- Infection, Immunity and Inflammation, UCL GOS Institute of Child Health, London, UNITED KINGDOM
- Centre for Adolescent Rheumatology Versus Arthritis, UCL, London, UNITED KINGDOM
| | - Stefan Bagby
- Biology and Biochemistry, University of Bath, Bath, UNITED KINGDOM
| | - Neil Mchugh
- Pharmacy and Pharmacology, University of Bath, Bath, UNITED KINGDOM
| | - Sarah Tansley
- Pharmacy and Pharmacology, University of Bath, Bath, UNITED KINGDOM
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Bowler E, Skwarska A, Wilson JD, Ramachandran S, Bolland H, Easton A, Ostheimer C, Hwang MS, Leszczynska KB, Conway SJ, Hammond EM. Pharmacological Inhibition of ATR Can Block Autophagy through an ATR-Independent Mechanism. iScience 2020; 23:101668. [PMID: 33134898 PMCID: PMC7588853 DOI: 10.1016/j.isci.2020.101668] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/25/2020] [Accepted: 10/07/2020] [Indexed: 12/26/2022] Open
Abstract
Inhibition of the ATR kinase has emerged as a therapeutically attractive means to target cancer since the development of potent inhibitors, which are now in clinical testing. We investigated a potential link between ATR inhibition and the autophagy process in esophageal cancer cells using four ATR inhibitors including two in clinical testing. The response to pharmacological ATR inhibitors was compared with genetic systems to investigate the ATR dependence of the effects observed. The ATR inhibitor, VX-970, was found to lead to an accumulation of p62 and LC3-II indicative of a blocked autophagy. This increase in p62 occurred post-transcriptionally and in all the cell lines tested. However, our data indicate that the accumulation of p62 occurred in an ATR-independent manner and was instead an off-target response to the ATR inhibitor. This study has important implications for the clinical response to pharmacological ATR inhibition, which in some cases includes the blockage of autophagy.
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Affiliation(s)
- Elizabeth Bowler
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Anna Skwarska
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Joseph D. Wilson
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Shaliny Ramachandran
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Hannah Bolland
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Alistair Easton
- Translational Histopathology Lab, Oxford Cancer Centre, Oxford OX3 7DQ, UK
| | - Christian Ostheimer
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Ming-Shih Hwang
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
| | - Katarzyna B. Leszczynska
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Stuart J. Conway
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Ester M. Hammond
- Oxford Institute for Radiation Oncology, Department of Oncology, The University of Oxford, Oxford OX3 7DQ, UK
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Stevens M, Star E, Lee M, Innes E, Li L, Bowler E, Harper S, Bates DO, Oltean S. The VEGF-A exon 8 splicing-sensitive fluorescent reporter mouse is a novel tool to assess the effects of splicing regulatory compounds in vivo. RNA Biol 2019; 16:1672-1681. [PMID: 31432737 PMCID: PMC6844573 DOI: 10.1080/15476286.2019.1652522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Vascular endothelial growth factor (VEGF)-A is differentially spliced to give two functionally different isoform families; pro-angiogenic, pro-permeability VEGF-Axxx and anti-angiogenic, anti-permeability VEGF-Axxxb. VEGF-A splicing is dysregulated in several pathologies, including cancer, diabetes, and peripheral arterial disease. The bichromatic VEGF-A splicing-sensitive fluorescent reporter harboured in a transgenic mouse is a novel approach to investigate the splicing patterns of VEGF-A in vivo. We generated a transgenic mouse harbouring a splicing-sensitive fluorescent reporter designed to mimic VEGF-A terminal exon splicing (VEGF8ab) by insertion into the ROSA26 genomic locus. dsRED expression denotes proximal splice site selection (VEGF-Axxx) and eGFP expression denotes distal splice site selection (VEGF-Axxxb). We investigated the tissue-specific expression patterns in the eye, skeletal muscle, cardiac muscle, kidney, and pancreas, and determined whether the splicing pattern could be manipulated in the same manner as endogenous VEGF-A by treatment with the SRPK1 inhibitor SPHINX 31. We confirmed expression of both dsRED and eGFP in the eye, skeletal muscle, cardiac muscle, kidney, and pancreas, with the highest expression of both fluorescent proteins observed in the exocrine pancreas. The ratio of dsRED and eGFP matched that of endogenous VEGF-Axxx and VEGF-Axxxb. Treatment of the VEGF8ab mice with SPHINX 31 increased the mRNA and protein eGFP/dsRED ratio in the exocrine pancreas, mimicking endogenous VEGF-A splicing. The VEGF-A exon 8 splicing-sensitive fluorescent reporter mouse is a novel tool to assess splicing regulation in the individual cell-types and tissues, which provides a useful screening process for potentially therapeutic splicing regulatory compounds in vivo.
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Affiliation(s)
- M Stevens
- Institute of Biomedical and Clinical Science, Medical School, College of Medicine and Health, University of Exeter, Exeter, UK
| | - E Star
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - M Lee
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - E Innes
- Institute of Biomedical and Clinical Science, Medical School, College of Medicine and Health, University of Exeter, Exeter, UK
| | - L Li
- Institute of Biomedical and Clinical Science, Medical School, College of Medicine and Health, University of Exeter, Exeter, UK
| | - E Bowler
- Institute of Biomedical and Clinical Science, Medical School, College of Medicine and Health, University of Exeter, Exeter, UK
| | - S Harper
- Institute of Biomedical and Clinical Science, Medical School, College of Medicine and Health, University of Exeter, Exeter, UK.,School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK
| | - D O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK
| | - S Oltean
- Institute of Biomedical and Clinical Science, Medical School, College of Medicine and Health, University of Exeter, Exeter, UK
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Abstract
Alternative splicing of pre-mRNA allows the generation of multiple splice isoforms from a given gene, which can have distinct functions. In fact, splice isoforms can have opposing functions and there are many instances whereby a splice isoform acts as an inhibitor of canonical isoform function, thereby adding an additional layer of regulation to important processes. Angiogenesis is an important process that is governed by alternative splicing mechanisms. This review focuses on the alternative spliced isoforms of key genes that are involved in the angiogenesis process; VEGF-A, VEGFR1, VEGFR2, NRP-1, FGFRs, Vasohibin-1, Vasohibin-2, HIF-1α, Angiopoietin-1 and Angiopoietin-2.
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Affiliation(s)
- Elizabeth Bowler
- Institute of Biomedical and Clinical Sciences, Medical School, College of Medicine and Health, University of Exeter, Exeter EX4 4PY, UK.
| | - Sebastian Oltean
- Institute of Biomedical and Clinical Sciences, Medical School, College of Medicine and Health, University of Exeter, Exeter EX4 4PY, UK.
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Abstract
A hypoxic environment can be defined as a region of the body or the whole body that is deprived of oxygen. Hypoxia is a feature of many diseases, such as cardiovascular disease, tissue trauma, stroke, and solid cancers. A loss of oxygen supply usually results in cell death; however, when cells gradually become hypoxic, they may survive and continue to thrive as described for conditions that promote metastatic growth. The role of hypoxia in these pathogenic pathways is therefore of great interest, and understanding the effect of hypoxia in regulating these mechanisms is fundamentally important. This chapter gives an extensive overview of these mechanisms. Moreover, given the challenges posed by tumor hypoxia we describe the current methods to simulate and detect hypoxic conditions followed by a discussion on current and experimental therapies that target hypoxic cells.
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Affiliation(s)
- Elizabeth Bowler
- College of Medicine and Health, University of Exeter Medical School, Exeter, UK.
| | - Michael R Ladomery
- Faculty Health and Applied Sciences, University of the West of England, Bristol, UK
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Liu D, Skomorovska Y, Song J, Bowler E, Harris R, Ravasz M, Bai S, Ayati M, Tamai K, Koyuturk M, Yuan X, Wang Z, Wang Y, Ewing R. ELF3 is an antagonist of oncogenic-signalling-induced expression of EMT-TF ZEB1. Cancer Biol Ther 2018; 20:90-100. [PMID: 30148686 PMCID: PMC6292503 DOI: 10.1080/15384047.2018.1507256] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/22/2018] [Accepted: 07/29/2018] [Indexed: 12/23/2022] Open
Abstract
Background: Epithelial-to-mesenchymal transition (EMT) is a key step in the transformation of epithelial cells into migratory and invasive tumour cells. Intricate positive and negative regulatory processes regulate EMT. Many oncogenic signalling pathways can induce EMT, but the specific mechanisms of how this occurs, and how this process is controlled are not fully understood. Methods: RNA-Seq analysis, computational analysis of protein networks and large-scale cancer genomics datasets were used to identify ELF3 as a negative regulator of the expression of EMT markers. Western blotting coupled to siRNA as well as analysis of tumour/normal colorectal cancer panels was used to investigate the expression and function of ELF3. Results: RNA-Seq analysis of colorectal cancer cells expressing mutant and wild-type β-catenin and analysis of colorectal cancer cells expressing inducible mutant RAS showed that ELF3 expression is reduced in response to oncogenic signalling and antagonizes Wnt and RAS oncogenic signalling pathways. Analysis of gene-expression patterns across The Cancer Genome Atlas (TCGA) and protein localization in colorectal cancer tumour panels showed that ELF3 expression is anti-correlated with β-catenin and markers of EMT and correlates with better clinical prognosis. Conclusions: ELF3 is a negative regulator of the EMT transcription factor (EMT-TF) ZEB1 through its function as an antagonist of oncogenic signalling.
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Affiliation(s)
- D Liu
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Y Skomorovska
- School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - J Song
- School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - E Bowler
- School of Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
| | - R Harris
- School of Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
| | - M Ravasz
- School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - S Bai
- School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - M Ayati
- Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio, USA
| | - K Tamai
- School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - M Koyuturk
- Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio, USA
| | - X Yuan
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Z Wang
- School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Y Wang
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- School of Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
| | - R.M. Ewing
- School of Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
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Uzor S, Zorzou P, Bowler E, Porazinski S, Wilson I, Ladomery M. Autoregulation of the human splice factor kinase CLK1 through exon skipping and intron retention. Gene 2018; 670:46-54. [PMID: 29802995 DOI: 10.1016/j.gene.2018.05.095] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/16/2018] [Accepted: 05/23/2018] [Indexed: 01/04/2023]
Abstract
Alternative splicing is a key process required for the regulation of gene expression in normal development and physiology. It is regulated by splice factors whose activities are in turn regulated by splice factor kinases and phosphatases. The CDC-like protein kinases are a widespread family of splice factor kinases involved in normal physiology and in several diseases including cancer. In humans they include the CLK1, CLK2, CLK3 and CLK4 genes. The expression of CLK1 is regulated through alternative splicing producing both full-length catalytically active and truncated catalytically inactive isoforms, CLKT1 (arising from exon 4 skipping) and CLKT2 (arising from intron 4 retention). We examined CLK1 alternative splicing in a range of cancer cell lines, and report widespread and highly variable rates of exon 4 skipping and intron 4 retention. We also examined the effect of severe environmental stress including heat shock, osmotic shock, and exposure to the alkaloid drug harmine on CLK1 alternative splicing in DU145 prostate cancer cells. All treatments rapidly reduced exon 4 skipping and intron 4 retention, shifting the balance towards full-length CLK1 expression. We also found that the inhibition of CLK1 with the benzothiazole TG003 reduced exon 4 skipping and intron 4 retention suggesting an autoregulatory mechanism. CLK1 inhibition with TG003 also resulted in modified alternative splicing of five cancer-associated genes.
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Affiliation(s)
- Simon Uzor
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, United Kingdom
| | - Panagiota Zorzou
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, United Kingdom
| | - Elizabeth Bowler
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, United Kingdom
| | - Sean Porazinski
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, United Kingdom
| | - Ian Wilson
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, United Kingdom
| | - Michael Ladomery
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, United Kingdom.
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Bowler E, Porazinski S, Uzor S, Thibault P, Durand M, Lapointe E, Rouschop KMA, Hancock J, Wilson I, Ladomery M. Hypoxia leads to significant changes in alternative splicing and elevated expression of CLK splice factor kinases in PC3 prostate cancer cells. BMC Cancer 2018; 18:355. [PMID: 29606096 PMCID: PMC5879922 DOI: 10.1186/s12885-018-4227-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 03/15/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mounting evidence suggests that one of the ways that cells adapt to hypoxia is through alternative splicing. The aim of this study was firstly to examine the effect of hypoxia on the alternative splicing of cancer associated genes using the prostate cancer cell line PC3 as a model. Secondly, the effect of hypoxia on the expression of several regulators of splicing was examined. METHODS PC3 cells were grown in 1% oxygen in a hypoxic chamber for 48 h, RNA extracted and sent for high throughput PCR analysis at the RNomics platform at the University of Sherbrooke, Canada. Genes whose exon inclusion rate PSI (ψ) changed significantly were identified, and their altered exon inclusion rates verified by RT-PCR in three cell lines. The expression of splice factors and splice factor kinases in response to hypoxia was examined by qPCR and western blotting. The splice factor kinase CLK1 was inhibited with the benzothiazole TG003. RESULTS In PC3 cells the exon inclusion rate PSI (ψ) was seen to change by > 25% in 12 cancer-associated genes; MBP, APAF1, PUF60, SYNE2, CDC42BPA, FGFR10P, BTN2A2, UTRN, RAP1GDS1, PTPN13, TTC23 and CASP9 (caspase 9). The expression of the splice factors SRSF1, SRSF2, SRSF3, SAM68, HuR, hnRNPA1, and of the splice factor kinases SRPK1 and CLK1 increased significantly in hypoxia. We also observed that the splice factor kinase CLK3, but not CLK2 and CLK4, was also induced in hypoxic DU145 prostate, HT29 colon and MCF7 breast cancer cell lines. Lastly, we show that the inhibition of CLK1 in PC3 cells with the benzothiazole TG003 increased expression of the anti-apoptotic isoform caspase 9b. CONCLUSIONS Significant changes in alternative splicing of cancer associated genes occur in prostate cancer cells in hypoxic conditions. The expression of several splice factors and splice factor kinases increases during hypoxia, in particular the Cdc-like splice factor kinases CLK1 and CLK3. We suggest that in hypoxia the elevated expression of these regulators of splicing helps cells adapt through alternative splicing of key cancer-associated genes. We suggest that the CLK splice factor kinases could be targeted in cancers in which hypoxia contributes to resistance to therapy.
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Affiliation(s)
- Elizabeth Bowler
- Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK
| | - Sean Porazinski
- Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK
| | - Simon Uzor
- Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK
| | - Philippe Thibault
- Z8 Pavillon de Recherche Appliquée sur le Cancer (PRAC), Université de Sherbrooke, 3201 Jean-Mignault, Sherbrooke, Québec, J1E 4K8, Canada
| | - Mathieu Durand
- Z8 Pavillon de Recherche Appliquée sur le Cancer (PRAC), Université de Sherbrooke, 3201 Jean-Mignault, Sherbrooke, Québec, J1E 4K8, Canada
| | - Elvy Lapointe
- Z8 Pavillon de Recherche Appliquée sur le Cancer (PRAC), Université de Sherbrooke, 3201 Jean-Mignault, Sherbrooke, Québec, J1E 4K8, Canada
| | - Kasper M A Rouschop
- Department of Radiation Oncology (Maastro Lab), GROW-School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands
| | - John Hancock
- Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK
| | - Ian Wilson
- Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK
| | - Michael Ladomery
- Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK.
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Chen Q, Xu H, Xu A, Ross T, Bowler E, Hu Y, Lesnefsky EJ. Inhibition of Bcl-2 sensitizes mitochondrial permeability transition pore (MPTP) opening in ischemia-damaged mitochondria. PLoS One 2015; 10:e0118834. [PMID: 25756500 PMCID: PMC4354902 DOI: 10.1371/journal.pone.0118834] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 01/15/2015] [Indexed: 11/21/2022] Open
Abstract
Background Mitochondria are critical to cardiac injury during reperfusion as a result of damage sustained during ischemia, including the loss of bcl-2. We asked if bcl-2 depletion not only leads to selective permeation of the outer mitochondrial membrane (MOMP) favoring cytochrome c release and programmed cell death, but also favors opening of the mitochondrial permeability transition pore (MPTP). An increase in MPTP susceptibility would support a role for bcl-2 depletion mediated cell death in the calcium overload setting of early reperfusion via MPTP as well as later in reperfusion via MOMP as myocardial calcium content normalizes. Methods Calcium retention capacity (CRC) was used to reflect the sensitivity of the MPTP opening in isolated cardiac mitochondria. To study the relationship between bcl-2 inhibition and MPTP opening, mitochondria were incubated with a bcl-2 inhibitor (HA14-1) and CRC measured. The contribution of preserved bcl-2 content to MPTP opening following ischemia-reperfusion was explored using transgenic bcl-2 overexpressed mice. Results CRC was decreased in mitochondria following reperfusion compared to ischemia alone, indicating that reperfusion further sensitizes to MPTP opening. Incubation of ischemia-damaged mitochondria with increasing HA14-1concentrations increased calcium-stimulated MPTP opening, supporting that functional inhibition of bcl-2 during simulated reperfusion favors MPTP opening. Moreover, HA14-1 sensitivity was increased by ischemia compared to non-ischemic controls. Overexpression of bcl-2 attenuated MPTP opening in following ischemia-reperfusion. HA14-1 inhibition also increased the permeability of the outer membrane in the absence of exogenous calcium, indicating that bcl-2 inhibition favors MOMP when calcium is low. Conclusions The depletion and functional inhibition of bcl-2 contributes to cardiac injury by increasing susceptibility to MPTP opening in high calcium environments and MOMP in the absence of calcium overload. Thus, ischemia-damaged mitochondria with decreased bcl-2 content are susceptible to MPTP opening in early reperfusion and MOMP later in reperfusion when cytosolic calcium has normalized.
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Affiliation(s)
- Qun Chen
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Haishan Xu
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Aijun Xu
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Anesthesiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Thomas Ross
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Elizabeth Bowler
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- University of the West of England, Bristol, United Kingdom
| | - Ying Hu
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Edward J. Lesnefsky
- Department of Medicine, Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Medicine, Pauley Heart Center, Division of Biochemistry, Virginia Commonwealth University, Richmond, Virginia, United States of America
- McGuire Department of Veterans Affairs Medical Center, Richmond, Virginia, United States of America
- * E-mail:
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Xu A, Szczepanek K, Maceyka MW, Ross T, Bowler E, Hu Y, Kenny B, Mehfoud C, Desai PN, Baumgarten CM, Chen Q, Lesnefsky EJ. Transient complex I inhibition at the onset of reperfusion by extracellular acidification decreases cardiac injury. Am J Physiol Cell Physiol 2014; 306:C1142-53. [PMID: 24696146 DOI: 10.1152/ajpcell.00241.2013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A reversible inhibition of mitochondrial respiration by complex I inhibition at the onset of reperfusion decreases injury in buffer-perfused hearts. Administration of acidic reperfusate for a brief period at reperfusion decreases cardiac injury. We asked if acidification treatment decreased cardiac injury during reperfusion by inhibiting complex I. Exposure of isolated mouse heart mitochondria to acidic buffer decreased the complex I substrate-stimulated respiration, whereas respiration with complex II substrates was unaltered. Evidence of the rapid and reversible inhibition of complex I by an acidic environment was obtained at the level of isolated complex, intact mitochondria and in situ mitochondria in digitonin-permeabilized cardiac myocytes. Moreover, ischemia-damaged complex I was also reversibly inhibited by an acidic environment. In the buffer-perfused mouse heart, reperfusion with pH 6.6 buffer for the initial 5 min decreased infarction. Compared with untreated hearts, acidification treatment markedly decreased the mitochondrial generation of reactive oxygen species and improved mitochondrial calcium retention capacity and inner mitochondrial membrane integrity. The decrease in infarct size achieved by acidic reperfusion approximates the reduction obtained by a reversible, partial blockade of complex I at reperfusion. Extracellular acidification decreases cardiac injury during reperfusion in part via the transient and reversible inhibition of complex I, leading to a reduction of oxyradical generation accompanied by a decreased susceptibility to mitochondrial permeability transition during early reperfusion.
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Affiliation(s)
- Aijun Xu
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Anesthesiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China; and
| | - Karol Szczepanek
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Michael W Maceyka
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Thomas Ross
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Elizabeth Bowler
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; University of the West of England, Bristol, United Kingdom
| | - Ying Hu
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Barrett Kenny
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Chris Mehfoud
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Pooja N Desai
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Clive M Baumgarten
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Qun Chen
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia; McGuire Veterans Affairs Medical Center, Richmond, Virginia;
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12
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Ross T, Szczepanek K, Bowler E, Hu Y, Larner A, Lesnefsky EJ, Chen Q. Reverse electron flow-mediated ROS generation in ischemia-damaged mitochondria: role of complex I inhibition vs. depolarization of inner mitochondrial membrane. Biochim Biophys Acta Gen Subj 2013; 1830:4537-42. [PMID: 23747300 DOI: 10.1016/j.bbagen.2013.05.035] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 05/17/2013] [Accepted: 05/27/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND The reverse electron flow-induced ROS generation (RFIR) is decreased in ischemia-damaged mitochondria. Cardiac ischemia leads to decreased complex I activity and depolarized inner mitochondrial membrane potential (ΔΨ) that are two key factors to affect the RFIR in isolated mitochondria. We asked if a partial inhibition of complex I activity without alteration of the ΔΨ is able to decrease the RFIR. METHODS Cardiac mitochondria were isolated from mouse heart (C57BL/6) with and without ischemia. The rate of H2O2 production from mitochondria was determined using amplex red coupled with horseradish peroxidase. Mitochondria were isolated from the mitochondrial-targeted STAT3 overexpressing mouse (MLS-STAT3E) to clarify the role of partial complex I inhibition in RFIR production. RESULTS The RFIR was decreased in ischemia-damaged mouse heart mitochondria with decreased complex I activity and depolarized ΔΨ. However, the RFIR was not altered in the MLS-STAT3E heart mitochondria with complex I defect but without depolarization of the ΔΨ. A slight depolarization of the ΔΨ in wild type mitochondria completely eliminated the RFIR. CONCLUSIONS The mild uncoupling but not the partially decreased complex I activity contributes to the observed decrease in RFIR in ischemia-damaged mitochondria. GENERAL SIGNIFICANCE The RFIR is less likely to be a key source of cardiac injury during reperfusion.
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Affiliation(s)
- Thomas Ross
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
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13
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Hagen RM, Chedea VS, Mintoff CP, Bowler E, Morse HR, Ladomery MR. Epigallocatechin-3-gallate promotes apoptosis and expression of the caspase 9a splice variant in PC3 prostate cancer cells. Int J Oncol 2013; 43:194-200. [PMID: 23615977 DOI: 10.3892/ijo.2013.1920] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/29/2013] [Indexed: 11/06/2022] Open
Abstract
Growing evidence suggests that the flavonoid epigallocatechin-3-gallate (EGCG), notably abundant in green tea, has health-promoting properties. We examined the effect of EGCG on cell survival and apoptosis in the prostate cancer cell line PC3. Cell survival was reduced and apoptosis increased significantly with a low dose of 1 µM EGCG. The ability of the anticancer drug cisplatin to promote apoptosis was enhanced by EGCG. Furthermore, EGCG, both alone and in combination with cisplatin, promoted the expression of the pro-apoptotic splice isoform of caspase 9.
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Affiliation(s)
- Rachel M Hagen
- Centre for Research in Bioscience, Faculty of Health and Life Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, UK
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Riley PA, Canagaratna C, Bowler LM, Latter T, Bowler E. Slide cases for cell culture preparations for autoradiography and other procedures. Lab Pract 1973; 22:116-7. [PMID: 4688711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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16
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Abstract
The filamentous roots of mustard (Raphanus sativus), radish (Brassica nigra), squash (Cucurbita pepo), and wheat (Triticum aestivum) are covered throughout their length with living nucleated root hairs which may measure 1600 micro or more. The outer walls of piliferous and nonpiliferous cells consist of successive layers of mucilage, cutin, and the cellulose-pectic framework of the cell. Plasmodesmata and pits occur on all cell walls. Under the electron microscope individual pores and pits in the microfibrillar wall are evident throughout the length of the root hair. The "semipermeable membrane" of the root hair zone is thus structurally complex.
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