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Nenasheva VV, Makarova IV, Stepanenko EA, Antonov SA, Novosadova EV, Narsullaeva AR, Kozikova LV, Polteva EA, Sleptsova LA, Shcherbatova NA, Khaidarova NV, Andreeva LE, Tarantul VZ. Human TAF-Iα promotes oncogenic transformation via enhancement of cell proliferation and suppression of apoptosis. In Vitro Cell Dev Biol Anim 2021; 57:531-538. [PMID: 34021475 DOI: 10.1007/s11626-021-00572-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/29/2021] [Indexed: 11/24/2022]
Abstract
Template activating factor-I (TAF-I) is a multifunctional protein involved in various biological processes including the inhibition of histone acetylation, DNA replication, cell cycle regulation, and oncogenesis. Two main TAF-I isoforms with different N-termini, TAF-Iα and TAF-Iβ (SET), are expressed in cells. There are numerous data about functional properties of TAF-Iβ, whereas the effects of TAF-Iα remain largely unexplored. Here, we employed focus formation and cell proliferation assays, TUNEL staining, cytological analysis, and RT-qPCR to compare the effects of human TAF-Iα and TAF-Iβ genes, transiently expressed in Rat2 cells and in Misgurnus fossilis loaches. We found that both TAF-I isoforms possessed equal oncogenic potential in these systems. Furthermore, an overexpression of human TAF-Iα and TAF-Iβ in Rat2 cells promoted their proliferation. Accordingly, the mitotic index was increased in the transgenic loaches expressing human TAF-Iα or TAF-Iβ. TUNEL assay as well as downregulation of p53 gene and upregulation of bcl-2 gene in these transgenic loaches demonstrated that both isoforms suppressed apoptosis. Thus, TAF-Iα isoform exerts the same oncogenic potential as TAF-Iβ, likely by suppressing the apoptosis and promoting cell proliferation.
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Affiliation(s)
- Valentina V Nenasheva
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia.
| | - Irina V Makarova
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Ekaterina A Stepanenko
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Stanislav A Antonov
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Ekaterina V Novosadova
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Anastasia R Narsullaeva
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Larisa V Kozikova
- Russian Research Institute of Farm Animal Genetics and Breeding - Branch of the L. K. Ernst Federal Science Center for Animal Husbandry, St. Petersburg, 196601, Russia
| | - Ekaterina A Polteva
- Russian Research Institute of Farm Animal Genetics and Breeding - Branch of the L. K. Ernst Federal Science Center for Animal Husbandry, St. Petersburg, 196601, Russia
| | - Lyudmila A Sleptsova
- Faculty of Biology, Department of Embryology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Natalya A Shcherbatova
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Nella V Khaidarova
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Lyudmila E Andreeva
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Vyacheslav Z Tarantul
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
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The involvement of toll-like receptors 2 and 4 in human platelet signalling pathways. Cell Signal 2020; 76:109817. [PMID: 33132157 DOI: 10.1016/j.cellsig.2020.109817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 01/01/2023]
Abstract
In addition to haemostasis, platelets play an essential role in mechanisms of inflammation and in immunological reactions. Platelets express various toll-like receptors (TLR) on their surface, among them TLR2 and TLR4, which are important for the recognition of bacterial patterns. This study compared TLR2- and TLR4-dependent platelet signalling and their effect on platelet function. Platelet-rich-plasma and washed platelets were prepared from peripheral blood samples of healthy donors. Pam3CSK4 or LPS (lipopolysaccharides from Escherichia coli) were used for stimulation of TLR2 and TLR4. Intracellular signalling pathways were investigated by Western blot. TLR2- and TLR4-mediated specific transcription factor DNA binding activity was measured by the nuclear factor kappa B (NFκB) transcription factor assay kit. Platelet adhesion and glycoprotein Ib function were assessed by immunofluorescence staining and analysis of ristocetin-induced agglutination. Both, Pam3CSK4 and LPS were able to induce NFκB-mediated and classical activating platelet signalling with a higher stimulatory capacity of TLR2. In addition, TLR2 and TLR4 activation led to a similar activation of inhibitory pathways. In contrast to TLR2, stimulation of TLR4 resulted in decreased Akt/protein kinase B phosphorylation conditioned by enhanced protein phosphatase 2A activity. TLR4-mediated signalling induced platelet adhesion and facilitated ristocetin-induced platelet agglutination. In conclusion, Pam3CSK4 directly induces aggregation via classical activation cascades, whereas LPS enhances platelet adhesion and glycoprotein receptor Ib-dependent platelet agglutination.
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Aldehyde dehydrogenase 2 regulates autophagy via the Akt-mTOR pathway to mitigate renal ischemia-reperfusion injury in hypothermic machine perfusion. Life Sci 2020; 253:117705. [PMID: 32334008 DOI: 10.1016/j.lfs.2020.117705] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/14/2020] [Accepted: 04/19/2020] [Indexed: 01/15/2023]
Abstract
AIMS Ischemia-reperfusion injury (IRI) is harmful to patients following kidney transplantation. Hypothermic machine perfusion (HMP) can be adopted to preserve grafts and reduce consequential injury. We hypothesized that aldehyde dehydrogenase 2 (ALDH2) partly mitigates kidney IRI via regulating excessive autophagy in HMP. MATERIALS AND METHODS The rabbits were assigned to 5 groups: Normal, HMP, HMP + Alda-1, HMP + CYA and cold storage (CS). After the rabbit autologous kidney transplantation, renal pathology and function were evaluated by histological analysis, glomerular related proteins (desmin, nephrin), tubular injury factors (NGAL, Ki67), serum creatinine (Cr) and blood urea nitrogen (BUN). Oxidative stress molecular Malondialdehyde (MDA) and superoxide dismutase (SOD2) expression, as well as inflammatory cytokines (TNF-α, IL-6, IL-10) were assessed by immunohistochemistry. The expression of LC3, p62, ALDH2, p-Akt, mTOR, PTEN, p-PTEN, and 4-HNE were measured by immunohistochemistry, RT-PCR, Western blot analysis or ELISA. KEY FINDINGS HMP was more effective than CS for kidney preservation, with p- ALDH2 expressed in greater quantities in HMP. The results of kidney pathology and function in HMP + Alda-1 were the best. The MDA & SOD2 and the Vyacheslav score were improved in HMP + CYA. ALDH2 reduced 4-HNE-induced oxidative stress, inflammatory infiltration, the expression of LC3, p62 and inhibited autophagy accompanied by activation of p-Akt and mTOR via p-PTEN/PTEN. SIGNIFICANCE Akt-mTOR autophagy pathway is a novel target for ALDH2 to reduce renal IRI partly by inhibition of 4-HNE in HMP, then protecting the donated kidney received after cardiac death (DCD).
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Wei H, Zhang HL, Xie JZ, Meng DL, Wang XC, Ke D, Zeng J, Liu R. Protein Phosphatase 2A as a Drug Target in the Treatment of Cancer and Alzheimer's Disease. Curr Med Sci 2020; 40:1-8. [PMID: 32166659 DOI: 10.1007/s11596-020-2140-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 12/10/2019] [Indexed: 01/22/2023]
Abstract
Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase which participates in the regulation of multiple cellular processes. As a confirmed tumor suppressor, PP2A activity is downregulated in tumors and its re-activation can induce apoptosis of cancer cells. In the brains of Alzheimer's disease (AD) patients, decreased PP2A activity also plays a key role in promoting tau hyperphosphorylation and Aβ generation. In this review, we discussed compounds aiming at modulating PP2A activity in the treatment of cancer or AD. The upstream factors that inactivate PP2A in diseases have not been fully elucidated and further studies are needed. It will help for the refinement and development of novel and clinically tractable PP2A-targeted compounds or therapies for the treatment of tumor and AD.
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Affiliation(s)
- Hui Wei
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hui-Liang Zhang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jia-Zhao Xie
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Dong-Li Meng
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xiao-Chuan Wang
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Dan Ke
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Ji Zeng
- Department of Clinic Laboratory, Wuhan Fourth Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Rong Liu
- Department of Pathophysiology, Key Laboratory of Ministry of Education for Neurological Disorders, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
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SET protein accumulation prevents cell death in head and neck squamous cell carcinoma through regulation of redox state and autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:623-637. [DOI: 10.1016/j.bbamcr.2019.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 01/06/2019] [Accepted: 01/08/2019] [Indexed: 12/29/2022]
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6
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Zhang S, Fang C, Yuan W, Zhang Y, Yan G, Zhang L, Di Y, Cai Y, Lu H. Selective Identification and Site-Specific Quantification of 4-Hydroxy-2-nonenal-Modified Proteins. Anal Chem 2019; 91:5235-5243. [DOI: 10.1021/acs.analchem.8b05970] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Caiyun Fang
- Department of Chemistry, Fudan University, Shanghai, 200433, P. R. China
| | | | | | | | | | | | | | - Haojie Lu
- Department of Chemistry, Fudan University, Shanghai, 200433, P. R. China
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7
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Vanaja KG, Timp W, Feinberg AP, Levchenko A. A Loss of Epigenetic Control Can Promote Cell Death through Reversing the Balance of Pathways in a Signaling Network. Mol Cell 2018; 72:60-70.e3. [PMID: 30244832 DOI: 10.1016/j.molcel.2018.08.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 06/04/2018] [Accepted: 08/15/2018] [Indexed: 12/31/2022]
Abstract
Epigenetic control of regulatory networks is only partially understood. Expression of Insulin-like growth factor-II (IGF2) is controlled by genomic imprinting, mediated by silencing of the maternal allele. Loss of imprinting of IGF2 (LOI) is linked to intestinal and colorectal cancers, causally in murine models and epidemiologically in humans. However, the molecular underpinnings of the LOI phenotype are not clear. Surprisingly, in LOI cells, we find a reversal of the relative activities of two canonical signaling pathways triggered by IGF2, causing further rebalancing between pro- and anti-apoptotic signaling. A predictive mathematical model shows that this network rebalancing quantitatively accounts for the effect of receptor tyrosine kinase inhibition in both WT and LOI cells. This mechanism also quantitatively explains both the stable LOI phenotype and the therapeutic window for selective killing of LOI cells, and thus prevention of epigenetically controlled cancers. These findings suggest a framework for understanding epigenetically modified cell signaling.
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Affiliation(s)
- Kiran G Vanaja
- Yale Systems Biology Institute and Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD 21205, USA
| | - Winston Timp
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD 21205, USA
| | - Andrew P Feinberg
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD 21205, USA; Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
| | - Andre Levchenko
- Yale Systems Biology Institute and Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD 21205, USA.
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Panisello-Roselló A, Lopez A, Folch-Puy E, Carbonell T, Rolo A, Palmeira C, Adam R, Net M, Roselló-Catafau J. Role of aldehyde dehydrogenase 2 in ischemia reperfusion injury: An update. World J Gastroenterol 2018; 24:2984-2994. [PMID: 30038465 PMCID: PMC6054945 DOI: 10.3748/wjg.v24.i27.2984] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/28/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023] Open
Abstract
Aldehyde dehydrogenase 2 (ALDH2) is best known for its critical detoxifying role in liver alcohol metabolism. However, ALDH2 dysfunction is also involved in a wide range of human pathophysiological situations and is associated with complications such as cardiovascular diseases, diabetes mellitus, neurodegenerative diseases and aging. A growing body of research has shown that ALDH2 provides important protection against oxidative stress and the subsequent loading of toxic aldehydes such as 4-hydroxy-2-nonenal and adducts that occur in human diseases, including ischemia reperfusion injury (IRI). There is increasing evidence of its role in IRI pathophysiology in organs such as heart, brain, small intestine and kidney; however, surprisingly few studies have been carried out in the liver, where ALDH2 is found in abundance. This study reviews the role of ALDH2 in modulating the pathways involved in the pathophysiology of IRI associated with oxidative stress, autophagy and apoptosis. Special emphasis is placed on the role of ALDH2 in different organs, on therapeutic “preconditioning” strategies, and on the use of ALDH2 agonists such as Alda-1, which may become a useful therapeutic tool for preventing the deleterious effects of IRI in organ transplantation.
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Affiliation(s)
- Arnau Panisello-Roselló
- Department of Experimental Pathology, Institute of Biomedical Research of Barcelona (IIBB)-CSIC, Barcelona 08036, Spain
| | - Alexandre Lopez
- Centre Hepatobiliare, AP-HP Hôpital Paul Brousse, Villejuif 75008, France
| | - Emma Folch-Puy
- Department of Experimental Pathology, Institute of Biomedical Research of Barcelona (IIBB)-CSIC, Barcelona 08036, Spain
| | - Teresa Carbonell
- Department of Physiology, Faculty of Biology, Universitat de Barcelona, Barcelona 08036, Spain
| | - Anabela Rolo
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-517, Portugal
| | - Carlos Palmeira
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-517, Portugal
| | - René Adam
- Centre Hepatobiliare, AP-HP Hôpital Paul Brousse, Villejuif 75008, France
| | - Marc Net
- Institute Georges Lopez, Lissieu 69380, France
| | - Joan Roselló-Catafau
- Department of Experimental Pathology, Institute of Biomedical Research of Barcelona (IIBB)-CSIC, Barcelona 08036, Spain
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Zhang H, Forman HJ. 4-hydroxynonenal-mediated signaling and aging. Free Radic Biol Med 2017; 111:219-225. [PMID: 27876535 PMCID: PMC5438786 DOI: 10.1016/j.freeradbiomed.2016.11.032] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/14/2016] [Accepted: 11/17/2016] [Indexed: 02/07/2023]
Abstract
4-Hydroxy-2-nonenal (HNE), one of the major α, β-unsaturated aldehydes produced during lipid peroxidation, is a potent messenger in mediating signaling pathways. Lipid peroxidation and HNE production appear to increase with aging. Although the cause and effect relation remains arguable, aging is associated with significant changes in diverse signaling events, characterized by enhanced or diminished responses of specific signaling pathways. In this review we will discuss how HNE may contribute to aging-related alterations of signaling pathways.
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Affiliation(s)
- Hongqiao Zhang
- Andrus Gerontology Center of the Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Ave, Los Angeles, CA 90089-0191, USA
| | - Henry Jay Forman
- Andrus Gerontology Center of the Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Ave, Los Angeles, CA 90089-0191, USA.
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Zhou H, Luo W, Zeng C, Zhang Y, Wang L, Yao W, Nie C. PP2A mediates apoptosis or autophagic cell death in multiple myeloma cell lines. Oncotarget 2017; 8:80770-80789. [PMID: 29113343 PMCID: PMC5655238 DOI: 10.18632/oncotarget.20415] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/27/2017] [Indexed: 02/05/2023] Open
Abstract
The crosstalk between apoptosis and autophagy contributes to tumorigenesis and cancer therapy. The process by which BetA (betulinic acid), a naturally occurring triterpenoid, regulates apoptosis and autophagy as a cancer therapy is unclear. In this study, we show for the first time that protein phosphatase 2A (PP2A) acts as a switch to regulate apoptosis and autophagic cell death mediated by BetA. Under normal conditions, caspase-3 is activated by the mitochondrial pathway upon BetA treatment. Activated caspase-3 cleaves the A subunit of PP2A (PP2A/A), resulting in the association of PP2A and Akt. This association inactivates Akt to initiate apoptosis. Overexpression of Bcl-2 attenuates the mitochondrial apoptosis pathway, resulting in caspase-3 inactivation and the dissociation of PP2A and Akt. PP2A isolated from Akt binds with DAPK to induce autophagic cell death. Meanwhile, in vivo tumor experiments have demonstrated that BetA initiates different types of cell death in a myeloma xenograft model. Thus, PP2A can shift myeloma cells from apoptosis to autophagic cell death. These findings have important implications for the therapeutic application of BetA, particularly against apoptosis-resistant cancers.
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Affiliation(s)
- Hang Zhou
- Department of Chemotherapy, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Wei Luo
- Department of Pharmacy, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Chao Zeng
- Department of Gastroenterology, the Third People's Hospital of Chengdu, Chengdu, China
| | - Yu Zhang
- Department of Oncology, Guizhou People's Hospital, Guizhou, China
| | - Liyang Wang
- Department of Chemotherapy, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Wenxiu Yao
- Department of Chemotherapy, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Chunlai Nie
- Department of Chemotherapy, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.,Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, China
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11
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Shimura T, Sasatani M, Kamiya K, Kawai H, Inaba Y, Kunugita N. Mitochondrial reactive oxygen species perturb AKT/cyclin D1 cell cycle signaling via oxidative inactivation of PP2A in lowdose irradiated human fibroblasts. Oncotarget 2016; 7:3559-70. [PMID: 26657292 PMCID: PMC4823127 DOI: 10.18632/oncotarget.6518] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/21/2015] [Indexed: 12/20/2022] Open
Abstract
Here we investigated the cellular response of normal human fibroblasts to repeated exposure to low-dose radiation. In contrast to acute single radiation, low-dose fractionated radiation (FR) with 0.01 Gy/fraction or 0.05 Gy/fraction for 31 days increased in mitochondrial mass, decreased cellular levels of the antioxidant glutathione and caused persistent accumulation of mitochondrial reactive oxygen species (ROS). Excess ROS promoted oxidative inactivation of protein phosphatase PP2A which in turn led to disruption of normal negative feed-back control of AKT/cyclin D1 signaling in cells treated with long-term FR. The resulting abnormal nuclear accumulation of cyclin D1 causes growth retardation, cellular senescence and genome instability in low-dose irradiated cells. Thus, loss of redox control and subsequently elevated levels of ROS perturb signal transduction as a result of oxidative stress. Our study highlights a specific role of mitochondrial ROS in perturbation of AKT/cyclin D1 cell cycle signaling after low-dose long-term FR. The antioxidants N-acetyl-L-cysteine, TEMPO and mitochondrial-targeted antioxidant Mito-TEMPO provided protection against the harmful cell cycle perturbations induced by low-dose long-term FR.
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Affiliation(s)
- Tsutomu Shimura
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
| | - Megumi Sasatani
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine (RIRBM), Hiroshima University, Hiroshima, Japan
| | - Kenji Kamiya
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine (RIRBM), Hiroshima University, Hiroshima, Japan
| | - Hidehiko Kawai
- Department of Molecular Radiobiology, Research Center for Radiation Genome Medicine, Research Institute for Radiation Biology and Medicine (RIRBM), Hiroshima University, Hiroshima, Japan
| | - Yohei Inaba
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
| | - Naoki Kunugita
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
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12
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Sharma P, Arias EB, Cartee GD. Protein Phosphatase 1-α Regulates AS160 Ser588 and Thr642 Dephosphorylation in Skeletal Muscle. Diabetes 2016; 65:2606-17. [PMID: 27246912 PMCID: PMC5001182 DOI: 10.2337/db15-0867] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 05/23/2016] [Indexed: 01/09/2023]
Abstract
Akt substrate of 160 kDa (AS160) phosphorylation on Thr(642) and Ser(588) by Akt is essential for insulin's full effect on glucose transport. However, protein phosphorylation is determined by the balance of actions by kinases and phosphatases, and the specific phosphatase(s) controlling AS160 dephosphorylation is (are) unknown. Accordingly, we assessed roles of highly expressed skeletal muscle serine/threonine phosphatases (PP1, PP2A, PP2B, and PP2C) on AS160 dephosphorylation. Preliminary screening of candidate phosphatases used an AS160 dephosphorylation assay. Lysates from insulin-stimulated skeletal muscle were treated with pharmacological phosphatase inhibitors and assessed for AS160 Ser(588) and Thr(642) dephosphorylation. AS160 dephosphorylation on both phosphorylation sites was unaltered by PP2B or PP2C inhibitors. Okadaic acid (low dose inhibits PP2A; high dose inhibits PP1) delayed AS160 Ser(588) (both doses) and Thr(642) (high dose only) dephosphorylation concomitant with greater Akt phosphorylation (both doses). AS160 was coimmunoprecipitated with PP1-α but not with PP1-β, PP1-γ1, or PP2A. Recombinant inhibitor-2 protein (a selective PP1 inhibitor) delayed AS160 dephosphorylation on both phosphorylation sites without altering Akt phosphorylation. Furthermore, knockdown of PP1-α but not PP1-β or PP1-γ1 by small interfering RNA caused greater AS160 Ser(588) and Thr(642) phosphorylation concomitant with unaltered Akt phosphorylation. Together, these results identified PP1-α as a regulator of AS160 Thr(642) and Ser(588) dephosphorylation in skeletal muscle.
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Affiliation(s)
- Pragya Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Edward B Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI Institute of Gerontology, University of Michigan, Ann Arbor, MI
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Shimura T, Kunugita N. Mitochondrial reactive oxygen species-mediated genomic instability in low-dose irradiated human cells through nuclear retention of cyclin D1. Cell Cycle 2016; 15:1410-4. [PMID: 27078622 DOI: 10.1080/15384101.2016.1170271] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mitochondria are associated with various radiation responses, including adaptive responses, mitophagy, the bystander effect, genomic instability, and apoptosis. We recently identified a unique radiation response in the mitochondria of human cells exposed to low-dose long-term fractionated radiation (FR). Such repeated radiation exposure inflicts chronic oxidative stresses on irradiated cells via the continuous release of mitochondrial reactive oxygen species (ROS) and decrease in cellular levels of the antioxidant glutathione. ROS-induced oxidative mitochondrial DNA (mtDNA) damage generates mutations upon DNA replication. Therefore, mtDNA mutation and dysfunction can be used as markers to assess the effects of low-dose radiation. In this study, we present an overview of the link between mitochondrial ROS and cell cycle perturbation associated with the genomic instability of low-dose irradiated cells. Excess mitochondrial ROS perturb AKT/cyclin D1 cell cycle signaling via oxidative inactivation of protein phosphatase 2A after low-dose long-term FR. The resulting abnormal nuclear accumulation of cyclin D1 induces genomic instability in low-dose irradiated cells.
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Affiliation(s)
- Tsutomu Shimura
- a Department of Environmental Health , National Institute of Public Health , Wako , Saitama , Japan
| | - Naoki Kunugita
- a Department of Environmental Health , National Institute of Public Health , Wako , Saitama , Japan
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14
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Bekele RT, Venkatraman G, Liu RZ, Tang X, Mi S, Benesch MGK, Mackey JR, Godbout R, Curtis JM, McMullen TPW, Brindley DN. Oxidative stress contributes to the tamoxifen-induced killing of breast cancer cells: implications for tamoxifen therapy and resistance. Sci Rep 2016; 6:21164. [PMID: 26883574 PMCID: PMC4756695 DOI: 10.1038/srep21164] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/14/2016] [Indexed: 02/07/2023] Open
Abstract
Tamoxifen is the accepted therapy for patients with estrogen receptor-α (ERα)-positive breast cancer. However, clinical resistance to tamoxifen, as demonstrated by recurrence or progression on therapy, is frequent and precedes death from metastases. To improve breast cancer treatment it is vital to understand the mechanisms that result in tamoxifen resistance. This study shows that concentrations of tamoxifen and its metabolites, which accumulate in tumors of patients, killed both ERα-positive and ERα-negative breast cancer cells. This depended on oxidative damage and anti-oxidants rescued the cancer cells from tamoxifen-induced apoptosis. Breast cancer cells responded to tamoxifen-induced oxidation by increasing Nrf2 expression and subsequent activation of the anti-oxidant response element (ARE). This increased the transcription of anti-oxidant genes and multidrug resistance transporters. As a result, breast cancer cells are able to destroy or export toxic oxidation products leading to increased survival from tamoxifen-induced oxidative damage. These responses in cancer cells also occur in breast tumors of tamoxifen-treated mice. Additionally, high levels of expression of Nrf2, ABCC1, ABCC3 plus NAD(P)H dehydrogenase quinone-1 in breast tumors of patients at the time of diagnosis were prognostic of poor survival after tamoxifen therapy. Therefore, overcoming tamoxifen-induced activation of the ARE could increase the efficacy of tamoxifen in treating breast cancer.
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Affiliation(s)
- Raie T Bekele
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | - Ganesh Venkatraman
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | - Rong-Zong Liu
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Xiaoyun Tang
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | - Si Mi
- Department of Agricultural, Food and Nutritional Science (Lipid Chemistry Group), University of Alberta, Edmonton, Alberta, T6G 2P5, Canada
| | - Matthew G K Benesch
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | - John R Mackey
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Roseline Godbout
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Jonathan M Curtis
- Department of Agricultural, Food and Nutritional Science (Lipid Chemistry Group), University of Alberta, Edmonton, Alberta, T6G 2P5, Canada
| | - Todd P W McMullen
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada.,Department of Surgery, Walter C Mackenzie Health Science Centre, University of Alberta, Edmonton, T6G 2R7, Alberta, Canada
| | - David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
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15
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Resistin, a fat-derived secretory factor, promotes metastasis of MDA-MB-231 human breast cancer cells through ERM activation. Sci Rep 2016; 6:18923. [PMID: 26729407 PMCID: PMC4700449 DOI: 10.1038/srep18923] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/30/2015] [Indexed: 01/08/2023] Open
Abstract
Resistin, an adipocyte-secreted factor, is known to be elevated in breast cancer patients. However, the molecular mechanism by which resistin acts is not fully understood. The aim of this study was to investigate whether resistin could stimulate invasion and migration of breast cancer cells. Here, we report that resistin stimulated invasion and migration of breast cancer cells as well as phosphorylation of c-Src. Inhibition of c-Src blocked resistin-induced breast cancer cell invasion. Resistin increased intracellular calcium concentration, and chelation of intracellular calcium blocked resistin-mediated activation of Src. Resistin also induced phosphorylation of protein phosphatase 2A (PP2A). Inhibition of c-Src blocked resistin-mediated PP2A phosphorylation. In addition, resistin increased phosphorylation of PKCα. Inhibition of PP2A enhanced resistin-induced PKCα phosphorylation, demonstrating that PP2A activity is critical for PKCα phosphorylation. Resistin also increased phosphorylation of ezrin, radixin, and moesin (ERM). Additionally, ezrin interacted with PKCα, and resistin promoted co-localization of ezrin and PKCα. Either inhibition of c-Src and PKCα or knock-down of ezrin blocked resistin-induced breast cancer cells invasion. Moreover, resistin increased expression of vimentin, a key molecule for cancer cell invasion. Knock-down of ezrin abrogated resistin-induced vimentin expression. These results suggest that resistin play as a critical regulator of breast cancer metastasis.
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16
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Zhang H, Forman HJ. 4-Hydroxynonenal activates Src through a non-canonical pathway that involves EGFR/PTP1B. Free Radic Biol Med 2015; 89:701-7. [PMID: 26453921 PMCID: PMC4684732 DOI: 10.1016/j.freeradbiomed.2015.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/20/2015] [Accepted: 08/26/2015] [Indexed: 12/30/2022]
Abstract
Src, a non-receptor protein tyrosine kinase involved in many biological processes, can be activated through both redox-dependent and independent mechanisms. 4-Hydroxy-2-nonenal (HNE) is a lipid peroxidation product that is increased in pathophysiological conditions associated with Src activation. This study examined how HNE activates human c-Src. In the canonical pathway Src activation is initiated by dephosphorylation of pTyr530 followed by conformational change that causes Src auto-phosphorylation at Tyr419 and its activation. HNE increased Src activation in both dose- and time-dependent manner, while it also increased Src phosphorylation at Tyr530 (pTyr530 Src), suggesting that HNE activated Src via a non-canonical mechanism. Protein tyrosine phosphatase 1B inhibitor (539741), at concentrations that increased basal pTyr530 Src, also increased basal Src activity and significantly reduced HNE-mediated Src activation. The EGFR inhibitor, AG1478, and EGFR silencing, abrogated HNE-mediated EGFR activation and inhibited basal and HNE-induced Src activity. In addition, AG1478 also eliminated the increase of basal Src activation by a PTP1B inhibitor. Taken together these data suggest that HNE can activate Src partly through a non-canonical pathway involving activation of EGFR and inhibition of PTP1B.
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Affiliation(s)
- Hongqiao Zhang
- Andrus Gerontology Center, Davis School of Gerontology, University of Southern, California
| | - Henry Jay Forman
- Andrus Gerontology Center, Davis School of Gerontology, University of Southern, California.
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17
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Ding Q, Chen Y, Zhang Q, Guo Y, Huang Z, Dai L, Cao S. 8‑bromo‑7‑methoxychrysin induces apoptosis by regulating Akt/FOXO3a pathway in cisplatin‑sensitive and resistant ovarian cancer cells. Mol Med Rep 2015; 12:5100-8. [PMID: 26151347 PMCID: PMC4581817 DOI: 10.3892/mmr.2015.4039] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 07/22/2014] [Indexed: 12/24/2022] Open
Abstract
8-bromo-7-methoxychrysin (BrMC), a novel chrysin analog, was reported to have anti-cancer activities. The aim of the present study was to investigate the molecular mechanism of 8-bromo-7-methoxychrysin (BrMC)-induced apoptosis via the Akt/forkhead box O3a (FOXO3a) pathway in cisplatin (DDP)-sensitive and -resistant ovarian cancer cells. The human ovarian cancer cell lines A2780 and A2780/DDP were cultured in vitro. Various molecular techniques were used to assess the expression of FOXO3a and B cell lymphoma 2 (Bcl-2)-interacting mediator of cell death (Bim) in cisplatin-sensitive and -resistant ovarian cancer cells. Different concentrations of BrMC induced apoptosis in cisplatin-sensitive and -resistant ovarian cancer cells. BrMC-induced apoptotic cell death occurred mainly by the activation of Akt, which was accompanied by the overexpression of transcription factor FOXO3a, with a concomitant increase in the expression levels of Bim. Silencing Bim expression by using small interfering RNA, attenuated the induction of apoptosis by BrMC treatment. The results indicated that BrMC-induced apoptosis in cisplatin-sensitive and -resistant ovarian cancer cells may occur via the regulation of Akt/FOXO3a, leading to Bim transcription.
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Affiliation(s)
- Qing Ding
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
| | - Yi Chen
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
| | - Qing Zhang
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
| | - Yanling Guo
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
| | - Zhi Huang
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
| | - Liqing Dai
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
| | - Sudan Cao
- Hunan University of Traditional Chinese Medicine, Changsha, Hunan 410208, P.R.China
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18
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Chen B, Ning JL, Gu JT, Cui J, Yang Y, Wang Z, Zeng J, Yi B, Lu KZ. Caspase-3 inhibition prevents the development of hepatopulmonary syndrome in common bile duct ligation rats by alleviating pulmonary injury. Liver Int 2015; 35:1373-82. [PMID: 25113058 DOI: 10.1111/liv.12655] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 08/05/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Common bile duct ligation (CBDL) rats is an accepted experimental model of hepatopulmonary syndrome (HPS), defined as liver disease and intrapulmonary vascular dilatation and hypoxaemia. Pulmonary Akt and ERK activation followed by angiogenesis in the later stages of CBDL, contribute to the pathogenesis of HPS. However, the mechanisms behind Akt and ERK activation remain undefined. Pulmonary injury induced by increased bilirubin, endotoxin and inflammatory mediators occurs in the early stages of CBDL. We assessed the effects of relieving pulmonary injury on Akt and ERK activation and on the development of HPS following CBDL. METHODS Pulmonary injury, angiogenesis, arterial oxygenation, cell proliferation and, phospho-Akt and ERK1 were evaluated in CBDL animals with or without caspase-3 inhibition (Z-DEVD-FMK). Pulmonary injury was assessed by histology and quantifying apoptosis and aquaporin-1 (AQP1) levels. Lung angiogenesis was assessed by quantifying AQP1 level, vWF-positive cells and microvessel count. RESULTS Pulmonary apoptosis and caspase-3 activation were markedly increased in the early stages of CBDL. Caspase-3 inhibition alleviated apoptosis, the reduction in AQP1, phospho-Akt and ERK1 levels and pulmonary injury 1 week after CBDL. Caspase-3 inhibition also reduced AQP1, phospho-Akt and ERK1 levels, vWF-positive cells, cell proliferation, microvessel count, and microvascular dilatation and improved arterial oxygenation 3 weeks following CBDL. CONCLUSIONS Caspase-3 inhibition alleviates pulmonary injury, thereby preventing angiogenesis as well as the development of HPS in CBDL rats. These effects are related to the regulation of the Akt and ERK1 pathways.
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Affiliation(s)
- Bing Chen
- Department of Anesthesia, Southwest Hospital, Third Military Medical University, Chongqing, China
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19
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Csala M, Kardon T, Legeza B, Lizák B, Mandl J, Margittai É, Puskás F, Száraz P, Szelényi P, Bánhegyi G. On the role of 4-hydroxynonenal in health and disease. Biochim Biophys Acta Mol Basis Dis 2015; 1852:826-38. [PMID: 25643868 DOI: 10.1016/j.bbadis.2015.01.015] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/16/2014] [Accepted: 01/23/2015] [Indexed: 02/08/2023]
Abstract
Polyunsaturated fatty acids are susceptible to peroxidation and they yield various degradation products, including the main α,β-unsaturated hydroxyalkenal, 4-hydroxy-2,3-trans-nonenal (HNE) in oxidative stress. Due to its high reactivity, HNE interacts with various macromolecules of the cell, and this general toxicity clearly contributes to a wide variety of pathological conditions. In addition, growing evidence suggests a more specific function of HNE in electrophilic signaling as a second messenger of oxidative/electrophilic stress. It can induce antioxidant defense mechanisms to restrain its own production and to enhance the cellular protection against oxidative stress. Moreover, HNE-mediated signaling can largely influence the fate of the cell through modulating major cellular processes, such as autophagy, proliferation and apoptosis. This review focuses on the molecular mechanisms underlying the signaling and regulatory functions of HNE. The role of HNE in the pathophysiology of cancer, cardiovascular and neurodegenerative diseases is also discussed.
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Affiliation(s)
- Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University Budapest, Budapest, Hungary
| | - Tamás Kardon
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University Budapest, Budapest, Hungary
| | - Balázs Legeza
- Department of Pediatrics, University of California, San Francisco, CA, USA
| | - Beáta Lizák
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University Budapest, Budapest, Hungary
| | - József Mandl
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University Budapest, Budapest, Hungary
| | - Éva Margittai
- Institute of Human Physiology and Clinical Experimental Research, Semmelweis University, Budapest, Hungary
| | - Ferenc Puskás
- Department of Anesthesiology, University of Colorado, Denver, CO, USA
| | - Péter Száraz
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Péter Szelényi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University Budapest, Budapest, Hungary
| | - Gábor Bánhegyi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University Budapest, Budapest, Hungary.
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20
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Bhowmik M, Khanam R, Saini N, Vohora D. Activation of AKT/GSK3β pathway by TDZD-8 attenuates kainic acid induced neurodegeneration but not seizures in mice. Neurotoxicology 2015; 46:44-52. [DOI: 10.1016/j.neuro.2014.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/20/2014] [Accepted: 11/04/2014] [Indexed: 10/24/2022]
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21
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Shimura T, Kobayashi J, Komatsu K, Kunugita N. DNA damage signaling guards against perturbation of cyclin D1 expression triggered by low-dose long-term fractionated radiation. Oncogenesis 2014; 3:e132. [PMID: 25486524 PMCID: PMC4275562 DOI: 10.1038/oncsis.2014.48] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/24/2014] [Accepted: 11/02/2014] [Indexed: 12/20/2022] Open
Abstract
Cyclin D1 expression is precisely controlled during cell-cycle progression. However, repeated exposure to low-dose fractionated radiation (FR) abrogates cell cycle-dependent cyclin D1 degradation by constitutive activation of AKT survival signaling in normal human fibroblasts. The resulting abnormal nuclear cyclin D1 accumulation induces defects in DNA replication and resulting DNA double-strand breaks, and is associated with induction of genomic instability in low-dose irradiated cells. Here, we investigated the role of DNA damage signaling against such perturbed cell-cycle control of cyclin D1 expression. Nuclear cyclin D1 accumulation was induced within 7 days after low-dose FR (0.01 Gy or 0.05 Gy per fraction) in ATM-deficient cells (AT5BIVA), but appeared later in AT5BIVA cells harboring human ATM cDNA. Thus, ATM prevents abnormal nuclear cyclin D1 accumulation at early time points after low-dose FR. We further demonstrated that ATM-mediated downregulation of protein phosphatase 2A activity caused activation of the AKT/cyclin D1 pathway after long-term FR. Perturbation of cyclin D1 expression induced Rad51 foci that indicate homologous recombination repair (HRR) in control cells, while ATM- and NBS1-deficient cells (GM7166) failed to induce Rad51 foci after long-term low-dose FR. After 21 days of FR, NBS1- and ATM-deficient cells showed a decrease in nuclear cyclin D1-positive cells, and an increase in apoptotic cells. Similarly, inhibition of ATM with KU55933 abrogated nuclear cyclin D1 accumulation by induction of apoptosis in ATM-complemented cells exposed to low-dose FR. In conclusion, we here demonstrate that ATM is involved in controlling cyclin D1 levels after low-dose FR. DNA damage signaling mitigates the harmful effects of low-dose long-term FR by suppression of cell death induced by perturbation of cyclin D1 expression.
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Affiliation(s)
- T Shimura
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
| | - J Kobayashi
- Department of Genome Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - K Komatsu
- Department of Genome Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - N Kunugita
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
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22
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Shearn CT, Backos DS, Orlicky DJ, Smathers-McCullough RL, Petersen DR. Identification of 5' AMP-activated kinase as a target of reactive aldehydes during chronic ingestion of high concentrations of ethanol. J Biol Chem 2014; 289:15449-62. [PMID: 24722988 DOI: 10.1074/jbc.m113.543942] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The production of reactive aldehydes including 4-hydroxy-2-nonenal (4-HNE) is a key component of the pathogenesis in a spectrum of chronic inflammatory hepatic diseases including alcoholic liver disease (ALD). One consequence of ALD is increased oxidative stress and altered β-oxidation in hepatocytes. A major regulator of β-oxidation is 5' AMP protein kinase (AMPK). In an in vitro cellular model, we identified AMPK as a direct target of 4-HNE adduction resulting in inhibition of both H2O2 and 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR)-induced downstream signaling. By employing biotin hydrazide capture, it was confirmed that 4-HNE treatment of cells resulted in carbonylation of AMPKα/β, which was not observed in untreated cells. Using a murine model of alcoholic liver disease, treatment with high concentrations of ethanol resulted in an increase in phosphorylated as well as carbonylated AMPKα. Despite increased AMPK phosphorylation, there was no significant change in phosphorylation of acetyl CoA carboxylase. Mass spectrometry identified Michael addition adducts of 4-HNE on Cys(130), Cys(174), Cys(227), and Cys(304) on recombinant AMPKα and Cys(225) on recombinant AMPKβ. Molecular modeling analysis of identified 4-HNE adducts on AMPKα suggest that inhibition of AMPK occurs by steric hindrance of the active site pocket and by inhibition of hydrogen peroxide induced oxidation. The observed inhibition of AMPK by 4-HNE provides a novel mechanism for altered β-oxidation in ALD, and these data demonstrate for the first time that AMPK is subject to regulation by reactive aldehydes in vivo.
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Affiliation(s)
| | | | - David J Orlicky
- Department of Pathology, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado 80045 and
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23
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Ceramide-activated phosphatase mediates fatty acid-induced endothelial VEGF resistance and impaired angiogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:1562-76. [PMID: 24606881 DOI: 10.1016/j.ajpath.2014.01.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/25/2013] [Accepted: 01/02/2014] [Indexed: 11/23/2022]
Abstract
Endothelial dysfunction, including endothelial hyporesponsiveness to prototypical angiogenic growth factors and eNOS agonists, underlies vascular pathology in many dysmetabolic states. We investigated effects of a saturated free fatty acid, palmitic acid (PA), on endothelial cell responses to VEGF. PA-pretreated endothelial cells had markedly diminished Akt, eNOS, and ERK activation responses to VEGF, despite normal VEGFR2 phosphorylation. PA inhibited VEGF-induced angiogenic cord formation in Matrigel, and PA-treated endothelial cells accumulated early species (C16) ceramide. The serine palmitoyltransferase inhibitor myriocin reversed these defects. Protein phosphatase 2A (PP2A) became more eNOS-associated in PA-treated cells; the PP2A inhibitor okadaic acid reversed PA-induced signaling defects. Mice fed a diet high in saturated fat for 2 to 3 weeks had impaired i) aortic Akt and eNOS phosphorylation to infused VEGF, ii) ear angiogenic responses to intradermal adenoviral-VEGF injection, and iii) vascular flow recovery to hindlimb ischemia as indicated by laser Doppler and αVβ3 SPECT imaging. High-fat feeding did not impair VEGF-induced signaling or angiogenic responses in mice with reduced serine palmitoyltransferase expression. Thus, de novo ceramide synthesis is required for these detrimental PA effects. The findings demonstrate an endothelial VEGF resistance mechanism conferred by PA, which comprises ceramide-induced, PP2A-mediated dephosphorylation of critical activation sites on enzymes central to vascular homeostasis and angiogenesis. This study defines potential molecular targets for preservation of endothelial function in metabolic syndrome.
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Dwivedi S, Sharma A, Patrick B, Sharma R, Awasthi YC. Role of 4-hydroxynonenal and its metabolites in signaling. Redox Rep 2013; 12:4-10. [PMID: 17263900 DOI: 10.1179/135100007x162211] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Available evidence from a multitude of studies on the effects of 4-hydroxynonenal (HNE) on cellular processes seem to converge on some common themes: (i) concentration-dependent opposing effects of HNE on key signaling components (e.g. protein kinase C, adenylate cyclase) predict that certain constitutive levels of HNE may be needed for normal cell functions - lowering of this constitutive HNE level in cells promotes proliferative machinery while an increase in this level promotes apoptotic signaling; (ii) HNE is a common denominator in stress-induced apoptosis caused by H(2)O(2), superoxide, UV, heat or oxidant chemicals such as doxorubicin; and (iii) HNE can modulate ligand-independent signaling by membrane receptors such as EGFR or Fas (CD95) and may act as a sensor of external stimuli for eliciting stress-response. Against a backdrop of various reported effects of HNE, in vitro and in vivo, we have critically evaluated the above mentioned hypotheses suggesting a key role of HNE in signaling.
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Affiliation(s)
- Seema Dwivedi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-0647, USA
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25
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Kamat PK, Rai S, Nath C. Okadaic acid induced neurotoxicity: An emerging tool to study Alzheimer's disease pathology. Neurotoxicology 2013; 37:163-72. [DOI: 10.1016/j.neuro.2013.05.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 04/25/2013] [Accepted: 05/03/2013] [Indexed: 12/18/2022]
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26
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Yu Y, Huang H, Li J, Zhang J, Gao J, Lu B, Huang C. GADD45β mediates p53 protein degradation via Src/PP2A/MDM2 pathway upon arsenite treatment. Cell Death Dis 2013; 4:e637. [PMID: 23681232 PMCID: PMC3674369 DOI: 10.1038/cddis.2013.162] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Growth arrest and DNA-damage-inducible, beta (GADD45β) has been reported to inhibit apoptosis via attenuating c-Jun N-terminal kinase (JNK) activation. We demonstrated here that GADD45β mediated its anti-apoptotic effect via promoting p53 protein degradation following arsenite treatment. We found that p53 protein expression was upregulated in GADD45β−/− cells upon arsenite exposure as compared with those in GADD45β+/+ cells. Further studies showed that GADD45β attenuated p53 protein expression through Src/protein phosphatase 2A/murine double minute 2-dependent p53 protein-degradation pathway. Moreover, we identified that GADD45β-mediated p53 protein degradation was crucial for its anti-apoptotic effect due to arsenite exposure, whereas increased JNK activation was not involved in the increased cell apoptotic response in GADD45β−/− cells under same experimental conditions. Collectively, our results demonstrate a novel molecular mechanism responsible for GADD45β protection of arsenite-exposed cells from cell death, which provides insight into our understanding of GADD45β function and a unique compound arsenite as both a cancer therapeutic reagent and an environmental carcinogen. Those novel findings may also enable us to design more effective strategies for utilization of arsenite for the treatment of cancers.
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Affiliation(s)
- Y Yu
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987, USA
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27
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Liao J, Sun A, Xie Y, Isse T, Kawamoto T, Zou Y, Ge J. Aldehyde dehydrogenase-2 deficiency aggravates cardiac dysfunction elicited by endoplasmic reticulum stress induction. Mol Med 2012; 18:785-93. [PMID: 22430940 DOI: 10.2119/molmed.2011.00466] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 03/13/2012] [Indexed: 01/02/2023] Open
Abstract
Mitochondrial aldehyde dehydrogenase-2 (ALDH2) has been characterized as an important mediator of endogenous cytoprotection in the heart. This study was designed to examine the role of ALDH2 knockout (KO) in the regulation of cardiac function after endoplasmic reticulum (ER) stress. Wild-type (WT) and ALDH2 KO mice were subjected to a tunicamycin challenge, and the echocardiographic property was examined. Protein levels of six items--78 kDa glucose-regulated protein (GRP78), phosphorylation of eukaryotic initiation factor 2 subunit α (p-eIF2α), CCAAT/enhancer-binding protein homologous protein (CHOP), phosphorylation of Akt, p47(phox) nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and 4-hydroxynonenal--were determined by using Western blot analysis. Cytotoxicity and apoptosis were estimated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay and caspase-3 activity, respectively. ALDH2 deficiency exacerbated cardiac contractile dysfunction and promoted ER stress after ER stress induction, manifested by the changes of ejection fraction and fractional shortening. In vitro study revealed that tunicamycin significantly upregulated the levels of GRP78, p-eIF2α, CHOP, p47(phox) NADPH oxidase and 4-hydroxynonenal, which was exacerbated by ALDH2 knockdown and abolished by ALDH2 overexpression, respectively. Overexpression of ALDH2 abrogated tunicamycin-induced dephosphorylation Akt. Inhibition of phosphatidylinositol 3-kinase using LY294002 did not affect ALDH2-conferred protection against ER stress, although LY294002 reversed the antiapoptotic action of ALDH2 associated with p47(phox) NADPH oxidase. These results suggest a pivotal role of ALDH2 in the regulation of ER stress and ER stress-induced apoptosis. The protective role of ALDH2 against ER stress-induced cell death was probably mediated by Akt via a p47(phox) NADPH oxidase-dependent manner. These findings indicate the critical role of ALDH2 in the pathogenesis of ER stress in heart disease.
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Affiliation(s)
- Jianquan Liao
- Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China
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28
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Abstract
Cell death is regulated by a myriad of intracellular molecular pathways, with many involving protein phosphorylation and dephosphorylation. In this review, we will focus on Ser/Thr phosphatases-mediated regulation in cell apoptosis as well as on their potential roles in cell necrosis. The emerging functional importance of Ser/Thr protein phosphatases in cell death regulation adds new dimension to the signaling mechanisms of cellular function, physiology, and diseases.
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Affiliation(s)
- Haipeng Sun
- Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Department of Pathophysiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
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3,3'-Diindolylmethane exhibits antileukemic activity in vitro and in vivo through a Akt-dependent process. PLoS One 2012; 7:e31783. [PMID: 22363731 PMCID: PMC3283648 DOI: 10.1371/journal.pone.0031783] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 01/16/2012] [Indexed: 12/15/2022] Open
Abstract
3,3′-diindolylmethane (DIM), one of the active products derived from Brassica plants, is a promising antitumor agent. The present study indicated that DIM significantly induced apoptosis in U937 human leukemia cells in dose- and time-dependent manners. These events were also noted in other human leukemia cells (Jurkat and HL-60) and primary human leukemia cells (AML) but not in normal bone marrow mononuclear cells. We also found that DIM-induced lethality is associated with caspases activation, myeloid cell leukemia-1 (Mcl-1) down-regulation, p21cip1/waf1 up-regulation, and Akt inactivation accompanied by c-jun NH2-terminal kinase (JNK) activation. Enforced activation of Akt by a constitutively active Akt construct prevented DIM-mediated caspase activation, Mcl-1 down-regulation, JNK activation, and apoptosis. Conversely, DIM lethality was potentiated by the PI3K inhibitor LY294002. Interruption of the JNK pathway by pharmacologic or genetic approaches attenuated DIM-induced caspases activation, Mcl-1 down-regulation, and apoptosis. Lastly, DIM inhibits tumor growth of mouse U937 xenograft, which was related to induction of apoptosis and inactivation of Akt, as well as activation of JNK. Collectively, these findings suggest that DIM induces apoptosis in human leukemia cell lines and primary human leukemia cells, and exhibits antileukemic activity in vivo through Akt inactivation and JNK activation.
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Liu GP, Wei W, Zhou X, Zhang Y, Shi HH, Yin J, Yao XQ, Peng CX, Hu J, Wang Q, Li HL, Wang JZ. I2PP2A regulates p53 and Akt correlatively and leads the neurons to abort apoptosis. Neurobiol Aging 2012; 33:254-64. [DOI: 10.1016/j.neurobiolaging.2010.01.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 01/18/2010] [Accepted: 01/19/2010] [Indexed: 01/07/2023]
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Fedida-Metula S, Feldman B, Koshelev V, Levin-Gromiko U, Voronov E, Fishman D. Lipid rafts couple store-operated Ca 2+ entry to constitutive activation of PKB/Akt in a Ca 2+ /calmodulin-, Src- and PP2A-mediated pathway and promote melanoma tumor growth. Carcinogenesis 2012; 33:740-50. [DOI: 10.1093/carcin/bgs021] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kim SY, Lee JH, Huh JW, Ro JY, Oh YM, Lee SD, An S, Lee YS. Cigarette smoke induces Akt protein degradation by the ubiquitin-proteasome system. J Biol Chem 2011; 286:31932-43. [PMID: 21778238 PMCID: PMC3173210 DOI: 10.1074/jbc.m111.267633] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 07/13/2011] [Indexed: 11/06/2022] Open
Abstract
Emphysema is one of the characteristic features of chronic obstructive pulmonary disease, which is caused mainly by cigarette smoking. Recent data have suggested that apoptosis and cell cycle arrest may contribute to the development of emphysema. In this study, we addressed the question of whether and how cigarette smoke affected Akt, which plays a critical role in cell survival and proliferation. In normal human lung fibroblasts, cigarette smoke extract (CSE) caused cell death, accompanying degradation of total and phosphorylated Akt (p-Akt), which was inhibited by MG132. CSE exposure resulted in preferential ubiquitination of the active Akt (myristoylated), rather than the inactive (T308A/S473A double mutant) Akt. Consistent with cytotoxicity, CSE induced a progressive decrease of phosphorylated human homolog of mouse double minute homolog 2 (p-HDM2) and phosphorylated apoptosis signal regulating kinase 1 (p-ASK1) with concomitant elevation of p53, p21, and phosphorylated p38 MAPK. Forced expression of the active Akt reduced both CSE-induced cytotoxicity and alteration in HDM2/p53/p21 and ASK1/p38 MAPK, compared with the inactive Akt. Of note, CSE induced expression of the tetratrico-peptide repeat domain 3 (TTC3), known as a ubiquitin ligase for active Akt. TTC3 siRNAs suppressed not only CSE-induced Akt degradation but also CSE-induced cytotoxicity. Accordingly, rat lungs exposed to cigarette smoke for 3 months showed elevated TTC3 expression and reduced Akt and p-Akt. Taken together, these data suggest that cigarette smoke induces cytotoxicity, partly through Akt degradation via the ubiquitin-proteasome system, in which TTC3 acts as a ubiquitin ligase for active Akt.
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Affiliation(s)
- Sun-Yong Kim
- From the Division of Pharmacology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 440-746
| | - Ji-Hyun Lee
- the Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, College of Medicine, Pochon CHA University, Seongnam 463-712
| | - Jin Won Huh
- the Department of Pulmonary and Critical Care Medicine, Asthma Center, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, and
| | - Jai Youl Ro
- From the Division of Pharmacology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 440-746
| | - Yeon-Mock Oh
- the Department of Pulmonary and Critical Care Medicine, Asthma Center, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, and
| | - Sang-Do Lee
- the Department of Pulmonary and Critical Care Medicine, Asthma Center, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, and
| | - Sungkwan An
- the Functional Genoproteome Research Centre, Konkuk University, Seoul 143-701, Republic of Korea
| | - Yun-Song Lee
- From the Division of Pharmacology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon 440-746
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Yuan Z, Wang F, Zhao Z, Zhao X, Qiu J, Nie C, Wei Y. BIM-mediated AKT phosphorylation is a key modulator of arsenic trioxide-induced apoptosis in cisplatin-sensitive and -resistant ovarian cancer cells. PLoS One 2011; 6:e20586. [PMID: 21655183 PMCID: PMC3105099 DOI: 10.1371/journal.pone.0020586] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 05/06/2011] [Indexed: 02/05/2023] Open
Abstract
Background Chemo-resistance to cisplatin-centered cancer therapy is a major obstacle to the effective treatment of human ovarian cancer. Previous reports indicated that arsenic trioxide (ATO) induces cell apoptosis in both drug-sensitive and -resistant ovarian cancer cells. Principal Findings In this study, we determined the molecular mechanism of ATO-induced apoptosis in ovarian cancer cells. Our data demonstrated that ATO induced cell apoptosis by decreasing levels of phosphorylated AKT (p-AKT) and activating caspase-3 and caspase-9. Importantly, BIM played a critical role in ATO-induced apoptosis. The inhibition of BIM expression prevented AKT dephosphorylation and inhibited caspase-3 activation during cell apoptosis. However, surprisingly, gene silencing of AKT or FOXO3A had little effect on BIM expression and phosphorylation. Moreover, the activation of caspase-3 by ATO treatment improved AKT dephosphorylation, not only by cleaving the regulatory A subunit of protein phosphatase 2A (PP2A), but also by increasing its activation. Furthermore, our data indicated that the c-Jun N-terminal kinases (JNK) pathway is involved in the regulation of BIM expression. Conclusions We demonstrated the roles of BIM in ATO-induced apoptosis and the molecular mechanisms of BIM expression regulated by ATO during ovarian cancer cell apoptosis. Our findings suggest that BIM plays an important role in regulating p-AKT by activating caspase-3 and that BIM mediates the level of AKT phosphorylation to determine the threshold for overcoming cisplatin resistance in ovarian cancer cells.
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Affiliation(s)
- Zhu Yuan
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Fang Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Zhiwei Zhao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xinyu Zhao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Ji Qiu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Chunlai Nie
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
- * E-mail:
| | - Yuquan Wei
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
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Voronkov M, Braithwaite SP, Stock JB. Phosphoprotein phosphatase 2A: a novel druggable target for Alzheimer's disease. Future Med Chem 2011; 3:821-33. [PMID: 21644827 PMCID: PMC3292348 DOI: 10.4155/fmc.11.47] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Tau hyperphosphorylation is thought to play an important role in the etiology of Alzheimer's disease by facilitating the formation of neurofibrillary tangles. Reducing phosphorylation through kinase inhibition has therefore emerged as a target for drug development, but despite considerable efforts to develop therapeutic kinase inhibitors, success has been limited. An alternative approach is to develop pharmaceuticals to enhance the activity of the principal phospho-tau phosphatase, phosphoprotein phosphatase 2A (PP2A). In this article we review evidence that this mechanism is pharmacologically achievable and has promise for delivering the next generation of Alzheimer's disease therapeutics. A number of different chemotypes have been reported to lead to enhanced PP2A activity through a range of proposed mechanisms. Some of these compounds appear to act directly as allosteric activators of PP2A, while others act indirectly by inhibiting the binding of PP2A inhibitors or by altering post-translational modifications that act in turn to regulate PP2A activity towards phospho-tau. These results indicate that PP2A may provide a useful target that can be safely, selectively and effectively modulated through pharmaceutical intervention to treat Alzheimer's disease.
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Affiliation(s)
| | | | - Jeffry B Stock
- Signum Biosciences, Monmouth Junction, NJ 08852, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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Shearn CT, Fritz KS, Reigan P, Petersen DR. Modification of Akt2 by 4-Hydroxynonenal Inhibits Insulin-Dependent Akt Signaling in HepG2 Cells. Biochemistry 2011; 50:3984-96. [DOI: 10.1021/bi200029w] [Citation(s) in RCA: 238] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. T. Shearn
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
| | - K. S. Fritz
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
| | - P. Reigan
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
| | - Dennis R. Petersen
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
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Shearn CT, Smathers RL, Stewart BJ, Fritz KS, Galligan JJ, Hail N, Petersen DR. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibition by 4-hydroxynonenal leads to increased Akt activation in hepatocytes. Mol Pharmacol 2011; 79:941-52. [PMID: 21415306 DOI: 10.1124/mol.110.069534] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The production of reactive aldehydes such as 4-hydroxynonenal (4-HNE) is proposed to be an important factor in the etiology of alcoholic liver disease. To understand the effects of 4-HNE on homeostatic signaling pathways in hepatocytes, cellular models consisting of the human hepatocellular carcinoma cell line (HepG2) and primary rat hepatocytes were evaluated. Treatment of both HepG2 cells and primary hepatocytes with subcytotoxic concentrations of 4-HNE resulted in the activation of Akt within 30 min as demonstrated by increased phosphorylation of residues Ser473 and Thr308. Quantification and subsequent immunocytochemistry of phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P(3)[rsqb] resulted in a 6-fold increase in total PtdIns(3,4,5)P(3) and increased immunostaining at the plasma membrane after 4-HNE treatment. Cotreatment of HepG2 cells with 4-HNE and the phosphatidylinositol 3-kinase (PI3K) inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (Ly294002) or the protein phosphatase 2A (PP2A) inhibitor okadaic acid revealed that the mechanism of activation of Akt is PI3K-dependent and PP2A-independent. Using biotin hydrazide detection, it was established that the incubation of HepG2 cells with 4-HNE resulted in increased carbonylation of the lipid phosphatase known as "phosphatase and tensin homolog deleted on chromosome 10" (PTEN), a key regulator of Akt activation. Activity assays both in HepG2 cells and recombinant PTEN revealed a decrease in PTEN lipid phosphatase activity after 4-HNE application. Mass spectral analysis of 4-HNE-treated recombinant PTEN detected a single 4-HNE adduct. Subsequent analysis of Akt dependent physiological consequences of 4-HNE in HepG2 cells revealed significant increases in the accumulation of neutral lipids. These results provide a potential mechanism of Akt activation and cellular consequences of 4-HNE in hepatocytes.
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Affiliation(s)
- Colin T Shearn
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, Aurora, Colorado, USA
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37
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Dubinina EE, Dadali VA. Role of 4-hydroxy-trans-2-nonenal in cell functions. BIOCHEMISTRY (MOSCOW) 2010; 75:1069-87. [DOI: 10.1134/s0006297910090014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Dabrowski MJ, Zolnerciks JK, Balogh LM, Greene RJ, Kavanagh TJ, Atkins WM. Stereoselective effects of 4-hydroxynonenal in cultured mouse hepatocytes. Chem Res Toxicol 2010; 23:1601-7. [PMID: 20873854 DOI: 10.1021/tx100190k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
4-Hydroxynonenal (HNE) is produced from arachidonic acid or linoleic acid during oxidative stress. Although HNE is formed in tissues as a racemate, enantiospecific HNE effects have not been widely documented, nor considered. Therefore, a panel of cellular responses was compared after treatment with (R)-HNE, (S)-HNE, or racemic HNE. The phosphorylation status of Jun kinase (JNK) or Akt increased 28-fold or 2-3-fold, respectively, after treatment with 100 μM (S)-HNE and racemic HNE compared to (R)-HNE. In contrast, the increase in phosphorylation of MAPK was greatest for (R)-HNE. Caspase-3-dependent cleavage of the glutamate cysteine ligase (GCL) catalytic subunit and focal adhesion kinase (FAK) were greater in cells treated with (S)-HNE at 48 h. (S)-HNE also caused a greater number of subG1 nuclei, a hallmark of apoptosis, at 30 h after treatment. Together, the results demonstrate different dose- and time-dependent responses to (R)-HNE and (S)-HNE. The results further suggest that HNE enantiomers could differentially contribute to the progression of different diseases or contribute by different mechanisms.
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Affiliation(s)
- Michael J Dabrowski
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195-7610, USA
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39
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Cetrullo S, Tantini B, Facchini A, Pignatti C, Stefanelli C, Caldarera CM, Flamigni F. A pro-survival effect of polyamine depletion on norepinephrine-mediated apoptosis in cardiac cells: role of signaling enzymes. Amino Acids 2010; 40:1127-37. [DOI: 10.1007/s00726-010-0736-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 08/26/2010] [Indexed: 12/30/2022]
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40
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Ma H, Guo R, Yu L, Zhang Y, Ren J. Aldehyde dehydrogenase 2 (ALDH2) rescues myocardial ischaemia/reperfusion injury: role of autophagy paradox and toxic aldehyde. Eur Heart J 2010; 32:1025-38. [PMID: 20705694 DOI: 10.1093/eurheartj/ehq253] [Citation(s) in RCA: 267] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
AIMS The present study was designed to examine the mechanism involved in mitochondrial aldehyde dehydrogenase (ALDH2)-induced cardioprotection against ischaemia/reperfusion (I/R) injury with a focus on autophagy. METHODS Wild-type (WT), ALDH2 overexpression, and knockout (KO) mice (n = 4-6 for each index measured) were subjected to I/R, and myocardial function was assessed using echocardiographic, Langendroff, and edge-detection systems. Western blotting was used to evaluate AMP-dependent protein kinase (AMPK), Akt, autophagy, and the AMPK/Akt upstream signalling LKB1 and PTEN. RESULTS ALDH2 overexpression and KO significantly attenuated and accentuated, respectively, infarct size, factional shortening, and recovery of post-ischaemic left ventricular function following I/R as well as hypoxia/reoxygenation-induced cardiomyocyte contractile dysfunction. Autophagy was induced during ischaemia and remained elevated during reperfusion. ALDH2 significantly promoted autophagy during ischaemia, which was accompanied by AMPK activation and mammalian target of rapamycin (mTOR) inhibition. On the contrary, ALDH2 overtly inhibited autophagy during reperfusion accompanied by the activation of Akt and mTOR. Inhibition and induction of autophagy mitigated ALDH2-induced protection against cell death in hypoxia and reoxygenation, respectively. In addition, levels of the endogenous toxic aldehyde 4-hydroxy-2-nonenal (4-HNE) were elevated by ischaemia and reperfusion, which was abrogated by ALDH2. Furthermore, ALDH2 ablated 4-HNE-induced cardiomyocyte dysfunction and protein damage, whereas 4-HNE directly decreased pan and phosphorylated LKB1 and PTEN expression. CONCLUSION Our data suggest a myocardial protective effect of ALDH2 against I/R injury possibly through detoxification of toxic aldehyde and a differential regulation of autophagy through AMPK- and Akt-mTOR signalling during ischaemia and reperfusion, respectively.
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Affiliation(s)
- Heng Ma
- Department of Physiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, China
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41
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Rosales-Corral S, Reiter RJ, Tan DX, Ortiz GG, Lopez-Armas G. Functional aspects of redox control during neuroinflammation. Antioxid Redox Signal 2010; 13:193-247. [PMID: 19951033 DOI: 10.1089/ars.2009.2629] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neuroinflammation is a CNS reaction to injury in which some severe pathologies, regardless of their origin, converge. The phenomenon emphasizes crosstalk between neurons and glia and reveals a complex interaction with oxidizing agents through redox sensors localized in enzymes, receptors, and transcription factors. When oxidizing pressures cause reversible molecular changes, such as minimal or transitory proinflammatory cytokine overproduction, redox couples provide a means of translating the presence of reactive oxygen or nitrogen species into useful signals in the cell. Additionally, thiol-based redox sensors convey information about localized changes in redox potential induced by physiologic or pathologic situations. They are susceptible to oxidative changes and become key events during neuroinflammation, altering the course of a signaling response or the behavior of specific transcription factors. When oxidative stress augments the pressure on the intracellular environment, the effective reduction potential of redox pairs diminishes, and cell signaling shifts toward proinflammatory and proapoptotic signals, creating a vicious cycle between oxidative stress and neuroinflammation. In addition, electrophilic compounds derived from the oxidative cascade react with key protein thiols and interfere with redox signaling. This article reviews the relevant functional aspects of redox control during the neuroinflammatory process.
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Affiliation(s)
- Sergio Rosales-Corral
- Lab. Desarrollo-Envejecimiento, Enfermedades Neurodegenerativas, División de Neurociencias, Centro de Investigación Biomédica de Occidente (CIBO) del Instituto Mexicano del Seguro Social (IMSS) , Guadalajara, Jalisco. Mexico.
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Calvo N, de Boland AR, Gentili C. PTH inactivates the AKT survival pathway in the colonic cell line Caco-2. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:343-51. [PMID: 20005908 DOI: 10.1016/j.bbamcr.2009.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 11/25/2009] [Accepted: 11/30/2009] [Indexed: 12/28/2022]
Abstract
In previous works, we found that PTH promotes the apoptosis of human Caco-2 intestinal cells, through the mitochondrial pathway. This study was conducted to investigate the modulation of different players implicated in the AKT survival pathway in PTH-induced intestinal cell apoptosis. We demonstrate, for the first time, that PTH modulates AKT phosphorylation in response to apoptosis via the serine/threonine phosphatase PP2A. PTH treatment induces an association of AKT with the catalytic subunit of PP2A and increases its phosphatase activity. PTH also promotes the translocation of PP2Ac from the cytosol to the mitochondria. Furthermore, our results suggest that PP2A plays a role in hormone-dependent Caco-2 cells viability and in the cleavage of caspase-3 and its substrate PARP. The cAMP pathway also contributes to PTH-mediated AKT dephosphorylation while PKC and p38 MAPK do not participate in this event. Finally, we show that PTH induces the dissociation between 14-3-3 and AKT, but the significance of this response remains unknown. In correlation with PTH-induced Bad dephosphorylation, the hormone also decreases the basal association of 14-3-3 and Bad. Overall, our data suggest that in Caco-2 cells, PP2A and the cAMP pathway act in concert to inactivate the AKT survival pathway in PTH-induced intestinal cell apoptosis.
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Affiliation(s)
- Natalia Calvo
- Department Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, (8000) Bahía Blanca, Argentina
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Ahmed N, Pany S, Rahman A, Srivastava SS, Sneh A, Krishnasastry MV. Modulation of PP2A activity by Jacalin: is it through caveolae and ER chaperones? Glycoconj J 2009; 27:723-34. [PMID: 19823931 DOI: 10.1007/s10719-009-9258-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 03/08/2009] [Accepted: 08/21/2009] [Indexed: 10/20/2022]
Abstract
Plant lectins have been reported to affect the proliferation of different human cancer cell line probably by binding to the specific carbohydrate moieties. In the present study, Badan labeled single cysteine mutant (present in the caveolin-1 binding motif) of jacalin (rJacalin) was found to penetrate the target membrane, indicating a protein-protein or protein-membrane interaction apart from its primary mode of binding i.e. protein-carbohydrate interaction. Further, Jacalin treatment has resulted in the movement of the GFP-Caveolin-1 predominantly at the cell-cell contact region with much restricted dynamics. Jacalin treatment has resulted in the perinuclear accumulation of PP2A and dissociation of the PHAP1/PP2A complex. PP2A was found to act as a negative regulator of ERK signaling and a significant decrease in the phosphorylation level of MEK and AKT (T308) in A431. In addition, we have also identified several ER resident proteins including molecular chaperones like ORP150, Hsp70, Grp78, BiP of A431 cells, which were bound to the Jacalin-sepharose column. Among various ER chaperones that were identified, ORP150 was found to present on the cell surface of A431 cells.
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Affiliation(s)
- Neesar Ahmed
- National Centre for Cell Science, Ganeshkhind Road, University of Pune Campus, Pune, 411007, India
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44
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Hu X, Wu X, Xu J, Zhou J, Han X, Guo J. Src kinase up-regulates the ERK cascade through inactivation of protein phosphatase 2A following cerebral ischemia. BMC Neurosci 2009; 10:74. [PMID: 19602257 PMCID: PMC2714518 DOI: 10.1186/1471-2202-10-74] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 07/14/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The regulation of protein phosphorylation requires a balance in the activity of protein kinases and protein phosphatases. Our previous data indicates that Src can increase ERK activity through Raf kinase in response to ischemic stimuli. This study examined the molecular mechanisms by which Src activates ERK cascade through protein phosphatases following cerebral ischemia. RESULTS Ischemia-induced Src activation is followed by phosphorylation of PP2A at Tyr307 leading to its inhibition in the rat hippocampus. SU6656, a Src inhibitor, up-regulates PP2A activity, resulting in a significant decreased activity in ERK and its targets, CREB and ERalpha. In addition, the PP2A inhibitor, cantharidin, led to an up-regulation of ERK activity and was able to counteract Src inhibition during ischemia. CONCLUSION Src induces up-regulation of ERK activity and its target transcription factors, CREB and ERalpha, through attenuation of PP2A activity. Therefore, activation of ERK is the result of a crosstalk between two pathways, Raf-dependent positive regulators and PP2A-dependent negative regulators.
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Affiliation(s)
- Xiaohan Hu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing 210029, PR China.
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45
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Joshi-Barve S, Amancherla K, Patil M, Bhatnagar A, Mathews S, Gobejishvili L, Cave M, McClain C, Barve S. Acrolein, a ubiquitous pollutant and lipid hydroperoxide product, inhibits antiviral activity of interferon-alpha: relevance to hepatitis C. Free Radic Biol Med 2009; 47:47-54. [PMID: 19345260 PMCID: PMC3947765 DOI: 10.1016/j.freeradbiomed.2009.03.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 03/26/2009] [Accepted: 03/26/2009] [Indexed: 01/31/2023]
Abstract
Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and can lead to hepatocellular carcinoma and end-stage liver disease. The current FDA-approved treatment for HCV (pegylated interferon-alpha (IFNalpha) with ribavirin) is effective in only about 50% of patients. Epidemiological evidence suggests that obesity, alcohol, smoking, and environmental pollutants may contribute to resistance to IFNalpha therapy in HCV. Acrolein, a ubiquitous environmental pollutant and major component of cigarette smoke, is also generated endogenously by cellular metabolism and lipid peroxidation. This study examines the effects of acrolein on (i) IFNalpha-mediated signaling and antiviral gene expression in cultured and primary human hepatocytes and (ii) HCV replication in an HCV-replicon system. Our data demonstrate that nontoxic concentrations of acrolein significantly inhibited IFNalpha-induced tyrosine phosphorylation of both cytoplasmic and nuclear STAT1 and STAT2, without altering the total levels. Also, acrolein down-regulated IFNalpha-stimulated gene transcription, resulting in reduced expression of antiviral genes. Importantly, acrolein abolished the IFNalpha-mediated down-regulation of HCV viral expression in the HCV-replicon system. This study defines mechanisms involved in resistance to IFNalpha and identifies the pathogenic role of acrolein, and potentially other environmental pollutants, in suppressing IFNalpha antiviral activity and establishes their adverse impact on HCV therapy.
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Affiliation(s)
- Swati Joshi-Barve
- Department of Medicine, University of Louisville Medical Center
- Department of Pharmacology & Toxicology, University of Louisville Medical Center
| | | | - Madhuvanti Patil
- Department of Pharmacology & Toxicology, University of Louisville Medical Center
| | - Aruni Bhatnagar
- Department of Medicine, University of Louisville Medical Center
- Department of Pharmacology & Toxicology, University of Louisville Medical Center
| | - Stephanie Mathews
- Department of Pharmacology & Toxicology, University of Louisville Medical Center
| | | | - Matthew Cave
- Department of Medicine, University of Louisville Medical Center
- Louisville VA Medical Center, Louisville, Kentucky
| | - Craig McClain
- Department of Medicine, University of Louisville Medical Center
- Department of Pharmacology & Toxicology, University of Louisville Medical Center
- Louisville VA Medical Center, Louisville, Kentucky
| | - Shirish Barve
- Department of Medicine, University of Louisville Medical Center
- Department of Pharmacology & Toxicology, University of Louisville Medical Center
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46
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Schwartz L, Abolhassani M, Pooya M, Steyaert JM, Wertz X, Israël M, Guais A, Chaumet-Riffaud P. Hyperosmotic stress contributes to mouse colonic inflammation through the methylation of protein phosphatase 2A. Am J Physiol Gastrointest Liver Physiol 2008; 295:G934-41. [PMID: 18755808 DOI: 10.1152/ajpgi.90296.2008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
There are several reports suggesting hyperosmotic contents in the feces of patients suffering from inflammatory bowel disease (IBD). Previous works have documented that hyperosmolarity can cause inflammation attributable to methylation of the catalytic subunit of protein phosphatase 2A (PP2A) and subsequent NF-kappaB activation resulting in cytokine secretion. In this study, we demonstrate that dextran sulfate sodium (DSS) induces colitis due to hyperosmolarity and subsequent PP2A activation. Mice were randomized and fed with increased concentrations of DSS (0 mOsm, 175 mOsm, 300 mOsm, and 627 mOsm) for a duration of 3 wk or with hyperosmotic concentrations of DSS (627 mOsm) or mannitol (450 mOsm) for a duration of 12 wk. Long-term oral administration of hyposmotic DSS or mannitol had no demonstrable effect. Hyperosmotic DSS or mannitol produced a significant increase in colonic inflammation, as well as an increase in the weight of sacral lymph nodes and in serum amyloid A protein levels. Similar results were obtained through the ingestion of comparable osmolarities of mannitol. Hyperosmolarity induces the methylation of PP2A, nuclear p65 NF-kappaB activation. and cytokine secretion. The rectal instillation of okadaic acid, a well-known PP2A inhibitor, reverses the IBD. Short inhibiting RNAs (siRNAs) targeted toward PP2Ac reverse the effect of hyperosmotic DSS. The present study strongly suggests that DSS-induced chronic colitis is a consequence of the methylation of PP2Ac induced by hyperosmolarity.
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Affiliation(s)
- Laurent Schwartz
- Service de Radiothérapie Hôpital Pitié-Salpétrière, bd. de l'Hôpital, 75013 Paris, France.
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Vaillancourt F, Fahmi H, Shi Q, Lavigne P, Ranger P, Fernandes JC, Benderdour M. 4-Hydroxynonenal induces apoptosis in human osteoarthritic chondrocytes: the protective role of glutathione-S-transferase. Arthritis Res Ther 2008; 10:R107. [PMID: 18782442 PMCID: PMC2592788 DOI: 10.1186/ar2503] [Citation(s) in RCA: 253] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 08/16/2008] [Accepted: 09/09/2008] [Indexed: 11/11/2022] Open
Abstract
Introduction 4-Hydroxynonenal (HNE) is one of the most abundant and reactive aldehydes of lipid peroxidation products and exerts various effects on intracellular and extracellular signalling cascades. We have previously shown that HNE at low concentrations could be considered as an important mediator of catabolic and inflammatory processes in osteoarthritis (OA). In the present study, we focused on characterizing the signalling cascade induced by high HNE concentration involved in cell death in human OA chondrocytes. Methods Markers of apoptosis were quantified with commercial kits. Protein levels were evaluated by Western blotting. Glutathione (GSH) and ATP levels were measured with commercial kits. Glucose uptake was assessed by 2-deoxy-D-[3H]-glucose. The role of GSH-S-transferase A4-4 (GSTA4-4) in controlling HNE-induced chondrocyte apoptosis was investigated by chondrocyte transfection with small interfering RNA (siRNA) or with the expression vector of GSTA4-4. Results Our data showed that HNE at concentrations of up to 10 μM did not alter cell viability but was cytotoxic at concentrations of greater than or equal to 20 μM. HNE-induced chondrocyte death exhibited several classical hallmarks of apoptosis, including caspase activation, cytochrome c and apoptosis-induced factor release from mitochondria, poly (ADP-ribose) polymerase cleavage, Bcl-2 downregulation, Bax upregulation, and DNA fragmentation. Our study of signalling pathways revealed that HNE suppressed pro-survival Akt kinase activity but, in contrast, induced Fas/CD95 and p53 expression in chondrocytes. All of these effects were inhibited by an antioxidant, N-acetyl-cysteine. Analysis of cellular energy and redox status showed that HNE induced ATP, NADPH, and GSH depletion and inhibited glucose uptake and citric acid cycle activity. GSTA4-4 ablation by the siRNA method augmented HNE cytotoxicity, but, conversely, its overexpression efficiently protected chondrocytes from HNE-induced cell death. Conclusion Our study provides novel insights into the potential mechanisms of cell death in OA cartilage and suggests the potential role of HNE in OA pathophysiology. GSTA4-4 expression is critically important for cellular defence against oxidative stress-induced cell death in OA cartilage, possibly by HNE elimination.
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Affiliation(s)
- France Vaillancourt
- Orthopaedic Research Laboratory, Hôpital du Sacré-Caeur de Montréal, Department of Surgery, University of Montreal, 5400 Gouin Blvd, West, Montreal, QC, H4J 1C5, Canada.
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Awasthi YC, Sharma R, Sharma A, Yadav S, Singhal SS, Chaudhary P, Awasthi S. Self-regulatory role of 4-hydroxynonenal in signaling for stress-induced programmed cell death. Free Radic Biol Med 2008; 45:111-8. [PMID: 18456001 PMCID: PMC2664084 DOI: 10.1016/j.freeradbiomed.2008.04.007] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 04/02/2008] [Accepted: 04/06/2008] [Indexed: 11/26/2022]
Abstract
Within the last two decades, 4-hydroxynonenal has emerged as an important second messenger involved in the regulation of various cellular processes. Our recent studies suggest that HNE can induce apoptosis in various cells through the death receptor Fas (CD95)-mediated extrinsic pathway as well as through the p53-dependent intrinsic pathway. Interestingly, through its interaction with the nuclear protein Daxx, HNE can self-limit its apoptotic role by translocating Daxx to cytoplasm where it binds to Fas and inhibits Fas-mediated apoptosis. In this paper, after briefly describing recent studies on various biological activities of HNE, based on its interactions with Fas, Daxx, and p53, we speculate on possible mechanisms through which HNE may affect a multitude of cellular processes and draw a parallel between signaling roles of H(2)O(2) and HNE.
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Affiliation(s)
- Yogesh C Awasthi
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA.
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Hong K, Lou L, Gupta S, Ribeiro-Neto F, Altschuler DL. A novel Epac-Rap-PP2A signaling module controls cAMP-dependent Akt regulation. J Biol Chem 2008; 283:23129-38. [PMID: 18550542 DOI: 10.1074/jbc.m800478200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rap1b has been implicated in the transduction of the cAMP mitogenic signal. It is phosphorylated and activated by cAMP, and its expression in models where cAMP is mitogenic leads to proliferation and tumorigenesis. Akt is a likely downstream effector of cAMP-Rap1 action. cAMP elevation induced a rapid and transient Akt inhibition that required activated and phosphorylated Rap1b. However, the mechanism(s) by which cAMP-Rap regulates Akt remains unclear. Here we show that (i) upstream regulators, PIK and PDK1, are not the target(s) of the cAMP inhibitory action; (ii) constitutively active Akt and calyculin A-stimulated Akt are resistant to cAMP inhibition, suggesting the action of a phosphatase; (iii) cAMP increases the rate of Akt dephosphorylation, directly implicating an Akt-phosphatase; (iv) Epac- and protein kinase A (PKA)-specific analogs synergistically inhibit Akt, indicating the involvement of both cAMP-dependent effector pathways; (v) H89 and dominant negative Epac 279E block cAMP-inhibitory action; (vi) Epac associates in a complex with Akt and PP2A, and the associated-phosphatase activity is positively modulated by cAMP in a PKA- and Rap1-dependent manner; (vii) like its action on Akt inhibition, PKA- and Epac-specific analogs synergistically activate Epac-associated PP2A; and (viii) dominant negative PP2A blocks cAMP-inhibitory action. Thus, we uncovered a novel cAMP-Epac/PKA-Rap1b-PP2A signaling module involved in Akt regulation that may represent a physiological event in the process of cAMP stimulation of thyroid mitogenesis.
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Affiliation(s)
- Kyoungja Hong
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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Zitzmann K, Vlotides G, Göke B, Auernhammer CJ. PI(3)K-Akt-mTOR pathway as a potential therapeutic target in neuroendocrine tumors. Expert Rev Endocrinol Metab 2008; 3:207-222. [PMID: 30764093 DOI: 10.1586/17446651.3.2.207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Constitutive activation of PI(3)K-Akt-mTOR signaling is a frequently occurring event in human cancer and has also been detected in the majority of neuroendocrine tumors (NETs) of the gastroenteropancreatic system. Molecular analysis of NETs suggests, that in addition to mutations in certain tumor-suppressor genes (e.g., PTEN), multiple autocrine growth factor loops contribute to hyperactive PI(3)K-Akt-mTOR signaling, thus promoting unrestricted proliferation and resistance to apoptosis. These insights opened new perspectives for targeted therapy in NETs. In particular, several novel small-molecule inhibitors of tyrosine and serine/threonine kinases have demonstrated potent anti-tumor activity. This review will summarize current knowledge on PI(3)K-Akt-mTOR signaling, its role in proliferation and apoptosis, as well as novel therapeutic approaches targeting PI(3)K-Akt-mTOR pathway components in NET disease.
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Affiliation(s)
- Kathrin Zitzmann
- a Department of Internal Medicine II - Grosshadern, Ludwig-Maximilians- University of Munich, Marchioninistr. 15, 81377 Munich, Germany.
| | - George Vlotides
- b Department of Medicine, Cedars-Sinai Medical Center, University of California School of Medicine, Los Angeles, CA 90048, USA.
| | - Burkhard Göke
- c Department of Internal Medicine II - Grosshadern, Ludwig-Maximilians-University of Munich, Marchioninistr. 15, 81377 Munich, Germany.
| | - Christoph J Auernhammer
- d Department of Internal Medicine II - Grosshadern, Ludwig-Maximilians-University of Munich, Marchioninistr. 15, 81377 Munich, Germany.
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