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Mondal P, Aljizeeri A, Small G, Malhotra S, Harikrishnan P, Affandi JS, Buechel RR, Dwivedi G, Al-Mallah MH, Jain D. Coronary artery disease in patients with human immunodeficiency virus infection. J Nucl Cardiol 2021; 28:510-530. [PMID: 32820424 DOI: 10.1007/s12350-020-02280-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 05/01/2020] [Indexed: 01/02/2023]
Abstract
The life expectancy of people infected with human immunodeficiency virus (HIV) is rising due to better access to combination anti-retroviral therapy (ART). Although ART has reduced acquired immune deficiency syndrome (AIDS) related mortality and morbidity, there has been an increase in non-AIDS defining illnesses such as diabetes mellitus, hypercholesterolemia and coronary artery disease (CAD). HIV is a disease marked by inflammation which has been associated with specific biological vascular processes increasing the risk of premature atherosclerosis. The combination of pre-existing risk factors, atherosclerosis, ART, opportunistic infections and coagulopathy contributes to rising CAD incidence. The prevalence of CAD has emerged as a major contributor of morbidity in these patients due to longer life expectancy. However, ART has been associated with lipodystrophy, dyslipidemia, insulin resistance, diabetes mellitus and CAD. These adverse effects, along with drug-drug interactions when ART is combined with cardiovascular drugs, result in significant challenges in the care of this group of patients. Exercise tolerance testing, echocardiography, myocardial perfusion imaging, coronary computed tomography angiography and magnetic resonance imaging help in the diagnosis of CAD and heart failure and help predict cardiovascular outcomes in a manner similar to non-infected individuals. This review will highlight the pathogenesis and factors that link HIV to CAD, presentation and treatment of HIV-patients presenting with CAD and review briefly the cardiac imaging modalities used to identify this entity and help prognosticate future outcomes.
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Affiliation(s)
- Pratik Mondal
- Department of Cardiology and Nuclear Cardiovascular Imaging Laboratory, New York Medical College, Westchester Medical Center, 100 Woods Road, Valhalla, NY, 10595, USA
| | - Ahmed Aljizeeri
- King Abdulaziz Cardiac Center, Ministry of National Guard-Health Affaire, Riyadh, Saudi Arabia
- King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Gary Small
- Division of Cardiology, University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Saurabh Malhotra
- Division of Cardiology, Cook County Health, Chicago, IL, USA
- Division of Cardiology, Rush Medical College, Chicago, IL, USA
| | | | | | - Ronny R Buechel
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Zurich, Switzerland
| | - Girish Dwivedi
- Fiona Stanley Hospital, Murdoch, WA, Australia
- Harry Perkins Institute of Medical Research, Murdoch, WA, Australia
- The University of Western Australia, Crawley, WA, Australia
| | - Mouaz H Al-Mallah
- Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, TX, USA
| | - Diwakar Jain
- Department of Cardiology and Nuclear Cardiovascular Imaging Laboratory, New York Medical College, Westchester Medical Center, 100 Woods Road, Valhalla, NY, 10595, USA.
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2
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Panda S, Behera S, Alam MF, Syed GH. Endoplasmic reticulum & mitochondrial calcium homeostasis: The interplay with viruses. Mitochondrion 2021; 58:227-242. [PMID: 33775873 DOI: 10.1016/j.mito.2021.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 03/08/2021] [Accepted: 03/22/2021] [Indexed: 02/08/2023]
Abstract
Calcium ions (Ca2+) act as secondary messengers in a plethora of cellular processes and play crucial role in cellular organelle function and homeostasis. The average resting concentration of Ca2+ is nearly 100 nM and in certain cells it can reach up to 1 µM. The high range of Ca2+ concentration across the plasma membrane and intracellular Ca2+ stores demands a well-coordinated maintenance of free Ca2+ via influx, efflux, buffering and storage. Endoplasmic Reticulum (ER) and Mitochondria depend on Ca2+ for their function and also serve as major players in intracellular Ca2+ homeostasis. The ER-mitochondria interplay helps in orchestrating cellular calcium homeostasis to avoid any detrimental effect resulting from Ca2+ overload or depletion. Since Ca2+ plays a central role in many biological processes it is an essential component of the virus-host interactions. The large gradient across membranes enable the viruses to easily modulate this buffered environment to meet their needs. Viruses exploit Ca2+ signaling to establish productive infection and evade the host immune defense. In this review we will detail the interplay between the viruses and cellular & ER-mitochondrial calcium signaling and the significance of these events on viral life cycle and disease pathogenesis.
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Affiliation(s)
- Swagatika Panda
- Institute of Life Sciences, Bhubaneswar, Virus-Host Interaction Lab, Institute of Life Sciences, Bhubaneswar, India
| | - Suchismita Behera
- Institute of Life Sciences, Bhubaneswar, Clinical Proteomics Laboratory, Institute of Life Sciences, Bhubaneswar, India
| | - Mohd Faraz Alam
- Institute of Life Sciences, Bhubaneswar, Virus-Host Interaction Lab, Institute of Life Sciences, Bhubaneswar, India
| | - Gulam Hussain Syed
- Institute of Life Sciences, Bhubaneswar, Virus-Host Interaction Lab, Institute of Life Sciences, Bhubaneswar, India.
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3
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Moreno-Altamirano MMB, Kolstoe SE, Sánchez-García FJ. Virus Control of Cell Metabolism for Replication and Evasion of Host Immune Responses. Front Cell Infect Microbiol 2019; 9:95. [PMID: 31058096 PMCID: PMC6482253 DOI: 10.3389/fcimb.2019.00095] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/22/2019] [Indexed: 12/11/2022] Open
Abstract
Over the last decade, there has been significant advances in the understanding of the cross-talk between metabolism and immune responses. It is now evident that immune cell effector function strongly depends on the metabolic pathway in which cells are engaged in at a particular point in time, the activation conditions, and the cell microenvironment. It is also clear that some metabolic intermediates have signaling as well as effector properties and, hence, topics such as immunometabolism, metabolic reprograming, and metabolic symbiosis (among others) have emerged. Viruses completely rely on their host's cell energy and molecular machinery to enter, multiply, and exit for a new round of infection. This review explores how viruses mimic, exploit or interfere with host cell metabolic pathways and how, in doing so, they may evade immune responses. It offers a brief outline of key metabolic pathways, mitochondrial function and metabolism-related signaling pathways, followed by examples of the mechanisms by which several viral proteins regulate host cell metabolic activity.
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Affiliation(s)
- María Maximina B Moreno-Altamirano
- Laboratorio de Inmunorregulación, Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Simon E Kolstoe
- School of Health Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Francisco Javier Sánchez-García
- Laboratorio de Inmunorregulación, Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
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Kumar P, Rawat K, Sharma T, Kumari S, Saxena R, Kumar B, Baghel T, Afshan T, Siddiqi MI, Nazir A, Ghosh JK, Tripathi RK. HIV-1 Nef physically associate with CAMKIIδ - ASK-1 complex to inhibit p38MAPK signalling and apoptosis in infected cells. Life Sci 2019; 224:263-273. [PMID: 30902545 DOI: 10.1016/j.lfs.2019.03.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/13/2019] [Accepted: 03/16/2019] [Indexed: 11/15/2022]
Abstract
Human immunodeficiency type 1 virus accessory protein Nef is a key modulator of AIDS pathogenesis. With no enzymatic activity, Nef regulated functions in host cells largely depends on its ability to form multi-protein complex with the cellular proteins. Here, we identified Calcium (Ca2+)/Calmodulin dependent protein kinase II subunit delta (CAMKIIδ) as novel Nef interacting host protein. Further, we confirmed that Nef mediated [Ca2+]I promote formation of Nef-CAMKIIδ - apoptosis signal-regulating kinase (ASK-1) heterotrimeric complex. The assembly of Nef with CAMKIIδ - ASK-1 inhibits the downstream p38MAPK phosphorylation resulting in abrogation of apoptosis. Further, using competitive peptide inhibitors against Nef binding domains to CAMKIIδ, identified in the present study and ASK-1, individually blocked physical interaction of Nef with CAMKIIδ-ASK-1 complex and restored p38MAPK phosphorylation and apoptosis. Altogether, our study indicates that HIV-Nef modulates cytosolic [Ca2+]I and blocks CAMKIIδ - ASK-1 kinase activity to inhibit apoptosis of infected cells.
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Affiliation(s)
- Pradeep Kumar
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Kavita Rawat
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Tanuj Sharma
- Division of Molecular and Structural Biology, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Sushila Kumari
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Reshu Saxena
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Balawant Kumar
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Tanvi Baghel
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Tayyaba Afshan
- Division of Molecular and Structural Biology, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Mohammad Imran Siddiqi
- Division of Molecular and Structural Biology, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Aamir Nazir
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Jimut Kanti Ghosh
- Division of Molecular and Structural Biology, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India
| | - Raj Kamal Tripathi
- Division of Toxicology and Experimental Medicine, Central Drug Research Institute, Council of Scientific & Industrial Research, BS-10/1, Sector-10 Jankipuram Extension, Uttar Pradesh, India..
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Slow Release of HIV-1 Protein Nef from Vesicle-like Structures Is Inhibited by Cytosolic Calcium Elevation in Single Human Microglia. Mol Neurobiol 2018; 56:102-118. [DOI: 10.1007/s12035-018-1072-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/09/2018] [Indexed: 12/14/2022]
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6
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Popkov VA, Zorova LD, Korvigo IO, Silachev DN, Jankauskas SS, Babenko VA, Pevzner IB, Danilina TI, Zorov SD, Plotnikov EY, Zorov DB. Do Mitochondria Have an Immune System? BIOCHEMISTRY (MOSCOW) 2016; 81:1229-1236. [PMID: 27908248 DOI: 10.1134/s0006297916100217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The question if mitochondria have some kind of immune system is not trivial. The basis for raising this question is the fact that bacteria, which are progenitors of mitochondria, do have an immune system. The CRISPR system in bacteria based on the principle of RNA interference serves as an organized mechanism for destroying alien nucleic acids, primarily those of viral origin. We have shown that mitochondria are also a target for viral attacks, probably due to a related organization of genomes in these organelles and bacteria. Bioinformatic analysis performed in this study has not given a clear answer if there is a CRISPR-like immune system in mitochondria. However, this does not preclude the possibility of mitochondrial immunity that can be difficult to decipher or that is based on some principles other than those of CRISPR.
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Affiliation(s)
- V A Popkov
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119991, Russia.
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Pawlak EN, Dikeakos JD. HIV-1 Nef: a master manipulator of the membrane trafficking machinery mediating immune evasion. Biochim Biophys Acta Gen Subj 2015; 1850:733-41. [PMID: 25585010 DOI: 10.1016/j.bbagen.2015.01.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/09/2014] [Accepted: 01/06/2015] [Indexed: 11/25/2022]
Abstract
BACKGROUND Many viral genomes encode a limited number of proteins, illustrating their innate efficiency in bypassing host immune surveillance. This concept of genomic efficiency is exemplified by the 9 kb RNA genome of human immunodeficiency virus 1 (HIV-1), encoding 15 proteins sub-divided according to function. The enzymatic group includes proteins such as the drug targets reverse transcriptase and protease. In contrast, the accessory proteins lack any known enzymatic or structural function, yet are essential for viral fitness and HIV-1 pathogenesis. Of these, the HIV-1 accessory protein Nef is a master manipulator of host cellular processes, ensuring efficient counterattack against the host immune response, as well as long-term evasion of immune surveillance. In particular, the ability of Nef to downmodulate major histocompatibility complex class I (MHC-I) is a key cellular event that enables HIV-1 to bypass the host's defenses by evading the adaptive immune response. SCOPE OF REVIEW In this article, we briefly review how various pathogenic viruses control cell-surface MHC-I, and then focus on the mechanisms and implications of HIV-1 Nef-mediated MHC-I downregulation via modulation of the host membrane trafficking machinery. CONCLUSION The extensive interaction network formed between Nef and numerous membrane trafficking regulators suggests that Nef's role in evading the immune surveillance system intersects multiple host membrane trafficking pathways. SIGNIFICANCE Nef's ability to evade the immune surveillance system is linked to AIDS pathogenesis. Thus, a complete understanding of the molecular pathways that are subverted by Nef in order to downregulate MHC-I will enhance our understanding of HIV-1's progression to AIDS.
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Affiliation(s)
- Emily N Pawlak
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada, N6A 5C1
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada, N6A 5C1.
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8
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Wang T, Green LA, Gupta SK, Kim C, Wang L, Almodovar S, Flores SC, Prudovsky IA, Jolicoeur P, Liu Z, Clauss M. Transfer of intracellular HIV Nef to endothelium causes endothelial dysfunction. PLoS One 2014; 9:e91063. [PMID: 24608713 PMCID: PMC3946685 DOI: 10.1371/journal.pone.0091063] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 02/07/2014] [Indexed: 12/17/2022] Open
Abstract
With effective antiretroviral therapy (ART), cardiovascular diseases (CVD) are emerging as a major cause of morbidity and death in the aging HIV-infected population. To address whether HIV-Nef, a viral protein produced in infected cells even when virus production is halted by ART, can lead to endothelial activation and dysfunction, we tested Nef protein transfer to and activity in endothelial cells. We demonstrated that Nef is essential for major endothelial cell activating effects of HIV-infected Jurkat cells when in direct contact with the endothelium. In addition, we found that Nef protein in endothelial cells is sufficient to cause apoptosis, ROS generation and release of monocyte attractant protein-1 (MCP-1). The Nef protein-dependent endothelial activating effects can be best explained by our observation that Nef protein rapidly transfers from either HIV-infected or Nef-transfected Jurkat cells to endothelial cells between these two cell types. These results are of in vivo relevance as we demonstrated that Nef protein induces GFP transfer from T cells to endothelium in CD4.Nef.GFP transgenic mice and Nef is present in chimeric SIV-infected macaques. Analyzing the signal transduction effects of Nef in endothelial cells, we found that Nef-induced apoptosis is mediated through ROS-dependent mechanisms, while MCP-1 production is NF-kB dependent. Together, these data indicate that inhibition of Nef-associated pathways may be promising new therapeutic targets for reducing the risk for cardiovascular disease in the HIV-infected population.
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Affiliation(s)
- Ting Wang
- Department of Microbiology & Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Cellular & Integrative Physiology and Indiana Center for Vascular Biology & Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- R. L. Roudebush VA Medical Center, Indianapolis, Indiana, United States
| | - Linden A. Green
- Department of Cellular & Integrative Physiology and Indiana Center for Vascular Biology & Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- R. L. Roudebush VA Medical Center, Indianapolis, Indiana, United States
| | - Samir K. Gupta
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Chul Kim
- Department of Cellular & Integrative Physiology and Indiana Center for Vascular Biology & Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Liang Wang
- Department of Cellular & Integrative Physiology and Indiana Center for Vascular Biology & Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- R. L. Roudebush VA Medical Center, Indianapolis, Indiana, United States
| | - Sharilyn Almodovar
- Department of Medicine, Pulmonary Sciences & Critical Care Medicine, University of Colorado, Denver, Colorado, United States of America
| | - Sonia C. Flores
- Department of Medicine, Pulmonary Sciences & Critical Care Medicine, University of Colorado, Denver, Colorado, United States of America
| | - Igor A. Prudovsky
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, United States of America
| | - Paul Jolicoeur
- Institut de Recherches Cliniques de Montréal University of Montréal, Montréal, Quebec, Canada
| | - Ziyue Liu
- Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Matthias Clauss
- Department of Microbiology & Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Cellular & Integrative Physiology and Indiana Center for Vascular Biology & Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- R. L. Roudebush VA Medical Center, Indianapolis, Indiana, United States
- * E-mail:
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Shrestha S, Irvin MR, Grunfeld C, Arnett DK. HIV, inflammation, and calcium in atherosclerosis. Arterioscler Thromb Vasc Biol 2013; 34:244-50. [PMID: 24265418 DOI: 10.1161/atvbaha.113.302191] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Atherosclerosis is consistently higher among the HIV-positive patients, with or without treatment, than among the HIV-negative population. Risk factors linked to atherosclerotic cardiovascular disease in HIV infection are both traditional and HIV specific although the underlying mechanisms are not fully delineated. Three key sequential biological processes are postulated to accelerate progression of atherosclerosis in the context of HIV: (1) inflammation, (2) transformation of monocytes to macrophages and then foam cells, and (3) apoptosis of foam cells leading to plaque development through Ca(2+)-dependent endoplasmic reticulum stress. These proatherogenic mechanisms are further affected when HIV interacts with the genes involved in various phases within this network.
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Affiliation(s)
- Sadeep Shrestha
- From the Department of Epidemiology, School of Public Health, University of Alabama at Birmingham (S.S., M.R.I., D.K.A.); Division of Endocrinology and Metabolism, University of California, San Francisco (C.G.); and Veterans Affairs Medical Center, San Francisco, CA (C.G.)
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10
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Anand SK, Tikoo SK. Viruses as modulators of mitochondrial functions. Adv Virol 2013; 2013:738794. [PMID: 24260034 PMCID: PMC3821892 DOI: 10.1155/2013/738794] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/30/2013] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are multifunctional organelles with diverse roles including energy production and distribution, apoptosis, eliciting host immune response, and causing diseases and aging. Mitochondria-mediated immune responses might be an evolutionary adaptation by which mitochondria might have prevented the entry of invading microorganisms thus establishing them as an integral part of the cell. This makes them a target for all the invading pathogens including viruses. Viruses either induce or inhibit various mitochondrial processes in a highly specific manner so that they can replicate and produce progeny. Some viruses encode the Bcl2 homologues to counter the proapoptotic functions of the cellular and mitochondrial proteins. Others modulate the permeability transition pore and either prevent or induce the release of the apoptotic proteins from the mitochondria. Viruses like Herpes simplex virus 1 deplete the host mitochondrial DNA and some, like human immunodeficiency virus, hijack the host mitochondrial proteins to function fully inside the host cell. All these processes involve the participation of cellular proteins, mitochondrial proteins, and virus specific proteins. This review will summarize the strategies employed by viruses to utilize cellular mitochondria for successful multiplication and production of progeny virus.
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Affiliation(s)
- Sanjeev K. Anand
- Vaccine & Infection Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- Veterinary Microbiology, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
| | - Suresh K. Tikoo
- Vaccine & Infection Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- Veterinary Microbiology, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- School of Public Health, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
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Mekahli D, Bultynck G, Parys JB, De Smedt H, Missiaen L. Endoplasmic-reticulum calcium depletion and disease. Cold Spring Harb Perspect Biol 2011; 3:a004317. [PMID: 21441595 PMCID: PMC3098671 DOI: 10.1101/cshperspect.a004317] [Citation(s) in RCA: 329] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER) as an intracellular Ca(2+) store not only sets up cytosolic Ca(2+) signals, but, among other functions, also assembles and folds newly synthesized proteins. Alterations in ER homeostasis, including severe Ca(2+) depletion, are an upstream event in the pathophysiology of many diseases. On the one hand, insufficient release of activator Ca(2+) may no longer sustain essential cell functions. On the other hand, loss of luminal Ca(2+) causes ER stress and activates an unfolded protein response, which, depending on the duration and severity of the stress, can reestablish normal ER function or lead to cell death. We will review these various diseases by mainly focusing on the mechanisms that cause ER Ca(2+) depletion.
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Affiliation(s)
- Djalila Mekahli
- Laboratory of Molecular and Cellular Signaling, Department of Molecular Cell Biology, KU Leuven Campus Gasthuisberg O&N I, Belgium
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12
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Zhou Y, Frey TK, Yang JJ. Viral calciomics: interplays between Ca2+ and virus. Cell Calcium 2009; 46:1-17. [PMID: 19535138 PMCID: PMC3449087 DOI: 10.1016/j.ceca.2009.05.005] [Citation(s) in RCA: 217] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 05/15/2009] [Accepted: 05/18/2009] [Indexed: 12/23/2022]
Abstract
Ca2+ is one of the most universal and versatile signaling molecules and is involved in almost every aspect of cellular processes. Viruses are adept at utilizing the universal Ca2+ signal to create a tailored cellular environment that meets their own demands. This review summarizes most of the known mechanisms by which viruses perturb Ca2+ homeostasis and utilize Ca2+ and cellular Ca2+-binding proteins to their benefit in their replication cycles. Ca2+ plays important roles in virion structure formation, virus entry, viral gene expression, posttranslational processing of viral proteins and virion maturation and release. As part of the review, we introduce an algorithm to identify linear “EF-hand” Ca2+-binding motifs which resulted in the prediction of a total of 93 previously unrecognized Ca2+-binding motifs in virus proteins. Many of these proteins are nonstructural proteins, a class of proteins among which Ca2+ interactions had not been formerly appreciated. The presence of linear Ca2+-binding motifs in viral proteins enlarges the spectrum of Ca2+–virus interplay and expands the total scenario of viral calciomics.
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Affiliation(s)
- Yubin Zhou
- Department of Chemistry, Georgia State University, 50 Decatur St., Atlanta, GA 30303 USA
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13
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Nef-induced CD4 endocytosis in human immunodeficiency virus type 1 host cells: role of p56lck kinase. J Virol 2009; 83:7117-28. [PMID: 19439470 DOI: 10.1128/jvi.01648-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Nef interferes with the endocytic machinery to modulate the cell surface expression of CD4. However, the basal trafficking of CD4 is governed by different rules in the target cells of HIV-1: whereas CD4 is rapidly internalized from the cell surface in myeloid cells, CD4 is stabilized at the plasma membrane through its interaction with the p56(lck) kinase in lymphoid cells. In this study, we showed that Nef was able to downregulate CD4 in both lymphoid and myeloid cell lines but that an increase in the internalization rate of CD4 could be observed only in lymphoid cells. Expression of p56(lck) in nonlymphoid CD4-expressing cells restores the ability of Nef in order to increase the internalization rate of CD4. Concurrent with this observation, the expression of a p56(lck)-binding-deficient mutant of CD4 in lymphoid cells abrogates the Nef-induced acceleration of CD4 internalization. We also show that the expression of Nef causes a decrease in the association of p56(lck) with cell surface-expressed CD4. Regardless of the presence of p56(lck), the downregulation of CD4 by Nef was followed by CD4 degradation. Our results imply that Nef uses distinct mechanisms to downregulate the cell surface expression levels of CD4 in either lymphoid or myeloid target cells of HIV-1.
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14
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Chami M, Oulès B, Paterlini-Bréchot P. Cytobiological consequences of calcium-signaling alterations induced by human viral proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1344-62. [PMID: 17059849 DOI: 10.1016/j.bbamcr.2006.09.025] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 09/13/2006] [Accepted: 09/15/2006] [Indexed: 01/25/2023]
Abstract
Since calcium-signaling regulates specific and fundamental cellular processes, it represents the ideal target of viral proteins, in order for the virus to control cellular functions and favour its persistence, multiplication and spread. A detailed analysis of reports focused on the impact of viral proteins on calcium-signaling has shown that virus-related elevations of cytosolic calcium levels allow increased viral protein expression (HIV-1, HSV-1/2), viral replication (HBx, enterovirus 2B, HTLV-1 p12(I), HHV-8, EBV), viral maturation (rotavirus), viral release (enterovirus 2B) and cell immortalization (EBV). Interestingly, virus-induced decreased cytosolic calcium levels have been found to be associated with inhibition of immune cells functions (HIV-1 Tat, HHV-8 K15, EBV LMP2A). Finally, several viral proteins are able to modulate intracellular calcium-signaling to control cell viability (HIV-1 Tat, HTLV-1 p13(II), HCV core, HBx, enterovirus 2B, HHV-8 K7). These data point out calcium-signaling as a key cellular target for viral infection and should stimulate further studies exploring new calcium-related therapeutic strategies.
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15
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Martins-Silva J, Santos NC, Doroana M, Duarte N, Tavares L, Antunes F, Saldanha C. Changes in blood cell membrane properties in HIV type-1-infected patients. AIDS Res Hum Retroviruses 2006; 22:849-53. [PMID: 16989609 DOI: 10.1089/aid.2006.22.849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To evaluate the possible HIV-1 infection-induced changes in cell membrane properties and in calcium signaling, membrane fluidity, acetylcholinesterase (AChE, a glycosylphosphatidylinositol-anchored protein) activity, and intracellular calcium concentration ([Ca2(+)](int)) were evaluated in lymphocytes and erythrocytes of infected individuals, previous to their engagement in antiretroviral therapy. Membrane fluidity was assessed by fluorescence spectroscopy measurements, using the fluorescence probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-(trimethylamino)-phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH). AChE activity was determined by the colorimetric Ellman's method and [Ca2(+)](int) using the fluorescent fura-2 acetoxymethyl ester. When compared with the control group, lymphocytes of infected patients presented significantly decreased membrane fluidity, decreased AChE activity, and increased [Ca2(+)](int). Erythrocytes from HIV-infected patients presented decreased [Ca2(+)](int) when compared with the control group and decreased membrane fluidity near the lipid/water interface. Our data show that HIV-1 infection leads to biochemical and biophysical changes in the membrane itself and in membrane protein activity in lymphocytes (average of infected and noninfected subpopulations) and even in erythrocytes. The present observations are in agreement with a process of facilitated propagation of the infection to new cells, stimulation of virion production, and maintenance of a reservoir of erythrocyte-bound infectious virus.
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Affiliation(s)
- J Martins-Silva
- Instituto de Biopatologia Química/Faculdade de Medicina de Lisboa and Unidade de Biopatologia Vascular/Instituto de Medicina Molecular, 1649-028 Lisboa, Portugal
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16
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Lynch GW, Turville S, Carter B, Sloane AJ, Chan A, Muljadi N, Li S, Low L, Armati P, Raison R, Zoellner H, Williamson P, Cunningham A, Church WB. Marked differences in the structures and protein associations of lymphocyte and monocyte CD4: resolution of a novel CD4 isoform. Immunol Cell Biol 2006; 84:154-65. [PMID: 16519733 DOI: 10.1111/j.1440-1711.2005.01403.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structures, molecular interactions and functions of CD4 in a subset of T lymphocytes have been well characterized. The CD4 receptors of other cell types have, however, been poorly documented. We have previously shown that lymphocytes and monocytes/macrophages differ in their expression of CD4 monomers and dimers. In the present study, we have shown further significant differences. Variability in the blocking of CD4 mAb binding by sulfated polyanions indicated differences in exofacial CD4 structures. In contrast to the well-documented 55 kDa monomers in lymphocytic cells, monocytic cells were found to coexpress two monomer isoforms: the 55 kDa form and a novel 59 kDa species. Experimental uncoupling of CD4 disulfides indicated that the oxidized 55 kDa monomer could be converted to the 59 kDa form. This was achieved by chemical reduction of purified native or recombinant CD4, or in cell transfection experiments by mutation of cysteine to alanine in domain 1 (D1) (Cys16 or Cys84) and in domain 4 (D4) (Cys303 or Cys345). All of these modifications promote CD4 distension on SDS-PAGE analysis and indicate that, when CD4 inter-beta-sheet disulfides in the D1 and D4 Ig folds are disrupted, there is an unravelling of the oxidized form to an extended 59 kDa unfolded state. We hypothesize that this may be a transition-state, structural-intermediate in the formation of disulfide-linked homodimers. Also identified were CD4-tyrosine kinase dissimilarities in which lymphocyte CD4 associated with Lck, but monocyte CD4 associated with HcK. These findings show that there is complex heterogeneity in structures and interactions in the CD4 of T lymphocytes and monocytes.
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Affiliation(s)
- Garry W Lynch
- HIV-Protein Interactions Laboratory, Westmead Millennium Institute, Westmead, Australia.
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17
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Milicic A, Price DA, Zimbwa P, Booth BL, Brown HL, Easterbrook PJ, Olsen K, Robinson N, Gileadi U, Sewell AK, Cerundolo V, Phillips RE. CD8+ T cell epitope-flanking mutations disrupt proteasomal processing of HIV-1 Nef. THE JOURNAL OF IMMUNOLOGY 2005; 175:4618-26. [PMID: 16177107 DOI: 10.4049/jimmunol.175.7.4618] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CTL play a critical role in the control of HIV and SIV. However, intrinsic genetic instability enables these immunodeficiency viruses to evade detection by CTL through mutation of targeted antigenic sites. These mutations can impair binding of viral epitopes to the presenting MHC class I molecule or disrupt TCR-mediated recognition. In certain regions of the virus, functional constraints are likely to limit the capacity for variation within epitopes. Mutations elsewhere in the protein, however, might still enable immune escape through effects on Ag processing. In this study, we describe the coincident emergence of three mutations in a highly conserved region of Nef during primary HIV-1 infection. These mutations (R69K, A81G, and H87R) flank the HLA B*35-restricted VY8 epitope and persisted to fixation as the early CTL response to this Ag waned. The variant form of Nef showed a reduced capacity to activate VY8-specific CTL, although protein stability and expression levels were unchanged. This effect was associated with altered processing by the proteasome that caused partial destruction of the VY8 epitope. Our data demonstrate that a variant HIV genotype can significantly impair proteasomal epitope processing and substantiate the concept of immune evasion through diminished Ag generation. These observations also indicate that the scale of viral escape may be significantly underestimated if only intraepitope variation is evaluated.
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Affiliation(s)
- Anita Milicic
- James Martin 21st Century School and Nuffield Department of Clinical Medicine, The Peter Medawar Building, University of Oxford, Oxford, United Kingdom.
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18
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Malathi K, Li X, Krizanova O, Ondrias K, Sperber K, Ablamunits V, Jayaraman T. Cdc2/Cyclin B1 Interacts with and Modulates Inositol 1,4,5-Trisphosphate Receptor (Type 1) Functions. THE JOURNAL OF IMMUNOLOGY 2005; 175:6205-10. [PMID: 16237118 DOI: 10.4049/jimmunol.175.9.6205] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The resistance of inositol 1,4,5-trisphosphate receptor (IP3R)-deficient cells to multiple forms of apoptosis demonstrates the importance of IP3-gated calcium (Ca2+) release to cellular apoptosis. However, the specific upstream biochemical events leading to IP3-gated Ca2+ release during apoptosis induction are not known. We have shown previously that the cyclin-dependent kinase 1/cyclin B (cdk1/CyB or cdc2/CyB) complex phosphorylates IP3R1 in vitro and in vivo at Ser421 and Thr799. In this study, we show that: 1) the cdc2/CyB complex directly interacts with IP3R1 through Arg391, Arg441, and Arg871; 2) IP3R1 phosphorylation at Thr799 by the cdc2/CyB complex increases IP3 binding; and 3) cdc2/CyB phosphorylation increases IP3-gated Ca2+ release. Taken together, these results demonstrate that cdc2/CyB phosphorylation positively regulates IP3-gated Ca2+ signaling. In addition, identification of a CyB docking site(s) on IP3R1 demonstrates, for the first time, a direct interaction between a cell cycle component and an intracellular calcium release channel. Blocking this phosphorylation event with a specific peptide inhibitor(s) may constitute a new therapy for the treatment of several human immune disorders.
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Affiliation(s)
- Krishnamurthy Malathi
- Vascular Biology Laboratory, Department of Neurosurgery, St. Luke's Roosevelt Hospital Center, New York, NY 10025, USA
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19
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Coleman SH, Day JR, Guatelli JC. The HIV-1 Nef protein as a target for antiretroviral therapy. Expert Opin Ther Targets 2005; 5:1-22. [PMID: 15992165 DOI: 10.1517/14728222.5.1.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
HIV-1 Nef is a peripheral membrane protein that affects both signal transduction and membrane trafficking in infected cells. Alterations in these cellular processes enhance the efficiency of viral replication and the pathogenesis of AIDS in vivo. The precise mechanisms by which Nef functions are not fully elucidated. Nef is not an enzyme but appears to act as a linker molecule, mediating a variety of protein-protein interactions. Structural, biochemical and mutational data have allowed tentative identification of the key interactive surfaces on Nef, their cellular partners and their roles in Nef activity. Nef contains an SH3-binding surface through which it can interact with cellular Src-family tyrosine kinases and/or activator molecules for small GTPases involved in signal transduction. This SH3-binding surface is important for the ability of Nef to facilitate the activation of host T-lymphocytes, a process which renders the cells more permissive for viral replication. Nef also contains two relatively unstructured, solvent-exposed loops, through which it interacts with the cellular proteins that coat vesicles involved in membrane trafficking. These surfaces are important for Nef-mediated alterations in the subcellular distribution of transmembrane proteins, a process which causes diverse effects, including the assembly of maximally infectious viral particles and viral evasion of the host immune system. These data provide precise molecular targets within the Nef protein. Molecules that bind these interactive surfaces are predicted to inhibit Nef activity and provide the basis for novel chemotherapeutic agents for the treatment of HIV-infection.
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Affiliation(s)
- S H Coleman
- Department of Medicine, University of California San Diego, La Jolla 92093-0679, USA
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20
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Cartier L, Dubois-Dauphin M, Hartley O, Irminger-Finger I, Krause KH. Chemokine-induced cell death in CCR5-expressing neuroblastoma cells. J Neuroimmunol 2003; 145:27-39. [PMID: 14644028 DOI: 10.1016/j.jneuroim.2003.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CCR5 is expressed in neurons but its function in this cellular context is hitherto poorly understood. We have generated CCR5-expressing SH-SY5Y neuroblastoma cells. CCR5 ligands induced cell death in these cells, but not in control neuroblastoma cells or in CCR5-expressing fibroblasts. CCR5-dependent killing of neuroblastoma cells occurred through apoptosis, since it was accompanied by caspase-3 activation and could be prevented by a caspase-3 inhibitor. Finally, cell killing by activated microglia was more rapid and extensive in CCR5-expressing neuroblastoma cells than in control cells. In summary, CCR5 may act as a death receptor in cells of neuronal lineage and therefore be involved in inflammatory neurodegeneration.
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Affiliation(s)
- Laetitia Cartier
- Biology of Ageing Laboratory, Department of Geriatrics, Geneva University Hospitals, 1225 Chêne-Bourg, Switzerland
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21
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Vilhardt F, Plastre O, Sawada M, Suzuki K, Wiznerowicz M, Kiyokawa E, Trono D, Krause KH. The HIV-1 Nef protein and phagocyte NADPH oxidase activation. J Biol Chem 2002; 277:42136-43. [PMID: 12207012 DOI: 10.1074/jbc.m200862200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nef, a multifunctional HIV protein, activates the Vav/Rac/p21-activated kinase (PAK) signaling pathway. Given the potential role of this pathway in the activation of the phagocyte NADPH oxidase, we have investigated the effect of the HIV-1 Nef protein on the phagocyte respiratory burst. Microglia (cell line and primary culture) were transduced with lentiviral expression vectors. Expression of Nef did not activate the NADPH oxidase by itself but led to a massive enhancement of the responses to a variety of stimuli (Ca(2+) ionophore, formyl peptide, endotoxin). These effects were not caused by up-regulation of phagocyte NADPH oxidase subunits. Nef mutants lacking motifs involved in the interaction with Vav and PAK failed to reproduce the effects of wild type Nef, suggesting a role for the Vav/Rac/PAK signaling pathway. The following results suggest a key role for Rac in the priming effect of Nef. (i) Inactivation of Rac by Clostridium difficile toxin B abolished the Nef effect. (ii) The fraction of activated Rac1 was increased in Nef-transduced cells, and (iii) the dominant positive Rac1(V12) mutant mimicked the effect of Nef. These results are to our knowledge the first analysis of the effect of Rac activation on the NADPH oxidase in intact phagocytes. Rac activation is not sufficient to stimulate the phagocyte NADPH oxidase; however, it markedly enhances the NADPH oxidase response to other stimuli.
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Affiliation(s)
- Frederik Vilhardt
- Biology of Ageing Laboratory, Department of Geriatrics, Geneva University Hospitals, Switzerland.
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22
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Manninen A, Saksela K. HIV-1 Nef interacts with inositol trisphosphate receptor to activate calcium signaling in T cells. J Exp Med 2002; 195:1023-32. [PMID: 11956293 PMCID: PMC2193699 DOI: 10.1084/jem.20012039] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
HIV-1 pathogenicity factor Nef has been shown to modulate calcium signaling in host cells, but the underlying molecular mechanisms have remained unclear. Here we show that calcium/calcineurin-dependent activation of nuclear factor of activated T cells (NFAT) by Nef in Jurkat T cells requires the endoplasmic reticulum-resident inositol trisphosphate receptor (IP(3)R), but yet does not involve increase in phospholipase-C gamma 1 (PLC gamma 1)-catalyzed production of IP(3) or depletion of IP(3)-regulated intracellular calcium stores. Nef could be coprecipitated with endogenous IP(3)R type-1 (IP(3)R1) from Nef-transfected Jurkat T cells as well as from HIV-infected primary human peripheral mononuclear cells. Thus, the Nef/IP(3)R1-interaction defines a novel T cell receptor-independent mechanism by which Nef can promote T cell activation, and appears to involve atypical IP(3)R-triggered activation of plasma membrane calcium influx channels in a manner that is uncoupled from depletion of intracellular calcium stores.
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Affiliation(s)
- Aki Manninen
- Institute of Medical Technology, University of Tampere, Tampere FIN-33014, Finland
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23
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Picard C, Greenway A, Holloway G, Olive D, Collette Y. Interaction with simian Hck tyrosine kinase reveals convergent evolution of the Nef protein from simian and human immunodeficiency viruses despite differential molecular surface usage. Virology 2002; 295:320-7. [PMID: 12033791 DOI: 10.1006/viro.2002.1381] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Simian and human immunodeficiency virus type 1 (SIV and HIV-1) Nef proteins are thought to use different molecular surfaces to mediate the protein-protein interactions required for their otherwise similar functions. This genetically separable function suggests convergent evolution of primate lentiviruses and/or structural differences between human and nonhuman primate cellular target proteins. However, such comparative molecular analyses have not been undertaken so far using the respective natural host-derived cellular targets. We cloned simian Src family kinase Hck and analyzed structurally and biochemically its interaction with SIV Nef.
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Affiliation(s)
- C Picard
- Institut de Cancérologie et d'Immunologie de Marseille, U119 INSERM, 27 boulevard Leï Roure, 13009, France
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24
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Hanna Z, Weng X, Kay DG, Poudrier J, Lowell C, Jolicoeur P. The pathogenicity of human immunodeficiency virus (HIV) type 1 Nef in CD4C/HIV transgenic mice is abolished by mutation of its SH3-binding domain, and disease development is delayed in the absence of Hck. J Virol 2001; 75:9378-92. [PMID: 11533201 PMCID: PMC114506 DOI: 10.1128/jvi.75.19.9378-9392.2001] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2000] [Accepted: 06/23/2001] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Nef protein is an important determinant of AIDS pathogenesis. We have previously reported that HIV-1 Nef is responsible for the induction of a severe AIDS-like disease in CD4C/HIV transgenic (Tg) mice. To understand the molecular mechanisms of this Nef-induced disease, we generated Tg mice expressing a mutated Nef protein in which the SH3 ligand-binding domain (P(72)XXP(75)XXP(78)) was mutated to A(72)XXA(75)XXQ(78). This mutation completely abolished the pathogenic potential of Nef, although a partial downregulation of the CD4 cell surface expression was still observed in these Tg mice. We also studied whether Hck, one of the effectors previously found to bind to this PXXP motif of Nef, was involved in disease development. Breeding of Tg mice expressing wild-type Nef on an hck(-/-) (knockout) background did not abolish any of the pathological phenotypes. However, the latency of disease development was prolonged. These data indicate that an intact PXXP domain is essential for inducing an AIDS-like disease in CD4C/HIV Tg mice and suggest that interaction of a cellular effector(s) with this domain is required for the induction of this multiorgan disease. Our findings indicate that Hck is an important, but not an essential, effector of Nef and suggest that another factor(s), yet to be identified, may be more critical for disease development.
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Affiliation(s)
- Z Hanna
- Laboratory of Molecular Biology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada.
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25
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Ahn IP, Lee YH. A viral double-stranded RNA up regulates the fungal virulence of Nectria radicicola. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2001; 14:496-507. [PMID: 11310737 DOI: 10.1094/mpmi.2001.14.4.496] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Double-stranded RNAs (dsRNAs) are widespread in plant pathogenic fungi, but their functions in fungal hosts remain mostly unclear, with a few exceptions. We analyzed dsRNAs from Nectria radicicola, the causal fungus of ginseng root rot. Four distinct sizes of dsRNAs, 6.0, 5.0, 2.5, and 1.5 kbp, were detected in 24 out of the 81 strains tested. Curing tests of individual dsRNAs suggested that the presence of 6.0-kbp dsRNA was associated with high levels of virulence, sporulation, laccase activity, and pigmentation in this fungus. The 6.0-kbp dsRNA-cured strains completely lost virulence-related phenotypes. This 6.0-kbp dsRNA was reintroduced by hyphal anastomosis to a dsRNA-cured strain marked with hygromycin resistance, which resulted in the restoration of virulence-related phenotypes. These results strongly suggest that 6.0-kbp dsRNA up regulates fungal virulence in N. radicicola. Sequencing of several cDNA clones derived from 6.0-kbp dsRNA revealed the presence of a RNA-dependent RNA polymerase (RDRP) gene. Phylogenetic analysis showed that this gene is closely related to those of plant cryptic viruses. Biochemical analyses suggested that the 6.0-kbp dsRNA may regulate fungal virulence through signal-transduction pathways involving cyclic AMP-dependent protein kinase and protein kinase C.
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Affiliation(s)
- I P Ahn
- School of Agricultural Biotechnology and Research Center for New Bio-Materials in Agriculture, Seoul National University, Korea
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26
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Foster JL, Molina RP, Luo T, Arora VK, Huang Y, Ho DD, Garcia JV. Genetic and functional diversity of human immunodeficiency virus type 1 subtype B Nef primary isolates. J Virol 2001; 75:1672-80. [PMID: 11160665 PMCID: PMC114076 DOI: 10.1128/jvi.75.4.1672-1680.2001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have characterized the functional integrity of seven primary Nef isolates: five from a long-term nonprogressing human immunodeficiency virus (HIV)-infected individual and one each from two patients with AIDS. One of the seven Nefs was defective for CD4 downregulation, two others were defective for PAK-2 activation, and one Nef was defective for PAK-2 activation and major histocompatibility complex (MHC) class I downregulation. Five of the Nefs were tested and found to be functional for the enhancement of virus particle infectivity. The structural basis for each of the functional defects has been analyzed by constructing a consensus nef, followed by mutational analysis of the variant amino acid residues. Mutations A29V and F193I were deleterious to CD4 downregulation and PAK-2 activation, respectively, while S189R rendered Nef defective for both MHC class I downregulation and PAK-2 activation. A search of the literature identified HIVs from five patients with Nefs predominantly mutated at F193 and from one patient with Nefs predominantly mutated at A29. A29 is highly conserved in all HIV subtypes except for subtype E. F193 is conserved in subtype B (and possibly in the closely related subtype D), but none of the other HIV group M subtypes. Our results suggest that functional distinctions may exist between HIV subtypes.
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Affiliation(s)
- J L Foster
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA
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27
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Affiliation(s)
- Željka Korade‐Mirnics
- Department of Pediatrics and Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania
| | - Seth J. Corey
- Department of Pediatrics and Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania
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28
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Affiliation(s)
- T K Howcroft
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-1360, USA.
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29
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Manninen A, Renkema GH, Saksela K. Synergistic activation of NFAT by HIV-1 nef and the Ras/MAPK pathway. J Biol Chem 2000; 275:16513-7. [PMID: 10748182 DOI: 10.1074/jbc.m910032199] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nef is a lentiviral protein involved in pathogenesis of AIDS, but its molecular mechanisms of action remain incompletely understood. Here we report a novel effect of Nef on lymphocyte signaling, which is mediated via a T cell receptor (TCR)-independent contribution of Nef to induction of nuclear factor of activated T cells (NFAT), a transcription factor that plays a central role in coordinating T cell activation. Expression of Nef did not significantly alter the basal level of NFAT activity in Jurkat cells nor the increased activity following T cell receptor stimulation by anti-CD3 or anti-CD3 + anti-CD28. We also mimicked NFAT induction by TCR triggering by simultaneous activation of the Ras and calcium signaling pathways with phorbol 12-myristate 13-acetate and ionomycin, respectively. Strikingly, whereas activation of either of these pathways individually did not induce NFAT activity in control cells, in Nef-expressing cells phorbol 12-myristate 13-acetate treatment alone resulted in a 100-fold increase in NFAT-directed gene expression. Experiments with different dominant negative mutant signaling proteins, inhibitory chemicals, and Lck-deficient Jurkat cells revealed that this effect was mediated via activation of calcineurin by Nef-induced changes in calcium metabolism, but was independent of TCR-associated signaling events. This ability of Nef to substitute for triggering of the calcium pathway in induction of NFAT could promote activation of human immunodeficiency virus (HIV)-infected T cells in response to stimuli mediated via TCR or other cell surface receptors under conditions when activation of Ras rather than calcium signaling would otherwise predominate.
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Affiliation(s)
- A Manninen
- Institute of Medical Technology, University of Tampere, P. O. Box 607, FIN-33101 and the Department of Clinical Chemistry, Tampere University Hospital, P. O. Box 2000, FIN-33521, Tampere, Finland
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