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Jorfi S, Ansa-Addo EA, Mariniello K, Warde P, Bin Senian AA, Stratton D, Bax BE, Levene M, Lange S, Inal JM. A Coxsackievirus B1-mediated nonlytic Extracellular Vesicle-to-cell mechanism of virus transmission and its possible control through modulation of EV release. J Gen Virol 2023; 104. [PMID: 37665326 DOI: 10.1099/jgv.0.001884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023] Open
Abstract
Like most non-enveloped viruses, CVB1 mainly uses cell lysis to spread. Details of a nonlytic virus transmission remain unclear. Extracellular Vesicles (EVs) transfer biomolecules between cells. We show that CVB1 entry into HeLa cells results in apoptosis and release of CVB1-induced 'medium-sized' EVs (CVB1i-mEVs). These mEVs (100-300 nm) harbour CVB1 as shown by immunoblotting with anti-CVB1-antibody; viral capsids were detected by transmission electron microscopy and RT-PCR revealed CVB1 RNA. The percentage of mEVs released from CVB1-infected HeLa cells harbouring virus was estimated from TEM at 34 %. Inhibition of CVB1i-mEV production, with calpeptin or siRNA knockdown of CAPNS1 in HeLa cells limited spread of CVB1 suggesting these vesicles disseminate CVB1 virions to new host cells by a nonlytic EV-to-cell mechanism. This was confirmed by detecting CVB1 virions inside HeLa cells after co-culture with CVB1i-mEVs; EV release may also prevent apoptosis of infected cells whilst spreading apoptosis to secondary sites of infection.
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Affiliation(s)
- Samireh Jorfi
- Cell Communication in Disease Pathology, School of Human Sciences, London Metropolitan University, London N7 8DB, UK
| | - Ephraim Abrokwa Ansa-Addo
- Cell Communication in Disease Pathology, School of Human Sciences, London Metropolitan University, London N7 8DB, UK
- Present address: Pelotonia Institute for Immuno-Oncology, The James, Ohio State University, Columbus, OH 43210, USA
| | - Katia Mariniello
- Cell Communication in Disease Pathology, School of Human Sciences, London Metropolitan University, London N7 8DB, UK
- Present address: William Harvey Research Institute, Queen Mary, University of London, London, UK
| | - Purva Warde
- Biosciences Research Group, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9EU, UK
| | - Ahmad Asyraf Bin Senian
- Biosciences Research Group, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9EU, UK
- Present address: Clinical Research Centre, Sarawak General Hospital, Kuching, Malaysia
| | - Dan Stratton
- School of Life, Health & Chemical Sciences, The Open University, Milton Keynes MK7 6AE, UK
| | - Bridget E Bax
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, London SW17 0RE, UK
| | - Michelle Levene
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, London SW17 0RE, UK
| | - Sigrun Lange
- Tissue Architecture and Regeneration Research Group, School of Life Sciences, University of Westminster, 116, New Cavendish St., London, UK
- University College London School of Pharmacy, Brunswick Sq., London, UK
| | - Jameel Malhador Inal
- Cell Communication in Disease Pathology, School of Human Sciences, London Metropolitan University, London N7 8DB, UK
- Biosciences Research Group, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9EU, UK
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Clostridioides difficile toxin B alone and with pro-inflammatory cytokines induces apoptosis in enteric glial cells by activating three different signalling pathways mediated by caspases, calpains and cathepsin B. Cell Mol Life Sci 2022; 79:442. [PMID: 35864342 PMCID: PMC9304068 DOI: 10.1007/s00018-022-04459-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 06/22/2022] [Accepted: 06/29/2022] [Indexed: 11/03/2022]
Abstract
Clostridioides difficile infection (CDI) causes nosocomial/antibiotic-associated gastrointestinal diseases with dramatically increasing global incidence and mortality rates. The main C. difficile virulence factors, toxins A and B (TcdA/TcdB), cause cytopathic/cytotoxic effects and inflammation. We demonstrated that TcdB induces caspase-dependent, mitochondria-independent enteric glial cell (EGC) apoptosis that is enhanced by the pro-inflammatory cytokines TNF-α and IFN-γ (CKs) by increasing caspase-3/7/9 and PARP activation. Because this cytotoxic synergism is important for CDI pathogenesis, we investigated the apoptotic pathways involved in TcdB- and TcdB + CK-induced apoptosis indepth. EGCs were pre-treated with the inhibitors BAF or Q-VD-OPh (pan-caspase), Z-DEVD-fmk (caspase-3/7), Z-IETD-fmk (caspase-8), PD150606 (calpains), and CA-074Me (cathepsin B) 1 h before TcdB exposure, while CKs were given 1.5 h after TcdB exposure, and assays were performed at 24 h. TcdB and TcdB + CKs induced apoptosis through three signalling pathways activated by calpains, caspases and cathepsins, which all are involved both in induction and execution apoptotic signalling under both conditions but to different degrees in TcdB and TcdB + CKs especially as regards to signal transduction mediated by these proteases towards downstream effects (apoptosis). Calpain activation by Ca2+ influx is the first pro-apoptotic event in TcdB- and TcdB + CK-induced EGC apoptosis and causes caspase-3, caspase-7 and PARP activation. PARP is also directly activated by calpains which are responsible of about 75% of apoptosis in TcdB and 62% in TcdB + CK which is both effector caspase-dependent and -independent. Initiator caspase-8 activation mediated by TcdB contributes to caspase-3/caspase-7 and PARP activation and is responsible of about 28% of apoptosis in both conditions. Caspase-3/caspase-7 activation is weakly responsible of apoptosis, indeed we found that it mediates 27% of apoptosis only in TcdB. Cathepsin B contributes to triggering pro-apoptotic signal and is responsible in both conditions of about 35% of apoptosis by a caspase-independent manner, and seems to regulate the caspase-3 and caspase-7 cleaved fragment levels, highlighting the complex interaction between these cysteine protease families activated during TcdB-induced apoptosis. Further a relevant difference between TcdB- and TcdB + CK-induced apoptosis is that TcdB-induced apoptosis increased slowly reaching at 72 h the value of 18.7%, while TcdB + CK-induced apoptosis increased strongly reaching at 72 h the value of 60.6%. Apoptotic signalling activation by TcdB + CKs is enriched by TNF-α-induced NF-κB signalling, inhibition of JNK activation and activation of AKT. In conclusion, the ability of C. difficile to activate three apoptotic pathways represents an important strategy to overcome resistance against its cytotoxic activity.
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Host Cell Calpains Can Cleave Structural Proteins from the Enterovirus Polyprotein. Viruses 2019; 11:v11121106. [PMID: 31795245 PMCID: PMC6950447 DOI: 10.3390/v11121106] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 11/26/2019] [Accepted: 11/26/2019] [Indexed: 12/25/2022] Open
Abstract
Enteroviruses are small RNA viruses that cause diseases with various symptoms ranging from mild to severe. Enterovirus proteins are translated as a single polyprotein, which is cleaved by viral proteases to release capsid and nonstructural proteins. Here, we show that also cellular calpains have a potential role in the processing of the enteroviral polyprotein. Using purified calpains 1 and 2 in an in vitro assay, we show that addition of calpains leads to an increase in the release of VP1 and VP3 capsid proteins from P1 of enterovirus B species, detected by western blotting. This was prevented with a calpain inhibitor and was dependent on optimal calcium concentration, especially for calpain 2. In addition, calpain cleavage at the VP3-VP1 interface was supported by a competition assay using a peptide containing the VP3-VP1 cleavage site. Moreover, a mass spectrometry analysis showed that calpains can cleave this same peptide at the VP3-VP1 interface, the cutting site being two amino acids aside from 3C’s cutting site. Furthermore, we show that calpains cannot cleave between P1 and 2A. In conclusion, we show that cellular proteases, calpains, can cleave structural proteins from enterovirus polyprotein in vitro. Whether they assist polyprotein processing in infected cells remains to be shown.
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Neuroprotective effect of (-)-tetrahydropalmatine in Japanese encephalitis virus strain GP-78 infected mouse model. Microb Pathog 2017; 114:197-203. [PMID: 29191708 DOI: 10.1016/j.micpath.2017.11.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 11/24/2017] [Accepted: 11/24/2017] [Indexed: 02/01/2023]
Abstract
Japanese encephalitis virus (JEV), known to affect children, is a major cause of severe encephalopathy. Its prevalence has been percolated over wider regions of Southern Asia. JEV is associated with neurodegeneration, severe inflammation, increased oxidative stress and elevated levels of stress linked proteins. Four groups of 15 mice each (4-5 weeks old BALB/c mice of either sex) was used for the study. Mice were intravenously infected with lethal dose of 3 × 105 pfu of JEV, followed by mortality after 8 days. On the next day and onwards, the animals were administered intraperitonially with (-)-tetrahydropalmatine (LTHP) solution (0.1 mg/mL in PBS) for the next 7 days. Animals exhibited protection against JEV infection, after being administered with LTHP. Reduction in levels of, viral population, caspase-2 expression, reactive oxygen and nitrogen species, microglial cells and proinflammatory mediators, stress linked protein molecules and neuronal apoptosis was exhibited in JEV infected animals treated with LTHP. The effects produced by the administration of LTHP indicated its possible use to treat JEV in mouse model. Potential to reduce viral count in brain and subsequent neuronal apoptosis, reduction in mediators of inflammation and oxidative stress, strictly advocate the use of LTHP for treatment of JEV. Thus, the present investigation indorses LTHP as a potentially strong drug candidate for the treatment of JEV infection due to its neuroprotective, anti-inflammatory, antiviral and anti-oxidative effect.
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Kumar V, Ahmad A. Targeting calpains: A novel immunomodulatory approach for microbial infections. Eur J Pharmacol 2017; 814:28-44. [PMID: 28789934 DOI: 10.1016/j.ejphar.2017.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 08/01/2017] [Accepted: 08/03/2017] [Indexed: 02/09/2023]
Abstract
Calpains are a family of Ca2+ dependent cytosolic non-lysosomal proteases with well conserved cysteine-rich domains for enzymatic activity. Due to their functional dependency on Ca2+ concentrations, they are involved in various cellular processes that are regulated by intracellular ca2+ concentration (i.e. embryo development, cell development and migration, maintenance of cellular architecture and structure etc.). Calpains are widely studied proteases in mammalian (i.e. mouse and human) physiology and pathophysiology due to their ubiquitous presence. For example, these proteases have been found to be involved in various inflammatory disorders such as neurodegeneration, cancer, brain and myocardial ischemia and infarction, cataract and muscular dystrophies etc. Besides their role in these sterile inflammatory conditions, calpains have also been shown to regulate a wide range of infectious diseases (i.e. sepsis, tuberculosis, gonorrhoea and bacillary dysentery etc.). One of these regulatory mechanisms mediated by calpains (i.e. calpain 1 and 2) during microbial infections involves the regulation of innate immune response, inflammation and cell death. Thus, the major emphasis of this review is to highlight the importance of calpains in the pathogenesis of various microbial (i.e. bacterial, fungal and viral) diseases and the use of calpain modulators as potential immunomodulators in microbial infections.
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Affiliation(s)
- Vijay Kumar
- Department of Paediatrics and Child Health, Children's Health Queensland Clinical Unit, School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
| | - Ali Ahmad
- Laboratory of innate immunity, CHU Ste-Justine Research Center/Department of Microbiology, Infectious Diseases and Immunology, University of Montreal, 3175 Cote Ste Catherine, Montreal, Quebec, Canada H3T 1C5.
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Chen S, Yan J, Deng HX, Long LL, Hu YJ, Wang M, Shang L, Chen D, Huang JF, Xiong K. Inhibition of calpain on oxygen glucose deprivation-induced RGC-5 necroptosis. JOURNAL OF HUAZHONG UNIVERSITY OF SCIENCE AND TECHNOLOGY. MEDICAL SCIENCES = HUA ZHONG KE JI DA XUE XUE BAO. YI XUE YING DE WEN BAN = HUAZHONG KEJI DAXUE XUEBAO. YIXUE YINGDEWEN BAN 2016; 36:639-645. [PMID: 27752886 DOI: 10.1007/s11596-016-1639-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 07/01/2016] [Indexed: 12/21/2022]
Abstract
The purpose of this study was to investigate the effect of inhibition of calpain on retinal ganglion cell-5 (RGC-5) necroptosis following oxygen glucose deprivation (OGD). RGC-5 cells were cultured in Dulbecco's-modified essential medium and necroptosis was induced by 8-h OGD. PI staining and flow cytometry were performed to detect RGC-5 necrosis. The calpain expression was detected by Western blotting and immunofluorescence staining. The calpain activity was tested by activity detection kit. Flow cytometry was used to detect the effect of calpain on RGC-5 necroptosis following OGD with or without N-acetyl-leucyl-leucyl-norleucinal (ALLN) pre-treatment. Western blot was used to detect the protein level of truncated apoptosis inducing factor (tAIF) in RGC-5 cells following OGD. The results showed that there was an up-regulation of the calpain expression and activity following OGD. Upon adding ALLN, the calpain activity was inhibited and tAIF was reduced following OGD along with the decreased number of RGC-5 necroptosis. In conclusion, calpain was involved in OGD-induced RGC-5 necroptosis with the increased expression of its downstream molecule tAIF.
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Affiliation(s)
- Shuang Chen
- Department of Anatomy and Neurobiology, Central South University, Changsha, 410013, China
| | - Jie Yan
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha, 410013, China
| | - Hai-Xiao Deng
- Five-year Medicine Program, Grade 2013, Xiangya School of Medicine, Central South University, Changsha, 410013, China
| | - Ling-Ling Long
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha, 410013, China
| | - Yong-Jun Hu
- Department of Cardiology, People's Hospital of Hunan Province, Changsha, 410008, China
| | - Mi Wang
- Department of Anatomy and Neurobiology, Central South University, Changsha, 410013, China
| | - Lei Shang
- Jiangxi Research Institute of Ophthalmology and Visual Sciences, Affiliated Eye Hospital of Nanchang University, Nanchang, 330006, China
| | - Dan Chen
- Department of Anatomy and Neurobiology, Central South University, Changsha, 410013, China
| | - Ju-Fang Huang
- Department of Anatomy and Neurobiology, Central South University, Changsha, 410013, China
| | - Kun Xiong
- Department of Anatomy and Neurobiology, Central South University, Changsha, 410013, China.
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The Toxic Effect of ALLN on Primary Rat Retinal Neurons. Neurotox Res 2016; 30:392-406. [DOI: 10.1007/s12640-016-9624-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 04/04/2016] [Accepted: 04/16/2016] [Indexed: 10/21/2022]
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Hiller BE, Berger AK, Danthi P. Viral gene expression potentiates reovirus-induced necrosis. Virology 2015; 484:386-394. [PMID: 26226583 PMCID: PMC4567420 DOI: 10.1016/j.virol.2015.06.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/14/2015] [Accepted: 06/12/2015] [Indexed: 12/22/2022]
Abstract
Infection of some cell types by reovirus evokes a caspase-independent form of cell death resembling necrosis. While reovirus strain T3D induces necrosis much more efficiently than strain T1L, which viral components contribute to this difference is not known. In this study, we identified that the sialic acid binding property of the reovirus σ1 protein affects necrosis efficiency. We found that in addition to sialic acid engagement by the virus particles, viral gene expression, in the form of viral RNA or protein synthesis, is also required for necrosis induction. Our studies reveal that sialic acid does not directly participate in necrosis induction by initiating a signaling pathway. Instead, sialic acid engagement augments necrosis induction indirectly, by increasing reovirus gene expression in each infected cell. Comparison of our results with previous studies suggests that reovirus-induced apoptosis and necrosis are initiated by distinct stages of viral infection.
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Affiliation(s)
- Bradley E Hiller
- Department of Biology, Indiana University, Bloomington, IN 47405, United States
| | - Angela K Berger
- Interdisciplinary Program in Biochemistry, Indiana University, Bloomington, IN 47405, United States
| | - Pranav Danthi
- Department of Biology, Indiana University, Bloomington, IN 47405, United States; Interdisciplinary Program in Biochemistry, Indiana University, Bloomington, IN 47405, United States..
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Permeability changes of integrin-containing multivesicular structures triggered by picornavirus entry. PLoS One 2014; 9:e108948. [PMID: 25299706 PMCID: PMC4191987 DOI: 10.1371/journal.pone.0108948] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 08/25/2014] [Indexed: 11/23/2022] Open
Abstract
Cellular uptake of clustered α2β1-integrin induces the formation of membrane compartments that subsequently mature into a multivesicular body (MVB). Enhanced internalization mediated by clustered integrins was observed upon infection by the picornavirus echovirus 1 (EVI). We elucidated the structural features of virus-induced MVBs (vMVBs) in comparison to antibody-induced control MVBs (mock infection) by means of high-pressure cryo fixation of cells followed by immuno electron tomography during early entry of the virus. Three-dimensional tomograms revealed a marked increase in the size and complexity of these vMVBs and the intraluminal vesicles (ILVs) at 2 and 3.5 hours post infection (p.i.), in contrast to the control MVBs without virus. Breakages in the membranes of vMVBs were detected from tomograms after 2 and especially after 3.5 h suggesting that these breakages could facilitate the genome release to the cytoplasm. The in situ neutral-red labeling of viral genome showed that virus uncoating starts as early as 30 min p.i., while an increase of permeability was detected in the vMVBs between 1 and 3 hours p.i., based on a confocal microscopy assay. Altogether, the data show marked morphological changes in size and permeability of the endosomes in the infectious entry pathway of this non-enveloped enterovirus and suggest that the formed breakages facilitate the transfer of the genome to the cytoplasm for replication.
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Koriyama Y, Sugitani K, Ogai K, Kato S. Heat shock protein 70 induction by valproic acid delays photoreceptor cell death by N-methyl-N-nitrosourea in mice. J Neurochem 2014; 130:707-19. [PMID: 24773621 DOI: 10.1111/jnc.12750] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/18/2014] [Accepted: 04/28/2014] [Indexed: 12/28/2022]
Abstract
Retinal degenerative diseases (RDs) are a group of inherited diseases characterized by the loss of photoreceptor cells. Selective photoreceptor loss can be induced in mice by an intraperitoneal injection of N-methyl-N-nitrosourea (MNU) and, because of its selectivity, this model is widely used to study the mechanism of RDs. Although it is known that calcium-calpain activation and lipid peroxidation are involved in the initiation of cell death, the precise mechanisms of this process remain unknown. Heat shock protein 70 (HSP70) has been shown to function as a chaperone molecule to protect cells against environmental and physiological stresses. In this study, we investigated the role of HSP70 on photoreceptor cell death in mice. HSP70 induction by valproic acid, a histone deacetylase inhibitor, attenuated the photoreceptor cell death by MNU through inhibition of apoptotic caspase signals. Furthermore, HSP70 itself was rapidly and calpain-dependently cleaved after MNU treatment. Therefore, HSP70 induction by valproic acid was dually effective against MNU-induced photoreceptor cell loss as a result of its anti-apoptotic actions and its ability to prevent HSP70 degradation. These findings might help lead us to a better understanding of the pathogenic mechanism of RDs. Retinal degenerative diseases are characterized by the loss of photoreceptor cells. We proposed the following cascade for N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell death: MNU gives rise to cleavage of heat shock protein 70 (HSP70); HSP70 induction by valproic acid (VPA) is dually effective against MNU-induced photoreceptor cell loss because of its anti-apoptotic actions and its ability to prevent HSP70 degradation. We hope that the present study heralds a new era in developing therapeutic tools against retinal degenerative diseases.
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Affiliation(s)
- Yoshiki Koriyama
- Department of Molecular Neurobiology, Graduate School of Medicine, Kanazawa University, Kanazawa, Japan; Graduate School and Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan
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Kang JQ, Shen W, Macdonald RL. Trafficking-deficient mutant GABRG2 subunit amount may modify epilepsy phenotype. Ann Neurol 2013; 74:547-59. [PMID: 23720301 DOI: 10.1002/ana.23947] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 03/27/2013] [Accepted: 05/17/2013] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Genetic epilepsies and many other human genetic diseases display phenotypic heterogeneity, often for unknown reasons. Disease severity associated with nonsense mutations is dependent partially on mutation gene location and resulting efficiency of nonsense-mediated mRNA decay (NMD) to eliminate potentially toxic proteins. Nonsense mutations in the last exon do not activate NMD, thus producing truncated proteins. We compared the protein metabolism and the impact on channel biogenesis, function, and cellular homeostasis of truncated γ2 subunits produced by GABRG2 nonsense mutations associated with epilepsy of different severities and by a nonsense mutation in the last exon unassociated with epilepsy. METHODS γ-Aminobutyric acid type A receptor subunits were coexpressed in non-neuronal cells and neurons. NMD was studied using minigenes that support NMD. Protein degradation rates were determined using (35) S radiolabeling pulse chase. Channel function was determined by whole cell recordings, and subunits trafficking and cellular toxicity were determined using flow cytometry, immunoblotting, and immunohistochemistry. RESULTS Although all GABRG2 nonsense mutations resulted in loss of γ2 subunit surface expression, the truncated subunits had different degradation rates and stabilities, suppression of wild-type subunit biogenesis and function, amounts of conjugation with polyubiquitin, and endoplasmic reticulum stress levels. INTERPRETATION We compared molecular phenotypes of GABRG2 nonsense mutations. The findings suggest that despite the common loss of mutant allele function, each mutation produced different intracellular levels of trafficking-deficient subunits. The concentration-dependent suppression of wild-type channel function and cellular disturbance resulting from differences in mutant subunit metabolism may contribute to associated epilepsy severities and by implication to phenotypic heterogeneity in many inherited human diseases.
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Affiliation(s)
- Jing-Qiong Kang
- Departments of Neurology, Vanderbilt University Medical Center, Nashville, TN
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Abstract
Virus-induced apoptosis is thought to be the primary mechanism of cell death following reovirus infection. Induction of cell death following reovirus infection is initiated by the incoming viral capsid proteins during cell entry and occurs via NF-κB-dependent activation of classical apoptotic pathways. Prototype reovirus strain T3D displays a higher cell-killing potential than strain T1L. To investigate how signaling pathways initiated by T3D and T1L differ, we methodically analyzed cell death pathways activated by these two viruses in L929 cells. We found that T3D activates NF-κB, initiator caspases, and effector caspases to a significantly greater extent than T1L. Surprisingly, blockade of NF-κB or caspases did not affect T3D-induced cell death. Cell death following T3D infection resulted in a reduction in cellular ATP levels and was sensitive to inhibition of the kinase activity of receptor interacting protein 1 (RIP1). Furthermore, membranes of T3D-infected cells were compromised. Based on the dispensability of caspases, a requirement for RIP1 kinase function, and the physiological status of infected cells, we conclude that reovirus can also induce an alternate, necrotic form of cell death described as necroptosis. We also found that induction of necroptosis requires synthesis of viral RNA or proteins, a step distinct from that necessary for the induction of apoptosis. Thus, our studies reveal that two different events in the reovirus replication cycle can injure host cells by distinct mechanisms. Virus-induced cell death is a determinant of pathogenesis. Mammalian reovirus is a versatile experimental model for identifying viral and host intermediaries that contribute to cell death and for examining how these factors influence viral disease. In this study, we identified that in addition to apoptosis, a regulated form of cell death, reovirus is capable of inducing an alternate form of controlled cell death known as necroptosis. Death by this pathway perturbs the integrity of host membranes and likely triggers inflammation. We also found that apoptosis and necroptosis following viral infection are activated by distinct mechanisms. Our results suggest that host cells can detect different stages of viral infection and attempt to limit viral replication through different forms of cellular suicide. While these death responses may aid in curbing viral spread, they can also exacerbate tissue injury and disease following infection.
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Soh BY, Song HO, Lee Y, Lee J, Kaewintajuk K, Lee B, Choi YY, Cho JH, Choi S, Park H. Identification of active Plasmodium falciparum calpain to establish screening system for Pf-calpain-based drug development. Malar J 2013; 12:47. [PMID: 23374507 PMCID: PMC3583800 DOI: 10.1186/1475-2875-12-47] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 01/30/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND With the increasing resistance of malaria parasites to available drugs, there is an urgent demand to develop new anti-malarial drugs. Calpain inhibitor, ALLN, is proposed to inhibit parasite proliferation by suppressing haemoglobin degradation. This provides Plasmodium calpain as a potential target for drug development. Pf-calpain, a cysteine protease of Plasmodium falciparum, belongs to calpain-7 family, which is an atypical calpain not harboring Ca2+-binding regulatory motifs. In this present study, in order to establish the screening system for Pf-calpain specific inhibitors, the active form of Pf-calpain was first identified. METHODS Recombinant Pf-calpain including catalytic subdomain IIa (rPfcal-IIa) was heterologously expressed and purified. Enzymatic activity was determined by both fluorogenic substrate assay and gelatin zymography. Molecular homology modeling was carried out to address the activation mode of Pf-calpain in the aspect of structural moiety. RESULTS Based on the measurement of enzymatic activity and protease inhibitor assay, it was found that the active form of Pf-calpain only contains the catalytic subdomain IIa, suggesting that Pf-calpain may function as a monomeric form. The sequence prediction indicates that the catalytic subdomain IIa contains all amino acid residues necessary for catalytic triad (Cys-His-Asn) formation. Molecular modeling suggests that the Pf-calpain subdomain IIa makes an active site, holding the catalytic triad residues in their appropriate orientation for catalysis. The mutation analysis further supports that those amino acid residues are functional and have enzymatic activity. CONCLUSION The identified active form of Pf-calpain could be utilized to establish high-throughput screening system for Pf-calpain inhibitors. Due to its unique monomeric structural property, Pf-calpain could be served as a novel anti-malarial drug target, which has a high specificity for malaria parasite. In addition, the monomeric form of enzyme may contribute to relatively simple synthesis of selective inhibitors.
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Affiliation(s)
- Byoung Yul Soh
- Laboratory of Cell & Molecular Biology, Department of Life Science, Seonam University, Namwon, Jeonbuk 590-711, Republic of Korea
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Chitra S, Nalini G, Rajasekhar G. The ubiquitin proteasome system and efficacy of proteasome inhibitors in diseases. Int J Rheum Dis 2012; 15:249-60. [DOI: 10.1111/j.1756-185x.2012.01737.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Selvarajan Chitra
- Sri Ramachandra Medical College and Research Institute; Sri Ramachandra University; Chennai; India
| | - Ganesan Nalini
- Sri Ramachandra Medical College and Research Institute; Sri Ramachandra University; Chennai; India
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Kim SM, Kim MY, Ann EJ, Mo JS, Yoon JH, Park HS. Presenilin-2 regulates the degradation of RBP-Jk protein through p38 mitogen-activated protein kinase. J Cell Sci 2012; 125:1296-308. [PMID: 22302987 DOI: 10.1242/jcs.095984] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Transcriptional regulation performs a central role in Notch1 signaling by recombining binding protein Suppressor of Hairless (RBP-Jk)--a signaling pathway that is widely involved in determination of cell fate. Our earlier work demonstrated the possible regulation of the Notch1-RBP-Jk pathway through protein degradation of RBP-Jk; however, the potential regulator for the degradation of RBP-Jk remains to be determined. Here, we report that the expression of endogenous and exogenous RBP-Jk was increased significantly in cells treated with proteasome- and lysosome-specific inhibitors. The effects of these inhibitors on RBP-Jk occurred in a dose- and time-dependent manner. The level of RBP-Jk protein was higher in presenilin-2 (PS2)-knockout cells than in presenilin-1 (PS1)-knockout cells. Furthermore, the level of RBP-Jk was decreased by expression of PS2 in PS1 and PS2 double-knockout cells. We also found that PS1-knockout cells treated with a specific inhibitor of p38 mitogen-activated protein kinase ∂ (MAPK) had significantly increased levels of RBP-Jk. p38 MAPK phosphorylates RBP-Jk at Thr339 by physical binding, which subsequently induces the degradation and ubiquitylation of the RBP-Jk protein. Collectively, our results indicate that PS2 modulates the degradation of RBP-Jk through phosphorylation by p38 MAPK.
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Affiliation(s)
- Su-Man Kim
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea
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16
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Proteomic study of calpeptin-induced differentiation on calpain-interacting proteins of C2C12 myoblast. In Vitro Cell Dev Biol Anim 2012; 48:175-85. [PMID: 22271316 DOI: 10.1007/s11626-012-9484-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 01/04/2012] [Indexed: 10/14/2022]
Abstract
Studies on skeletal muscle cell specification and development have demonstrated in the past that calpains interact with various transcriptional factors in regulating the cellular function. It has therefore, been assumed that transcriptional factors like myogenin, MyoD, Myf5, and MRF4 that are active during the myogenic differentiation might be affected and degraded by calpains. Therefore, to examine the biochemical adaptations of myoblasts during myocyte formation and muscle development comprehensively, the current study was designed to identify the effect of calpeptin (calpain inhibitors) on protein expression during differentiation of C2C12 mouse myoblast. Cells were proliferated to near 80% confluence under Dulbecco's modified eagle medium and differentiated further in 2% HS with 50 μM calpeptin. Incubated cells were collected at 0, 12, and 72 h and later the cell proteins were focused onto pH 4-7 IEF strip, followed by 12.5% SDS-PAGE. Obtained spots on the gels were compared and matched using commercial 2-DE analysis software and matched spots were identified by MALDI-ToF and/or Q-Tof systems. Conclusively, cell differentiation was observed to be active from 12 to 72 h however, calpeptin affected the differentiation process and cut down the rate of fusion by approximately 50%. Out of 41 proteins identified, 12 proteins were found to be upregulated where as 29 proteins were downregulated.
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Apoptosis induced by mammalian reovirus is beta interferon (IFN) independent and enhanced by IFN regulatory factor 3- and NF-κB-dependent expression of Noxa. J Virol 2011; 86:1650-60. [PMID: 22090144 DOI: 10.1128/jvi.05924-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A variety of signal transduction pathways are activated in response to viral infection, which dampen viral replication and transmission. These mechanisms involve both the induction of type I interferons (IFNs), which evoke an antiviral state, and the triggering of apoptosis. Mammalian orthoreoviruses are double-stranded RNA viruses that elicit apoptosis in vitro and in vivo. The transcription factors interferon regulatory factor 3 (IRF-3) and nuclear factor kappa light-chain enhancer of activated B cells (NF-κB) are required for the expression of IFN-β and the efficient induction of apoptosis in reovirus-infected cells. However, it is not known whether IFN-β induction is required for apoptosis, nor have the genes induced by IRF-3 and NF-κB that are responsible for apoptosis been identified. To determine whether IFN-β is required for reovirus-induced apoptosis, we used type I IFN receptor-deficient cells, IFN-specific antibodies, and recombinant IFN-β. We found that IFN synthesis and signaling are dispensable for the apoptosis of reovirus-infected cells. These results indicate that the apoptotic response following reovirus infection is mediated directly by genes responsive to IRF-3 and NF-κB. Noxa is a proapoptotic BH3-domain-only protein of the Bcl-2 family that requires IRF-3 and NF-κB for efficient expression. We found that Noxa is strongly induced at late times (36 to 48 h) following reovirus infection in a manner dependent on IRF-3 and NF-κB. The level of apoptosis induced by reovirus is significantly diminished in cells lacking Noxa, indicating a key prodeath function for this molecule during reovirus infection. These results suggest that prolonged innate immune response signaling induces apoptosis by eliciting Noxa expression in reovirus-infected cells.
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Dionne KR, Galvin JM, Schittone SA, Clarke P, Tyler KL. Type I interferon signaling limits reoviral tropism within the brain and prevents lethal systemic infection. J Neurovirol 2011; 17:314-26. [PMID: 21671121 PMCID: PMC3163031 DOI: 10.1007/s13365-011-0038-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 05/02/2011] [Accepted: 05/09/2011] [Indexed: 12/24/2022]
Abstract
In vivo and ex vivo models of reoviral encephalitis were utilized to delineate the contribution of type I interferon (IFN) to the host’s defense against local central nervous system (CNS) viral infection and systemic viral spread. Following intracranial (i.c.) inoculation with either serotype 3 (T3) or serotype 1 (T1) reovirus, increased expression of IFN-α, IFN-β, and myxovirus-resistance protein (Mx1; a prototypical IFN stimulated gene) was observed in mouse brain tissue. Type I IFN receptor deficient mice (IFNAR−/−) had accelerated lethality, compared to wildtype (B6wt) controls, following i.c. T1 or T3 challenge. Although viral titers in the brain and eyes of reovirus infected IFNAR−/− mice were significantly increased, these mice did not develop neurologic signs or brain injury. In contrast, increased reovirus titers in peripheral tissues (liver, spleen, kidney, heart, and blood) of IFNAR−/− mice were associated with severe intestinal and liver injury. These results suggest that reovirus-infected IFNAR−/− mice succumb to peripheral disease rather than encephalitis per se. To investigate the potential role of type I IFN in brain tissue, brain slice cultures (BSCs) were prepared from IFNAR−/− mice and B6wt controls for ex vivo T3 reovirus infection. Compared to B6wt controls, reoviral replication and virus-induced apoptosis were enhanced in IFNAR−/− BSCs indicating that a type I IFN response, initiated by resident CNS cells, mediates innate viral immunity within the brain. T3 reovirus tropism was extended in IFNAR−/− brains to include dentate neurons, ependymal cells, and meningeal cells indicating that reovirus tropism within the CNS is dependent upon type I interferon signaling.
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Affiliation(s)
- Kalen R Dionne
- Medical Scientist Training Program, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA
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Dionne KR, Leser JS, Lorenzen KA, Beckham JD, Tyler KL. A brain slice culture model of viral encephalitis reveals an innate CNS cytokine response profile and the therapeutic potential of caspase inhibition. Exp Neurol 2011; 228:222-31. [PMID: 21241693 DOI: 10.1016/j.expneurol.2011.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 12/30/2010] [Accepted: 01/08/2011] [Indexed: 01/04/2023]
Abstract
Viral encephalitis is a significant cause of human morbidity and mortality in large part due to suboptimal diagnosis and treatment. Murine reovirus infection serves as a classic experimental model of viral encephalitis. Infection of neonatal mice with T3 reoviruses results in lethal encephalitis associated with neuronal infection, apoptosis, and CNS tissue injury. We have developed an ex vivo brain slice culture (BSC) system that recapitulates the basic pathological features and kinetics of viral replication seen in vivo. We utilize the BSC model to identify an innate, brain-tissue specific inflammatory cytokine response to reoviral infection, which is characterized by the release of IL6, CXCL10, RANTES, and murine IL8 analog (KC). Additionally, we demonstrate the potential utility of this system as a pharmaceutical screening platform by inhibiting reovirus-induced apoptosis and CNS tissue injury with the pan-caspase inhibitor, Q-VD-OPh. Cultured brain slices not only serve to model events occurring during viral encephalitis, but can also be utilized to investigate aspects of pathogenesis and therapy that are not experimentally accessible in vivo.
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Affiliation(s)
- Kalen R Dionne
- Medical Scientist Training Program, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
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20
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A proapoptotic peptide derived from reovirus outer capsid protein {micro}1 has membrane-destabilizing activity. J Virol 2010; 85:1507-16. [PMID: 21106751 DOI: 10.1128/jvi.01876-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The reovirus outer capsid protein μ1 is responsible for cell membrane penetration during virus entry and contains determinants necessary for virus-induced apoptosis. Residues 582 to 611 of μ1 are necessary and sufficient for reovirus-induced apoptosis, and residues 594 and 595 independently regulate the efficiency of viral entry and reovirus-induced cell apoptosis, respectively. Two of three α-helices within this region, helix 1 (residues 582 to 611) and helix 3 (residues 644 to 675), play a role in reovirus-induced apoptosis. Here, we chemically synthesized peptides representing helix 1 (H1), H1:K594D, H1:I595K, and helix 3 (H3) and examined their biological properties. We found that H1, but not H3, was able to cause concentration- and size-dependent leakage of molecules from small unilamellar liposomes. We further found that direct application of H1, but not H1:K594D, H1:I595K, or H3, to cells resulted in cytotoxicity. Application of the H1 peptide to L929 cells caused rapid elevations in intracellular calcium concentration that were independent of phospholipase C activation. Cytotoxicity of H1 was not restricted to eukaryotic cells, as the H1 peptide also had bactericidal activity. Based on these findings, we propose that the proapoptotic function of the H1 region of μ1 is dependent on its capacity to destabilize cellular membranes and cause release of molecules from intracellular organelles that ultimately induces cell necrosis or apoptosis, depending on the dose.
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21
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Beckham JD, Tuttle KD, Tyler KL. Caspase-3 activation is required for reovirus-induced encephalitis in vivo. J Neurovirol 2010; 16:306-17. [PMID: 20626234 DOI: 10.3109/13550284.2010.499890] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Reovirus infection of neonatal mice provides a classic experimental system for understanding the molecular pathogenesis of central nervous system (CNS) viral infection. CNS tissue injury, caused by many human neurotropic viruses, including herpes viruses and West Nile virus, is associated with caspase-dependent apoptotic neuronal cell death. We have previously shown that reovirus-induced CNS tissue injury results from apoptosis and is associated with activation of both death-receptor and mitochondrial apoptotic pathways culminating in the activation of the downstream effector caspase, caspase-3. In order to directly investigate the role of caspase-3 in virus-induced neuronal death and CNS tissue injury during encephalitis, we have compared the pathogenesis of reovirus CNS infection in mice lacking the caspase-3 gene (caspase-3 (-/-)) to syngeneic wild-type mice. Prior studies of antiapoptotic treatments for reovirus-infected mice have indicated that protection from reovirus-induced neuronal injury can occur without altering the viral titer in the brains of infected mice. We now show that reovirus infection of caspase-3 (-/-) mice was associated with dramatic reduction in severity of CNS tissue injury, decreased viral antigen and titer in the brain, and enhanced survival of infected mice. Following intracerebral inoculation, the authors also show that virus spread from the brain to the eyes in reovirus-infected caspase-3 (-/-) mice, indicating that viral spread was intact in these mice. Examination of brains of long-term survivors of reovirus infection among caspase-3 (-/-) mice showed that these mice eventually clear their CNS viral infection, and do not manifest residual or delayed CNS tissue injury.
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Affiliation(s)
- J David Beckham
- Department of Medicine, Division of Infectious Diseases, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado 80045, USA.
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22
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Danthi P, Pruijssers AJ, Berger AK, Holm GH, Zinkel SS, Dermody TS. Bid regulates the pathogenesis of neurotropic reovirus. PLoS Pathog 2010; 6:e1000980. [PMID: 20617182 PMCID: PMC2895667 DOI: 10.1371/journal.ppat.1000980] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 06/02/2010] [Indexed: 11/19/2022] Open
Abstract
Reovirus infection leads to apoptosis in both cultured cells and the murine central nervous system (CNS). NF-kappaB-driven transcription of proapoptotic cellular genes is required for the effector phase of the apoptotic response. Although both extrinsic death-receptor signaling pathways and intrinsic pathways involving mitochondrial injury are implicated in reovirus-induced apoptosis, mechanisms by which either of these pathways are activated and their relationship to NF-kappaB signaling following reovirus infection are unknown. The proapoptotic Bcl-2 family member, Bid, is activated by proteolytic cleavage following reovirus infection. To understand how reovirus integrates host signaling circuits to induce apoptosis, we examined proapoptotic signaling following infection of Bid-deficient cells. Although reovirus growth was not affected by the absence of Bid, cells lacking Bid failed to undergo apoptosis. Furthermore, we found that NF-kappaB activation is required for Bid cleavage and subsequent proapoptotic signaling. To examine the functional significance of Bid-dependent apoptosis in reovirus disease, we monitored fatal encephalitis caused by reovirus in the presence and absence of Bid. Survival of Bid-deficient mice was significantly enhanced in comparison to wild-type mice following either peroral or intracranial inoculation of reovirus. Decreased reovirus virulence in Bid-null mice was accompanied by a reduction in viral yield. These findings define a role for NF-kappaB-dependent cleavage of Bid in the cell death program initiated by viral infection and link Bid to viral virulence.
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Affiliation(s)
- Pranav Danthi
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Andrea J. Pruijssers
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Angela K. Berger
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Geoffrey H. Holm
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Sandra S. Zinkel
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Terence S. Dermody
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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Thirukkumaran CM, Nodwell MJ, Hirasawa K, Shi ZQ, Diaz R, Luider J, Johnston RN, Forsyth PA, Magliocco AM, Lee P, Nishikawa S, Donnelly B, Coffey M, Trpkov K, Fonseca K, Spurrell J, Morris DG. Oncolytic viral therapy for prostate cancer: efficacy of reovirus as a biological therapeutic. Cancer Res 2010; 70:2435-44. [PMID: 20215509 DOI: 10.1158/0008-5472.can-09-2408] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Reovirus is a nonattenuated double-stranded RNA virus that exploits aberrant signaling pathways allowing selective cytotoxicity against multiple cancer histologies. The use of reovirus as a potential treatment modality for prostate cancer has not previously been described, and in this study evidence of in vitro and in vivo activity against prostate cancer was seen both in preclinical models and in six patients. The human prostate carcinoma cell lines PC-3, LN-CaP, and DU-145 exposed to replication-competent reovirus showed evidence of infection as illustrated by viral protein synthesis, cytopathic effect, and release of viral progeny. This oncolytic effect was found to be manifested through apoptosis, as DNA fragmentation, Apo 2.7 expression, Annexin V binding, and poly(ADP-ribose) polymerase cleavage were observed in live reovirus-infected cells, but not in uninfected or dead virus-treated cells. In vivo, hind flank severe combined immunodeficient/nonobese diabetic murine xenograft showed reduction in tumor size when treated with even a single intratumoral injection of reovirus. Finally, intralesional reovirus injections into a cohort of six patients with clinically organ-confined prostate cancer resulted in minimal side effects and evidence of antitumor activity. Histologic analysis after prostatectomy found a significant CD8 T-cell infiltration within the reovirus-injected areas as well as evidence of increased caspase-3 activity. These findings suggest that reovirus therapy may provide a promising novel treatment for prostate cancer and also imply a possible role for viral immune targeting of tumor.
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24
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Reovirus activates transforming growth factor beta and bone morphogenetic protein signaling pathways in the central nervous system that contribute to neuronal survival following infection. J Virol 2009; 83:5035-45. [PMID: 19279118 DOI: 10.1128/jvi.02433-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Viral infections of the central nervous system (CNS) are important causes of worldwide morbidity and mortality, and understanding how viruses perturb host cell signaling pathways will facilitate identification of novel antiviral therapies. We now show that reovirus infection activates transforming growth factor beta (TGF-beta) and bone morphogenetic protein (BMP) signaling in a murine model of encephalitis in vivo. TGF-beta receptor I (TGF-beta RI) expression is increased and its downstream signaling factor, SMAD3, is activated in the brains of reovirus-infected mice. TGF-beta signaling is neuroprotective, as inhibition with a TGF-beta RI inhibitor increases death of infected neurons. Similarly, BMP receptor I expression is increased and its downstream signaling factor, SMAD1, is activated in reovirus-infected neurons in the brains of infected mice in vivo. Activated SMAD1 and SMAD3 were both detected in regions of brain infected by reovirus, but activated SMAD1 was found predominantly in uninfected neurons in close proximity to infected neurons. Treatment of reovirus-infected primary mouse cortical neurons with a BMP agonist reduced apoptosis. These data provide the first evidence for the activation of TGF-beta and BMP signaling pathways following neurotropic viral infection and suggest that these signaling pathways normally function as part of the host's protective innate immune response against CNS viral infection.
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25
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Miyamoto SD, Brown RD, Robinson BA, Tyler KL, Long CS, Debiasi RL. Cardiac cell-specific apoptotic and cytokine responses to reovirus infection: determinants of myocarditic phenotype. J Card Fail 2009; 15:529-39. [PMID: 19643365 DOI: 10.1016/j.cardfail.2009.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 12/30/2008] [Accepted: 01/20/2009] [Indexed: 12/17/2022]
Abstract
BACKGROUND The pathophysiologic mechanisms underlying viral myocarditis are not well defined. As a result, effective treatments do not exist and viral myocarditis remains a potentially lethal infection of the heart. METHODS AND RESULTS We used cultured rat cardiac myocytes and fibroblasts to investigate apoptosis and cytokine production in response to infection by myocarditic vs. non-myocarditic strains of reovirus. Myocarditic reovirus strain 8B and non-myocarditic strain DB188 replicate comparably in each cardiac cell type. However, strain 8B and related myocarditic reoviruses preferentially increase apoptosis of myocytes relative to fibroblasts, whereas DB188 and nonmyocarditic strains preferentially increase fibroblast apoptosis. Infection of cardiac fibroblasts with the nonmyocarditic strain DB188 elicits substantial increases in a panel of cytokines compared to fibroblasts infected with strain 8B or mock-infected controls. Analysis of culture supernatants using cytometric bead arrays revealed that DB188 enhanced release of interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-12(p70), GRO-KC, tumor necrosis factor-alpha, and MCP-1 relative to 8B or mock-infected controls (all P < .05). CONCLUSION We hypothesize that differential cytokine production and cell-specific apoptosis are important determinants of myocarditic potential of reoviral strains. Therapies that target the beneficial effects of cytokines in limiting cytopathic damage may offer an effective and novel treatment approach to viral myocarditis.
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Affiliation(s)
- Shelley D Miyamoto
- Department of Pediatrics, University of Colorado Denver Health Sciences Center, Denver, Colorado, USA.
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26
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Abstract
Viral myocarditis is an elusive infection of the heart that is currently without an effective or definitive treatment. Viral myocarditis has a complex disease progression that can be divided into early, middle and late phases. Direct cytopathic injury, apoptosis, activation of the innate and adaptive immune system and cardiac remodeling have all been implicated in the pathogenesis of viral myocarditis. Novel treatment approaches are evolving at a rapid pace. The purpose of this review is to provide an update on current research focused on identifying potential treatment options for viral myocarditis.
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Affiliation(s)
- Shelley D Miyamoto
- Department of Pediatric Cardiology, University of Colorado at Denver & Health Sciences Center, The Children’s Hospital, 13123 E. 16th Avenue, B100 Aurora, CO 80045, USA
| | - Roberta L DeBiasi
- Children’s National Medical Center/Children’s Research Institute, Division of Pediatric Infectious Diseases, George Washington University School of Medicine, 111 Michigan Ave NW, Washington DC 20010, USA
| | - Carlin S Long
- Division of Cardiology, University of Colorado at Denver & Health Sciences Center, Box 0960, Denver Health Medical Center, 777 Bannock St, Denver, CO 80204, USA
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27
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Chiu WT, Tang MJ, Jao HC, Shen MR. Soft substrate up-regulates the interaction of STIM1 with store-operated Ca2+ channels that lead to normal epithelial cell apoptosis. Mol Biol Cell 2008; 19:2220-30. [PMID: 18337467 PMCID: PMC2366837 DOI: 10.1091/mbc.e07-11-1170] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 02/12/2008] [Accepted: 02/29/2008] [Indexed: 11/11/2022] Open
Abstract
We have demonstrated that soft substrate induced apoptosis in polarized cells, but not in transformed cells by disturbance of Ca(2+) homeostasis. This study aims to further investigate the regulatory mechanisms underlying the disruption of Ca(2+)-signaling integrity in soft substrate-induced epithelial apoptosis. Soft substrate up-regulated the store-operated Ca(2+) (SOC) entry across the plasma membrane of normal cervical epithelial cells, which resulted in increased cytosolic Ca(2+) levels. Concomitantly, soft substrate induced the aggregation and translocation of stromal interacting molecule 1 (STIM1) toward the cell periphery to colocalize with Orai1, an essential pore subunit of SOC channel, detected by fluorescence resonance energy transfer approach and confocal image analyses. The disturbed Ca(2+) homeostasis resulted in the activation of mu-calpain, which cleaved alpha-spectrin, induced actin disorganization, and caused apoptosis. In contrast, soft substrate did not disturb Ca(2+) homeostasis or induce apoptosis in cervical cancer cells. Chelating extracellular Ca(2+) by EGTA and down-regulated SOC entry by small interfering RNA targeting STIM1 or inhibitors targeting Ca(2+)-binding site of calpain significantly inhibited soft substrate-induced activation of mu-calpain and epithelial cell apoptosis. Thus, soft substrate up-regulates the interaction of STIM1 with SOC channels, which results in the activation of mu-calpain and subsequently induces normal epithelial cell apoptosis.
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Affiliation(s)
| | - Ming-Jer Tang
- Department of Physiology
- Center for Gene Regulation and Signal Transduction Research, and
| | | | - Meng-Ru Shen
- Center for Gene Regulation and Signal Transduction Research, and
- Departments of Pharmacology and
- Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
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28
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Experimental reovirus-induced acute flaccid paralysis and spinal motor neuron cell death. J Neuropathol Exp Neurol 2008; 67:231-9. [PMID: 18344914 DOI: 10.1097/nen.0b013e31816564f0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acute flaccid paralysis (AFP) describes the loss of motor function in 1 or more limbs commonly associated with viral infection and destruction of motor neurons in the anterior horns of the spinal cord. Therapy is limited, and the development of effective treatments is hampered by a lack of experimental models. Reovirus infection of neonatal mice provides a model for the study of CNS viral infection pathogenesis. Injection of the Reovirus serot Type 3 strains Abney (T3A) or Dearing (T3D) into the hindlimb of 1-day-old mice resulted in the development of AFP in more than 90% of infected mice. Acute flaccid paralysis began in the ipsilateral hindlimb at 8 to 10 days postinfection and progressed to paraplegia 24 hours later. Paralysis correlated with injury, neuron loss, and spread of viral antigen first to the ipsilateral and then to the contralateral anterior horns. As demonstrated by the activation of caspase 3 and its colocalization with viral antigen in the anterior horn and concomitant cleavage of poly-(adenosine diphosphate-ribose) polymerase, AFP was associated with apoptosis. Calpain activity and inducible nitric oxide synthase expression were both elevated in the spinal cords of paralyzed animals. This study represents the first detailed characterization of a novel and highly efficient experimental model of virus-induced AFP that will facilitate evaluation of therapeutic strategies targeting virus-induced paralysis.
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29
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Goody RJ, Beckham JD, Rubtsova K, Tyler KL. JAK-STAT signaling pathways are activated in the brain following reovirus infection. J Neurovirol 2007; 13:373-83. [PMID: 17849321 PMCID: PMC2367059 DOI: 10.1080/13550280701344983] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Reovirus infection provides a classic experimental model system for studying the pathogenesis of viral infections of the central nervous system (CNS), with apoptosis acting as the major mechanism of cell death. The authors have examined the role of signal transducer and activator of transcription (STAT)1, a component of Janus-activated kinase (JAK)-STAT signaling, a pathway implicated in antiviral responses and pathways regulating apoptosis, following reovirus infection. Infection of primary cortical neuron cultures with reovirus serotype 3 strain Abney (T3A) resulted in phosphorylation of STAT1 at sites critical for transcriptional activity. Activated STAT1 was also detected in the brain of neonatal mice following T3A infection, with a nuclear pattern of expression in areas of virus-induced injury. Activation of STAT proteins is typically mediated by JAKs. The authors observed JAK2 phosphorylation (Tyr 1007/1008) in brain lysates from T3A-infected mice. Inhibition of JAK activity with the inhibitor AG-490 blocked reovirus-induced STAT1 activation in neuronal cultures, indicating reovirus-induced STAT activation is JAK dependent. Pretreatment of neuronal cultures with antibody raised against interferon (IFN)-alpha/betaR2 inhibited T3A-induced STAT1 phosphorylation, whereas neither IFN-gamma or IFN-gammaR2 antibody pretreatment had any effect on T3A-induced STAT1 phosphorylation. Mice lacking the STAT1 gene demonstrated increased susceptibility to reovirus infection, with increased mortality and higher viral titers in the brain compared to wild-type animals. The results demonstrate activation of a type I IFN-mediated, JAK-dependent STAT signaling pathway following reovirus infection and suggest that STAT1 is a key component of host defense mechanisms against reovirus infection in the brain.
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Affiliation(s)
- Robin J Goody
- Departments of Neurology, University of Colorado at Denver and Health Sciences Center, Denver, Colorado, USA
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30
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Abstract
Calpains are calcium-dependent cysteine proteases that degrade cytoskeletal and cytoplasmic proteins. We have studied the role of calpains in the life cycle of human echovirus 1 (EV1). The calpain inhibitors, including calpeptin, calpain inhibitor 1, and calpain inhibitor 2 as well as calpain 1 and calpain 2 short interfering RNAs, completely blocked EV1 infection in the host cells. The effect of the inhibitors was not specific for EV1, because they also inhibited infection by other picornaviruses, namely, human parechovirus 1 and coxsackievirus B3. The importance of the calpains in EV1 infection also was supported by the fact that EV1 increased calpain activity 3 h postinfection. Confocal microscopy and immunoelectron microscopy showed that the EV1/caveolin-1-positive vesicles also contain calpain 1 and 2. Our results indicate that calpains are not required for virus entry but that they are important at a later stage of infection. Calpain inhibitors blocked the production of EV1 particles after microinjection of EV1 RNA into the cells, and they effectively inhibited the synthesis of viral RNA in the host cells. Thus, both calpain 1 and calpain 2 are essential for the replication of EV1 RNA.
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Beckham JD, Goody RJ, Clarke P, Bonny C, Tyler KL. Novel strategy for treatment of viral central nervous system infection by using a cell-permeating inhibitor of c-Jun N-terminal kinase. J Virol 2007; 81:6984-92. [PMID: 17475657 PMCID: PMC1933289 DOI: 10.1128/jvi.00467-07] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viral encephalitis is a major cause of morbidity and mortality worldwide, yet there is no proven efficacious therapy for most viral infections of the central nervous system (CNS). Many of the viruses that cause encephalitis induce apoptosis and activate c-Jun N-terminal kinase (JNK) following infection. We have previously shown that reovirus infection of epithelial cell lines activates JNK-dependent apoptosis. We now show that reovirus infection resulted in activation of JNK and caspase-3 in the CNS. Treatment of reovirus-infected mice with a cell-permeating peptide that competitively inhibits JNK activity resulted in significantly prolonged survival of intracerebrally infected mice following an otherwise lethal challenge with T3D (100 x 50% lethal dose). Protection correlated with reduced CNS injury, reduced neuronal apoptosis, and reduced c-Jun activation without altering the viral titer or viral antigen distribution. Given the efficacy of the inhibitor in protecting mice from viral encephalitis, JNK inhibition represents a promising and novel treatment strategy for viral encephalitis.
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Affiliation(s)
- J David Beckham
- Department of Medicine, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA
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Akimitsu N, Tanaka J, Pelletier J. Translation of nonSTOP mRNA is repressed post-initiation in mammalian cells. EMBO J 2007; 26:2327-38. [PMID: 17446866 PMCID: PMC1864977 DOI: 10.1038/sj.emboj.7601679] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 03/15/2007] [Indexed: 11/08/2022] Open
Abstract
We investigated the fate of aberrant mRNAs lacking in-frame termination codons (called nonSTOP mRNA) in mammalian cells. We found that translation of nonSTOP mRNA was considerably repressed although a corresponding reduction of mRNA was not observed. The repression appears to be post-initiation since (i) repressed nonSTOP mRNAs were associated with polysomes, (ii) translation of IRES-initiated and uncapped nonSTOP mRNA were repressed, and (iii) protein production from nonSTOP mRNA associating with polysomes was significantly reduced when used to program an in vitro run-off translation assay. NonSTOP mRNAs distributed into lighter polysome fractions compared to control mRNAs encoding a stop codon, and a significant amount of heterogeneous polypeptides were produced during in vitro translation of nonSTOP RNAs, suggesting premature termination of ribosomes translating nonSTOP mRNA. Moreover, a run-off translation assay using hippuristanol and RNAse protection assays suggested the presence of a ribosome stalled at the 3' end of nonSTOP mRNAs. Taken together, these data indicate that ribosome stalling at the 3' end of nonSTOP mRNAs can block translation by preventing upstream translation events.
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Affiliation(s)
- Nobuyoshi Akimitsu
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Higashi, Tsukuba-shi, Ibaraki, Japan.
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Fettucciari K, Fetriconi I, Mannucci R, Nicoletti I, Bartoli A, Coaccioli S, Marconi P. Group B Streptococcus induces macrophage apoptosis by calpain activation. THE JOURNAL OF IMMUNOLOGY 2006; 176:7542-56. [PMID: 16751401 DOI: 10.4049/jimmunol.176.12.7542] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Group B Streptococcus (GBS) has developed several strategies to evade immune defenses. We show that GBS induces macrophage (Mphi) membrane permeability defects and apoptosis, prevented by inhibition of calcium influx but not caspases. We analyze the molecular mechanisms of GBS-induced murine Mphi apoptosis. GBS causes a massive intracellular calcium increase, strictly correlated to membrane permeability defects and apoptosis onset. Calcium increase was associated with activation of calcium-dependent protease calpain, demonstrated by casein zymography, alpha-spectrin cleavage to a calpain-specific fragment, fluorogenic calpain-substrate cleavage, and inhibition of these proteolyses by calpain inhibitors targeting the calcium-binding, 3-(4-Iodophenyl)-2-mercapto-(Z)-2-propenoic acid, or active site (four different inhibitors), by calpain small-interfering-RNA (siRNA) and EGTA. GBS-induced Mphi apoptosis was inhibited by all micro- and m-calpain inhibitors used and m-calpain siRNA, but not 3-(5-Fluoro-3-indolyl)-2-mercapto-(Z)-2-propenoic acid (micro-calpain inhibitor) and micro-calpain siRNA indicating that m-calpain plays a central role in apoptosis. Calpain activation is followed by Bax and Bid cleavage, cytochrome c, apoptosis-inducing factor, and endonuclease G release from mitochondria. In GBS-induced apoptosis, cytochrome c did not induce caspase-3 and -7 activation because they and APAF-1 were degraded by calpains. Therefore, apoptosis-inducing factor and endonuclease G seem the main mediators of the calpain-dependent but caspase-independent pathway of GBS-induced apoptosis. Proapoptotic mediator degradations do not occur with nonhemolytic GBS, not inducing Mphi apoptosis. Apoptosis was reduced by Bax siRNA and Bid siRNA suggesting Bax and Bid degradation is apoptosis correlated. This signaling pathway, different from that of most pathogens, could represent a GBS strategy to evade immune defenses.
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Affiliation(s)
- Katia Fettucciari
- Department of Clinical and Experimental Medicine, General Pathology and Immunology Section, S. Maria Hospital, Didactic and Scientific Division of Terni, Perugia University, Italy
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Zhang Y, Bhavnani BR. Glutamate-induced apoptosis in neuronal cells is mediated via caspase-dependent and independent mechanisms involving calpain and caspase-3 proteases as well as apoptosis inducing factor (AIF) and this process is inhibited by equine estrogens. BMC Neurosci 2006; 7:49. [PMID: 16776830 PMCID: PMC1526740 DOI: 10.1186/1471-2202-7-49] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 06/15/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Glutamate, a major excitatory amino acid neurotransmitter, causes apoptotic neuronal cell death at high concentrations. Our previous studies have shown that depending on the neuronal cell type, glutamate-induced apoptotic cell death was associated with regulation of genes such as Bcl-2, Bax, and/or caspase-3 and mitochondrial cytochrome c. To further delineate the intracellular mechanisms, we have investigated the role of calpain, an important calcium-dependent protease thought to be involved in apoptosis along with mitochondrial apoptosis inducing factor (AIF) and caspase-3 in primary cortical cells and a mouse hippocampal cell line HT22. RESULTS Glutamate-induced apoptotic cell death in neuronal cells was associated with characteristic DNA fragmentation, morphological changes, activation of calpain and caspase-3 as well as the upregulation and/or translocation of AIF from mitochondria into cytosol and nuclei. Our results reveal that primary cortical cells and HT22 cells display different patterns of regulation of these genes/proteins. In primary cortical cells, glutamate induces activation of calpain, caspase-3 and translocation of AIF from mitochondria to cytosol and nuclei. In contrast, in HT22 cells, only the activation of calpain and upregulation and translocation of AIF occurred. In both cell types, these processes were inhibited/reversed by 17beta-estradiol and Delta8,17beta-estradiol with the latter being more potent. CONCLUSION Depending upon the neuronal cell type, at least two mechanisms are involved in glutamate-induced apoptosis: a caspase-3-dependent pathway and a caspase-independent pathway involving calpain and AIF. Since HT22 cells lack caspase-3, glutamate-induced apoptosis is mediated via the caspase-independent pathway in this cell line. Kinetics of this apoptotic pathway further indicate that calpain rather than caspase-3, plays a critical role in the glutamate-induced apoptosis. Our studies further indicate that glutamate- induced changes of these proteins can be inhibited by estrogens, with Delta8,17beta-estradiol, a novel equine estrogen being more potent than 17beta-estradiol. To our knowledge, this is the first demonstration that glutamate-induced apoptosis involves regulation of multiple apoptotic effectors that can be inhibited by estrogens. Whether these observations can help in the development of novel therapeutic approaches for the prevention of neurodegenerative diseases with estrogens and calpain inhibitors remains to be investigated.
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Affiliation(s)
- YueMei Zhang
- Department of Obstetrics and Gynecology, University of Toronto, Institute of Medical Sciences, University of Toronto, Department of Obstetrics and Gynecology, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Bhagu R Bhavnani
- Department of Obstetrics and Gynecology, University of Toronto, Institute of Medical Sciences, University of Toronto, Department of Obstetrics and Gynecology, St. Michael's Hospital, Toronto, Ontario, Canada
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Tan Y, Wu C, De Veyra T, Greer PA. Ubiquitous calpains promote both apoptosis and survival signals in response to different cell death stimuli. J Biol Chem 2006; 281:17689-98. [PMID: 16632474 DOI: 10.1074/jbc.m601978200] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The mu- and m-calpain proteases have been implicated in both pro- or anti-apoptotic functions. Here we compared cell death responses and apoptotic or survival signaling pathways in primary mouse embryonic fibroblasts (MEFs) derived from wild type or capn4 knock-out mice which lack both mu- and m-calpain activities. Capn4(-/-) MEFs displayed resistance to puromycin, camptothecin, etoposide, hydrogen peroxide, ultraviolet light, and serum starvation, which was consistent with pro-apoptotic roles for calpain. In contrast, capn4(-/-) MEFs were more susceptible to staurosporine (STS) and tumor necrosis factor alpha-induced cell death, which provided evidence for anti-apoptotic signaling roles for calpain. Bax activation, release of cytochrome c, and activation of caspase-9 and caspase-3 all correlated with the observed cell death responses of wild type or capn4(-/-) MEFs to the various challenges, suggesting that calpain might play distinct roles in transducing different death signals to the mitochondria. There was no evidence that calpain cleaved Bcl-2 family member proteins that regulate mitochondrial membrane permeability including Bcl-2, Bcl-xl, Bad, Bak, Bid, or Bim. However, activation of the phosphatidylinositol 3 (PI3)-kinase/Akt survival signaling pathway was compromised in capn4(-/-) MEFs under all challenges regardless of the cell death outcome, and blocking Akt activation using the PI3-kinase inhibitor LY294002 abolished the protective effect of calpain to STS challenge. We conclude that the anti-apoptotic function of calpain in tumor necrosis factor alpha- and STS-challenged cells relates to a novel role in activating the PI3-kinase/Akt survival pathway.
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Affiliation(s)
- Yinfei Tan
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Botterall Hall Rm. A309, Kingston, Ontario K7L-3N6, Canada
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Chen D, Texada DE, Duggan C, Deng Y, Redens TB, Langford MP. Caspase-3 and -7 mediate apoptosis of human Chang's conjunctival cells induced by enterovirus 70. Virology 2006; 347:307-22. [PMID: 16427675 DOI: 10.1016/j.virol.2005.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 10/20/2005] [Accepted: 12/02/2005] [Indexed: 10/25/2022]
Abstract
Enterovirus 70 (EV70) is the major etiological agent of acute hemorrhagic conjunctivitis (AHC). EV70 m.o.i.- (multiplicity of infection) and time-dependently induced apoptosis in human Chang's conjunctival (HCC) cells. UV- or heat-inactivated EV70 did not induce apoptosis. EV70-induced apoptosis was inhibited by cycloheximide and methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone (MPCMK), but not actinomycin D and guanidine.HCl (although guanidine.HCl inhibited the apoptosis induced by EV70 infection at 0.5 PFU/cell for 18 h). EV70 infection induced activation of caspase-3 and -7 and degradation of the constitutively activated caspase-6. EV70-induced apoptotic DNA ladders and activated caspase-3 and -7, correlated with virus release. Caspase inhibitor IX (Z-VD-FMK) inhibited EV70-induced apoptosis and virus release, but not intracellular viral production. The results suggest that infectious virus and the syntheses of viral proteins especially EV70 proteases, but not viral genome RNA, are required for caspase-3 and -7-mediated EV70-induced apoptosis, and that apoptosis through cell lysis promotes EV70 release from HCC cells.
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Affiliation(s)
- Dequan Chen
- Department of Ophthalmology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
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Smith JA, Schmechel SC, Raghavan A, Abelson M, Reilly C, Katze MG, Kaufman RJ, Bohjanen PR, Schiff LA. Reovirus induces and benefits from an integrated cellular stress response. J Virol 2006; 80:2019-33. [PMID: 16439558 PMCID: PMC1367166 DOI: 10.1128/jvi.80.4.2019-2033.2006] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Following infection with most reovirus strains, viral protein synthesis is robust, even when cellular translation is inhibited. To gain further insight into pathways that regulate translation in reovirus-infected cells, we performed a comparative microarray analysis of cellular gene expression following infection with two strains of reovirus that inhibit host translation (clone 8 and clone 87) and one strain that does not (Dearing). Infection with clone 8 and clone 87 significantly increased the expression of cellular genes characteristic of stress responses, including the integrated stress response. Infection with these same strains decreased transcript and protein levels of P58(IPK), the cellular inhibitor of the eukaryotic initiation factor 2alpha (eIF2alpha) kinases PKR and PERK. Since infection with host shutoff-inducing strains of reovirus impacted cellular pathways that control eIF2alpha phosphorylation and unphosphorylated eIF2alpha is required for translation initiation, we examined reovirus replication in a variety of cell lines with mutations that impact eIF2alpha phosphorylation. Our results revealed that reovirus replication is more efficient in the presence of eIF2alpha kinases and phosphorylatable eIF2alpha. When eIF2alpha is phosphorylated, it promotes the synthesis of ATF4, a transcription factor that controls cellular recovery from stress. We found that the presence of this transcription factor increased reovirus yields 10- to 100-fold. eIF2alpha phosphorylation also led to the formation of stress granules in reovirus-infected cells. Based on these results, we hypothesize that eIF2alpha phosphorylation facilitates reovirus replication in two ways-first, by inducing ATF4 synthesis, and second, by creating an environment that places abundant reovirus transcripts at a competitive advantage for limited translational components.
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Affiliation(s)
- Jennifer A Smith
- Department of Microbiology, University of Minnesota, 420 Delaware Street SE, MMC 196, Minneapolis, MN 55455, USA
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Goody RJ, Hoyt CC, Tyler KL. Reovirus infection of the CNS enhances iNOS expression in areas of virus-induced injury. Exp Neurol 2005; 195:379-90. [PMID: 16004984 PMCID: PMC2367058 DOI: 10.1016/j.expneurol.2005.05.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Revised: 05/24/2005] [Accepted: 05/27/2005] [Indexed: 10/25/2022]
Abstract
Nitric oxide (NO) has been implicated as a contributor to the host's innate defense against viral infections including those affecting the CNS. Reovirus infection of the CNS is a classic experimental system for understanding the pathogenesis of neurotropic viral infection. Infection with serotype 3 strains is associated with perturbations in various cellular signaling pathways including NF-kappaB and NO plays a regulatory role in many of these same pathways. We therefore examined whether NO production is dysregulated following reovirus serotype 3 strain Abney (T3A) infection of the mouse CNS. Nitric oxide synthase (NOS) activity was significantly higher in brain homogenates from T3A-infected animals compared to mock infected. Increased NOS activity correlated with inducible NOS (iNOS) expression in brain homogenates of T3A-infected animals. Expression of iNOS was confined to areas of viral infection and injury. T3A infection of primary neuronal and glial cultures was also associated with enhanced expression of iNOS. Immunocytochemical studies of primary glial cultures demonstrated that, in addition to its known neuronotropism, T3A was also capable of infecting immature microglial cells. T3A infection did not alter expression of either neuronal or endothelial NOS isoforms in neuronal or glial cultures or in mouse brain. The NO donor S-Nitroso-N-acetyl penicillamine (SNAP) significantly inhibited T3A growth in neuronal cultures, conversely the NOS inhibitor N-omega-Nitro-L-arginine methyl ester hydrochloride (L-NAME) augmented viral growth. Our findings provide the first evidence of reovirus-induced iNOS expression and the first demonstration that NO inhibits mammalian reovirus replication, suggesting that NO may play an antiviral role during reovirus infection.
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Affiliation(s)
- Robin J Goody
- Department of Neurology, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA
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Quiniou C, Sennlaub F, Beauchamp MH, Checchin D, Lahaie I, Brault S, Gobeil F, Sirinyan M, Kooli A, Hardy P, Pshezhetsky A, Chemtob S. Dominant Role for Calpain in Thromboxane-Induced Neuromicrovascular Endothelial Cytotoxicity. J Pharmacol Exp Ther 2005; 316:618-27. [PMID: 16214879 DOI: 10.1124/jpet.105.093898] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Thromboxane A(2) (TXA(2)) is an important lipid mediator generated during oxidative stress and implicated in ischemic neural injury. This autacoid was recently shown to partake in this injury process by directly inducing endothelial cytotoxicity. We explored the mechanisms for this TXA(2)-evoked neural microvascular endothelial cell death. Stable TXA(2) mimetics 5-heptenoic acid, 7-[6-(3-hydroxy-1-octenyl)-2-oxabicyclo[2.2.1]hept-5-yl]-[1R-[1alpha,4alpha,5beta(Z),6alpha,(1E,3S)]]-9,11-dedioxy-9alpha,11alpha-methanolpoxy (U-46619) [as well as [1S-[1alpha,2alpha(Z),3beta(1E,3S(*)),4alpha]]-7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo[2.1.1]-hept-2-yl]-5-heptenoic acid; I-BOP] induced a retinal microvascular degeneration in rat pups in vivo and in porcine retinal explants ex vivo and death of porcine brain endothelial cells (in culture). TXA(2) dependence of these effects was corroborated by antagonism using the selective TXA(2) receptor blocker (-)-6,8-difluoro-9-p-methyl-sulfonyl-benzyl-1,2,3,4-tetrahydrocarbazol-1-yl-acetic acid (L670596). In all cases, neurovascular endothelial cell death was prevented by pan-calpain and specific m-calpain inhibitors but not by caspase-3 or pan-caspase inhibitors. Correspondingly, TXA(2) (mimetics) augmented generation of known active m-calpain (but not mu-calpain) form and increased the activity of m-calpain (cleavage of fluorogenic substrate N-succinyl-Leu-Leu-Val-Tyr-7-amino-4-methylcoumarin; and of alpha-spectrin into specific fragments) but not of pan-caspase or specific caspase-3 (respectively, using sulforhodamine-Val-Arg-Asp-fluoromethyl ketone and detecting its active 17- and 12-kDa fragments). Interestingly, these effects were phospholipase C (PLC)-dependent [associated with increase in inositol triphosphate and inhibited by PLC blocker 1-[6-[[17beta-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122)] and required calcium but were not associated with increased intracellular calcium. U-46619-induced calpain activation resulted in translocation of Bax to the mitochondria, loss of polarization of the latter (using potentiometric probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide; JC-1) and in turn release of cytochrome c into the cytosol and depletion of cellular ATP; these effects were all blocked by calpain inhibitors. Overall, this work identifies (specifically) m-calpain as a dominant protease in TXA(2)-induced neurovascular endothelial cell death.
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Affiliation(s)
- Christiane Quiniou
- Department of Pediatrics, Centre de Recherche de l'Hôpital Ste-Justine, Université de Montréal, Québec, Canada
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Clarke P, Debiasi RL, Goody R, Hoyt CC, Richardson-Burns S, Tyler KL. Mechanisms of reovirus-induced cell death and tissue injury: role of apoptosis and virus-induced perturbation of host-cell signaling and transcription factor activation. Viral Immunol 2005; 18:89-115. [PMID: 15802955 PMCID: PMC2366905 DOI: 10.1089/vim.2005.18.89] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reoviruses have provided insight into the roles played by specific viral genes and the proteins they encode in virus-induced cell death and tissue injury. Apoptosis is a major mechanism of cell death induced by reoviruses. Reovirus-induced apoptosis involves both death-receptor and mitochondrial cell death pathways. Reovirus infection is associated with selective activation of mitogen activated protein kinase (MAPK) cascades including JNK/SAPK. Infection also perturbs transcription factor signaling resulting in the activation of c-Jun and initial activation followed by strain-specific inhibition of NF-kappaB. Infection results in changes in the expression of genes encoding proteins involved in cell cycle regulation, apoptosis, and DNA damage and repair processes. Apoptosis is a major mechanism of reovirus-induced injury to key target organs including the CNS and heart. Inhibition of apoptosis through the use of caspase or calpain inhibitors, minocycline, or in caspase 3(-/-) mice all reduce virus-associated tissue injury and enhance survival of infected animals. Reoviruses induce apoptotic cell death (oncolysis) in a wide variety of cancer cells and tumors. The capacity of reoviruses to grow efficiently in transformed cells is enhanced by the presence of an activated Ras signaling pathway likely through mechanisms involving inhibition of antiviral PKR signaling and activation of Ras/RalGEF/p38 pathways. The potential of reovirus-induced oncolysis in therapy of human cancers is currently being investigated in phase I/II clinical trials.
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Affiliation(s)
- P Clarke
- Department of Neurology, University of Colorado Health Sciences Center, 4200 East 9th Ave., Denver, CO 80262, USA
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Pal K, Kaetzel CS, Brundage K, Cunningham CA, Cuff CF. Regulation of polymeric immunoglobulin receptor expression by reovirus. J Gen Virol 2005; 86:2347-2357. [PMID: 16033983 DOI: 10.1099/vir.0.80690-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Polymeric immunoglobulin receptor (pIgR) transcytoses dimeric IgA and IgA-coated immune complexes from the lamina propria across epithelia and into secretions. The effect of reovirus infection on regulation of pIgR expression in the human intestinal epithelial cell line HT-29 was characterized in this report. Both replication-competent and UV-inactivated reovirus at m.o.i. equivalents of 1-100 p.f.u. per cell upregulated pIgR mRNA by 24 h post-infection and intracellular pIgR protein was increased at 48 h following exposure to UV-inactivated virus. Binding of virus to HT-29 cells was required, as pre-incubating virus with specific antiserum, but not non-immune serum, inhibited reovirus-mediated pIgR upregulation. Endosomal acidification leading to uncoating of virus is a required step for pIgR upregulation, as ammonium chloride or bafilomycin A1 pre-treatment inhibited virus-induced pIgR upregulation. Inhibition experiments using the calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal suggested that calpains are involved in reovirus-mediated pIgR upregulation. Upregulation of pIgR following virus infection appears to be an innate immune response against invading pathogens that could help the host clear infection effectively. Signalling induced by microbes and their products may serve to augment pIgR-mediated transcytosis of IgA, linking the innate and acquired immune responses to viruses.
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Affiliation(s)
- Kasturi Pal
- Department of Microbiology, Immunology and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, PO Box 9177, Morgantown, WV 26506-9177, USA
| | - Charlotte S Kaetzel
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA
| | - Kathleen Brundage
- Department of Microbiology, Immunology and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, PO Box 9177, Morgantown, WV 26506-9177, USA
| | - Cynthia A Cunningham
- Department of Microbiology, Immunology and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, PO Box 9177, Morgantown, WV 26506-9177, USA
| | - Christopher F Cuff
- Department of Microbiology, Immunology and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, PO Box 9177, Morgantown, WV 26506-9177, USA
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Cinatl J, Michaelis M, Hoever G, Preiser W, Doerr HW. Development of antiviral therapy for severe acute respiratory syndrome. Antiviral Res 2005; 66:81-97. [PMID: 15878786 PMCID: PMC7132397 DOI: 10.1016/j.antiviral.2005.03.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 03/16/2005] [Accepted: 03/17/2005] [Indexed: 02/09/2023]
Abstract
A new disease, the severe acute respiratory distress syndrome (SARS), caused by the SARS coronavirus (SARS-CoV), emerged at the beginning of 2003 and rapidly spread throughout the world. Although the disease had disappeared in June 2003 its re-emergence cannot be excluded. The development of vaccines against SARS-CoV may take years. Therefore, the availability of effective antiviral drugs against SARS-CoV may be crucial for the control of future SARS outbreaks. In this review, experimental and clinical data about potential anti-SARS drugs is summarised and discussed. Animal model studies will be needed to help to determine which interventions warrant controlled clinical testing.
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Affiliation(s)
- Jindrich Cinatl
- Institut für Medizinische Virologie, Klinikum der Johann Wolfgang Goethe-Universität, Paul Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany.
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Clarke P, Richardson-Burns SM, DeBiasi RL, Tyler KL. Mechanisms of apoptosis during reovirus infection. Curr Top Microbiol Immunol 2005; 289:1-24. [PMID: 15791949 PMCID: PMC2367090 DOI: 10.1007/3-540-27320-4_1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Reovirus infection has proven to be an excellent experimental system for studying mechanisms of virus-induced pathogenesis. Reoviruses induce apoptosis in a wide variety of cultured cells in vitro and in target tissues in vivo, including the heart and central nervous system. In vivo, viral infection, tissue injury, and apoptosis colocalize, suggesting that apoptosis is a critical mechanism by which disease is triggered in the host. This review examines the mechanisms of reovirus-induced apoptosis and investigates the possibility that inhibition of apoptosis may provide a novel strategy for limiting virus-induced tissue damage following infection.
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Affiliation(s)
- P. Clarke
- Department of Neurology (B 182), University of Colorado Health Sciences Center, 4200 East 9th Ave., Denver, CO 80262, USA
- Denver VA Medical Center, 1055 Clermont St, Denver, CO 80220, USA
| | - S. M. Richardson-Burns
- Department of Neurology (B 182), University of Colorado Health Sciences Center, 4200 East 9th Ave., Denver, CO 80262, USA
- Denver VA Medical Center, 1055 Clermont St, Denver, CO 80220, USA
| | - R. L. DeBiasi
- Department of Neurology (B 182), University of Colorado Health Sciences Center, 4200 East 9th Ave., Denver, CO 80262, USA
- Denver VA Medical Center, 1055 Clermont St, Denver, CO 80220, USA
| | - K. L. Tyler
- Department of Neurology (B 182), University of Colorado Health Sciences Center, 4200 East 9th Ave., Denver, CO 80262, USA
- Denver VA Medical Center, 1055 Clermont St, Denver, CO 80220, USA
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van Wijngaarden J, de Rooij K, van Beek E, Bernsen H, Que I, van Hinsbergh VWM, Löwik C. Identification of differentially expressed genes in a renal cell carcinoma tumor model after endostatin-treatment. J Transl Med 2004; 84:1472-83. [PMID: 15273700 DOI: 10.1038/labinvest.3700157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Endostatin is a cleavage product of collagen XVIII that has shown to inhibit tumor-angiogenesis in experimental tumor models. At present, the exact molecular mechanism of action of endostatin is not completely elucidated. In this study, we wanted to identify specific target genes of endostatin. For this purpose, the human renal cell carcinoma RC-9 was subcutaneously implanted in nude mice and treated with endostatin. Tumor growth was inhibited by endostatin after 4 days of treatment. Using immunohistochemistry and the hypoxia marker pimonidazole, we demonstrate disintegration of blood vessels and hypoxia and anoxia as a result of the treatment. Hereafter, we applied the polymerase chain reaction (PCR)-based subtractive suppression hybridization (SSH) method, together with the mirror orientation selection (MOS) technique to identify specifically induced and suppressed genes after endostatin-treatment. We found eight genes to be specifically induced and 11 to be suppressed by the endostatin-treatment. Among other genes, core binding factor a-1/osteoblast-specific factor-2 (cbfa1/osf2) was found to be specifically suppressed by endostatin. Unexpectedly, cbfa1/osf2 was found to be specifically expressed in granulocytes in the tumor, not only in the experimental RC-9 tumor model, but in sections of human breast cancer as well. Since an effect of antiangiogenic therapy on granulocytes has been reported before, this might lead to new insights in the role of granulocytes in antiangiogenic therapy in general. In conclusion, the SSH-PCR implemented with the MOS-technique is a powerful tool to identify differentially expressed genes. Using these techniques, we have identified several target genes of endostatin, of which cbfa1/osf2 was found to be specifically expressed in granulocytes in the tumor.
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MESH Headings
- Angiogenesis Inhibitors/therapeutic use
- Animals
- Antineoplastic Agents/therapeutic use
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Renal Cell/drug therapy
- Carcinoma, Renal Cell/genetics
- Carcinoma, Renal Cell/metabolism
- Cell Line, Tumor
- Core Binding Factor Alpha 1 Subunit
- Core Binding Factors
- Endostatins/therapeutic use
- Gene Expression Regulation, Neoplastic/drug effects
- Granulocytes/drug effects
- Granulocytes/metabolism
- Humans
- Kidney Neoplasms/drug therapy
- Kidney Neoplasms/genetics
- Kidney Neoplasms/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Mice, Nude
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Neoplasm Transplantation
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/pathology
- Neovascularization, Pathologic/prevention & control
- Transcription Factors/genetics
- Transcription Factors/metabolism
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Affiliation(s)
- Jens van Wijngaarden
- Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
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Kim WY, Horbinski C, Sigurdson W, Higgins D. Proteasome inhibitors suppress formation of polyglutamine-induced nuclear inclusions in cultured postmitotic neurons. J Neurochem 2004; 91:1044-56. [PMID: 15569248 DOI: 10.1111/j.1471-4159.2004.02788.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
At least nine neurodegenerative disorders are caused by expansion of polyglutamine repeats in various genes. This expansion induces the formation of nuclear inclusions (NI) within various cell types. In this study, we developed a model for polyglutamine diseases using primary cultures of sympathetic neurons from the superior cervical ganglia of prenatal rat pups. Transfection with a plasmid encoding 127 glutamine repeats causes NI to develop in approximately 70% of the sympathetic neurons within 6 days. In addition, it causes somatic atrophy and inhibits dendritic growth. The NIs contain ubiquitinated proteins and sequester the molecular chaperone heat shock protein 70 (Hsp70). We found that two specific proteasome inhibitors, lactacystin and CEP1612, suppress thezformation of polyglutamine-induced NI. In addition, lactacystin treatment induced the removal of preexisting NI. Western blotting and immunocytochemistry revealed that lactacystin and CEP1612 strongly induce the expression of Hsp70, whereas less specific proteasome inhibitor such as N-acetyl-Leu-Leu-Norleucinal does not. Coexpression of 127 glutamines with a plasmid encoding wild-type Hsp70 gene resulted in a marked reduction of the percentage of neurons containing NI. In addition, transfection with plasmids encoding mutant Hsp70 blocked the effects of lactacystin. These findings further implicate Hsp70 as a neuroprotective molecule and they suggest the potential utility of certain proteasome inhibitors in the treatment of polyglutamine diseases.
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Affiliation(s)
- Woo-Yang Kim
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA
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Fleeton MN, Contractor N, Leon F, Wetzel JD, Dermody TS, Kelsall BL. Peyer's patch dendritic cells process viral antigen from apoptotic epithelial cells in the intestine of reovirus-infected mice. ACTA ACUST UNITED AC 2004; 200:235-45. [PMID: 15263030 PMCID: PMC2212021 DOI: 10.1084/jem.20041132] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We explored the role of Peyer's patch (PP) dendritic cell (DC) populations in the induction of immune responses to reovirus strain type 1 Lang (T1L). Immunofluorescence staining revealed the presence of T1L structural (σ1) and nonstructural (σNS) proteins in PPs of T1L-infected mice. Cells in the follicle-associated epithelium contained both σ1 and σNS, indicating productive viral replication. In contrast, σ1, but not σNS, was detected in the subepithelial dome (SED) in association with CD11c+/CD8α−/CD11blo DCs, suggesting antigen uptake by these DCs in the absence of infection. Consistent with this possibility, PP DCs purified from infected mice contained σ1, but not σNS, and PP DCs from uninfected mice could not be productively infected in vitro. Furthermore, σ1 protein in the SED was associated with fragmented DNA by terminal deoxy-UTP nick-end labeling staining, activated caspase-3, and the epithelial cell protein cytokeratin, suggesting that DCs capture T1L antigen from infected apoptotic epithelial cells. Finally, PP DCs from infected mice activated T1L-primed CD4+ T cells in vitro. These studies show that CD8α−/CD11blo DCs in the PP SED process T1L antigen from infected apoptotic epithelial cells for presentation to CD4+ T cells, and therefore demonstrate the cross-presentation of virally infected cells by DCs in vivo during a natural viral infection.
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Affiliation(s)
- Marina N Fleeton
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 10, Room 11N228, Bethesda, MD 20892, USA
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Enjolras N, Plantier JL, Rodriguez MH, Rea M, Attali O, Vinciguerra C, Negrier C. Two novel mutations in EGF-like domains of human factor IX dramatically impair intracellular processing and secretion. J Thromb Haemost 2004; 2:1143-54. [PMID: 15219198 DOI: 10.1111/j.1538-7836.2004.00756.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigated the mechanisms responsible for severe factor IX (FIX) deficiency in two cross-reacting material (CRM)-negative hemophilia B patients with a mutation in the first and second epidermal growth factor (EGF) domains of FIX (C71Y and C109Y, respectively). We have determined the kinetics of mutant FIX biosynthesis and secretion in comparison with wild-type FIX (FIXwt). In transfected cells, FIXwt was retrieved as two intracellular molecular forms, rapidly secreted into the culture medium. One appeared to be correctly N-glycosylated, and corresponded to a form trafficking between the endoplasmic reticulum (ER) and Golgi apparatus. The other corresponded to the mature form, ready to be secreted, exhibiting correct N-glycosylation and sialylation. In contrast, the two mutants, FIXC71Y and FIXC109Y, were not secreted from the cells and did not accumulate intracellularly. Relative to FIXwt, they were retained longer in the ER and were only N-glycosylated. In addition, the intracellular concentration of the FIX mutants increased when ALLN, an inhibitor of cysteine proteases and of the proteasome degradation pathway, was added to the culture medium. Both the FIX mutants and FIXwt were associated in the ER with the 78-kDa glucose-regulated protein (GRP78/BiP) and calreticulin (CRT), though the amount of CRT associated with the two mutants was twice as strong as with FIXwt. These results strongly suggest that chaperone and lectin molecules act in concert to ensure both proper folding of FIXwt and the retention of mutant molecules.
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Affiliation(s)
- N Enjolras
- Laboratoire d'Hémobiologie EA 1508, Faculté de Médecine RTH Laennec, Lyon, France.
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Shih WL, Hsu HW, Liao MH, Lee LH, Liu HJ. Avian reovirus sigmaC protein induces apoptosis in cultured cells. Virology 2004; 321:65-74. [PMID: 15033566 DOI: 10.1016/j.virol.2003.12.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2003] [Revised: 12/03/2003] [Accepted: 12/03/2003] [Indexed: 10/26/2022]
Abstract
The avian reovirus (ARV) infection is associated with various disease conditions in poultry. However, the pathogenesis mechanisms are poorly characterized. In the present study, we clearly demonstrated that the sigmaC of ARV S1133 strain induced apoptosis in both BHK-21 and Vero cells. Five kinds of assays for apoptosis were used in analyzing ARV-infected BHK-21 and Vero cells: (1) assay for DNA ladders, (2) ELISA detection of cytoplasmic histone-associated DNA fragments, (3) nuclear staining with acridine orange, (4) Western blot, Northern blot, and immunofluorescent assay (IFA), and (5) flow cytometric analysis. The sigmaC protein of ARV could elicit apoptosis occurring in a dose- and time-dependent manner. The current results further our understanding of the function of sigmaC in cultured cells and suggest that sigmaC is a viral-encoded apoptin and possesses apoptosis-inducing ability. Furthermore, deletion analysis of the ARV sigmaC protein suggests that the carboxyl-terminus of sigmaC is important in mediating sigmaC-induced apoptosis because its deletion abolished the induction of apoptosis.
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Affiliation(s)
- Wen L Shih
- Department of Life Science, Tzu-Chi University, Hualien, Taiwan
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Affiliation(s)
- J Craig Forrest
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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