Mitochondrial Cell Death Suppressors Carried by Human and Murine Cytomegalovirus Confer Resistance to Proteasome Inhibitor-Induced Apoptosis

McCormick, A. Louise; Meiering, Christopher D.; Smith, Geoffrey B.; Mocarski, Edward S.

doi:10.1128/jvi.79.19.12205-12217.2005

Cited by 71 publications

(154 citation statements)

References 62 publications

(104 reference statements)

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“…vMIA protects CMV-infected cells from apoptosis in the late phase of the viral life cycle (Reboredo et al, 2004), and vMIA-deficient/vICA-deficient CMV cannot replicate (because it kills the infected cells prematurely) unless it infects cells that overexpress a Bcl-2-like apoptosis inhibitor (Reboredo et al, 2004). A laboratory strain of vICA-expressing/vMIA-deficient CMV can replicate on human cells (McCormick et al, 2005), but a freshly isolated clinical strain of CMV encoding functionally active vICA loses its replication ability upon knocking out vMIA expression, suggesting that at least in some clinical CMV strains, vMIA is indispensable for viral replication (Jurak and Brune, 2006). The vMIA protein is largely confined to the mitochondrial compartment, where it physically interacts with the protein Bax, recruiting it to mitochondria while neutralizing its proapoptotic function (Arnoult et al, 2004;Poncet et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Structure–function analysis of the interaction between Bax and the cytomegalovirus-encoded protein vMIA

et al. 2007

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The viral mitochondrial inhibitor of apoptosis (vMIA) encoded by the human cytomegalovirus exerts cytopathic effects and neutralizes the proapoptotic endogenous Bcl-2 family member Bax by recruiting it to mitochondria, inducing its oligomerization and membrane insertion. Using a combination of computational modeling and mutational analyses, we addressed the structure-function relationship of the molecular interaction between the protein Bax and the viral antiapoptotic protein vMIA. We propose a model in which vMIA exhibits an overall fold similar to Bcl-X L . In contrast to Bcl-X L , however, this predicted conformation of vMIA does not bind to the BH3 domain of Bax and rather engages in electrostatic interactions that involve a stretch of amino acids between the BH3 and BH2 domains of Bax and an a-helical domain located within the previously defined Bax-binding domain of vMIA, between the putative BH1-like and BH2-like domains. According to this model, vMIA is likely to bind Bax preferentially in its membraneinserted conformation. The capacity of vMIA to cause fragmentation of the mitochondrial network and disorganization of the actin cytoskeleton is independent of its Baxbinding function. We found that D131-147 vMIA mutant, which lacks both the Bax-binding function and cell-death suppression but has intact mitochondria-targeting capacity, is similar to vMIA in its ability to disrupt the mitochondrial network and to disorganize the actin cytoskeleton. vMIAD131-147 is a dominant-negative inhibitor of the antiapoptotic function of wild-type vMIA. Our experiments with vMIAD131-147 suggest that vMIA forms homooligomers, which may engage in cooperative and/or multivalent interactions with Bax, leading to its functional neutralization.

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Section: Introductionmentioning

confidence: 99%

Structure–function analysis of the interaction between Bax and the cytomegalovirus-encoded protein vMIA

et al. 2007

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“…The HCMV UL36 -38 locus encodes five proteins with antiapoptotic activities, including the predominant UL37 exon 1 protein (pUL37ϫ1), also known as viral mitochondria localized inhibitor of apoptosis (vMIA), the lower abundance UL37 Medium protein and the UL37 glycoprotein, the UL36 protein and the early UL38 protein (9 -12). pUL37ϫ1 blocks mitochondrial-mediated apoptosis by translocating proapoptotic Bax to the outer mitochondrial membrane (OMM) and suppressing its proapoptotic activity (13)(14)(15). In addition, pUL37ϫ1/vMIA has been reported to alter mitochondrial ATP synthesis by decreasing the activity of the mitochondrial phosphate carrier in transfected cells (16).…”

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confidence: 99%

Quantitative Proteomic Analyses of Human Cytomegalovirus-Induced Restructuring of Endoplasmic Reticulum-Mitochondrial Contacts at Late Times of Infection

Zhang

Williamson

Wong

et al. 2011

Molecular & Cellular Proteomics

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Endoplasmic reticulum-mitochondrial contacts, known as mitochondria-associated membranes, regulate important cellular functions including calcium signaling, bioenergetics, and apoptosis. Human cytomegalovirus is a medically important herpesvirus whose growth increases energy demand and depends upon continued cell survival. To gain insight into how human cytomegalovirus infection affects endoplasmic reticulum-mitochondrial contacts, we undertook quantitative proteomics of mitochondriaassociated membranes using differential stable isotope labeling by amino acids in cell culture strategy and liquid chromatography-tandem MS analysis. This is the first reported quantitative proteomic analyses of a suborganelle during permissive human cytomegalovirus infection. Human fibroblasts were uninfected or human cytomegalovirus-infected for 72 h. Heavy mitochondria-associated membranes were isolated from paired unlabeled, uninfected cells and stable isotope labeling by amino acids in cell culture-labeled, infected cells and analyzed by liquid chromatography-tandem MS analysis. The results were verified by a reverse labeling experiment. Human cytomegalovirus infection dramatically altered endoplasmic reticulum-mitochondrial contacts by late times. Notable is the increased abundance of several fundamental networks in the mitochondria-associated membrane fraction of human cytomegalovirus-infected fibroblasts. Chaperones, including HSP60 and BiP, which is required for human cytomegalovirus assembly, were prominently increased at endoplasmic reticulum-mitochondrial contacts after infection. Minimal translational and translocation machineries were also associated with endoplasmic reticulum-mitochondrial contacts and increased after human cytomegalovirus infection as were glucose regulated protein 75 and the voltage dependent anion channel, which can form an endoplasmic reticulum-mitochondrial calcium signaling complex. Surprisingly, mitochondrial metabolic enzymes and cytosolic glycolytic enzymes were confidently detected in the mitochondria-associated membrane fraction and increased therein after infection. Finally, proapoptotic regulatory proteins, including Bax, cytochrome c, and Opa1, were augmented in endoplasmic reticulum-mitochondrial contacts after infection, suggesting attenuation of proapoptotic signaling by their increased presence therein. Together, these results suggest that human cytomegalovirus infection restructures

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“…Details of plasmids generated by PCR are reported in Supplementary Table S1 available in JGV Online. LGFP GFPnoSTOP was created by replacing the green fluorescent protein (GFP) ORF in LGFP (McCormick et al, 2005) with a GFP ORF lacking the termination codon TAA. LNCX-mRFP was produced by inserting the monomeric red fluorescent protein (mRFP) ORF amplified by PCR from the pRSET B-mRFP vector (a kind gift from G. Dekaban, Robarts Research Institute, London, ON, Canada) into the BamHI and SalI restriction sites (rs) of LNCX (Miller & Rosman, 1989).…”

Section: Methodsmentioning

confidence: 99%

Human cytomegalovirus US9 protein contains an N-terminal signal sequence and a C-terminal mitochondrial localization domain, and does not alter cellular sensitivity to apoptosis

Mandic

Miller

Coulter

et al. 2009

Journal of General Virology

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The human cytomegalovirus (CMV) US2-US11 genomic region contains a cluster of genes whose products interfere with antigen presentation by the major histocompatibility complex (MHC) proteins. Although included in this cluster, the US9 gene encodes a glycoprotein that does not affect MHC activity and whose function is still largely uncharacterized. An in silico analysis of the US9 amino-acid sequence uncovered the presence of an N-terminal signal sequence (SS) and a C-terminal transmembrane domain containing the specific hallmarks of known mitochondrial localization sequences (MLS). Expression of full-length US9 and of US9 deletion mutants fused to GFP revealed that the N-terminal SS mediates US9 targeting to the endoplasmic reticulum (ER) and that the C-terminal MLS is both necessary and sufficient to direct US9 to mitochondria in the absence of a functional SS. This dual localization suggested a possible role for US9 in protection from apoptosis triggered by ER-to-mitochondria signalling. Fibroblasts infected with the US2-US11 deletion mutant virus RV798 or with the parental strain AD169varATCC were equally susceptible to death triggered by exposure to tumour necrosis factor (TNF)-a, tunicamycin, thapsigargin, brefeldin A, lonidamine and carbonyl cyanide m-chloro phenyl hydrazone, but were 1.6-fold more sensitive to apoptosis induced by hygromycin B. Expression of US9 in human embryonic kidney 293T cells or in fibroblasts, however, did not protect cells from hygromycin B-mediated death. Together, these results classify US9 as the first CMV-encoded protein to contain an N-terminal SS and a C-terminal MLS, and suggest a completely novel role for this protein during infection. INTRODUCTIONHuman cytomegalovirus (CMV) is a very prevalent betaherpesvirus that poses serious medical concerns in immunocompromised individuals . The ability to evade or modulate host immune responses, coupled with the capacity to establish latency after primary infection, is at the basis of the tremendous success of CMV as a human pathogen.The US2-US11 genomic region has been shown to be dispensable for viral replication in primary human fibroblasts (HF) (Jones & Muzithras, 1992;Kollert-Jons et al., 1991), and to encode five endoplasmic reticulum (ER)-resident glycoproteins, US2, US3, US6, US10 and US11, that disrupt antigen presentation by the major histocompatibility complex (MHC) class I and class II proteins (Lin et al., 2007). Despite sharing some very limited homology with US6, US10 and US11, US9 does not bind to or reduce MHC cell surface levels (Hegde et al., 2002(Hegde et al., , 2006Pereira et al., 1995). US9 was originally described as a member of the US6 family of proteins, which includes the products of the US6-US11 genes. These proteins contain markedly hydrophobic sequences at both the N-and C-termini, and were predicted to insert into cellular membranes (Weston & Barrell, 1986). US9 intracellular localization was initially examined in nonpolarized Madin-Darby canine kidney cells constitutively expressing a C-terminal-tagged ...

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Mitochondrial Cell Death Suppressors Carried by Human and Murine Cytomegalovirus Confer Resistance to Proteasome Inhibitor-Induced Apoptosis

Cited by 71 publications

References 62 publications

Structure–function analysis of the interaction between Bax and the cytomegalovirus-encoded protein vMIA

Structure–function analysis of the interaction between Bax and the cytomegalovirus-encoded protein vMIA

Quantitative Proteomic Analyses of Human Cytomegalovirus-Induced Restructuring of Endoplasmic Reticulum-Mitochondrial Contacts at Late Times of Infection

Human cytomegalovirus US9 protein contains an N-terminal signal sequence and a C-terminal mitochondrial localization domain, and does not alter cellular sensitivity to apoptosis

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