scholarly journals Human Cytomegalovirus-Encoded Immune Modulators Partner To Downregulate Major Histocompatibility Complex Class I Molecules

2008 ◽  
Vol 83 (3) ◽  
pp. 1359-1367 ◽  
Author(s):  
Vanessa M. Noriega ◽  
Domenico Tortorella
Keyword(s):  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
Immune Recognition ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Presentation Pathway ◽  
In Cells

ABSTRACT Throughout the course of natural evolution with its host, the human cytomegalovirus (HCMV) has developed a variety of strategies to avoid immune recognition and clearance. The major histocompatibility complex (MHC) class I antigen presentation pathway is a major target of the virus. HCMV encodes at least six gene products that modulate the processing of endoplasmic reticulum (ER)-resident MHC class I molecules. Here, we show that two virus-encoded proteins, US2 and US3, coordinate their functions toward the common goal of attenuating class I protein surface expression. In cells stably expressing both US2 and US3, class I molecules were almost completely downregulated from the cell surface. In addition, pulse-chase analysis revealed that the proteasome-dependent turnover of class I molecules occurs more rapidly in cells expressing both US2 and US3 than either US2 or US3 alone. The ability of US3 to retain class I molecules in the ER produces a target-rich environment for US2 to mediate the destruction of class I heavy chains. In fact, expression of US3 enhanced the association between US2 and class I molecules, thus encouraging their dislocation and degradation. This immune evasion strategy ensures that viral antigens are not presented on the cell surface during the early phase of HCMV infection, a critical time of replication and viral proliferation.

scholarly journals Human Cytomegalovirus Protein pp71 Disrupts Major Histocompatibility Complex Class I Cell Surface Expression

2006 ◽  
Vol 80 (2) ◽  
pp. 951-963 ◽  
Author(s):  
Joanne Trgovcich ◽  
Colleen Cebulla ◽  
Pete Zimmerman ◽  
Daniel D. Sedmak
Keyword(s):  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
Cell Surface Expression ◽  
Dependent Manner ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Presentation Pathway

ABSTRACT The human cytomegalovirus tegument protein pp71 is the product of the UL82 gene. Roles for pp71 in stimulating gene transcription, increasing infectivity of viral DNA, and the degradation of retinoblastoma family proteins have been described. Here we report a novel function for pp71 in limiting accumulation of cell surface major histocompatibility complex (MHC) class I complexes. MHC molecules were analyzed in glioblastoma cells exposed to a replication-defective adenovirus expressing UL82 (Adpp71) or after transient transfection of the UL82 gene. Accumulation of cell surface MHC class I levels diminished in a specific and dose-dependent manner after exposure to Adpp71 but not after exposure to an adenovirus expressing β-galactosidase (Adβgal). UL82 expression did not interfere with accumulation of either MHC class I heavy-chain transcript or protein, nor did UL82 expression correlate with markers of apoptosis. Rather, UL82 expression correlated with an increased proportion of MHC class I molecules exhibiting sensitivity to endoglycosidase H treatment. Finally, we show that, in cells infected with recombinant virus strain missing all of the unique short region MHC class I evasion genes, disruption of UL82 expression by short, interfering RNAs led to increased accumulation of cell surface MHC class I complexes. These findings support a novel role for HCMV pp71 in disruption of the MHC class I antigen presentation pathway.

scholarly journals Human Cytomegalovirus US2 Causes Similar Effects on Both Major Histocompatibility Complex Class I and II Proteins in Epithelial and Glial Cells

2003 ◽  
Vol 77 (17) ◽  
pp. 9287-9294 ◽  
Author(s):  
Nagendra R. Hegde ◽  
David C. Johnson
Keyword(s):  
Major Histocompatibility Complex ◽  
Human Cytomegalovirus ◽  
Adenovirus Vector ◽  
Class Ii ◽  
Class I ◽  
Major Histocompatibility ◽  
Biologically Relevant ◽  
Histocompatibility Complex ◽  
In Cells

ABSTRACT The human cytomegalovirus (HCMV) glycoprotein US2 specifically binds to major histocompatibility complex (MHC) class I heavy chain (HC) and class II proteins DRα and DMα, triggering their degradation by proteasomes. Effects of US2 on class II proteins were originally characterized in HCMV- or adenovirus vector-infected U373 astroglioma cells. Here, we have extended characterization of US2-mediated degradation of class II DRα to two other cell lines, including biologically relevant epithelial cells. Comparison of the effects of US2 in cells expressing both class I and II proteins demonstrated only a slight preference for class I HC. Moreover, US2 caused degradation of DRα and DMα when these proteins were expressed by transfection without DRβ, invariant chain (Ii), or DMβ. Therefore, US2 binds to α chains of DR and DM and triggers endoplasmic reticulum degradation without formation of class II DR αβ/Ii or DM αβ complexes. Similar levels of degradation of class II α were observed in cells expressing vastly different amounts of class II, suggesting that cellular factors, other than class II, were limiting. We concluded that US2 has broad effects in a variety of cells that express both class I and II proteins and is relevant to HCMV infection in vivo.

scholarly journals E3/19K from adenovirus 2 is an immunosubversive protein that binds to a structural motif regulating the intracellular transport of major histocompatibility complex class I proteins.

1990 ◽  
Vol 172 (6) ◽  
pp. 1653-1664 ◽  
Author(s):  
W A Jefferies ◽  
H G Burgert
Keyword(s):  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Mhc Class I ◽  
Intracellular Transport ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Mhc Class I Molecules

We have previously expressed in transgenic mice a chimeric H-2Kd/Kk protein called C31, which contains the extracellular alpha 1 domain of Kd, whereas the rest of the molecule is of Kk origin. This molecule functions as a restriction element for alloreactive and influenza A-specific cytotoxic T lymphocytes (CTL) but is only weakly expressed at the cell surface of splenocytes. Here, we show that the low cell surface expression is the result of slow intracellular transport and processing of the C31 protein. A set of hybrid molecules between Kd and Kk were used to localize the regions in major histocompatibility complex (MHC) molecules that are important for their intracellular transport and to further localize the structures responsible for binding to the adenovirus 2 E3/19K protein. This protein appears to be an important mediator of adenovirus persistence. It acts by binding to the immaturely glycosylated forms of MHC class I proteins in the endoplasmic reticulum (ER), preventing their passage to the cell surface and thereby reducing the recognition of infected cells by virus-specific T cells. We find the surprising result that intracellular transport and E3/19K binding are controlled primarily by the first half of the second domain of Kd, thus localizing these phenomena to the five polymorphic residues in this region of the Kd protein. This result implies that the E3/19K protein may act by inhibiting peptide binding or by disrupting the oligomerization of MHC class I molecules required for transport out of the ER. Alternatively, the E3/19K protein may inhibit the function of a positively acting transport molecule necessary for cell surface expression of MHC class I molecules.

scholarly journals Trophoblast Class I Major Histocompatibility Complex (MHC) Products Are Resistant to Rapid Degradation Imposed by the Human Cytomegalovirus (HCMV) Gene Products US2 and US11

1998 ◽  
Vol 188 (3) ◽  
pp. 497-503 ◽  
Author(s):  
Danny J. Schust ◽  
Domenico Tortorella ◽  
Jörg Seebach ◽  
Cindy Phan ◽  
Hidde L. Ploegh
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
Gene Products ◽  
Major Histocompatibility ◽  
Human Trophoblast ◽  
Heavy Chains ◽  
Histocompatibility Complex ◽  
Encode Gene

US11 and US2 encode gene products expressed early in the replicative cycle of human cytomegalovirus (HCMV), which cause dislocation of human and murine major histocompatibility complex (MHC) class I molecules from the lumen of the endoplasmic reticulum to the cytosol, where the class I heavy chains are rapidly degraded. Human histocompatibility leukocyte antigens (HLA)-C and HLA-G are uniquely resistant to the effects of both US11 and US2 in a human trophoblast cell line as well as in porcine endothelial cells stably transfected with human class I genes. Dislocation and degradation of MHC class I heavy chains do not appear to involve cell type–specific factors, as US11 and US2 are fully active in this xenogeneic model. Importantly, trophoblasts HLA-G and HLA-C possess unique characteristics that allow their escape from HCMV-associated MHC class I degradation. Trophoblast class I molecules could serve not only to block recognition by natural killer cells, but also to guide virus-specific HLA-C– and possibly HLA-G–restricted cytotoxic T-lymphocytes to their targets.

scholarly journals Genetic Variability of the Major Histocompatibility Complex Class I Homologue Encoded by Human Cytomegalovirus Leads to Differential Binding to the Inhibitory Receptor ILT2

2005 ◽  
Vol 79 (4) ◽  
pp. 2251-2260 ◽  
Author(s):  
Mar Valés-Gómez ◽  
Mitsunori Shiroishi ◽  
Katsumi Maenaka ◽  
Hugh T. Reyburn
Keyword(s):  
Major Histocompatibility Complex ◽  
Nk Cells ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
Inhibitory Receptor ◽  
Major Histocompatibility ◽  
Mhc Molecules ◽  
Histocompatibility Complex ◽  
Virus Isolates

ABSTRACT Human cytomegalovirus carries a gene, UL18, that is homologous to cellular major histocompatibility complex (MHC) class I genes. Like MHC class I molecules, the protein product of the UL18 gene associates with β2-microglobulin, and the stability of this complex depends on peptide loading. UL18 protein binds to ILT2 (CD85j), an inhibitory receptor present on B cells, monocytes, dendritic cells, T cells, and NK cells that also recognizes classical and nonclassical MHC molecules. These observations suggest that UL18 may play a role in viral immune evasion, but its real function is unclear. Since this molecule has similarity with polymorphic MHC proteins, we explored whether the UL18 gene varied between virus isolates. We report here that the UL18 gene varies significantly between virus isolates: amino acid substitutions were found in the predicted α1, α2, and α3 domains of the UL18 protein molecule. We also studied the ability of several variant UL18 proteins to bind to the ILT2 receptor. All of the variants tested bound to ILT2, but there were marked differences in the affinity of binding to this receptor. These differences were reflected in functional assays measuring inhibition of the cytotoxic capacity of NK cells via interaction with ILT2. In addition, the variants did not bind other members of the CD85 family. The implications of these data are discussed.

scholarly journals Calnexin retains unassembled major histocompatibility complex class I free heavy chains in the endoplasmic reticulum.

1994 ◽  
Vol 180 (1) ◽  
pp. 407-412 ◽  
Author(s):  
S Rajagopalan ◽  
M B Brenner
Keyword(s):  
Endoplasmic Reticulum ◽  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Mhc Class I ◽  
Cytoplasmic Tail ◽  
Class I ◽  
Major Histocompatibility ◽  
Stable Transfectants ◽  
Histocompatibility Complex ◽  
Er Retention

The assembly of major histocompatibility complex (MHC) class I molecules involves the association of heavy (H) chain with beta 2-microglobulin (beta 2m) and peptide. Unassembled class I H chains do not exit the endoplasmic reticulum (ER) and this is exemplified by the beta 2m-deficient human melanoma FO-1 where free class I H chains are unable to complete assembly. In pulse chase experiments involving FO-1 cells, unassembled free class I H chains were shown to be stably associated with calnexin (IP90/p88), a 90-kD integral membrane molecular chaperone of the ER. To establish a role for calnexin in mediating this retention, we transfected FO-1 cells with a cytoplasmic tail deletion mutant of calnexin. Since the cytoplasmic tail contains the ER retention motif, these mutant calnexin molecules leave the ER and progress to the cell surface. In these stable transfectants of FO-1, free class I H chains also exited the ER and trafficked to the cell surface with calnexin, thus establishing a role for calnexin in the quality control of MHC class I assembly through mediating the ER retention of incompletely assembled class I H chains.

scholarly journals Human Cytomegalovirus US2 Endoplasmic Reticulum-Lumenal Domain Dictates Association with Major Histocompatibility Complex Class I in a Locus-Specific Manner

2001 ◽  
Vol 75 (11) ◽  
pp. 5197-5204 ◽  
Author(s):  
Benjamin E. Gewurz ◽  
Evelyn W. Wang ◽  
Domenico Tortorella ◽  
Danny J. Schust ◽  
Hidde L. Ploegh
Keyword(s):  
Endoplasmic Reticulum ◽  
Major Histocompatibility Complex ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Peptide Sequence ◽  
Class I ◽  
Major Histocompatibility ◽  
Independent Manner ◽  
Histocompatibility Complex ◽  
Lumenal Domain

ABSTRACT The human cytomegalovirus-encoded US2 glycoprotein targets endoplasmic reticulum-resident major histocompatibility complex (MHC) class I heavy chains for rapid degradation by the proteasome. We demonstrate that the endoplasmic reticulum-lumenal domain of US2 allows tight interaction with class I molecules encoded by the HLA-A locus. Recombinant soluble US2 binds properly folded, peptide-containing recombinant HLA-A2 molecules in a peptide sequence-independent manner, consistent with US2's ability to broadly downregulate class I molecules. The physicochemical properties of the US2/MHC class I complex suggest a 1:1 stoichiometry. These results demonstrate that US2 does not require additional cellular proteins to specifically interact with soluble class I molecules. Binding of US2 does not significantly alter the conformation of class I molecules, as a soluble T-cell receptor can simultaneously recognize class I molecules associated with US2. The lumenal domain of US2 can differentiate between the products of distinct class I loci, as US2 binds several HLA-A locus products while being unable to bind recombinant HLA-B7, HLA-B27, HLA-Cw4, or HLA-E. We did not observe interaction between soluble US2 and either recombinant HLA-DR1 or recombinant HLA-DM. The substrate specificity of US2 may help explain the presence in human cytomegalovirus of multiple strategies for downregulation of MHC class I molecules.

scholarly journals Delivery of CD8+ T-Cell Epitopes into Major Histocompatibility Complex Class I Antigen Presentation Pathway by Bordetella pertussis Adenylate Cyclase: Delineation of Cell Invasive Structures and Permissive Insertion Sites

2000 ◽  
Vol 68 (1) ◽  
pp. 247-256 ◽  
Author(s):  
Radim Osička ◽  
Adriana Osičková ◽  
Tümay Basar ◽  
Pierre Guermonprez ◽  
Marie Rojas ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
T Cell ◽  
Adenylate Cyclase ◽  
Mhc Class I ◽  
Bordetella Pertussis ◽  
Class I ◽  
T Cell Epitopes ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Presentation Pathway

ABSTRACT Bordetella pertussis adenylate cyclase (AC) toxin-hemolysin (ACT-Hly) can penetrate a variety of eukaryotic cells. Recombinant AC toxoids have therefore been recently used for delivery of CD8+ T-cell epitopes into antigen-presenting cells in vivo and for induction of protective antiviral, as well as therapeutic antitumor cytotoxic T-cell responses. We have explored the carrier potential of the ACT molecule by insertional mutagenesis scanning for new permissive sites, at which integration of two- to nine-residue-long peptides does not interfere with membrane interaction and translocation of ACT. A model CD8+ T-cell epitope of ovalbumin was incorporated at 10 of these permissive sites along the toxin molecule, and the capacity of ACT constructs to penetrate into cell cytosol and deliver the epitope into the major histocompatibility complex (MHC) class I antigen processing and presentation pathway was examined. While all six constructs bearing the epitope within the Hly portion of ACT failed to deliver the epitope to the MHC class I molecules, all four toxoids with inserts within different permissive sites in the AC domain efficiently delivered the epitope into this cytosolic pathway, giving rise to stimulation of a specific CD8+ T-cell hybridoma. The results suggest that, in contrast to the AC domain, the hemolysin moiety of ACT does not reach the cytosolic entry of the MHC class I pathway.

scholarly journals The Human Cytomegalovirus US8 Glycoprotein Binds to Major Histocompatibility Complex Class I Products

2002 ◽  
Vol 76 (13) ◽  
pp. 6832-6835 ◽  
Author(s):  
Rebecca S. Tirabassi ◽  
Hidde L. Ploegh
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
Type I ◽  
Major Histocompatibility ◽  
Surface Distribution ◽  
Heavy Chains ◽  
Histocompatibility Complex ◽  
Lysosomal Proteins

ABSTRACT Human cytomegalovirus US8 is a type I membrane protein that partially colocalizes with cellular endosomal and lysosomal proteins. Although US8 does not have discernible effects on the processing and cell surface distribution of major histocompatibility complex (MHC) class I products, we have demonstrated that US8 binds to MHC class I heavy chains in the endoplasmic reticulum.

scholarly journals Structural and Functional Dissection of Human Cytomegalovirus US3 in Binding Major Histocompatibility Complex Class I Molecules

2000 ◽  
Vol 74 (23) ◽  
pp. 11262-11269 ◽  
Author(s):  
Sungwook Lee ◽  
Juhan Yoon ◽  
Boyoun Park ◽  
Youngsoo Jun ◽  
Mirim Jin ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
In Vitro Translation ◽  
Cell Surface Expression ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Er Retention ◽  
Mhc Class I Molecules

ABSTRACT The human cytomegalovirus US3, an endoplasmic reticulum (ER)-resident transmembrane glycoprotein, forms a complex with major histocompatibility complex (MHC) class I molecules and retains them in the ER, thereby preventing cytolysis by cytotoxic T lymphocytes. To identify which parts of US3 confine the protein to the ER and which parts are responsible for the association with MHC class I molecules, we constructed truncated mutant and chimeric forms in which US3 domains were exchanged with corresponding domains of CD4 and analyzed them for their intracellular localization and the ability to associate with MHC class I molecules. All of the truncated mutant and chimeric proteins containing the luminal domain of US3 were retained in the ER, while replacement of the US3 luminal domain with that of CD4 led to cell surface expression of the chimera. Thus, the luminal domain of US3 was sufficient for ER retention. Immunolocalization of the US3 glycoprotein after nocodazole treatment and the observation that the carbohydrate moiety of the US3 glycoprotein was not modified by Golgi enzymes indicated that the ER localization of US3 involved true retention, without recycling through the Golgi. Unlike the ER retention signal, the ability to associate with MHC class I molecules required the transmembrane domain in addition to the luminal domain of US3. Direct interaction between US3 and MHC class I molecules could be demonstrated after in vitro translation by coimmunoprecipitation. Together, the present data indicate that the properties that allow US3 to be localized in the ER and bind MHC class I molecules are located in different parts of the molecule.

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