scholarly journals Dengue Virus Replicon Expressing the Nonstructural Proteins Suffices To Enhance Membrane Expression of HLA Class I and Inhibit Lysis by Human NK Cells

2008 ◽  
Vol 82 (15) ◽  
pp. 7666-7676 ◽  
Author(s):  
Oren Hershkovitz ◽  
Alon Zilka ◽  
Ahuva Bar-Ilan ◽  
Shai Abutbul ◽  
Andrew Davidson ◽  
...  
Keyword(s):  
Cell Surface ◽  
Dengue Virus ◽  
Nk Cells ◽  
Mhc Class I ◽  
Class I ◽  
Cell Surface Expression ◽  
Lower Sensitivity ◽  
Inhibitory Receptors ◽  
Nonstructural Proteins ◽  
Mhc Class I Molecules

ABSTRACT Many viruses escape the cellular immune response by downregulating cell surface expression of major histocompatibility complex (MHC) class I molecules. However, infection of cells with flaviviruses can upregulate the expression of these molecules. In this study we analyzed the expression of MHC class I in K562 and THP-1 human cell lines that were stably transfected with self-replicating subgenomic dengue virus RNA (replicons) and express all the dengue virus nonstructural proteins together. We show that MHC class I expression is upregulated in the dengue virus replicon-expressing cells and that the binding of natural killer (NK) inhibitory receptors to these cells is augmented. This upregulation results in reduced susceptibility of the dengue virus replicon-expressing cells to NK lysis, indicating a possible mechanism for evasion of the dengue virus from NK cell recognition. Visualizing MHC class I expression in replicon-containing K562 and THP-1 cells by confocal microscopy demonstrated aggregation of MHC class I molecules on the cell surface. Finally, replicon-expressing K562 cells manifested increased TAP (transporter associated with antigen processing) and LMP (low-molecular-mass protein) gene transcription, while replicon-expressing THP-1 cells manifested increased NF-κB activity and MHC class I transcription. We suggest that expression of dengue virus nonstructural proteins is sufficient to induce MHC class I upregulation through both TAP-dependent and -independent mechanisms. Additionally, aggregation of MHC class I molecules on the cell membrane also contributes to significantly higher binding of low-affinity NK inhibitory receptors, resulting in lower sensitivity to lysis by NK cells.

scholarly journals Modulation of Transporter Associated with Antigen Processing (TAP)-Mediated Peptide Import into the Endoplasmic Reticulum by Flavivirus Infection

2001 ◽  
Vol 75 (12) ◽  
pp. 5663-5671 ◽  
Author(s):  
Frank Momburg ◽  
Arno Müllbacher ◽  
Mario Lobigs
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Mhc Class I ◽  
Antigen Processing ◽  
Surface Expression ◽  
Class I ◽  
Peptide Transport ◽  
Cell Surface Expression ◽  
Flavivirus Infection ◽  
Mhc Class I Molecules

ABSTRACT In contrast to many other viruses that escape the cellular immune response by downregulating major histocompatibility complex (MHC) class I molecules, flavivirus infection can upregulate their cell surface expression. Previously we have presented evidence that during flavivirus infection, peptide supply to the endoplasmic reticulum is increased (A. Müllbacher and M. Lobigs, Immunity 3:207–214, 1995). Here we show that during the early phase of infection with different flaviviruses, the transport activity of the peptide transporter associated with antigen processing (TAP) is augmented by up to 50%. TAP expression is unaltered during infection, and viral but not host macromolecular synthesis is required for enhanced peptide transport. This study is the first demonstration of transient enhancement of TAP-dependent peptide import into the lumen of the endoplasmic reticulum as a consequence of a viral infection. We suggest that the increased supply of peptides for assembly with MHC class I molecules in flavivirus-infected cells accounts for the upregulation of MHC class I cell surface expression with the biological consequence of viral evasion of natural killer cell recognition.

scholarly journals Cell Surface Expression of Major Histocompatibility Complex Class I Molecules Is Reduced in Hepatitis C Virus Subgenomic Replicon-Expressing Cells

2003 ◽  
Vol 77 (21) ◽  
pp. 11644-11650 ◽  
Author(s):  
Keith D. Tardif ◽  
Aleem Siddiqui
Keyword(s):  
Major Histocompatibility Complex ◽  
Hepatitis C ◽  
Cell Surface ◽  
Mhc Class I ◽  
Surface Expression ◽  
Protein Glycosylation ◽  
Class I ◽  
Cell Surface Expression ◽  
Histocompatibility Complex ◽  
Mhc Class I Molecules

ABSTRACT The hepatitis C virus (HCV) causes chronic hepatitis in most infected individuals by evading host immune defenses. In this investigation, we show that HCV-infected cells may go undetected in the immune system by suppressing major histocompatibility complex (MHC) class I antigen presentation to cytotoxic T lymphocytes. Cells expressing HCV subgenomic replicons have lower MHC class I cell surface expression. This is due to reduced levels of properly folded MHC class I molecules. HCV replicons induce endoplasmic reticulum (ER) stress (K. Tardif, K. Mori, and A. Siddiqui, J. Virol. 76:7453-7459, 2002), which results from a decline in protein glycosylation. Decreasing protein glycosylation can disrupt protein folding, preventing the assembly of MHC class I molecules. This results in the accumulation of unfolded MHC class I. Therefore, the persistence and pathogenesis of HCV may depend upon the ER stress-mediated interference of MHC class I assembly and cell surface expression.

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.

HFE cross-talks with the MHC class I antigen presentation pathway

Blood ◽  
2005 ◽  
Vol 106 (3) ◽  
pp. 971-977 ◽  
Author(s):  
Sérgio F. de Almeida ◽  
Isabel F. Carvalho ◽  
Carla S. Cardoso ◽  
João V. Cordeiro ◽  
Jorge E. Azevedo ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class I ◽  
Mononuclear Cells ◽  
Hereditary Hemochromatosis ◽  
Class I ◽  
Cell Surface Expression ◽  
Peripheral Blood Mononuclear ◽  
Presentation Pathway ◽  
Peptide Loading ◽  
Mhc Class I Molecules

AbstractHFE is a protein known to be involved in iron metabolism; yet, other than its homology with major histocompatibility complex (MHC) class I molecules, it has not been described as having an immunologic function. Here we report that peripheral blood mononuclear cells (PBMCs) from patients with hereditary hemochromatosis (HH) carrying the C282Y mutation in HFE have reduced cell-surface expression of MHC class I due to an enhanced endocytosis rate of MHC class I molecules caused by premature peptide and β2-microglobulin dissociation. This faster turnover also leads to increased expression levels of cell-surface free class I heavy chains in mutant PBMCs. Biochemical analysis indicates an earlier peptide loading and endoplasmic reticulum maturation of MHC class I molecules in C282Y mutant cells. Thermostability assays further showed that in HFE mutants the MHC class I peptide loading gives rise to low-stability heterotrimers that dissociate prematurely during its intracellular traffic. The present results suggest the existence of an intriguing cross-talk between a particular HFE mutation and the classical MHC class I route. These findings constitute the first description of peptide presentation pathway abnormalities linked to HFE and provide additional evidence for the occurrence of immunologic defects in patients with HH.

scholarly journals The Switch from Latent to Productive Infection in Epstein-Barr Virus-Infected B Cells Is Associated with Sensitization to NK Cell Killing

2006 ◽  
Vol 81 (2) ◽  
pp. 474-482 ◽  
Author(s):  
Isabel Y. Pappworth ◽  
Eddie C. Wang ◽  
Martin Rowe
Keyword(s):  
B Cells ◽  
Nk Cells ◽  
Mhc Class I ◽  
Epstein Barr Virus ◽  
Nk Cell ◽  
Class I ◽  
Inhibitory Receptors ◽  
Barr Virus ◽  
Epstein Barr ◽  
Mhc Class I Molecules

ABSTRACT Following activation of Epstein-Barr virus (EBV)-infected B cells from latent to productive (lytic) infection, there is a concomitant reduction in the level of cell surface major histocompatibility complex (MHC) class I molecules and an impaired antigen-presenting function that may facilitate evasion from EBV-specific CD8+ cytotoxic T cells. In some other herpesviruses studied, most notably human cytomegalovirus (HCMV), evasion of virus-specific CD8+ effector responses via downregulation of surface MHC class I molecules is supplemented with specific mechanisms for evading NK cells. We now report that EBV differs from HCMV in this respect. While latently infected EBV-positive B cells were resistant to lysis by two NK lines and by primary polyclonal NK cells from peripheral blood, these effectors efficiently killed cells activated into the lytic cycle. Susceptibility to NK lysis coincided not only with downregulation of HLA-A, -B, and -C molecules that bind to the KIR family of inhibitory receptors on NK cells but also with downregulation of HLA-E molecules binding the CD94/NKG2A inhibitory receptors. Conversely, ULBP-1 and CD112, ligands for the NK cell-activating receptors NKG2D and DNAM-1, respectively, were elevated. Susceptibility of the virus-producing target cells to NK cell lysis was partially reversed by blocking ULBP-1 or CD112 with specific antibodies. These results highlight a fundamental difference between EBV and HCMV with regards to evasion of innate immunity.

scholarly journals Crystal structures of lysophospholipid-bound MHC class I molecules

2020 ◽  
Vol 295 (20) ◽  
pp. 6983-6991 ◽  
Author(s):  
Yoko Shima ◽  
Daisuke Morita ◽  
Tatsuaki Mizutani ◽  
Naoki Mori ◽  
Bunzo Mikami ◽  
...  
Keyword(s):  
Cell Surface ◽  
Crystal Structures ◽  
Mhc Class I ◽  
Antigen Processing ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Peptide Antigens ◽  
Histocompatibility Complex ◽  
Mhc Class I Molecules

Newly synthesized major histocompatibility complex (MHC) class I proteins are stabilized in the endoplasmic reticulum (ER) by binding 8–10-mer-long self-peptide antigens that are provided by transporter associated with antigen processing (TAP). These MHC class I:peptide complexes then exit the ER and reach the plasma membrane, serving to sustain the steady-state MHC class I expression on the cell surface. A novel subset of MHC class I molecules that preferentially bind lipid-containing ligands rather than conventional peptides was recently identified. The primate classical MHC class I allomorphs, Mamu-B*098 and Mamu-B*05104, are capable of binding the N-myristoylated 5-mer (C14-Gly-Gly-Ala-Ile-Ser) or 4-mer (C14-Gly-Gly-Ala-Ile) lipopeptides derived from the N-myristoylated SIV Nef protein, respectively, and of activating lipopeptide antigen-specific cytotoxic T lymphocytes. We herein demonstrate that Mamu-B*098 samples lysophosphatidylethanolamine and lysophosphatidylcholine containing up to a C20 fatty acid in the ER. The X-ray crystal structures of Mamu-B*098 and Mamu-B*05104 complexed with lysophospholipids at high resolution revealed that the B and D pockets in the antigen-binding grooves of these MHC class I molecules accommodate these lipids through a monoacylglycerol moiety. Consistent with the capacity to bind cellular lipid ligands, these two MHC class I molecules did not require TAP function for cell-surface expression. Collectively, these results indicate that peptide- and lipopeptide-presenting MHC class I subsets use distinct sources of endogenous ligands.

The Transporter Associated With Antigen Processing: Function and Implications in Human Diseases

2002 ◽  
Vol 82 (1) ◽  
pp. 187-204 ◽  
Author(s):  
Brigitte Lankat-Buttgereit ◽  
Robert Tampé
Keyword(s):  
Cell Surface ◽  
Mhc Class I ◽  
Antigen Processing ◽  
Immune Surveillance ◽  
Class I ◽  
Cell Surface Expression ◽  
Atp Binding ◽  
Binding Motif ◽  
Antigenic Peptides ◽  
Mhc Class I Molecules

The adaptive immune systems have evolved to protect the organism against pathogens encountering the host. Extracellular occurring viruses or bacteria are mainly bound by antibodies from the humoral branch of the immune response, whereas infected or malignant cells are identified and eliminated by the cellular immune system. To enable the recognition, proteins are cleaved into peptides in the cytosol and are presented on the cell surface by class I molecules of the major histocompatibility complex (MHC). The transport of the antigenic peptides into the lumen of the endoplasmic reticulum (ER) and loading onto the MHC class I molecules is an essential process for the presentation to cytotoxic T lymphocytes. The delivery of these peptides is performed by the transporter associated with antigen processing (TAP). TAP is a heterodimer of TAP1 and TAP2, each subunit containing transmembrane domains and an ATP-binding motif. Sequence homology analysis revealed that TAP belongs to the superfamily of ATP-binding cassette transporters. Loss of TAP function leads to a loss of cell surface expression of MHC class I molecules. This may be a strategy for tumors and virus-infected cells to escape immune surveillance. Structure and function of the TAP complex as well as the implications of loss or downregulation of TAP is the topic of this review.

scholarly journals Ly-49-independent natural killer (NK) cell specificity revealed by NK cell clones derived from p53-deficient mice.

1995 ◽  
Vol 181 (5) ◽  
pp. 1785-1795 ◽  
Author(s):  
F M Karlhofer ◽  
M M Orihuela ◽  
W M Yokoyama
Keyword(s):  
T Cell ◽  
Cell Surface ◽  
Nk Cells ◽  
Mhc Class I ◽  
Target Cell ◽  
Nk Cell ◽  
Class I ◽  
Cell Specificity ◽  
Cell Clones ◽  
Mhc Class I Molecules

Natural killer (NK) cells are heterogeneous in their specificity and expression of cell surface molecules. In the mouse, the Ly-49A molecule is a primary determinant of NK cell specificity because of its ability to downregulate NK cell activation after physical interaction with target cell MHC class I molecules. Ly-49A is expressed on an NK cell subset, and it belongs to a family of highly related molecules that may similarly dictate major histocompatibility complex (MHC) class I-associated specificity of Ly-49A- NK cells. It is not known, however, whether murine NK cell specificity may occur independently of the Ly-49 family and target cell MHC class I molecules. Similar to the impact of cloned murine T cell lines on molecular description of T cell recognition, derivation of cloned murine NK cells should permit dissection of NK cell specificity but, to date, it has not been possible to produce such effector cells. In this study, we derived NK cell clones from mice that were homozygous for a mutation in the p53 tumor suppressor gene. The cloned cells displayed the molecular, cell surface, and functional phenotype of NK cells. Significantly, the NK cell clones displayed clonal differences in ability to kill a panel of murine tumor targets and did not lyse normal cells. Target lysis was unaffected by target cell MHC class I expression, and none of the clones expressed Ly-49A on the cell surface or transcripts for Ly-49 isoforms. Although consistent with the possibility that NK cell specificity for MHC class I molecules is mediated by the Ly-49 family of molecules, the results indicate that NK cell specificity also is regulated by a mechanism independent of target cell MHC class I and the Ly-49 family.

scholarly journals Expression levels of MHC class I molecules are inversely correlated with promiscuity of peptide binding

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Paul E Chappell ◽  
El Kahina Meziane ◽  
Michael Harrison ◽  
Łukasz Magiera ◽  
Clemens Hermann ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class I ◽  
Peptide Binding ◽  
Fundamental Property ◽  
Surface Expression ◽  
Pathogen Resistance ◽  
Class I ◽  
Cell Surface Expression ◽  
Mhc Molecules ◽  
Mhc Class I Molecules

Highly polymorphic major histocompatibility complex (MHC) molecules are at the heart of adaptive immune responses, playing crucial roles in many kinds of disease and in vaccination. We report that breadth of peptide presentation and level of cell surface expression of class I molecules are inversely correlated in both chickens and humans. This relationship correlates with protective responses against infectious pathogens including Marek's disease virus leading to lethal tumours in chickens and human immunodeficiency virus infection progressing to AIDS in humans. We propose that differences in peptide binding repertoire define two groups of MHC class I molecules strategically evolved as generalists and specialists for different modes of pathogen resistance. We suggest that differences in cell surface expression level ensure the development of optimal peripheral T cell responses. The inverse relationship of peptide repertoire and expression is evidently a fundamental property of MHC molecules, with ramifications extending beyond immunology and medicine to evolutionary biology and conservation.

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