scholarly journals LMP-associated proteolytic activities and TAP-dependent peptide transport for class 1 MHC molecules are suppressed in cell lines transformed by the highly oncogenic adenovirus 12.

1996 ◽  
Vol 183 (2) ◽  
pp. 499-514 ◽  
Author(s):  
R Rotem-Yehudar ◽  
M Groettrup ◽  
A Soza ◽  
P M Kloetzel ◽  
R Ehrlich
Keyword(s):  
Antigen Processing ◽  
Regulatory Elements ◽  
Class I ◽  
Peptide Transport ◽  
Cell Surface Expression ◽  
Transformed Cells ◽  
Recombinant Vaccinia ◽  
Mhc Molecules ◽  
Vaccinia Viruses ◽  
Proteolytic Activities

Expression of class I major histocompatibility complex antigens on the surface of cells transformed by adenovirus 12 (Ad12) is generally very low, and correlates with the in vivo oncogenicity of this virus. In primary embryonal fibroblasts (H-2b) that express transgenic swine class I antigen (PD1), Ad12-mediated transformation results in inhibition in transport of newly synthesized class I molecules, as well as significant reduction in transporter associated with antigen presentation (TAP) gene expression. In this report we show that reexpression of TAP molecules either by stable transfection of mouse TAP genes or by infection with recombinant vaccinia viruses expressing human TAP genes, only partially reconstitutes the expression and transport of the class I molecules. Further analysis of Ad12-transformed cells revealed that the expression of both LMP2 and LMP7, but not of other proteasome complex components, was downregulated, resulting in altered proteolytic activities of the 20S proteasomes. Reconstitution of both TAP and LMP expression resulted in complete restoration of PD1 cell surface expression and enhanced expression of the endogenous H-2D(b) molecules encoded by recombinant vaccinia viruses, in reconstituted Ad12-transformed cells, efficient transport of H-2 class I molecules could only be achieved by treatment of the cells with gamma-interferon. These data suggest that an additional factor(s) that is interferon-regulated plays a role in the biosynthetic pathway of the class I complex, and that its function is deficient in this cell system. Thus, Ad12 viral transformation appears to suppress the expression of multiple genes that are important for antigen processing and presentation, which allows such transformed cells to escape immune surveillance. This coordinate downregulation of immune response genes must likely occur through their use of common regulatory elements.

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 A 15 amino acid fragment of influenza nucleoprotein synthesized in the cytoplasm is presented to class I-restricted cytotoxic T lymphocytes.

1989 ◽  
Vol 170 (3) ◽  
pp. 1051-1056 ◽  
Author(s):  
K Gould ◽  
J Cossins ◽  
J Bastin ◽  
G G Brownlee ◽  
A Townsend
Keyword(s):  
Cell Clone ◽  
Recombinant Vaccinia Virus ◽  
Class I ◽  
Peptide Transport ◽  
Cytotoxic T Cell ◽  
Target Cells ◽  
Recombinant Vaccinia ◽  
Acid Fragment ◽  
T Cell Clone ◽  
Membrane Bound

A recombinant vaccinia has been designed to express amino acids 366-379 of influenza nucleoprotein, previously shown to be the minimal epitope recognized by a class I-restricted cytotoxic T cell clone. Target cells infected with the recombinant vaccinia virus expressing this peptide are recognized by CTL as efficiently as target cells expressing the complete nucleoprotein. The results imply the existence of a peptide transport system that constitutively passes the products of degraded proteins from the cytoplasm into a membrane-bound compartment of the cell.

scholarly journals Rhesus Cytomegalovirus Contains Functional Homologues of US2, US3, US6, and US11

2005 ◽  
Vol 79 (9) ◽  
pp. 5786-5798 ◽  
Author(s):  
Nupur T. Pande ◽  
Colin Powers ◽  
Kwangseog Ahn ◽  
Klaus Früh
Keyword(s):  
Antigen Presentation ◽  
Antigen Processing ◽  
Genomic Sequence ◽  
Structural Features ◽  
Peptide Transport ◽  
Mhc I ◽  
Mhc Molecules ◽  
Presentation Pathway ◽  
Rhesus Cytomegalovirus

ABSTRACT Human cytomegalovirus (HCMV) is a paradigm for mechanisms subverting antigen presentation by major histocompatibility complex (MHC) molecules. Due to its limited host range, HCMV cannot be studied in animals. Thus, the in vivo importance of inhibiting antigen presentation for the establishment and maintenance of infection with HCMV is unknown. Rhesus cytomegalovirus (RhCMV) is an emerging animal model that shares many of the features of HCMV infection. The recent completion of the genomic sequence of RhCMV revealed a significant degree of homology to HCMV. Strikingly, RhCMV contains several genes with low homology to the HCMV US6 gene family of inhibitors of the MHC I antigen presentation pathway. Here, we examine whether the RhCMV US6 homologues (open reading frames Rh182, -184, -185, -186, -187, and -189) interfere with the MHC I antigen-processing pathway. We demonstrate that Rh182 and Rh189 function similarly to HCMV US2 and US11, respectively, mediating the proteasomal degradation of newly synthesized MHC I. The US3 homologue, Rh184, delayed MHC I maturation. Unlike US3, MHC I molecules eventually escaped retention by Rh184, so that steady-state surface levels of MHC I remained unchanged. Rh185 acted similarly to US6 and inhibited peptide transport by TAP and, consequently, peptide loading of MHC I molecules. Thus, despite relatively low sequence conservation, US6 family-related genes in RhCMV are functionally closely related to the conserved structural features of HCMV immunomodulators. The conservation of these mechanisms implies their importance for immune evasion in vivo, a question that can now be addressed experimentally.

scholarly journals Identification of human cancers deficient in antigen processing.

1993 ◽  
Vol 177 (2) ◽  
pp. 265-272 ◽  
Author(s):  
N P Restifo ◽  
F Esquivel ◽  
Y Kawakami ◽  
J W Yewdell ◽  
J J Mulé ◽  
...  
Keyword(s):  
T Cells ◽  
Endoplasmic Reticulum ◽  
Mhc Class I ◽  
Cell Lines ◽  
Antigen Processing ◽  
Human Tumor ◽  
Class I ◽  
Cell Lung Carcinoma ◽  
Mhc Molecules ◽  
Mhc Class I Molecules

Intracellular antigens must be processed before presentation to CD8+ T cells by major histocompatibility complex (MHC) class I molecules. Using a recombinant vaccinia virus (Vac) to transiently express the Kd molecule, we studied the antigen processing efficiency of 26 different human tumor lines. Three cell lines, all human small cell lung carcinoma, consistently failed to process endogenously synthesized proteins for presentation to Kd-restricted, Vac-specific T cells. Pulse-chase experiments showed that MHC class I molecules were not transported by these cell lines from the endoplasmic reticulum to the cell surface. This finding suggested that peptides were not available for binding to nascent MHC molecules in the endoplasmic reticulum. Northern blot analysis of these cells revealed low to nondetectable levels of mRNAs for MHC-encoded proteasome components LMP-7 and LMP-2, as well as the putative peptide transporters TAP-1 and TAP-2. Treatment of cells with interferon gamma enhanced expression of these mRNAs and reversed the observed functional and biochemical deficits. Our findings suggest that downregulation of antigen processing may be one of the strategies used by tumors to escape immune surveillance. Potential therapeutic applications of these findings include enhancing antigen processing at the level of the transcription of MHC-encoded proteasome and transporter genes.

scholarly journals Peptide transport activity of the transporter associated with antigen processing (TAP) is inhibited by an early protein of equine herpesvirus-1

2004 ◽  
Vol 85 (2) ◽  
pp. 349-353 ◽  
Author(s):  
Aruna P. N. Ambagala ◽  
Raju S. Gopinath ◽  
S. Srikumaran
Keyword(s):  
Antigen Processing ◽  
Protein S ◽  
Class I ◽  
Peptide Transport ◽  
Equine Herpesvirus ◽  
Equine Herpesvirus 1 ◽  
Early Protein ◽  
Infected Cells ◽  
Herpesvirus 1

Equine herpesvirus-1 (EHV-1) downregulates surface expression of major histocompatibility complex (MHC) class I molecules on infected cells. The objective of this study was to investigate whether EHV-1 interferes with peptide translocation by the transporter associated with antigen processing (TAP) and to identify the proteins responsible. Using an in vitro transport assay, we showed that EHV-1 inhibited transport of peptides by TAP as early as 2 h post-infection (p.i). Complete shutdown of peptide transport was observed by 8 h p.i. Furthermore, pulse–chase experiments revealed that maturation of class I molecules in the endoplasmic reticulum (ER) was delayed in EHV-1-infected cells, which may be due to reduced availability of peptides in the ER as a result of TAP inhibition. Metabolic inhibition studies indicated that an early protein(s) of EHV-1 is responsible for this effect.

scholarly journals Peptide influences the folding and intracellular transport of free major histocompatibility complex class I heavy chains.

1995 ◽  
Vol 181 (3) ◽  
pp. 1111-1122 ◽  
Author(s):  
R P Machold ◽  
S Andrée ◽  
L Van Kaer ◽  
H G Ljunggren ◽  
H L Ploegh
Keyword(s):  
Major Histocompatibility Complex ◽  
Antigen Processing ◽  
Intracellular Transport ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Major Histocompatibility ◽  
Con A ◽  
Heavy Chains ◽  
Histocompatibility Complex

Class I major histocompatibility complex molecules require both beta 2-microglobulin (beta 2m) and peptide for efficient intracellular transport. With the exception of H-2Db and Ld, class I heavy chains have not been detectable at the surface of cells lacking beta 2m. We show that properly conformed class I heavy chains can be detected in a terminally glycosylated form indicative of cell surface expression in H-2b, H-2d, and H-2s beta 2m-/- concanavalin A (Con A)-stimulated splenocytes incubated at reduced temperature. Furthermore, we demonstrate the presence of Kb molecules at the surface of beta 2m-/- cells cultured at 37 degrees C. The mode of assembly of class I molecules encompasses two major pathways: binding of peptide to preformed "empty" heterodimers, and binding of peptide to free heavy chains, followed by recruitment of beta 2m. In support of the existence of the latter pathway, we provide evidence for a role of peptide in intracellular transport of free class I heavy chains, through analysis of Con A-stimulated splenocytes from transporter associated with antigen processing 1 (TAP1)-/-, beta 2m-/-, and double-mutant TAP1/beta 2m-/- mice.

scholarly journals RMA/S cells present endogenously synthesized cytosolic proteins to class I-restricted cytotoxic T lymphocytes.

1992 ◽  
Vol 175 (1) ◽  
pp. 163-168 ◽  
Author(s):  
F Esquivel ◽  
J Yewdell ◽  
J Bennink
Keyword(s):  
T Lymphocytes ◽  
Cell Surface ◽  
Cytotoxic T Lymphocytes ◽  
Antigen Processing ◽  
Mutant Cell ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Antigenic Peptides ◽  
Infected Cells

RMA/S is a mutant cell line with decreased cell surface expression of major histocompatibility complex class I molecules that has been reported to be deficient in presenting endogenously synthesized influenza virus nucleoprotein (NP) to cytotoxic T lymphocytes (CTL). In the present study we show that RMA/S cells can present vesicular stomatitis virus nucleocapsid protein, and, under some conditions, NP, to Kb-and Db-restricted CTL, respectively. Antigen presentation results from processing of cytosolic pools of endogenously synthesized proteins, and not the binding to cell surface class I molecules of antigenic peptides present in the virus inoculum or released from infected cells. Antigen processing of RMA/S differs, however, from processing by wild-type cells in requiring greater amounts of antigen, longer times to assemble or transport class I-peptide complexes, and in being more sensitive to blocking by anti-CD8 antibody. Thus, the antigen processing deficit in RMA/S cells is of a partial rather than absolute nature.

scholarly journals The HCMV membrane glycoprotein US10 selectively targets HLA-G for degradation

2010 ◽  
Vol 207 (9) ◽  
pp. 2033-2041 ◽  
Author(s):  
Boyoun Park ◽  
Eric Spooner ◽  
Brandy L. Houser ◽  
Jack L. Strominger ◽  
Hidde L. Ploegh
Keyword(s):  
Nk Cell ◽  
Cytoplasmic Tail ◽  
Surface Expression ◽  
Class I ◽  
Cell Surface Expression ◽  
Immune Recognition ◽  
Class I Mhc ◽  
Mhc Molecules ◽  
Classical Class ◽  
Maternal Immune System

Human cytomegalovirus (HCMV) encodes an endoplasmic reticulum (ER)-resident transmembrane glycoprotein, US10, expressed early in the replicative cycle of HCMV as part of the same cluster that encodes the known immunoevasins US2, US3, US6, and US11. We show that US10 down-regulates cell surface expression of HLA-G, but not that of classical class I MHC molecules. The unique and short cytoplasmic tail of HLA-G (RKKSSD) is essential in its role as a US10 substrate, and a tri-leucine motif in the cytoplasmic tail of US10 is responsible for down-regulation of HLA-G. Both the kinetics of HLA-G degradation and the mechanisms responsible appear to be distinct from those used by the US2 and US11 pathways, suggesting the existence of a third route of protein dislocation from the ER. We show that US10-mediated degradation of HLA-G interferes with HLA-G–mediated NK cell inhibition. Given the role of HLA-G in protecting the fetus from attack by the maternal immune system and in directing the differentiation of human dendritic cells to promote the evolution of regulatory T cells, HCMV likely targets the HLA-G–dependent axis of immune recognition no less efficiently than it interferes with classical class I MHC–restricted antigen presentation.

scholarly journals Mapping and characterization of visna/maedi virus cytotoxic T-lymphocyte epitopes

2008 ◽  
Vol 89 (10) ◽  
pp. 2586-2596 ◽  
Author(s):  
Changxin Wu ◽  
Cyril Barbezange ◽  
Ian McConnell ◽  
Barbara A. Blacklaws
Keyword(s):  
Mhc Class I ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Class I ◽  
Virus Infections ◽  
Recombinant Vaccinia ◽  
Modified Vaccinia Virus Ankara ◽  
Immunodeficiency Virus ◽  
Vaccinia Viruses

CD8+ cytotoxic T-lymphocyte (CTL) responses have been shown to be important in the control of human and simian immunodeficiency virus infections. Infection of sheep with visna/maedi virus (VISNA), a related lentivirus, induces specific CD8+ CTL in vivo, but the specific viral proteins recognized are not known. To determine which VISNA antigens were recognized by sheep CTL, we used recombinant vaccinia viruses expressing the different genes of VISNA: in six sheep (Finnish Landrace×Dorset crosses, Friesland and Lleyn breeds) all VISNA proteins were recognized except TAT. Two sheep, shown to share major histocompatibility complex (MHC) class I alleles, recognized POL and were used to map the epitope. The pol gene is 3267 bp long encoding 1088 aa. By using recombinant vaccinia viruses a central portion (nt 1609–2176, aa 537–725) was found to contain the CTL epitope and this was mapped with synthetic peptides to a 25 aa region (aa 612–636). When smaller peptides were used, a cluster of epitopes was detected: at least three epitopes were present, at positions 612–623: DSRYAFEFMIRN; 620–631: MIRNWDEEVIKN; and 625–635: EEVIKNPIQAR. A DNA-prime-modified vaccinia virus Ankara (MVA)-boost strategy was employed to immunize four sheep shown to share MHC class I allele(s) with the sheep above. Specific CTL activity developed in all the immunized sheep within 3 weeks of the final MVA boost although half the sheep showed evidence of specific reactivity after the DNA-prime immunizations. This is the first report, to our knowledge, of induction of CTL by a DNA-prime-boost method in VISNA infection.

scholarly journals The peptide-binding motif for the human transporter associated with antigen processing.

1995 ◽  
Vol 182 (6) ◽  
pp. 1883-1895 ◽  
Author(s):  
P M van Endert ◽  
D Riganelli ◽  
G Greco ◽  
K Fleischhauer ◽  
J Sidney ◽  
...  
Keyword(s):  
Human Leukocyte Antigen ◽  
Antigen Processing ◽  
Human Leukocyte Antigen Class ◽  
Human Leukocyte ◽  
Class I ◽  
Peptide Transport ◽  
Binding Motif ◽  
Antigenic Peptides ◽  
Leukocyte Antigen ◽  
Leukocyte Antigen Class I

Presentation of antigenic peptides by human leukocyte antigen class I molecules is dependent on peptide transport into the endoplasmic reticulum by the transporters associated with antigen processing (TAP) (Germain, R. N. 1994. Cell. 76:287-299). This translocation step is currently regarded as permissive for all peptides with COOH-terminal residues capable of binding to HLA class I molecules (Momburg, F., J. Roelse, J. C. Howard, G. W. Butcher, G.J. Hämmerling, and J.J. Neefjes. 1994. Nature (Lond.). 367:648-651). In this report, we show that the human transporter selects peptides according to a binding motif based on the strong effects on peptide affinity of the three NH2-terminal positions and the COOH-terminal residues. TAP favors strongly hydrophobic residues in position 3 (P3) and hydrophobic or charged residues in P2, whereas aromatic or acidic residues in P1, as well as Pro in P1 and P2, have strong deleterious effects. Selection of naturally presented peptides by the transporter is suggested by their higher average affinity for TAP, as compared to nonselected peptides. The TAP preferences in the three NH2-terminal positions correspond to those of the vast majority of human leukocyte antigen class I alleles, but they represent an obstacle for peptide supply to some alleles, e.g., the B7-like group. We propose that peptides binding to these alleles, and in general, peptides with TAP affinities below a certain threshold, may be transported as extended precursors.

Sign in / Sign up

Export Citation Format

Share Document