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Immune self-reactivity triggered by drug-modified human leukocyte antigen-peptide presentation
Abstracts / Molecular Immunology 51 (2012) 5–41
stitutive proteasome (subunit 5c) favors hydrolysis after smaller hydrophobic residues. Additional ligand complex structures with the inhibitor PR-957 revealed that its binding to subunit 5c is hampered by a clash of its P1 phenylalanine side chain with Met45 and requires the dislocation of the latter. Moreover, investigation of the two-step reaction mechanism of PR-957 with the 5-subunit of the yeast proteasome indicated that binding of the inhibitor to the active site occurs only via its electrophilic headgroup and its P1 site and thereby proved the importance of the interactions of the S1 pocket of the proteasome with the P1 site of the ligand. In conclusion, PR-957 preferentially targets subunit 5i, as its large P1 phenyl side chain perfectly fits into the spacious S1 pocket of the chymotrypsin-like active site of the immunoproteasome. In contrast, the significantly smaller S1 pocket of subunit 5c of the constitutive proteasome has to undergo conformational changes to accommodate PR-957. With this knowledge specific inhibitory compounds for either constitutive or immunoproteasomes can now be developed. doi:10.1016/j.molimm.2012.02.047 Immune self-reactivity triggered by drug-modified human leukocyte antigen-peptide presentation Patricia Illing a,∗ , Julian Vivian b , Nadine Dudek c , Lyudmila Kostenko d , Zhenjun Chen d , Mandvi Bharadwaj d , Lars KjerNielsen d , Anthony Purcell c , Jamie Rossjohn b , James McCluskey d a
Department of Microbiology & Immunology, Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne b Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University c Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne d Department of Microbiology & Immunology, University of Melbourne The basis for strong immunogenetic associations between particular human leukocyte antigen (HLA) class I allotypes and inflammatory conditions like Behcet’s disease (HLA-B51) and ankylosing spondylitis (HLA-B27) remain mysterious. Recently, however, even stronger HLA associations are reported in drug hypersensitivities to the reverse-transcriptase inhibitor abacavir (HLA-B*57:01), the gout prophylactic allopurinol (HLA-B58), and the antiepileptic carbamazepine (HLA-B*15:02), providing a defined disease trigger and suggesting a general mechanism for these associations. However, little is known about the underlying mechanisms of this process, even for abacavir hypersensitivity syndrome (AHS), a prototypical HLA-associated drug reaction occurring exclusively in individuals with the common histocompatibility molecule, HLA-B*57:01+ and with a relative risk of >1000. We have previously shown that systemic reactions to abacavir were driven by drug-specific activation of cytokine-producing, cytotoxic CD8 + T cells. Recognition of abacavir required the transporter associated with antigen presentation and tapasin and was fixation sensitive. Abacavir-specific T cell responses were uniquely restricted by HLA-B*57:01 and not the closely related HLA allotypes including HLA-B*57:02, HLA-B*57:03, HLA-B*57:11, HLA-B*58:01 and selected site directed mutants of HLA-B*57:01. These natural and mutated forms of HLA-B*57:01 collectively contain polymorphisms in the C, D, E and F-pocket of the antigen-binding cleft. We now show a basis for the strong association of HLA-B*57:01 with abacavir hypersensitivity through perturbed Ag-presentation. Our findings simultaneously highlight the importance of HLA polymorphism in the evolution of pharmacogenomics as well as providing
19
a novel mechanism for the growing number of HLA-linked hypersensitivities that involve small molecule drugs. doi:10.1016/j.molimm.2012.02.048 Tetraspanins CD82 and CD37 play vital roles in antigen presentation and processing in dendritic cells Eleanor Jones a,∗ , Po Ki Villadangos b , Mark Wright a
Ho a , Javier
Vega
Ramos b , Jose
a
Department of Immunology, Monash Alfred Medical Research and Education Precinct b Department of Immunology, The Walter and Eliza Hall Institute of Medical Research Tetraspanins are a superfamily of membrane molecules which form microdomains to organise the cell surface. 33 tetraspanins have been identified in humans, and while some show functional overlap, individual tetraspanins have unique roles in complex cellular events such as trafficking, signalling, adhesion and migration. Here we examine the novel phenotype of a new knockout mouse model of the tetraspanin CD82. This broadly expressed molecule is best characterized as a metastasis suppressor gene, and is the closest phylogenic relative of the tetraspanin CD37. Our data indicates that CD82 often opposes the role of CD37 and is pivotal in antigen presentation. CD37 is known to negatively regulate MHC/peptide presentation, as CD37KO DCs are hyperstimulatory to T cells in vitro, and this effect is due to an increase in signal 1 (MHC presentation). Here, however, we show CD82 ablation causes a significant decease in the ability of dendritic cells to stimulate T cell proliferation in vitro. We present data to indicate this is not due to uptake, surface expression, costimulation or signal 1, but may be due to maturation and antigen processing. doi:10.1016/j.molimm.2012.02.049 Chicken TAP genes are polymorphic and co-evolve with the dominantly-expressed class I gene Anna Sowa a , Michael Harrison a , Clive Tregaskes a , Paul Chappell b , Pietro Roversi b , Susan Lea b , Megan O’Mara c , Rachelle Gaudet d , Jim Kaufman a,∗ a
University of Cambridge University of Oxford c University of Queensland d Harvard University b
In most mammals, the MHC class I molecules are polymorphic and determine the specificity of peptide presentation, while the transporter associated with antigen presentation (TAP) heterodimers are functionally monomorphic. In chickens, there are two classical class I genes but only one is expressed at a high level, which results in very strong MHC associations with resistance to particular infectious pathogens. We have eluted and sequenced peptides from cells, and determined peptide motifs for the dominantly-expressed class I molecule of seven MHC haplotypes. Using renaturation assays and X-ray crystallography, we have found two kinds of peptide motif, one simple but very fastidious and the other involving remodelling of the peptide binding site along with co-variation between various peptide positions. These two kinds of binding correlate with cell surface localisation as well as resistance to Marek’s disease caused by an oncogenic herpesvirus. We have determined the TAP1 and TAP2 sequences from the same seven MHC haplotypes, finding that both genes have high
stitutive proteasome (subunit 5c) favors hydrolysis after smaller hydrophobic residues. Additional ligand complex structures with the inhibitor PR-957 revealed that its binding to subunit 5c is hampered by a clash of its P1 phenylalanine side chain with Met45 and requires the dislocation of the latter. Moreover, investigation of the two-step reaction mechanism of PR-957 with the 5-subunit of the yeast proteasome indicated that binding of the inhibitor to the active site occurs only via its electrophilic headgroup and its P1 site and thereby proved the importance of the interactions of the S1 pocket of the proteasome with the P1 site of the ligand. In conclusion, PR-957 preferentially targets subunit 5i, as its large P1 phenyl side chain perfectly fits into the spacious S1 pocket of the chymotrypsin-like active site of the immunoproteasome. In contrast, the significantly smaller S1 pocket of subunit 5c of the constitutive proteasome has to undergo conformational changes to accommodate PR-957. With this knowledge specific inhibitory compounds for either constitutive or immunoproteasomes can now be developed. doi:10.1016/j.molimm.2012.02.047 Immune self-reactivity triggered by drug-modified human leukocyte antigen-peptide presentation Patricia Illing a,∗ , Julian Vivian b , Nadine Dudek c , Lyudmila Kostenko d , Zhenjun Chen d , Mandvi Bharadwaj d , Lars KjerNielsen d , Anthony Purcell c , Jamie Rossjohn b , James McCluskey d a
Department of Microbiology & Immunology, Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne b Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University c Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne d Department of Microbiology & Immunology, University of Melbourne The basis for strong immunogenetic associations between particular human leukocyte antigen (HLA) class I allotypes and inflammatory conditions like Behcet’s disease (HLA-B51) and ankylosing spondylitis (HLA-B27) remain mysterious. Recently, however, even stronger HLA associations are reported in drug hypersensitivities to the reverse-transcriptase inhibitor abacavir (HLA-B*57:01), the gout prophylactic allopurinol (HLA-B58), and the antiepileptic carbamazepine (HLA-B*15:02), providing a defined disease trigger and suggesting a general mechanism for these associations. However, little is known about the underlying mechanisms of this process, even for abacavir hypersensitivity syndrome (AHS), a prototypical HLA-associated drug reaction occurring exclusively in individuals with the common histocompatibility molecule, HLA-B*57:01+ and with a relative risk of >1000. We have previously shown that systemic reactions to abacavir were driven by drug-specific activation of cytokine-producing, cytotoxic CD8 + T cells. Recognition of abacavir required the transporter associated with antigen presentation and tapasin and was fixation sensitive. Abacavir-specific T cell responses were uniquely restricted by HLA-B*57:01 and not the closely related HLA allotypes including HLA-B*57:02, HLA-B*57:03, HLA-B*57:11, HLA-B*58:01 and selected site directed mutants of HLA-B*57:01. These natural and mutated forms of HLA-B*57:01 collectively contain polymorphisms in the C, D, E and F-pocket of the antigen-binding cleft. We now show a basis for the strong association of HLA-B*57:01 with abacavir hypersensitivity through perturbed Ag-presentation. Our findings simultaneously highlight the importance of HLA polymorphism in the evolution of pharmacogenomics as well as providing
19
a novel mechanism for the growing number of HLA-linked hypersensitivities that involve small molecule drugs. doi:10.1016/j.molimm.2012.02.048 Tetraspanins CD82 and CD37 play vital roles in antigen presentation and processing in dendritic cells Eleanor Jones a,∗ , Po Ki Villadangos b , Mark Wright a
Ho a , Javier
Vega
Ramos b , Jose
a
Department of Immunology, Monash Alfred Medical Research and Education Precinct b Department of Immunology, The Walter and Eliza Hall Institute of Medical Research Tetraspanins are a superfamily of membrane molecules which form microdomains to organise the cell surface. 33 tetraspanins have been identified in humans, and while some show functional overlap, individual tetraspanins have unique roles in complex cellular events such as trafficking, signalling, adhesion and migration. Here we examine the novel phenotype of a new knockout mouse model of the tetraspanin CD82. This broadly expressed molecule is best characterized as a metastasis suppressor gene, and is the closest phylogenic relative of the tetraspanin CD37. Our data indicates that CD82 often opposes the role of CD37 and is pivotal in antigen presentation. CD37 is known to negatively regulate MHC/peptide presentation, as CD37KO DCs are hyperstimulatory to T cells in vitro, and this effect is due to an increase in signal 1 (MHC presentation). Here, however, we show CD82 ablation causes a significant decease in the ability of dendritic cells to stimulate T cell proliferation in vitro. We present data to indicate this is not due to uptake, surface expression, costimulation or signal 1, but may be due to maturation and antigen processing. doi:10.1016/j.molimm.2012.02.049 Chicken TAP genes are polymorphic and co-evolve with the dominantly-expressed class I gene Anna Sowa a , Michael Harrison a , Clive Tregaskes a , Paul Chappell b , Pietro Roversi b , Susan Lea b , Megan O’Mara c , Rachelle Gaudet d , Jim Kaufman a,∗ a
University of Cambridge University of Oxford c University of Queensland d Harvard University b
In most mammals, the MHC class I molecules are polymorphic and determine the specificity of peptide presentation, while the transporter associated with antigen presentation (TAP) heterodimers are functionally monomorphic. In chickens, there are two classical class I genes but only one is expressed at a high level, which results in very strong MHC associations with resistance to particular infectious pathogens. We have eluted and sequenced peptides from cells, and determined peptide motifs for the dominantly-expressed class I molecule of seven MHC haplotypes. Using renaturation assays and X-ray crystallography, we have found two kinds of peptide motif, one simple but very fastidious and the other involving remodelling of the peptide binding site along with co-variation between various peptide positions. These two kinds of binding correlate with cell surface localisation as well as resistance to Marek’s disease caused by an oncogenic herpesvirus. We have determined the TAP1 and TAP2 sequences from the same seven MHC haplotypes, finding that both genes have high