Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.23.5 (cathepsin D)
4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myelin basic protein (MBP) is a candidate Ag for the autoimmune process believed to be involved in the pathogenesis of multiple sclerosis (MS). To investigate the fine specificity and HLA restriction of human MBP-specific CTL, long term T cell lines (TCL) were established from 22 MS patients and 16 healthy individuals by repeated antigenic restimulation. By using this approach, MBP-specific cytotoxic TCL were generated from 81% of the lines from MS patients and 69% of those from controls. TCL from both groups expressed the CD3+, CD4+, CD8- phenotype and secreted substantial amounts of IFN-gamma. By using large enzymatic and small synthetic peptides of MBP, TCL were primarily specific for the C-terminal part of the molecule and to a lesser extent for the N-terminal portion. Two regions of the molecule, MBP peptide 87-106 and MBP peptide 154-172, were recognized by the majority of the polyspecific lines and by four and three of 14 monospecific TCL, respectively. These highly immunogenic regions are of interest because they include sequences encephalitogenic in other species. The HLA restriction of each line was determined by using antibody blocking as well as various target cells including EBV-transformed B cells, homozygous typing cells, and fibroblasts transfected with cDNA for DR-alpha and DR-beta genes. All TCL were restricted by HLA-DR Ag. Several HLA-DR molecules restricted multiple cathepsin D-derived and synthetic MBP peptides, including the regions of peptides 87-106 and 154-172 which, respectively, were recognized in conjunction with four and three HLA-DR types. Three of these HLA-DR types are overrepresented in MS patients in different geographic regions. Together, these findings suggest that the MBP-specific cytotoxic T cell response, although not sufficient for disease, may be important for the pathogenesis of MS.
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PMID:Fine specificity and HLA restriction of myelin basic protein-specific cytotoxic T cell lines from multiple sclerosis patients and healthy individuals. 169 81

The binding of a T cell-presented peptide to MHC class II alpha,beta chains occurs as a concurrent process with the release of the associated invariant chain (Ii) by cathepsin B. Ii was digested by cathepsin B from solubilized, MHC class II alpha,beta,Ii complexes in the presence of N-hydroxysuccinimidyl-4-azidobenzoate-conjugated, 125I-labeled, influenza virus matrix (18-29) peptide. The peptide was crosslinked where it became bound. This HLA-DR1-restricted peptide bound about three times more efficiently to class II alpha,beta chains of DR1-positive B cells when present during cathepsin B digestion of Ii than when added afterward, also at pH 5.0. Binding was competed by similarly DR-restricted peptides. Cathepsin D cleaved Ii but did not enhance peptide binding. However, a trace level of cathepsin D, added to the assay for peptide binding in the presence of cathepsin B, further enhanced peptide binding about three times. These experiments support an hypothesis for the staged release of Ii fragments by cathepsin D and cathepsin B, catalyzing at one point the insertion of a peptide into the antigen binding site formed by class II alpha and beta chains.
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PMID:More efficient peptide binding to MHC class II molecules during cathepsin B digestion of Ii than after Ii release. 813 80

MHC class II molecules associate with peptides in the endocytic pathway. Different endosomal locations for peptide loading of class II molecules, varying from early endosomes (EE) to lysosomes, have been assigned on the basis of subcellular fractionation experiments. We have determined the intracellular location of HLA-DM, a molecule that supports peptide loading of class II molecules, by separating vesicles from the melanoma cell line Mel JuSo on the basis of buoying density and surface charge. In both fractionations, HLA-DM co-fractionated with a lysosomal compartment containing beta-hexosaminidase (beta-hex) activity and not with endosomes. Further analysis showed that HLA-DM mainly co-fractionated with a sub-lysosomal structure characterized by a relative low density and containing both pro- and mature cathepsin D and MHC class II molecules. Fluid phase markers first enter this compartment before entering high-density lysosomes that contain exclusively mature cathepsin D, some HLA-DM and no detectable MC class II molecules. Finally we determined the intracellular location of neutral and acidic peptidases. Whereas neutral peptidase activity was detected in the endoplasmic reticulum and/or plasma membrane fractions, acidic peptidase activity exclusively migrated at the position of HLA-DM containing lysosomal vesicles. Our results show that class II molecules co-migrate with HLA-DM, pro- and mature cathepsin D, beta-hex and acidic peptidase activity. HLA-DM, cathepsin d and class II molecules were not observed at the position of EE. Our data suggest that HLA-DM-mediated peptide loading of class II molecules occurs in a lysosomal subcompartment.
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PMID:HLA-DM and MHC class II molecules co-distribute with peptidase-containing lysosomal subcompartments. 867 50

The FACS-analysis of diseases as different as cancer, autoimmune disorders and chronic (retro)viral infections, including HIV-infection, shows -at least temporarily- a common feature of lymphocyte hyperactivation, characterized by cellular activation markers (HLA-DR, CD26, CD38, CD69, CD2R and/or CD30), as well as by solubilized membrane structures, such as beta-2m, sICAM-I, sIL-2R/sCD25, sCD8, and by some oversecreted immunocyte products (e.g. neopterin, lysozyme and/or cathepsin D). We tested two potential approaches to down-regulate the pathologically elevated CD8+ and HLA-DR+ T cells: (a) In animal model, we tested the sensibility of these, disease inducing and maintaining T cell subsets to in vitro pretreated (cell death preprogrammed) semi-syngeneic and allogeneic donor T cells in tumor-bearing mice. (b) In the first clinical study, we used a novel combination of FDA-approved drugs which inhibits Ca(2+)-influx and concomitantly down-regulates cytosolic cAMP in patient's overstimulated immunocompetent cells. We could achieve a 94.6-100% long-term survival in tumor-bearing mice. In patients, large primary tumors and large metastases shrinked by 80-85% and small metastases disappeared completely. Since in HIV-infected persons, the increased number of HLA-DR+ CD38+T (T8) cells is associated with a fall in CD4-level and with development of AIDS, we are looking for the elimination of these HLA-DR+ targets by our novel technique in two AIDS-simulating (FIV/FeLV and SIV) animal models.
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PMID:Treatment of solid tumors should obligatorily be combined with the in vivo codepletion of tumor-protecting, CD8+/HLA-DR(+)-suppressor T cells by alloreactive donor T cells whose preprogrammed cell death allows a high GvL-effect before GvHD can be established. Results of animal experiments, including more than 6000 mice. 873 48

In this study, we evaluated the role of the two functional HLA-DR heterodimers, DR2a (DR alpha paired with the beta chain encoded by DRB5*0101) and DR2b (DR alpha paired with the beta chain encoded by DRB1*1501), that are coexpressed in the multiple sclerosis (MS)-associated haplotype HLA-DR15 Dw2, in presenting myelin basic protein (MBP) peptides to MBP-specific T cell lines (TCL). Our results show that both HLA-DR molecules serve as restriction elements for HLA-DR15-restricted TCL. Slightly higher numbers of TCL use DR2a as restriction element, and the epitopes contained in the immunodominant C-terminal region (131-159) are uniquely restricted by DR2a. The immunodominant middle epitope (81-99) is recognized in the context of both DR2a and DR2b, but this specificity strongly dominates the DR2b-restricted T cell response. Overall, immunodominance in the MBP-specific T cell response correlated well with peptide binding to DR2a or DR2b, demonstrating that the affinity of MHC-peptide interactions is important for shaping the T cell response to this autoantigen. Furthermore, we show that binding of the middle MBP peptide to HLA-DR15 molecules prevents cleavage by cathepsin D, a protease abundantly found in endosomal processing compartments, and thus contributes to its immunodominance. Surprisingly, the restriction element employed by MBP-specific T cell clones influenced the effector function (i.e., cytotoxic activity) of T cells irrespective of their peptide fine specificity.
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PMID:T cell response to myelin basic protein in the context of the multiple sclerosis-associated HLA-DR15 haplotype: peptide binding, immunodominance and effector functions of T cells. 925 50

By applying density gradient electrophoresis (DGE) to human macrophages infected with Mycobacterium bovis BCG, we were able to separate three different bacterial fractions representing arrested phagosomes, phagolysosomes and mycobacterial clumps. After further purification of the phagosomal population, we found that isolated phagosomes containing live BCG were arrested in maturation as they exhibited only low amounts of the lysosomal glycoprotein LAMP-1 and processing of the lysosomal hydrolase cathepsin D was blocked. In addition, low amounts of MHC class I and class II molecules and the absence of HLA-DM suggest sequestration of mycobacterial phagosomes from antigen-processing pathways. We further investigated the involvement of the actin-binding protein coronin in intracellular survival of mycobacteria and showed that human coronin, as well as F-actin, were associated with early stages of mycobacterial phagocytosis but not with phagosome maintenance. Therefore, we conclude that the unique DGE migration pattern of arrested phagosomes is not as a result of retention of coronin, but that there are other proteins or lipids responsible for the block in maturation in human macrophages.
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PMID:Coronin is involved in uptake of Mycobacterium bovis BCG in human macrophages but not in phagosome maintenance. 1173 91

In humans, the small intestinal epithelial cells (IEC) have a high constitutive expression of MHC class II (MHC II), and contains lysosomes. The IEC also contains MHC II rich multivesicular compartments and has been shown to produce exosomes. This suggests a role for the IEC in antigen processing and presentation either directly or indirectly by the production of exosomes. However, the presence and localisation in the IEC of other key molecules involved in this process has not been studied previously. In the present work, we have investigated small intestinal biopsies from healthy adults and the HT29 IEC cell line with monoclonal antibodies against molecules involved in the antigen processing/presenting systems and molecules typically found on exosomes derived from professional APCs and IECs. Immunohistology was performed to study the expression and localisation of MHC II (HLA-DR), HLA-DM, MHC I (HLA-ABC), CD1d, Invariant chain, Lamp-1, CD68, CD63, B7.1, B7.2, ICAM-1, Cathepsin D/S/L and the IEC specific marker A33 in the IECs. We found that the IECs from the biopsies constitutively express MHC II, HLA-DM, MHC I, Invariant chain, Lamp-1, CD 68, CD63 and A33, and these markers were also found in the IFN-g treated HT-29 cells. All these molecules were found apically in the IECs of the biopsies, localised mainly in vesicular structures. Interestingly, in the baso-latereral area of the IEC, only MHC II, MHC I, Lamp 1, CD68, CD63 and A33 were found and also here with vesicular staining pattern which matches the molecules previously found on exosomes derived professional APCs and human IEC lines. CD1d, B7, ICAM-1, CD9 and cathepsin D and L were absent in the IEC compartment, but cathepsin S showed a relatively weak staining in the apical part of the IEC. The staining pattern and the morphological localisation of these markers suggest a prominent antigen processing/loading and trafficking compartment, and a possible baso-lateral release of exosomes in the normal human IEC.
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PMID:Human small intestinal epithelial cells constitutively express the key elements for antigen processing and the production of exosomes. 1602 13

HLA class II-restricted antigen (Ag) processing and presentation are important for the activation of CD4+ T cells, which are the central orchestrating cells of immune responses. The majority of melanoma cells either expresses, or can be induced to express, HLA class II proteins. Thus, they are prime targets for immune mediated elimination by class II-restricted CD4+ T cells. We have previously shown that human melanoma cells lack an important enzyme, gamma interferon-inducible lysosomal thiol-reductase (GILT), capable of perturbing immune recognition of these tumors. Here, we show that GILT expression in human melanoma cells enhances Ag processing and presentation via HLA class II molecules. We also show that GILT expression influences the generation of active forms of cysteinyl proteases, cathepsins B, L and S, as well as an aspartyl protease cathepsin D in melanoma cells. Mechanistic studies revealed that GILT does not regulate acidic cathepsins at the transcriptional level; rather it colocalizes with the cathepsins and influences HLA class II Ag processing. GILT expression in melanoma cells also elevated HLA-DM molecules, which favor epitope loading onto class II in the endolysosomal compartments, enhancing CD4+ T cell recognition. These data suggest that GILT-expressing melanoma cells could prove to be very promising for direct antigen presentation and CD4+ T cell recognition, and may have direct implications for the design of cancer vaccines.
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PMID:Gamma-IFN-inducible-lysosomal thiol reductase modulates acidic proteases and HLA class II antigen processing in melanoma. 1834 23

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