Ribosomal Proteins Regulate MHC Class I Peptide Generation for Immunosurveillance
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PROVIDER: PRJNA471521 | ENA |
REPOSITORIES: ENA
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Project description:The MHC class I antigen presentation system enables T cell immunosurveillance of cancers and viruses. Rapidly degraded nascent polypeptides (DRiPs) provide many class I peptide ligands. By knocking down each of the 80 ribosomal proteins, we identified proteins that modulate peptide generation without altering source protein expression. We show that 60S ribosomal proteins L6 (RPL6) and RPL28, which are adjacent on the ribosome, play opposite roles in generating an influenza A virus encoded peptide. RPL6 depletion decreases ubiquitin-dependent peptide presentation, while RPL28 depletion increases ubiquitin-dependent and -independent peptide presentation. 40S ribosomal protein S28 (RPS28) knockdown increases total peptide supply in uninfected cells by increasing DRiP synthesis from non-canonical translation of “untranslated” regions and non-AUG start codons, and sensitizes tumor cells for T cell targeting. RPL23 knocKDut decreases overall peptide supply, impairing T cell recognition of tumor cells. Our findings raise the possibility of modulating immunosurveillance by pharmacologically targeting ribosomes.
2019-01-21 | GSE114484 | GEO
Project description:Tumors frequently subvert MHC class I (MHC-I) peptide presentation to evade CD8+ T cell immunosurveillance, though how this is accomplished is not always well-defined. To identify the global regulatory networks controlling antigen presentation, we employed genome-wide screening in human diffuse large B cell lymphomas (DLBCLs). This approach revealed dozens of genes that positively and negatively modulate MHC-I cell surface expression. Validated genes clustered in multiple pathways including cytokine signaling, mRNA processing, endosomal trafficking, and protein metabolism. Genes can exhibit lymphoma subtype- or tumor-specific MHC-I regulation, and a majority of primary DLBCL tumors displayed genetic alterations in multiple regulators. We established SUGT1 as a major positive regulator of both MHC-I and MHC-II cell surface expression. Further, pharmacological inhibition of two negative regulators of antigen presentation, EZH2 and thymidylate synthase, enhanced DLBCL MHC-I presentation. These and other genes represent potential targets for manipulating MHC-I immunosurveillance in cancers, infectious diseases, and autoimmunity.
2020-11-02 | GSE160609 | GEO
Project description:Tumors frequently subvert MHC class I (MHC-I) peptide presentation to evade CD8+ T cell immunosurveillance, though how this is accomplished is not always well-defined. To identify the global regulatory networks controlling antigen presentation, we employed genome-wide screening in human diffuse large B cell lymphomas (DLBCLs). This approach revealed dozens of genes that positively and negatively modulate MHC-I cell surface expression. Validated genes clustered in multiple pathways including cytokine signaling, mRNA processing, endosomal trafficking, and protein metabolism. Genes can exhibit lymphoma subtype- or tumor-specific MHC-I regulation, and a majority of primary DLBCL tumors displayed genetic alterations in multiple regulators. We established SUGT1 as a major positive regulator of both MHC-I and MHC-II cell surface expression. Further, pharmacological inhibition of two negative regulators of antigen presentation, EZH2 and thymidylate synthase, enhanced DLBCL MHC-I presentation. These and other genes represent potential targets for manipulating MHC-I immunosurveillance in cancers, infectious diseases, and autoimmunity.
2020-11-02 | GSE160608 | GEO
Project description: Not available
| S-EPMC6697054 | biostudies-literature
Project description:TAP-binding protein-related (TAPBPR) is an endoplasmic reticulum-resident chaperone that facilitates class I MHC (MHC-I) processing and peptide loading. TAPBPR has (1) chaperone function to stabilize misfolded or partially folded nascent MHC-I substrates, and (2) editing function, in which it catalyzes the exchange of low affinity for high affinity antigenic peptides in the MHC-I peptide-binding groove. TAPBPR-TM is a chimera of the TAPBPR ectodomain and a canonical TM domain, which escapes the endoplasmic reticulum to reach the cell surface. We reasoned that at the cell surface, TAPBPR-TM is more likely to interact with folded MHC-I and thus surface interactions will be more representative of editing function. When tapasin, a homolog of TAPBPR and the main MHC-I-specific chaperone, is knocked out, surface trafficking of HLA-A2 (a human MHC-I allele) is severely diminished, but surface HLA-A2 levels are rescued by over-expression of TAPBPR-TM. Using this assay as the foundation for a fluorescence-based selection, we deep mutationally scanned 104 positions on TAPBPR-TM to identify sites critical for engaging folded MHC-I.
2023-03-09 | GSE218828 | GEO
Project description:An essential element of adaptive immunity is the selective binding of peptide antigens by major histocompatibility complex (MHC) class I proteins and their presentation to cytotoxic T lymphocytes on the cell surface. Using native mass spectrometry, we here analyze the binding of peptides to an empty disulfide-stabilized HLA-A*02:01 molecule. This novel approach allows us to examine the binding properties of diverse peptides. The unique stability of our MHC class I even enables us to determine the binding affinity of complexes, which are suboptimally loaded with truncated or charge-reduced peptides. Notably, a unique erucamide adduct decouples affinity analysis from peptide identity alleviating issues usually attributed to clustering. We discovered that two anchor positions at the binding surface between MHC and peptide can be stabilized independently and further analyze the contribution of other peptidic amino acids on the binding. We propose this as an alternative, likely universally applicable method to artificial prediction tools to estimate the binding strength of peptides to MHC class I complexes quickly and efficiently. This newly described MHC class I-peptide binding affinity quantitation represents a much needed orthogonal, confirmatory approach to existing computational affinity predictions and has the potential to eliminate binding affinity biases and thus accelerate drug discovery in infectious diseases autoimmunity, vaccine design, and cancer immunotherapy.
2022-05-31 | PXD027725 | Pride
Project description:In spontaneous type 1 diabetes (T1D) non-obese diabetic (NOD) mice, the insulin B chain peptide 9-23 (B:9-23) can bind to the MHC class II molecule (IAg7) in register 3 (R3), creating a bimolecular IAg7/InsulinB:9-23 register 3 conformational epitope (InsB:R3). Previously, we showed that the InsB:R3-specific chimeric antigen receptor (CAR), constructed using an InsB:R3-monoclonal antibody, could guide CAR-expressing CD8 T cells to migrate to the islets and pancreatic lymph nodes. Regulatory T cells (Tregs) specific for an islet antigen can broadly suppress various pathogenic immune cells in the islets and effectively halt the progression of islet destruction. Therefore, we hypothesized that InsB:R3 specific Tregs would suppress autoimmune reactivity in islets and efficiently protect against T1D. To test our hypothesis, we produced InsB:R3-Tregs and tested their disease-protective effects in spontaneous T1D NOD CD28-/- mice. InsB:R3-CAR expressing Tregs secrete IL-10 dominated cytokines upon engagement with InsB:R3 antigens. A single infusion of InsB:R3 Tregs delayed the onset of T1D in 95% of treated mice, with 35% maintaining euglycemia for two healthy lifespans, while whereas control Tregs did not. Our data demonstrate that Tregs specific for MHC class II: Insulin peptide epitope (MHCII/Insulin) protect mice against T1D more efficiently than polyclonal Tregs lacking islet antigen specificity, suggesting that the MHC II/insulin-specific Treg approach is a promising immune therapy for safely preventing T1D.
2023-07-24 | GSE238146 | GEO
Project description:Tapasin acts as the principal MHC-I-specific chaperone for facilitating folding and antigenic peptide loading of nascent MHC class I substrates in the cell. In cells where tapasin has been knocked out, the processing and surface trafficking of the human MHC-I allele HLA-A2 is substantially reduced. Over-expression of tapasin rescues HLA-A2 surface expression. Using this assay as the basis for a fluorescence-based selection, tapasin was deep mutationally scanned at 108 positions in the core, at the interface with MHC-I, and on the ‘backside’ distal from where MHC-I binds. Critical residues of tapasin for rescue of HLA-A2 processing map to sites that contact the underside of the MHC-I alpha-2 domain, to the surface contacting the MHC-1 beta2m and alpha-3 domains, and to the base of a protruding loop that rests above the peptide-binding groove (but not to the tip of the loop itself).
2020-10-09 | GSE159247 | GEO
Project description:Sequencing and annotation of equine MHC class II region
| PRJEB15527 | ENA
Project description:The loading of high affinity peptides onto nascent class I MHC (MHC-I) molecules is facilitated by chaperones, including the class I-specific chaperone TAP-binding protein-related (TAPBPR). TAPBPR features a ‘scoop’ loop that projects towards the empty MHC-I peptide binding groove and rests above the F pocket. The scoop loop is not found in the closely related homologue tapasin, and therefore may be partly responsible for the unique antigen editing properties of TAPBPR. A deep mutational scan of the TAPBPR scoop loop defines the relative effects of all single amino acid mutations on binding and peptide-mediated release of the murine H2-Dd MHC-I allomorph. Increased hydrophobic packing between the scoop loop and rim of the peptide binding groove tightens the TAPBPR-MHC-I interaction.
2019-10-31 | GSE118568 | GEO