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Jonathan W Yewdell

Publications and source records attributed to Jonathan W Yewdell.

At least 37 records · Page 2Linked to original sources
PubMed2005

Quantitating defective ribosome products.

The fidelity of the protein production process is monitored by quality control machinery, which ensures that aberrant proteins are not deployed throughout the cell. A significant fraction (upwards of 30%) of proteins are degraded by proteasomes shortly after their synthesis, and we have termed such proteins defective ribosomal proteins (DRiPs). It is of interest and importance to characterize qualitatively and quantitatively this cohort of rapidly degraded nascent proteins. Quantitating DRiPs entails employing a standard pulse-chase protocol using radiolabeled amino acids. Protein degradation kinetics can be determined by either acid precipitation or SDS-PAGE. The introduction of proteasome inhibitors enables quantitation of proteasome-mediated protein degradation in vivo.

Animals↗
PubMed2004

Identification of poxvirus CD8+ T cell determinants to enable rational design and characterization of smallpox vaccines.

The large size of poxvirus genomes has stymied attempts to identify determinants recognized by CD8+ T cells and greatly impeded development of mouse smallpox vaccination models. Here, we use a vaccinia virus (VACV) expression library containing each of the predicted 258 open reading frames to identify five peptide determinants that account for approximately half of the VACV-specific CD8+ T cell response in C57BL/6 mice. We show that the primary immunodominance hierarchy is greatly affected by the route of VACV infection and the poxvirus strain used. Modified vaccinia virus ankara (MVA), a candidate replacement smallpox vaccine, failed to induce responses to two of the defined determinants. This could not be predicted by genomic comparison of viruses and is not due strictly to limited MVA replication in mice. Several determinants are immunogenic in cowpox and ectromelia (mousepox) virus infections, and immunization with the immunodominant determinant provided significant protection against lethal mousepox. These findings have important implications for understanding poxvirus immunity in animal models and bench-marking immune responses to poxvirus vaccines in humans.

Amino Acid Sequence↗
PubMed2004

Reversal in the immunodominance hierarchy in secondary CD8+ T cell responses to influenza A virus: roles for cross-presentation and lysis-independent immunodomination.

Immunodominance is a central feature of CD8+ T cell (TCD8+) responses to pathogens, transplants, and tumors. Determinants occupy a stable position in an immunodominance hierarchy (alpha-, beta-, etc.) defined by the frequencies of responding TCD8+. In this paper, we study the mechanistic basis for place-swapping between alpha- (acid polymerase (PA)(224-233)) and beta-determinants (nuclear protein 366-374) in primary vs secondary anti-influenza A virus (IAV) responses in mice. This phenomena was recently correlated with the inability of IAV-infected nondendritic cells (DCs) to generate PA(224-233), and it was proposed that secondary TCD8+ are principally activated by IAV-infected epithelial cells, while primary TCD8+ are activated by IAV-infected DCs. In this study, we show that the inability of non-DCs to generate PA(224-232) is relative rather than absolute, and that the preferential use of cross-priming in secondary anti-IAV responses can also account for the revised hierarchy. We further show that immunodomination of PA(224-233)-specific TCD8+ by nucleoprotein 366-374-specific TCD8+ plays a critical role in the phenomena, and that this is unlikely to be mediated by TCD8+ lysis of APCs or other cells.

Adoptive Transfer↗
PubMed2004

Comparative immunopeptidomics of humans and their pathogens.

Major histocompatibility complex class I molecules present peptides of 8-10 residues to CD8+ T cells. We used 19 predicted proteomes to determine the influence of CD8+ T cell immune surveillance on protein evolution in humans and microbial pathogens by predicting immunopeptidomes, i.e., sets of class I binding peptides present in proteomes. We find that class I peptide binding specificities (i) have had little, if any, influence on the evolution of immunopeptidomes and (ii) do not take advantage of biases in amino acid distribution in proteins other than the concentration of hydrophobic residues in NH(2)-terminal leader sequences.

Animals↗
PubMed2004

The TL MHC class Ib molecule has only marginal effects on the activation, survival and trafficking of mouse small intestinal intraepithelial lymphocytes.

Thymus leukemia antigen (TL) is an MHC class Ib molecule that is highly conserved in rats and mice with no obvious human homolog. TL is expressed in mouse small intestinal epithelial cells and is known to interact with CD8alphaalpha homodimers, which are expressed by intraepithelial lymphocytes (IELs), some other T cell subsets and some non-T cells such as a subset of dendritic cells. We show here that TL is abundantly expressed on the basolateral surface of mouse small intestinal epithelial cells and that expression is abrogated in beta2m-/- mice but unaffected in TCR-/- mice or CD8alpha chain-/- mice. We demonstrate that the interaction between TL and CD8alphaalpha is not necessary for IEL survival in vitro or in vivo and does not modulate IEL trafficking in vivo. TL co-stimulation of alpha-CD3 antibody-activated IELs resulted in modestly enhanced production of IFN-gamma in one subset of IELs. The lack of effect on IEL survival and trafficking and the modest effect on IFN-gamma production suggest that the functional consequences of TL interaction with CD8alphaalpha as well as the more general biological role of TL in mucosal immunity remains to be discovered.

Animals↗
PubMed2004

CD8+ T cell cross-priming via transfer of proteasome substrates.

"Cross-priming" describes the activation of naïve CD8+ T cells by professional antigen-presenting cells that have acquired viral or tumor antigens from "donor" cells. Antigen transfer is believed to be mediated by donor cell-derived molecular chaperones bearing short peptide ligands generated by proteasome degradation of protein antigens. We show here that cross-priming is based on the transfer of proteasome substrates rather than peptides. These findings are potentially important for the rational design of vaccines that elicit CD8+ T cell responses.

Acetylcysteine↗
PubMed2004

Immune recognition of a human renal cancer antigen through post-translational protein splicing.

Cytotoxic T lymphocytes (CTLs) detect and destroy cells displaying class I molecules of the major histocompatibility complex (MHC) that present oligopeptides derived from aberrant self or foreign proteins. Most class I peptide ligands are created from proteins that are degraded by proteasomes and transported, by the transporter associated with antigen processing, from the cytosol into the endoplasmic reticulum, where peptides bind MHC class I molecules and are conveyed to the cell surface. C2 CTLs, cloned from human CTLs infiltrating a renal cell carcinoma, kill cancer cells overexpressing fibroblast growth factor-5 (FGF-5). Here we show that C2 cells recognize human leukocyte antigen-A3 MHC class I molecules presenting a nine-residue FGF-5 peptide generated by protein splicing. This process, previously described strictly in plants and unicellular organisms, entails post-translational excision of a polypeptide segment followed by ligation of the newly liberated carboxy-terminal and amino-terminal residues. The occurrence of protein splicing in vertebrates has important implications for the complexity of the vertebrate proteome and for the immune recognition of self and foreign peptides.

Amino Acid Sequence↗
PubMed2004

Cross-priming of CD8+ T cells by viral and tumor antigens is a robust phenomenon.

"Cross-priming" refers to the activation of naive CD8+ T cells by antigen-presenting cells that have acquired nominal antigens from another cell. The biological relevance of cross-priming of CD8+ T cells has recently been challenged (Zinkernagel, R. M., Eur. J. Immunol. 2002. 32: 2385-2392), on the basis that responses are weak or poorly quantitated, and the determinants recognized are undefined. Here we show that cross-priming is a robust process that elicits vigorous primary responses to multiple peptides in two well-defined systems. Our findings support the relevance of cross-priming in CD8+ T cell responses to viruses and tumor cells, and demonstrate that cross-priming elicits CD8+ T cells to determinants generated by the endogenous processing pathway.

Animals↗
PubMed2004

XBP1, downstream of Blimp-1, expands the secretory apparatus and other organelles, and increases protein synthesis in plasma cell differentiation.

The differentiation of B cells into immunoglobulin-secreting plasma cells is controlled by two transcription factors, Blimp-1 and XBP1. By gene expression profiling, we defined a set of genes whose induction during mouse plasmacytic differentiation is dependent on Blimp-1 and/or XBP1. Blimp-1-deficient B cells failed to upregulate most plasma cell-specific genes, including xbp1. Differentiating xbp1-deficient B cells induced Blimp-1 normally but failed to upregulate genes encoding many secretory pathway components. Conversely, ectopic expression of XBP1 induced a wide spectrum of secretory pathway genes and physically expanded the endoplasmic reticulum. In addition, XBP1 increased cell size, lysosome content, mitochondrial mass and function, ribosome numbers, and total protein synthesis. Thus, XBP1 coordinates diverse changes in cellular structure and function resulting in the characteristic phenotype of professional secretory cells.

Animals↗
PubMed2004

Immunodominance in TCD8+ responses to viruses: cell biology, cellular immunology, and mathematical models.

Highlights from a Fundación Juan March Interdisciplinary Meeting. CD8+ T cells (TCD8+) play a critical role in immunity to viruses. A central feature of antiviral TCD8+ responses is immunodominance: out of thousands of potential target peptides, only a handful generate measurable responses. A recent Fundación Juan March Meeting brought together scientists working on the various steps in antigen presentation and T cell biology that contribute to immunodominance, whose understanding is key to rationally developing vaccines meant to elicit effective antiviral TCD8+ responses.

Animals↗
PubMed2004

Proteasomes get by with lots of help from their friends.

Proteasomes can't do it all. It was previously known that aminopeptidases frequently degrade proteasome-generated peptides. Now it appears that another protease, tripeptidyl peptidase II (TPP II), plays a critical role in cleaving proteasomal produced peptides into shorter peptides that can then be degraded by aminopeptidases.

Aminopeptidases↗
PubMed2003

Systematic search fails to detect immunogenic MHC class-I-restricted determinants encoded by influenza A virus noncoding sequences.

It has been demonstrated in a number of systems that CD8+ T cells (T CD8+) can be induced by peptides encoded in alternative reading frames (ARFs) that do not appear to code for bona fide proteins. The biological relevance of ARF peptides remains to be firmly established, however. With this as a goal, we systematically searched for ARF determinants recognized by mouse T CD8+ induced by influenza A virus infection. Of 35 candidate ARF peptides that matched H-2 Db, Kb, or Kd binding motifs, we found that 13 bind to their respective class I molecules at or above the minimal affinity associated with immunogenicity established by past studies. Nine of these peptides were able to induce T CD8+ capable of recognizing peptide-coated target cells. Of these, only a lone determinant is antigenic and immunogenic in the context of influenza A virus infections. Ironically, this peptide is derived from a reading frame that encodes a previously unknown influenza virus protein. These findings suggest that alternative reading frames are not a significant source of antigenic peptides in influenza virus infections and raise doubts regarding the general biological significance of ARF determinants.

Animals↗
PubMed2003

Mild acid treatment induces cross-reactivity of 4H84 monoclonal antibody specific to nonclassical HLA-G antigen with classical HLA class I molecules.

Mild acid treatment by releasing beta(2)m and antigenic peptides leaves human leukocyte antigen (HLA) class I free heavy chains attached to the cell surface. Acid treatment thus allows detection of the cell surface class I antigens by monoclonal antibodies (mAbs) specific to HLA-free heavy chains. We found that acid treatment also enables detection of the cell surface non-classical HLA-G class I antigen with mAbs specific for HLA-G free heavy chains, including 4H84 mAb recognizing all isoforms. Furthermore, we found that 4H84 mAb, but not other mAbs specific to HLA-G free heavy chains, binds to the surface of 8 out of 16 acid-treated leukemia cell lines. Nevertheless, HLA-G antigen is not present in any of these leukemia cells. This was demonstrated by failure to detect any antigen with 4H84 mAb in immunoblotting as well as by inability to detect HLA-G mRNA by RT-PCR. The antigen recognized by 4H84 mAb in some acid treated leukemia cells was identified by immunoprecipitation as a 45 kDa protein. A number of observations indicate that 45 kDa proteins are none other than classical class I heavy chains. Acid treatment thus induces the ability of the 4H84 mAb to recognize some classical HLA class I molecules. Remarkably, 4H84 determinant on HLA-G is linear but corresponding determinant present on some partially folded classical HLA class I free heavy chains is conformational. In view of the unexpected cross-reactivity, detection of HLA-G with this mAb must be carefully evaluated to avoid false detection.

Antibodies, Monoclonal↗
PubMed2003

Quantitating protein synthesis, degradation, and endogenous antigen processing.

Using L929 cells, we quantitated the macroeconomics of protein synthesis and degradation and the microeconomics of producing MHC class I associated peptides from viral translation products. To maintain a content of 2.6 x 10(9) proteins, each cell's 6 x 10(6) ribosomes produce 4 x 10(6) proteins min(-1). Each of the cell's 8 x 10(5) proteasomes degrades 2.5 substrates min(-1), creating one MHC class I-peptide complex for each 500-3000 viral translation products degraded. The efficiency of complex formation is similar in dendritic cells and macrophages, which play a critical role in activating T cells in vivo. Proteasomes create antigenic peptides at different efficiencies from two distinct substrate pools: rapidly degraded newly synthesized proteins that clearly represent defective ribosomal products (DRiPs) and a less rapidly degraded pool in which DRiPs may also predominate.

Animals↗
PubMed2003

The latest killer AP.

Explore the source record for details and available documents.

Adaptor Protein Complex 3↗