910 Overexpression of miR-155–5p can upregulate antigen processing and presentation pathway via targeting tapasin

BackgroundDysregulation of major histocompatibility complex (MHC) class I antigen processing and presentation machinery (APM) components in the tumor as one main molecular mechanism of immune escape leading to deactivation of T cell immune surveillance could be due to post-transcriptional regulation via immune-modulatory microRNAs (miRNA). It is now well established from a variety of studies that several miRNAs could effectively modulate the expression of some MHC class I APM components in tumors. Tapasin is an important APM molecule involved in the association of MHC class I with transporter associated with antigen processing (TAP) and peptide loading. Since so far no detailed investigation of the posttranscriptional regulation of tapasin exists, the aim of this study is to identify and functionally characterize miRNAs targeting tapasin in melanoma.MethodsUsing miRNA trapping by RNA in vitro affinity purification (miTRAP) and in silico as well as small RNA sequencing, miRNAs will be identified, which bind to the 3’untranslated region (3’ UTR) of tapasin. Dual-luciferase assays will be performed to determine to bind of the miRNA. In silico analysis was performed to predict the effect of miRNAs on the survival of melanoma patients in correlation to tapasin. RT-qPCR, Western blot, flow cytometry, and other functional assays were performed after transfecting miRNA mimics in three melanoma cell lines.ResultsUsing the combination strategy of miTRAP and RNA seq we identified miR-155-5p to bind to the 3’UTR of tapasin, which was further confirmed by in silico analysis and dual-luciferase reporter assay. Transfection of miR-155-5p mimics demonstrated that miR-155-5p upregulate tapasin protein level, which was accompanied by an upregulation of the MHC class I (HLA-ABC) surface expression. Simultaneously, in several different types of cancer, including melanoma, the expression of miR-155-5p is significantly positively correlated with the patient‘s survival and HLA-A protein.ConclusionsOur data revealed for the first time a positive role of miR-155-5p in the posttranscriptional regulation of tapasin in melanoma and provide further insights into the miR-155-5p-mediated induction of HLA-ABC surface expression. This might lead to a better T cell response, avoidance tumor cell escape, improvement of patients‘ survival and thus might be a potential therapeutic target.AcknowledgementsThe work was supported by a grant from the DKH (BS).

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Antigen processing and presentation in cancer immunotherapy

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-001111 ◽

2020 ◽

Vol 8 (2) ◽

pp. e001111 ◽

Cited By ~ 1

Author(s):

Maxwell Y Lee ◽

Jun W Jeon ◽

Cem Sievers ◽

Clint T Allen

Keyword(s):

T Cell ◽

Mhc Class I ◽

In Silico ◽

Antigen Processing ◽

Tumor Antigens ◽

Epitope Prediction ◽

Cell Tumor ◽

Class I ◽

Wide Range ◽

Antigen Processing And Presentation

BackgroundKnowledge about and identification of T cell tumor antigens may inform the development of T cell receptor-engineered adoptive cell transfer or personalized cancer vaccine immunotherapy. Here, we review antigen processing and presentation and discuss limitations in tumor antigen prediction approaches.MethodsOriginal articles covering antigen processing and presentation, epitope discovery, and in silico T cell epitope prediction were reviewed.ResultsNatural processing and presentation of antigens is a complex process that involves proteasomal proteolysis of parental proteins, transportation of digested peptides into the endoplasmic reticulum, loading of peptides onto major histocompatibility complex (MHC) class I molecules, and shuttling of peptide:MHC complexes to the cell surface. A number of T cell tumor antigens have been experimentally validated in patients with cancer. Assessment of predicted MHC class I binding and total score for these validated T cell antigens demonstrated a wide range of values, with nearly one-third of validated antigens carrying an IC50 of greater than 500 nM.ConclusionsAntigen processing and presentation is a complex, multistep process. In silico epitope prediction techniques can be a useful tool, but comprehensive experimental testing and validation on a patient-by-patient basis may be required to reliably identify T cell tumor antigens.

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Molecular Mechanisms of Viral Immune Evasion Proteins to Inhibit MHC Class I Antigen Processing and Presentation

International Reviews of Immunology ◽

10.1080/08830180903013034 ◽

2009 ◽

Vol 28 (5) ◽

pp. 376-393 ◽

Cited By ~ 7

Author(s):

Fang Zhou

Keyword(s):

Mhc Class I ◽

Immune Evasion ◽

Antigen Processing ◽

Molecular Mechanisms ◽

Class I ◽

Viral Immune Evasion ◽

Mhc Class I Antigen ◽

Antigen Processing And Presentation

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A Flow Cytometry-Based Approach to Unravel Viral Interference with the MHC Class I Antigen Processing and Presentation Pathway

Antigen Processing - Methods in Molecular Biology ◽

10.1007/978-1-4939-9450-2_14 ◽

2019 ◽

pp. 187-198

Author(s):

Patrique Praest ◽

Hendrik de Buhr ◽

Emmanuel J. H. J. Wiertz

Keyword(s):

Flow Cytometry ◽

Mhc Class I ◽

Antigen Processing ◽

Class I ◽

Viral Interference ◽

Presentation Pathway ◽

Mhc Class I Antigen ◽

Antigen Processing And Presentation

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Modulation of Transporter Associated with Antigen Processing (TAP)-Mediated Peptide Import into the Endoplasmic Reticulum by Flavivirus Infection

Journal of Virology ◽

10.1128/jvi.75.12.5663-5671.2001 ◽

2001 ◽

Vol 75 (12) ◽

pp. 5663-5671 ◽

Cited By ~ 49

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.

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Evidence for the Presentation of Major Histocompatibility Complex Class I–restricted Epstein-Barr Virus Nuclear Antigen 1 Peptides to CD8+ T Lymphocytes

Journal of Experimental Medicine ◽

10.1084/jem.20031219 ◽

2004 ◽

Vol 199 (4) ◽

pp. 459-470 ◽

Cited By ~ 104

Author(s):

Kui Shin Voo ◽

Tihui Fu ◽

Helen Y. Wang ◽

Judy Tellam ◽

Helen E. Heslop ◽

...

Keyword(s):

T Cell ◽

Mhc Class I ◽

Antigen Processing ◽

Epstein Barr Virus ◽

Class I ◽

Nuclear Antigen ◽

T Cell Recognition ◽

Barr Virus ◽

Histocompatibility Complex ◽

Epstein Barr

The Epstein-Barr virus (EBV)-encoded nuclear antigen 1 (EBNA1) is expressed in all EBV-associated tumors, making it an important target for immunotherapy. However, evidence for major histocompatibility complex (MHC) class I–restricted EBNA1 peptides endogenously presented by EBV-transformed B and tumor cells remains elusive. Here we describe for the first time the identification of an endogenously processed human histocompatibility leukocyte antigen (HLA)-B8–restricted EBNA1 peptide that is recognized by CD8+ T cells. T cell recognition could be inhibited by the treatment of target cells with proteasome inhibitors that block the MHC class I antigen processing pathway, but not by an inhibitor (chloroquine) of MHC class II antigen processing. We also demonstrate that new protein synthesis is required for the generation of the HLA-B8 epitope for T cell recognition, suggesting that defective ribosomal products (DRiPs) are the major source of T cell epitopes. Experiments with protease inhibitors indicate that some serine proteases may participate in the degradation of EBNA1 DRiPs before they are further processed by proteasomes. These findings not only provide the first evidence of the presentation of an MHC class I–restricted EBNA1 epitope to CD8+ T cells, but also offer new insight into the molecular mechanisms involved in the processing and presentation of EBNA1.

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