Dataset Information

Multiplexed relative and absolute quantitative immunopeptidomics reveals MHC I repertoire alterations induced by CDK4/6 inhibition

ABSTRACT: Major histocompatibility complex (MHC) class I peptides play a critical role in immune cell recognition and can trigger an antitumor immune response in cancer. Surface MHC levels can be modulated by anticancer agents, altering immunity. However, understanding the peptide repertoire response to treatment remains challenging and is limited by quantitative mass spectrometry-based strategies lacking robust normalization controls. We describe a novel approach that leverages recombinant heavy isotope-coded peptide MHCs (hipMHCs) and multiplex isotope tagging to quantify peptide repertoire alterations using low sample input. HipMHCs improve quantitative accuracy of peptide repertoire changes by normalizing for variation across analyses and enable absolute quantification using internal calibrants to determine copies per cell of MHC antigens, which can inform targeted and combination immunotherapy design. Applying this platform to profile the immunopeptidome response to CDK4/6 inhibition and Interferon gamma, known modulators of antigen presentation, uncovered treatment-specific alterations, connecting the intracellular response to extracellular immune presentation.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Melanocyte, Epithelial Cell, Cell Culture

DISEASE(S): Brain Cancer,Breast Cancer

SUBMITTER: Lauren Stopfer

LAB HEAD: Forest White

PROVIDER: PXD017407 | Pride | 2020-06-04

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	20180228_SK28_Ifng_15_3.raw	Raw
	20180630_SKMEL5_P1uM_L7_.mzML	Mzml
	20180630_SKMEL5_P1uM_L7_.mzid	Mzid
	20180630_SKMEL5_Palbo_15_C18.raw	Raw
	20180630_SKMEL5_Palbo_15_C182.raw	Raw

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Publications

Multiplexed relative and absolute quantitative immunopeptidomics reveals MHC I repertoire alterations induced by CDK4/6 inhibition.

Stopfer Lauren E LE Mesfin Joshua M JM Joughin Brian A BA Lauffenburger Douglas A DA White Forest M FM

Nature communications 20200602 1

Peptides bound to class I major histocompatibility complexes (MHC) play a critical role in immune cell recognition and can trigger an antitumor immune response in cancer. Surface MHC levels can be modulated by anticancer agents, altering immunity. However, understanding the peptide repertoire's response to treatment remains challenging and is limited by quantitative mass spectrometry-based strategies lacking normalization controls. We describe an experimental platform that leverages recombinant ...[more]

PMID: 32488085

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Project description:All nucleated mammalian cells express major histocompatibility complex (MHC) proteins that present peptides on cell surfaces for immune surveillance. These MHC-presented peptides (pMHC) can convey non-self antigens derived from pathogens or mutations to amount T-cell responses. Alterations in tumor-specific antigens – particularly mutation-bearing peptides (neoantigens) presented by MHC — can serve as potent substrates for anti-tumor immune responses. Here we employed an integrated genomic and proteomic antigen discovery strategy aimed at measuring interferon gamma (IFN-γ) induced alterations to antigen presentation, using a lymphoma cell line. IFN-γ treatment resulted in a set of differentially expressed proteins (2 % of all quantified proteins) including components of antigen presentation machinery or interferon signaling pathways. In addition, several proteasome subunits were found to be modulated, consistent with previous reports of immunoproteasome induction by IFN-γ exposure. This finding suggests that a modest proteomic response to IFN-γ could create larger alteration to cells antigen repertoires. Accordingly, by surveying immunopeptides, distinct peptide repertoires were exclusively observed in the IFN-γ induced samples. Furthermore, an additional set of presented peptides distinguished control and the IFN-γ samples by their altered relative abundances including neoantigens. Accordingly, we developed a classification system to distinguish peptides which are differentially presented due to altered expression from novel peptides resulting from changes in antigen processing. Taken together, these data demonstrate that IFN-γ can re-shape antigen repertoires by identity and by abundance. Extending this approach to models with greater clinical relevance should help develop strategies by which immunopeptide repertoires are intentionally reshaped to improve endogenous or vaccine-induced anti-tumor immune responses and potentially anti-viral immune responses.

Project description:Peptides displayed by MHC molecules on a cell’s surface, referred to as its immunopeptidome, play an important role in the adaptive the immune response. Antigen processing for MHC class I presentation is a ubiquitous pathway present in all nucleated cells which generate and present peptides of both self and non-self origin. Peptides with post-translational modifications (PTMs) are one of the classes of peptides presented by MHC class I molecules. However, due to the high background of self-peptides presented by the cells, the diversity of peptides with post-translational modifications is not well reported. In this study, we have carried out MHC Class I immunopeptidomics analysis on Jurkat and A375 cell lines to characterize the diversity of post-translational modifications among MHC class I peptides. Using high resolution mass spectrometry, we identified 25,761 MHC-bound peptides across both the cell lines using Bolt and Sequest search engines. High specificity of the enrichment method is demonstrated by identifying ~90% of the peptides with typical length distribution of 8-12 aa and enriched motifs within those peptides similar to the binding motifs of MHC alleles. Among the MHC-bound peptides, we identified phosphorylation as a major post-translational modification followed by deamidation. We observed site-specific localization of these post-translational modifications, at position P4 for phosphorylated peptides and position P3 for deamidated peptides. We identified a smaller number of peptides with acetylated and methylated lysine, possibly due to very low stoichiometric levels of these post-translational modifications compared to phosphorylation and deamidation. Using PEAKS de novo sequencing algorithm, we identified spliced peptides that account for ~5-7% of MHC-bound peptides across the two cell lines. These peptides share similar features with respect to normal MHC-bound peptides such as peptide length distribution and binding motifs. We validated the identification of several post-translationally modified peptides and spliced peptides using synthetic peptide sequences. In conclusion, our study demonstrates unbiased identification of these low stoichiometric PTMs and unusual spliced peptides using high resolution mass spectrometry.