Dataset Information

Proteomics and Network Analyses Reveal Inhibition of Akt-mTOR Signaling in CD4+ T Cells by Mycobacterium tuberculosis Mannose-Capped Lipoarabinomannan.

ABSTRACT: Mycobacterium tuberculosis (Mtb) cell wall glycolipid mannose-capped lipoarabinomannan (ManLAM) inhibits CD4+ T-cell activation by inhibiting proximal T-cell receptor (TCR) signaling when activated by anti-CD3. To understand the impact of ManLAM on CD4+ T-cell function when both the TCR-CD3 complex and major costimulator CD28 are engaged, we performed label-free quantitative MS and network analysis. Mixed-effect model analysis of peptide intensity identified 149 unique peptides representing 131 proteins that were differentially regulated by ManLAM in anti-CD3- and anti-CD28-activated CD4+ T cells. Crosstalker, a novel network analysis tool identified dysregulated translation, TCA cycle, and RNA metabolism network modules. PCNA, Akt, mTOR, and UBC were found to be bridge node proteins connecting these modules of dysregulated proteins. Altered PCNA expression and cell cycle analysis showed arrest at the G2M phase. Western blot confirmed that ManLAM inhibited Akt and mTOR phosphorylation, and decreased expression of deubiquitinating enzymes Usp9x and Otub1. Decreased NF-?B phosphorylation suggested interference with CD28 signaling through inhibition of the Usp9x-Akt-mTOR pathway. Thus, ManLAM induced global changes in the CD4+ T-cell proteome by affecting Akt-mTOR signaling, resulting in broad functional impairment of CD4+ T-cell activation beyond inhibition of proximal TCR-CD3 signaling.

SUBMITTER: Karim AF

PROVIDER: S-EPMC5725663 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Publications

Proteomics and Network Analyses Reveal Inhibition of Akt-mTOR Signaling in CD4+ T Cells by Mycobacterium tuberculosis Mannose-Capped Lipoarabinomannan.

Karim Ahmad F AF Sande Obondo J OJ Tomechko Sara E SE Ding Xuedong X Li Ming M Maxwell Sean S Ewing Rob M RM Harding Clifford V CV Rojas Roxana E RE Chance Mark R MR Boom W Henry WH

Proteomics 20171101 22

Mycobacterium tuberculosis (Mtb) cell wall glycolipid mannose-capped lipoarabinomannan (ManLAM) inhibits CD4+ T-cell activation by inhibiting proximal T-cell receptor (TCR) signaling when activated by anti-CD3. To understand the impact of ManLAM on CD4+ T-cell function when both the TCR-CD3 complex and major costimulator CD28 are engaged, we performed label-free quantitative MS and network analysis. Mixed-effect model analysis of peptide intensity identified 149 unique pept ...[more]

PMID: 28994205

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Project description:CD4+ T cells have a central role in controlling Mtb infection (1). Despite immune control, Mtb persists by interfering with macrophage and T cell function, allowing for pathogen survival. Our group has demonstrated direct and indirect inhibition of CD4+ T cell activation by different Mtb molecules including lipoproteins LpqH, LprA and LprG, and ManLAM (2-5). ManLAM is an abundant glycolipid in the Mtb cell wall and interferes with TCR signaling by down-regulating phosphorylation of Lck, CD3, ZAP70 and LAT (6). Activation through the TCR-CD3 complex leads to marked changes in the proteome of T cells. Entry into cell cycle, production of cytokines and differentiation from naïve to effector and memory T cell are all reflected in the production and modification of multiple proteins. Mass spectrometry (MS) has been used to characterize TCR complex formation (7-11) and the effect of a range of stressors on the T cell proteome (12-14). Recent advances have overcome technical issues in quantitative MS and allow analysis of the complexity and dynamic range of the cellular proteome (15). To extract biological meaning different bioinformatic tools have been developed for MS based cellular studies (16, 17). In this study we used label-free quantitative MS to characterize the effect of ManLAM on the proteome of activated CD4+ T cells. Approximately 5000 peptides were identified and quantitated from three biological experimental datasets in primary murine CD4+ T cells treated with or without ManLAM and activated with anti-CD3 and anti-CD28 monoclonal antibodies (mAb). Peptides with varying abundance were selected by likelihood ratio based statistical significance by comparing the intensities under different experimental conditions. ManLAM treatment resulted in abundance changes for 149 peptides representing 131 proteins in the activated CD4+ T cell proteome that affected a variety of enriched cluster modules and pathways. Validation experiments confirmed Man LAM induced inhibition of Proliferating Cell Nuclear Antigen (PCNA) that regulates cell cycle progression. Protein-protein interaction (PPI) network analysis revealed a central role for the Akt/mTOR signaling pathway. WB studies revealed decreased phosphorylation of both Akt and mTOR in ManLAM treated CD4+ T cells as well as decreased expression of Otub1, a key molecule regulated by mTOR. Thus disruption of the activated CD4+ T cell proteome by ManLAM-mediated inhibition of proximal TCR signaling is primarily mediated through inhibition of Akt-mTOR signaling.

Dataset Information

Proteomics and Network Analyses Reveal Inhibition of Akt-mTOR Signaling in CD4+ T Cells by Mycobacterium tuberculosis Mannose-Capped Lipoarabinomannan.

Publications

Proteomics and Network Analyses Reveal Inhibition of Akt-mTOR Signaling in CD4<sup>+</sup> T Cells by Mycobacterium tuberculosis Mannose-Capped Lipoarabinomannan.

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