Quantitative phosphoproteomic analysis reveals involvement of PD-1 in multiple T cell functions

Anna S. Tocheva*, Michael Peled, Marianne Strazza, Kieran R. Adam, Shalom Lerrer, Shruti Nayak, Inbar Azoulay-Alfaguter, Connor J.R. Foster, Elliot A. Philips, Benjamin G. Neel, Beatrix Ueberheide, Adam Mor*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Programmed cell death protein 1 (PD-1) is a critical inhibitory receptor that limits excessive T cell responses. Cancer cells have evolved to evade these immunoregulatory mechanisms by upregulating PD-1 ligands and preventing T cell–mediated anti-tumor responses. Consequently, therapeutic blockade of PD-1 enhances T cell–mediated anti-tumor immunity, but many patients do not respond and a significant proportion develop inflammatory toxicities. To improve anti-cancer therapy, it is critical to reveal the mechanisms by which PD-1 regulates T cell responses. We performed global quantitative phosphoproteomic interrogation of PD-1 signaling in T cells. By complementing our analysis with functional validation assays, we show that PD-1 targets tyrosine phosphosites that mediate proximal T cell receptor signaling, cytoskeletal organization, and immune synapse formation. PD-1 ligation also led to differential phosphorylation of serine and threonine sites within proteins regulating T cell activation, gene expression, and protein translation. In silico predictions revealed that kinase/substrate relationships engaged downstream of PD-1 ligation. These insights uncover the phosphoproteomic landscape of PD-1–triggered pathways and reveal novel PD-1 substrates that modulate diverse T cell functions and may serve as future therapeutic targets. These data are a useful resource in the design of future PD-1–targeting therapeutic approaches.

Original languageEnglish
Pages (from-to)18036-18050
Number of pages15
JournalJournal of Biological Chemistry
Volume295
Issue number52
DOIs
StatePublished - 25 Dec 2020
Externally publishedYes

Funding

FundersFunder number
National Institutes of HealthAI125640
National Institutes of Health
National Cancer InstituteR21CA231277
National Cancer Institute
National Institute of Allergy and Infectious Diseases
Cancer Research Institute
Eppley Foundation for Research

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