Nuclear Phosphoproteomic Screen Uncovers ACLY as Mediator of IL-2-induced Proliferation of CD4+ T lymphocytes

Nerea Osinalde, Jone Mitxelena, Virginia Sánchez-Quiles, Vyacheslav Akimov, Kerman Aloria, Jesus M Arizmendi, Ana M Zubiaga, Blagoy Blagoev, Irina Kratchmarova

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Abstract

Anti-cancer immunotherapies commonly rely on the use of interleukin-2 (IL-2) to promote the expansion of T lymphocytes. IL-2- dependent proliferation is the culmination of a complex network of phosphorylation-driven signaling events that impact on gene transcription through mechanisms that are not clearly understood. To study the role of IL-2 in the regulation of nuclear protein function we have performed an unbiased mass spectrometry-based study of the nuclear phosphoproteome of resting and IL-2-treated CD4(+) T lymphocytes. We detected 8521distinct phosphosites including many that are not yet reported in curated phosphorylation databases. Although most phosphorylation sites remained unaffected upon IL-2 treatment, 391 sites corresponding to 288 gene products showed robust IL-2-dependent regulation. Importantly, we show that ATP-citrate lyase (ACLY) is a key phosphoprotein effector of IL-2-mediated T-cell responses. ACLY becomes phosphorylated on serine 455 in T lymphocytes upon IL-2-driven activation of AKT, and depletion or inactivation of ACLY compromises IL-2-promoted T-cell growth. Mechanistically, we demonstrate that ACLY is required for enhancing histone acetylation levels and inducing the expression of cell cycle regulating genes in response to IL-2. Thus, the metabolic enzyme ACLY emerges as a bridge between cytokine signaling and proliferation of T lymphocytes, and may be an attractive candidate target for the development of more efficient anti-cancer immunotherapies.

Original languageEnglish
JournalMolecular and Cellular Proteomics
Volume15
Issue number6
Pages (from-to)2076-92
Number of pages17
ISSN1535-9476
DOIs
Publication statusPublished - Jun 2016

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