Characterization of Receptor-Associated Protein Complex Assembly in Interleukin (IL)-2- and IL-15-Activated T-Cell Lines

Short-term IL-15 priming leaves a long-lasting signalling imprint in mouse NK cells independently of a metabolic switch

NK cell reactivity is dynamically regulated by IL-15, and NK cells do not need more than a few minutes of exposure to remember the cytokine for several hours.

IL-15 priming of NK cells is a broadly accepted concept, but the dynamics and underlying molecular mechanisms remain poorly understood. We show that as little as 5 min of IL-15 treatment in vitro, followed by removal of excess cytokines, results in a long-lasting, but reversible, augmentation of NK cell responsiveness upon activating receptor cross-linking. In contrast to long-term stimulation, improved NK cell function after short-term IL-15 priming was not associated with enhanced metabolism but was based on the increased steady-state phosphorylation level of signalling molecules downstream of activating receptors. Inhibition of JAK3 eliminated this priming effect, suggesting a cross talk between the IL-15 receptor and ITAM-dependent activating receptors. Increased signalling molecule phosphorylation levels, calcium flux, and IFN-γ secretion lasted for up to 3 h after IL-15 stimulation before returning to baseline. We conclude that IL-15 rapidly and reversibly primes NK cell function by modulating activating receptor signalling. Our findings suggest a mechanism by which NK cell reactivity can potentially be maintained in vivo based on only brief encounters with IL-15 trans-presenting cells.

Lighting Up T Lymphocyte Signaling with Quantitative Phosphoproteomics

Phosphorylation is the most abundant post-translational modification, regulating several aspects of protein and cell function. Quantitative phosphoproteomics approaches have expanded the scope of phosphorylation analysis enabling the quantification of changes in thousands of phosphorylation sites simultaneously in two or more conditions. These approaches offer a global view of the impact of cellular perturbations such as extracellular stimuli or gene ablation in intracellular signaling networks. Such great potential also brings on a new challenge: to identify, among the thousands of phosphorylations found in global phosphoproteomics studies, the small subset of site-specific phosphorylations expected to be functionally relevant. This review focus on updating and integrating findings on T lymphocyte signaling generated using global phosphoproteomics approaches, drawing attention on the biological relevance of the obtained data.

Data on interleukin (IL)-2- and IL-15-dependent changes in IL-2Rβ and IL-2Rγ complexes

We provide detailed datasets from our analysis of the proteins that associate with IL-2Rβ and IL-2Rγ in T-cells stimulated with IL-2 or IL-15 compared with resting T-cells, as identified by SILAC-based quantitative proteomics. We also include quantitative data regarding site-specific phosphorylation events observed both in IL-2Rβ and IL-2Rγ. Moreover, we provide results demonstrating the specific protein recruitment capacity of four of those site-specific phosphorylations. The proteomics and phosphoproteomics data described in this article is associated with a research article entitled “Characterization of receptor-associated protein complex assembly in Interleukin (IL)-2- and IL-15-activated T-lymphocytes” (Osinalde et al., 2016 [1]). The mass spectrometry data have been deposited to the ProteomeEXchange Constorium with the identifier PXD002386.