IL-2 induces a WAVE2-dependent pathway for actin reorganization that enables WASp-independent human NK cell function
Jordan S. Orange, … , Pinaki P. Banerjee, Rahul Pandey
Jordan S. Orange, … , Pinaki P. Banerjee, Rahul Pandey
Published March 7, 2011
Citation Information: J Clin Invest. 2011;121(4):1535-1548. https://doi.org/10.1172/JCI44862.
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Research Article Immunology

IL-2 induces a WAVE2-dependent pathway for actin reorganization that enables WASp-independent human NK cell function

Abstract

Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency associated with an increased susceptibility to herpesvirus infection and hematologic malignancy as well as a deficiency of NK cell function. It is caused by defective WAS protein (WASp). WASp facilitates filamentous actin (F-actin) branching and is required for F-actin accumulation at the NK cell immunological synapse and NK cell cytotoxicity ex vivo. Importantly, the function of WASp-deficient NK cells can be restored in vitro after exposure to IL-2, but the mechanisms underlying this remain unknown. Using a WASp inhibitor as well as cells from patients with WAS, we have defined a direct effect of IL-2 signaling upon F-actin that is independent of WASp function. We found that IL-2 treatment of a patient with WAS enhanced the cytotoxicity of their NK cells and the F-actin content at the immunological synapses formed by their NK cells. IL-2 stimulation of NK cells in vitro activated the WASp homolog WAVE2, which was required for inducing WASp-independent NK cell function, but not for baseline activity. Thus, WAVE2 and WASp define parallel pathways to F-actin reorganization and function in human NK cells; although WAVE2 was not required for NK cell innate function, it was accessible through adaptive immunity via IL-2. These results demonstrate how overlapping cytoskeletal activities can utilize immunologically distinct pathways to achieve synonymous immune function.

Authors

Jordan S. Orange, Sumita Roy-Ghanta, Emily M. Mace, Saumya Maru, Gregory D. Rak, Keri B. Sanborn, Anders Fasth, Rushani Saltzman, Allison Paisley, Linda Monaco-Shawver, Pinaki P. Banerjee, Rahul Pandey

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Figure 7

IL-2 stimulation of NK cells induces WASp-independent WAVE2 phosphorylation.

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IL-2 stimulation of NK cells induces WASp-independent WAVE2 phosphorylat...
YTS and ex vivo NK cells were pretreated with vehicle (C, control), wiskostatin (Wisk) and/or followed by IL-2 for 30 minutes. Whole-cell lysates of YTS (A) and ex vivo NK (B) cells were evaluated for WAVE2 by Western blot analysis. Membranes were stripped and reprobed for myosin-IIA as a loading control (bottom). Numbers beneath each lane represent densitometric ratios for WAVE2 protein normalized to loading control. (C) Supernatant of WAVE2 immunoprecipitate from YTS cells (treated as above) evaluated for the presence of phosphorylated and total STAT5. The WAVE2 immunoprecipitate from YTS (D and E) and ex vivo NK cells (F and G) was evaluated first for phosphoserine (top) by Western blot analysis; then the membrane was stripped and reprobed for WAVE2 (bottom). IgG immunoprecipitate (IgG) is included as a control for the WAVE2 (W2) immunoprecipitate. Numbers beneath each lane represent densitometric ratios for phosphorylated WAVE2 protein relative to control normalized to total WAVE2 content. Western blot analyses are representative of 3 independent experiments from which the mean densitometric ratios are shown graphically (E and G). Error bars show SD, and values significantly different from the mean in control-treated cells are noted (*P < 0.05). WAVE2 or IgG immunoprecipitate from (H) control, and (I) WASPdel patient NK cells (shown in Figure 2) that were pretreated with media control or IL-2 for 30 minutes was evaluated using Western blot analysis as for D and F.