Kai J Winterberg, Vanessa Schwentner, Feng Gu, Franziska Möckl, Gaoyang Li, Andreas Bauche, Stefanie Etzold, Anette Rosche, Mariella Weiß, Niκolaus Thuille, Fritz Förster, Lena Woelk, René Werner, Dejan Kovacevic, Boris Fehse, Roberta Kurelić, Mikołaj Nawrocki, Samuel Huber, Hans-Willi Mittrücker, Chris Meier, C MULLER, Baier Gottfried, Bjørn Steen Skålhegg, Xavier De Deken, Christian Wahl‐Schott, Thomas Mair, Bente Siebels, Roger Cugota Canals, Francesca Odoardi, Dmitri Lodygin, Alexander Flügel, Viacheslav O. Nikolaev, Björn‐Philipp Diercks, Andreas H. Guse
T cell activation critically depends on the calcium ion (Ca 2+ )–mobilizing second messenger NAADP (nicotinic acid adenine dinucleotide phosphate), which induces the formation of Ca 2+ microdomains that initiate global Ca 2+ signals. NAADP is produced in immune synapses in T cells by dual NADPH oxidase 2 (DUOX2). Here, we investigated the mechanisms that stimulate DUOX2 activity in T cells. DUOX2 activity was enhanced by a modest increase in intracellular Ca 2+ concentration, similar to that induced by Ca 2+ microdomains that arise in resting T cells through different T cell receptor (TCR)–independent mechanisms. In addition, DUOX2 was activated in vitro by phosphorylation of threonine-789 mediated by PKA Cβ or PKCθ, and genetic deficiency of PKA Cβ2 or PKCθ decreased NAADP-dependent Ca 2+ microdomain formation in T cells. PKA Cβ2 was activated downstream of adenosine A 2A receptors, independently of the TCR. In contrast, PKCθ was activated by the tyrosine kinase LCK downstream of TCR stimulation. Inhibition of A 2A receptors or PKCθ to prevent full DUOX2 activation decreased the production of the proinflammatory cytokine IL-17 by effector T cells. Thus, full stimulation of NAADP signaling that is critical for T cell activation requires integration of multiple TCR-independent and -dependent signals with different spatiotemporal characteristics by DUOX2, a fine-tuning mechanism that could be relevant for inflammation.