P2Y2 receptor signaling in neutrophils is regulated from inside by a novel cytoskeleton-dependent mechanism.

Functional selectivity, a process by which G-protein coupled receptors (GPCRs) can activate one signaling route while avoiding another, is regulated by ligand-mediated stabilization of specific receptor states that modulate different downstream signaling events. We propose a novel mechanism for functional selectivity, induced by the endogenous P2Y 2 R agonist ATP and regulated at the signaling interface by the cytoskeleton. Upon ATP stimulation of human neutrophils, a transient rise in the cytosolic concentration of free Ca 2+ was not followed by activation of the superoxide anion-generating NADPH-oxidase. This was in contrast to signals generated through the formyl peptide receptor 1 (FPR1), as its activation was accompanied by both a mobilization of Ca 2+ and activation of the NADPH-oxidase. The phospholipase C/Ca 2+ signaling route is not modulated by the cytoskeleton-disrupting drug latrunculin A, but this drug was able to launch a new signaling route downstream of P2Y 2 R that led to NADPH-oxidase activation. The signaling downstream of P2Y 2 R was rapidly terminated and the receptors were desensitized; however, in contrast to desensitized FPR1, no P2Y 2 receptor reactivation could be induced by latrunculin A. Thus, P2Y 2 R desensitization does not appear to involve the cytoskeleton, contrary to FPR1 desensitization. In summary, we hereby describe how ATP regulates functional selectivity via the cytoskeleton, leading to intracellular Ca 2+ increase, alone or with simultaneous NADPH-oxidase activation in neutrophils. [ABSTRACT FROM AUTHOR]