Calcineurin activity augments cAMP/PKA-dependent activation of V-ATPase in blowfly salivary glands

Abstract

We have examined the role of the Ca(2+)-dependent protein phosphatase 2B (calcineurin) in the regulation of the vacuolar H(+)-ATPase (V-ATPase) in blowfly salivary glands. In response to the neurohormone serotonin [5-hydroxytryptamine (5-HT)] and under the mediation of the cAMP/PKA signaling pathway, the secretory cells assemble and activate V-ATPase molecules at the apical membrane. We demonstrate that the inhibition of calcineurin activity by cyclosporin A, by FK-506, or by prevention of the elevation of Ca(2+) diminishes the 5-HT-induced assembly and activation of V-ATPase. The effect of calcineurin on V-ATPase is mediated by the cAMP/PKA signaling pathway, with calcineurin acting upstream of PKA, because 1) cyclosporin A does not influence the 8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphate (8-CPT-cAMP)-induced activation of V-ATPase, and 2) the 5-HT-induced rise in cAMP is highly reduced in the presence of cyclosporin A. Moreover, a Ca(2+) rise evoked by the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) inhibitor cyclopiazonic acid leads to an increase in intracellular cAMP concentration and a calcineurin-mediated PKA-dependent activation of V-ATPase. We propose that calcineurin activity mediates cross talk between the inositol 1,4,5-trisphosphate/Ca(2+) and the cAMP/PKA signaling pathways, thereby augmenting the 5-HT-induced rise in cAMP and thus the cAMP/PKA-mediated activation of V-ATPase.

Insight into Salivary Gland Proteomes of Two Polyphagous Stink Bugs: Nezara viridula L. and Halyomorpha halys Stål

“…Nonetheless, focusing on detoxification enzymes only, we could deduce a few statements from this preliminary proteomic study. First, both insects presented subunits of vacuolar proton ATPase and calcineurin in their salivary glands, whose expression level could explain variations in salivation intensity and duration . Second, both insects possessed proteins with antioxidant properties, with some minor differences between the species.…”

Intracellular Proton Pumps as Targets in Chemotherapy: V-ATPases and Cancer

“…Subunit C is considered by some authors one of the principal regulators of the assembly and disassembly of the holoenzyme [45]. Accordingly, work by Voss et al has shown a direct phosphorylation of subunit C by PKA that could influence V 1 /V 0 assembly [46,47]. On the other hand, PKA has already been reported to phosphorylate the catalytic subunit A and regulate V-ATPase activity in human kidney cells [48], although no data on dissociation of the complex was reported in this case.…”

Protein kinase A dependent and independent activation of the V-ATPase in Malpighian tubules ofAedes aegypti.

“…The cAMP effect is implemented by PKA, and inhibitors of PKA abolish the response of the V-ATPase to stimulation with serotonin even though intracellular cAMP and Ca 2+ levels do increase (Rein et al, 2008;Voss et al, 2010). Congruently, only subtle changes in subunit distribution were observed in Drosophila Malpighian tubules that had been diuretically stimulated with the Capa-1 neuropeptide, known to act via Ca that Ca 2+ regulates mitochondrial ATP-production and thereby indirectly influences V-ATPase activity via the ATP supply (Terhzaz et al, 2006).…”