Elsevier

Cell Calcium

Volume 29, Issue 5, May 2001, Pages 299-309
Cell Calcium

Regular Article
ATP induces intracellular calcium increases and actin cytoskeleton disaggregation via P2x receptors

https://doi.org/10.1054/ceca.2000.0194Get rights and content

Abstract

The consequences of purinoceptor activation on calcium signalling, inositol phosphate metabolism, protein secretion and the actin cytoskeleton were demonstrated in the WRK-1 cell line. Extracellular ATP was used as a secretagogue to induce a rise in int racellular Ca2+concentration ([Ca2+]i), acting via P2x purinergic receptors, which causes actin skeleton disaggregation and protein secretion. ATP bound specifically to purinergic receptors, with Ki of 0.8 μM. The magnitude order for binding of different nucleotides was α β-Met-ATP ≥ dATPαS > ATP ≥ ADP > UTP > AMP > suramin. No increase in inositol phosphates (IPs) was observed after ATP application suggesting that the purinergic sites in WRK-1 cells are not of a P2y type. ATP (1–100 μM) caused a concentration-dependent increase in [Ca2+]i(EC50= 30 μM). The responses were reproducible without any desensitization over several applications. The response to ATP was abolished when extracellular calcium ([Ca2+]e) was reduced to 100 nM. A non-specific purinergic antagonist, suramin, reversibly inhibited the ATP-response suggesting that ATP is able to bind to P2x purinergic sites to trigger Ca2+entry and increase of [Ca2+]i. ATP induced a concentration-dependent disaggregation of actin and exocytotic release of proteins both, which were dependent upon [Ca2+]e. Similarly, α,β-Met-ATP, a potent P2x agonist also stimulated Ca2+mobilization, actin network destructuration, and protein release. In the isolated rat neurohypophysial nerve terminals, ATP was shown to act as a physiological stimulus for vasopressin release via Ca2+entry through a P2x receptor [6]. Here, we show that in these nerve terminals, ATP is also able to induce actin disaggregation by a Ca2+dependent mechanism. Thus, actin cytoskeleton alterations induced by ATP through activation of P2x receptors could be a prelude to exocytosis.

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    Correspondence to: Dr G. Dayanithi, INSERM, U 432,University of Montpellier 11, F-34095 Montpellier cedex 5, France.Tel.: +33 467 14 93 25; fax : +33 467 14 36 96; e-mail:[email protected]

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