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Channels (Austin). 2014;8(2):142-56. doi: 10.4161/chan.28122. Epub 2014 Mar 3.

Pannexin1 channels act downstream of P2X 7 receptors in ATP-induced murine T-cell death.

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Departamento de Fisiología; Pontificia Universidad Católica de Chile; Santiago, Chile.
Department of Immunology; University of Connecticut Health Center; Farmington, CT USA.
Departamento de Fisiología; Pontificia Universidad Católica de Chile; Santiago, Chile; Instituto Milenio; Centro Interdisciplinario de Neurociencias de Valparaíso; Valparaíso, Chile.


Death of murine T cells induced by extracellular ATP is mainly triggered by activation of purinergic P2X 7 receptors (P2X 7Rs). However, a link between P2X 7Rs and pannexin1 (Panx1) channels, which are non-selective, has been recently demonstrated in other cell types. In this work, we characterized the expression and cellular distribution of pannexin family members (Panxs 1, 2 and 3) in isolated T cells. Panx1 was the main pannexin family member clearly detected in both helper (CD4+) and cytotoxic (CD8+) T cells, whereas low levels of Panx2 were found in both T-cell subsets. Using pharmacological and genetic approaches, Panx1 channels were found to mediate most ATP-induced ethidium uptake since this was drastically reduced by Panx1 channel blockers (10Panx1, Probenecid and low carbenoxolone concentration) and absent in T cells derived from Panx1-/- mice. Moreover, electrophysiological measurements in wild-type CD4+ cells treated with ATP unitary current events and pharmacological sensitivity compatible with Panx1 channels were found. In addition, ATP release from T cells treated with 4Br-A23187, a calcium ionophore, was completely blocked with inhibitors of both connexin hemichannels and Panx1 channels. Panx1 channel blockers drastically reduced the ATP-induced T-cell mortality, indicating that Panx1 channels mediate the ATP-induced T-cell death. However, mortality was not reduced in T cells of Panx1-/- mice, in which levels of P2X 7Rs and ATP-induced intracellular free Ca2+ responses were enhanced suggesting that P2X 7Rs take over Panx1 channels lose-function in mediating the onset of cell death induced by extracellular ATP.


P2X7Rs; dye uptake; membrane permeability; necrosis; pannexons

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