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Extracellular NAD Induced, P2x7 Pore Dependant ATP Release From Mouse Thymocytes
Author(s) -
Blum Andrew Edward,
Hong Shiyuan,
Dubyak George
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a487-b
Subject(s) - extracellular , nad+ kinase , carbenoxolone , purinergic receptor , intracellular , pannexin , chemistry , biochemistry , microbiology and biotechnology , connexin , connexon , biophysics , biology , gap junction , enzyme
Extracellular NAD can activate the ionotropic P2X7 receptor (P2x7R) on the plasma membrane of several leukocyte cell types, including the BW5147 mouse T‐lymphocyte cell line. NAD covalently modifies P2x7R by acting as a substrate for ecto‐ADPribosyl‐transferase 2 (eART2) and activates the receptor. Prolonged P2x7R activation, by either reversible ATP binding or covalent ADP‐ribosylation, induces a non‐selective porin‐type permeability that may involve pannexin or connexin hemichannels. Using a luciferase based assay extracellular ATP accumulation is detected in response to NAD, which is subject to inhibition by the hemichannel inhibitor carbenoxolone, the intracellular calcium chelator BAPTA, the phospholipase A2 inhibitor bromoenol lactone, but not by gap26 a specific inhibitor of connexin 43 hemichannels. In addition, millimolar quantities of dithiothreotol (DTT) potentiates ATP release. DTT has been shown to increase eART2 activity in vitro. These data provide evidence for channel mediated ATP release in response to stimulus and furthers the hypothesis that the P2X7R, which has low affinity for ATP, may be activated by NAD in some instances. The release of ATP (and NAD) through hemichannels and subsequent activation of P2X7R may constitute an autocrine activation loop. Support PO1‐HL18708, T32‐HL07653, T32‐GM07250