TY - JOUR
T1 - Phosphatidylinositol 3-kinase contributes to cell volume regulation through effects on ATP release
AU - Feranchak, Andrew P.
AU - Roman, Richard M.
AU - Schwiebert, Erik M.
AU - Fitz, J. Gregory
PY - 1998/6/12
Y1 - 1998/6/12
N2 - Regulated changes in cell volume represent a signal that modulates a broad range of cell and organ functions. In HTC hepatoma cells, increases in volume are coupled to membrane ion permeability through a pathway involving (i) ATP efflux, (ii) autocrine stimulation of P2 receptors, and (iii) increases in anion permeability and Cl- efflux, contributing to recovery of volume toward basal values. Based on recent evidence that cell volume increases also stimulate phosphoinositide kinases, the purpose of these studies was to determine if phosphatidylinositol 3-kinase (PI 3-kinase) modulates these pathways. Exposure of cells to hypotonic buffer (20 or 40% less NaCl) caused an initial increase in cell volume and stimulated a rapid increase in ATP release. Subsequent opening of Cl- channels was followed by recovery of cell volume toward basal values, despite the continuous presence of hypotonic buffer. Inhibition of PI 3-kinase with wortmannin (K(i) = 3 nM) significantly inhibited both the rate of volume recovery and activation of Cl- currents; similar results were obtained with LY294002 (10 μM). Additionally, current activation was inhibited by intracellular dialysis with antibodies specific for the 110-kDa catalytic subunit of PI 3-kinase. Since release of ATP is a critical element in the volume-regulatory pathway, the role of PI 3-kinase on volume-stimulated ATP release was assessed. Both wortmannin and LY294002 decreased basal and volume-stimulated ATP permeability but had no effect on the current response to exogenous ATP (10 μM). These findings indicate that PI 3-kinase plays a significant role in regulation of cell volume and suggest that the effects are mediated in part through modulation of cellular ATP release.
AB - Regulated changes in cell volume represent a signal that modulates a broad range of cell and organ functions. In HTC hepatoma cells, increases in volume are coupled to membrane ion permeability through a pathway involving (i) ATP efflux, (ii) autocrine stimulation of P2 receptors, and (iii) increases in anion permeability and Cl- efflux, contributing to recovery of volume toward basal values. Based on recent evidence that cell volume increases also stimulate phosphoinositide kinases, the purpose of these studies was to determine if phosphatidylinositol 3-kinase (PI 3-kinase) modulates these pathways. Exposure of cells to hypotonic buffer (20 or 40% less NaCl) caused an initial increase in cell volume and stimulated a rapid increase in ATP release. Subsequent opening of Cl- channels was followed by recovery of cell volume toward basal values, despite the continuous presence of hypotonic buffer. Inhibition of PI 3-kinase with wortmannin (K(i) = 3 nM) significantly inhibited both the rate of volume recovery and activation of Cl- currents; similar results were obtained with LY294002 (10 μM). Additionally, current activation was inhibited by intracellular dialysis with antibodies specific for the 110-kDa catalytic subunit of PI 3-kinase. Since release of ATP is a critical element in the volume-regulatory pathway, the role of PI 3-kinase on volume-stimulated ATP release was assessed. Both wortmannin and LY294002 decreased basal and volume-stimulated ATP permeability but had no effect on the current response to exogenous ATP (10 μM). These findings indicate that PI 3-kinase plays a significant role in regulation of cell volume and suggest that the effects are mediated in part through modulation of cellular ATP release.
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U2 - 10.1074/jbc.273.24.14906
DO - 10.1074/jbc.273.24.14906
M3 - Article
C2 - 9614094
AN - SCOPUS:0032510967
SN - 0021-9258
VL - 273
SP - 14906
EP - 14911
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 24
ER -