TY - JOUR
T1 - Insulin stimulates membrane conductance in a liver cell line
T2 - Evidence for insertion of ion channels through a phosphoinositide 3-kinase-dependent mechanism
AU - Kilic, Gordan
AU - Doctor, R. Brian
AU - Fitz, J. Gregory
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2001/7/20
Y1 - 2001/7/20
N2 - Activation of insulin receptors stimulates a rapid increase in the ion permeability of liver cells. To evaluate whether this response involves insertion of ion channels, plasma membrane turnover was measured in a model liver cell line using the fluorescent membrane marker FM1-43. Under basal conditions, the rate of constitutive membrane turnover was ∼2%min -1, and balanced exocytosis and endocytosis maintained the total cell membrane area constant. Exposure to insulin stimulated a transient increase in membrane turnover of up to 10-fold above constitutive rates. The response was concentration-dependent (0.001-10 μM). Insulin also caused a parallel increase in membrane conductance as measured by whole-cell patch clamp recording due to opening of Cl-- and K+-selective ion channels. The insulin-stimulated membrane turnover did not appear to involve the constitutive recycling compartments, suggesting that a distinct pool of vesicles may be involved. The effects of insulin on membrane turnover and membrane conductance were inhibited by blockers of phosphoinositide 3-kinase LY294002 and wortmannin or by disrupting microtubule assembly with nocodazole. Taken together, these findings indicate that insulin stimulates recruitment of new membranes through phosphoinositide 3-kinase-dependent mechanisms. Thus, regulated insertion of a separate population of ion channel-containing vesicles may represent one mechanism for mediating the changes in membrane conductance that are essential for the cellular response to insulin.
AB - Activation of insulin receptors stimulates a rapid increase in the ion permeability of liver cells. To evaluate whether this response involves insertion of ion channels, plasma membrane turnover was measured in a model liver cell line using the fluorescent membrane marker FM1-43. Under basal conditions, the rate of constitutive membrane turnover was ∼2%min -1, and balanced exocytosis and endocytosis maintained the total cell membrane area constant. Exposure to insulin stimulated a transient increase in membrane turnover of up to 10-fold above constitutive rates. The response was concentration-dependent (0.001-10 μM). Insulin also caused a parallel increase in membrane conductance as measured by whole-cell patch clamp recording due to opening of Cl-- and K+-selective ion channels. The insulin-stimulated membrane turnover did not appear to involve the constitutive recycling compartments, suggesting that a distinct pool of vesicles may be involved. The effects of insulin on membrane turnover and membrane conductance were inhibited by blockers of phosphoinositide 3-kinase LY294002 and wortmannin or by disrupting microtubule assembly with nocodazole. Taken together, these findings indicate that insulin stimulates recruitment of new membranes through phosphoinositide 3-kinase-dependent mechanisms. Thus, regulated insertion of a separate population of ion channel-containing vesicles may represent one mechanism for mediating the changes in membrane conductance that are essential for the cellular response to insulin.
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U2 - 10.1074/jbc.M100992200
DO - 10.1074/jbc.M100992200
M3 - Article
C2 - 11349127
AN - SCOPUS:0035920235
SN - 0021-9258
VL - 276
SP - 26762
EP - 26768
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 29
ER -