TY - JOUR
T1 - ATP modulates interaction of syntaxin-1A with sulfonylurea receptor 1 to regulate pancreatic β-Cell KATP channels
AU - Kang, Youhou
AU - Zhang, Yi
AU - Liang, Tao
AU - Leung, Yuk Man
AU - Ng, Betty
AU - Xie, Huanli
AU - Chang, Nathan
AU - Chan, Joseph
AU - Shyng, Show Ling
AU - Tsushima, Robert G.
AU - Gaisano, Herbert Y.
PY - 2011/2/18
Y1 - 2011/2/18
N2 - ATP-sensitive potassium (KATP) channels are regulated by a variety of cytosolic factors (adenine nucleotides, Mg2+, phospholipids, and pH). We previously reported that KATP channels are also regulated by endogenous membrane-bound SNARE protein syntaxin-1A (Syn-1A), which binds both nucleotide-binding folds of sulfonylurea receptor (SUR)1 and 2A, causing inhibition of KATP channel activity in pancreatic islet β-cells and cardiac myocytes, respectively. In this study, we show that ATP dose-dependently inhibits Syn-1A binding to SUR1 at physiological concentrations, with the addition of Mg2+ causing a decrease in the ATP-induced inhibitory effect. This ATP disruption of Syn-1A binding to SUR1 was confirmed by FRET analysis in living HEK293 cells. Electrophysiological studies in pancreatic β-cells demonstrated that reduced ATP concentrations increased KATP channel sensitivity to Syn-1A inhibition. Depletion of endogenous Syn-1A in insulinoma cells by botulinum neurotoxin C1 proteolysis followed by rescue with exogenous Syn-1A showed that Syn-1A modulates K ATP channel sensitivity to ATP. Thus, our data indicate that although both ATP and Syn-1A independently inhibit β-cell KATP channel gating, they could also influence the sensitivity of KATP channels to each other. These findings provide new insight into an alternate mechanism by which ATP regulates pancreatic β-cell KATP channel activity, not only by its direct actions on Kir6.2 pore subunit, but also via ATP modulation of Syn-1A binding to SUR1.
AB - ATP-sensitive potassium (KATP) channels are regulated by a variety of cytosolic factors (adenine nucleotides, Mg2+, phospholipids, and pH). We previously reported that KATP channels are also regulated by endogenous membrane-bound SNARE protein syntaxin-1A (Syn-1A), which binds both nucleotide-binding folds of sulfonylurea receptor (SUR)1 and 2A, causing inhibition of KATP channel activity in pancreatic islet β-cells and cardiac myocytes, respectively. In this study, we show that ATP dose-dependently inhibits Syn-1A binding to SUR1 at physiological concentrations, with the addition of Mg2+ causing a decrease in the ATP-induced inhibitory effect. This ATP disruption of Syn-1A binding to SUR1 was confirmed by FRET analysis in living HEK293 cells. Electrophysiological studies in pancreatic β-cells demonstrated that reduced ATP concentrations increased KATP channel sensitivity to Syn-1A inhibition. Depletion of endogenous Syn-1A in insulinoma cells by botulinum neurotoxin C1 proteolysis followed by rescue with exogenous Syn-1A showed that Syn-1A modulates K ATP channel sensitivity to ATP. Thus, our data indicate that although both ATP and Syn-1A independently inhibit β-cell KATP channel gating, they could also influence the sensitivity of KATP channels to each other. These findings provide new insight into an alternate mechanism by which ATP regulates pancreatic β-cell KATP channel activity, not only by its direct actions on Kir6.2 pore subunit, but also via ATP modulation of Syn-1A binding to SUR1.
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U2 - 10.1074/jbc.M109.089607
DO - 10.1074/jbc.M109.089607
M3 - Article
C2 - 21173146
AN - SCOPUS:79953144428
SN - 0021-9258
VL - 286
SP - 5876
EP - 5883
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 7
ER -