Glucose generates sub-plasma membrane ATP microdomains in single islet β-cells -: Potential role for strategically located mitochondria
Glucose generates sub-plasma membrane ATP microdomains in single islet β-cells -: Potential role for strategically located mitochondria
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DOI：
10.1074/jbc.274.19.13281
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发表时间：
1999-05-07
影响因子：
4.8
通讯作者：
Rutter, GA
中科院分区：
文献类型：
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作者：
Kennedy, HJ;Pouli, AE;Rutter, GA
胰岛β细胞内游离ATP浓度的增加可通过关闭ATP敏感性K+（K-ATP）通道和激活Ca 2+内流将血糖升高与胰岛素释放偶联。在这里，我们使用重组靶向腺苷三磷酸酶和光子计数成像来监测单个活的MING和原代β细胞的亚结构域中游离[ATP]的变化。细胞溶质（[ATP]（c））、线粒体基质（[ATP]（m））和质膜下（[ATP]（pm））中的静息[ATP]相似（与1 mM相似）。细胞外葡萄糖浓度升高（3-30 mM）增加了每个结构域中的游离[ATP]，具有不同的动力学。因此，观察到[ATP]（m）和[ATP]（pm）持续增加，但[ATP]（c）仅短暂增加。然而，[ATP]（c）和[ATP]（pm）可检测到的增加，但[ATP]（m）不增加，需要细胞外Ca 2+。高[K+]葡萄糖诱导的Ca 2+内流增加对[ATP]（c）和[ATP]（m）的表观增加影响不大，但增加了[ATP]（pm）的增加。在这些变化的基础上，葡萄糖增加了线粒体质子动力，这是高[K+]模拟的效果。这些数据支持了一个模型，其中葡萄糖增加[ATP]（m）通过增强底物供应和渐进的钙依赖性激活线粒体酶。这可能导致[ATP]（pm）的特权升高，这可能是K-ATP通道持续关闭所必需的。荧光素酶成像似乎是一个有用的新工具，在体内动态成像游离ATP浓度。
Increases in the concentration of free ATP within the islet beta-cell may couple elevations in blood glucose to insulin release by closing ATP sensitive K+ (K-ATP) channels and activating Ca2+ influx. Here, we use recombinant targeted luciferases and photon counting imaging to monitor changes in free [ATP] in subdomains of single living MING and primary beta-cells. Resting [ATP] in the cytosol ([ATP](c)), in the mitochondrial matrix ([ATP](m)), and beneath the plasma membrane ([ATP](pm)) were similar (similar to 1 mM). Elevations in extracellular glucose concentration (3-30 mM) increased free [ATP] in each domain with distinct kinetics. Thus, sustained increases in [ATP](m) and [ATP](pm) were observed, but only a transient increase in [ATP](c). However, detectable increases in [ATP](c) and [ATP](pm), but not [ATP](m), required extracellular Ca2+. Enhancement of glucose-induced Ca2+ influx with high [K+] had little effect on the apparent [ATP](c) and [ATP](m) increases but augmented the [ATP](pm) increase. Underlying these changes, glucose increased the mitochondrial proton motive force, an effect mimicked by high [K+]. These data support a model in which glucose increases [ATP](m) both through enhanced substrate supply and by progressive Ca2+ dependent activation of mitochondrial enzymes. This may then lead to a privileged elevation of [ATP](pm), which may be essential for the sustained closure of K-ATP channels. Luciferase imaging would appear to be a useful new tool for dynamic in vivo imaging of free ATP concentration.