来自瑞典最好的医科大学Karolinska研究所的科学家最近揭开了胰岛细胞的秘密：它们如何在表面维持合适数量的检测ATP的离子通道蛋白。结果发表在最新的Cell  Metabolism上，它解释了人体如何维持正常血糖浓度，避免糖尿病发生。

   从食物中吸收的血糖将进入肌肉作为能量供给，或是进入肝脏或脂肪作为能量储备。如果以上过程没有发生，糖尿病就产生了。葡萄糖输送过程受到胰岛素的精确控制，胰岛素是人体负责降低血糖的激素，它由胰脏中的胰岛细胞分泌。

    ATP调控的负责传输钾离子的通道蛋白（KATP通道）位于胰岛细胞表面，它们帮助感应血糖及控制胰岛素分泌。但长久以来科学家一直不知道胰岛细胞如何在表面维持合适数量的KATP通道。现在，来自Rolf  Luft糖尿病和内分泌研究所、Karolinska研究所的科学家发现了血糖促进KATP的新途径。

   传统上科学家相信胰岛细胞中只有两种途径负责将新产生的胰岛素转移到细胞表面以便释放。一种是胰岛素分泌调节路径，另一种则负责更新细胞表面脂类和蛋白，其中包括KATP。

    Per-Olof  Berggren说：“我们发现胰岛内新产生的KATP存在于一个不含胰岛素的结构中，这是含有分泌标记颗粒嗜铬粒蛋白的结构。随着和钙离子及蛋白激酶相关的血糖浓度上升，这些结构将移动到细胞表面。”Berggren教授认为此发现非常重要。全新的路径保证了胰岛细胞有效维持表面合适的KATP通道数量，从而将血糖浓度维持在正常水平，不会引发糖尿病。 （教育部科技发展中心）

   原文链接：http://www.physorg.com/news108223955.html

原始出处:

Cell Metabolism, Vol 6, 217-228, 05 September 2007

Article

Glucose Recruits KATP Channels via Non-Insulin-Containing Dense-Core Granules

Shao-Nian Yang,1, Nancy Dekki Wenna,1,2 Jia Yu,1,2 Guang Yang,1,2 Hua Qiu,1 Lina Yu,1 Lisa Juntti-Berggren,1 Martin Köhler,1 and Per-Olof Berggren1,

1 The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden

Corresponding author
Shao-Nian Yang
shao-nian.yang@ki.se

Corresponding author
Per-Olof Berggren
per-olof.berggren@ki.se

β cells rely on adenosine triphosphate-sensitive potassium (KATP) channels to initiate and end glucose-stimulated insulin secretion through changes in membrane potential. These channels may also act as a constituent of the exocytotic machinery to mediate insulin release independent of their electrical function. However, the molecular mechanisms whereby the β cell plasma membrane maintains an appropriate number of KATP channels are not known. We now show that glucose increases KATP current amplitude by increasing the number of KATP channels in the β cell plasma membrane. The effect was blocked by inhibition of protein kinase A (PKA) as well as by depletion of extracellular or intracellular Ca2+. Furthermore, glucose promoted recruitment of the potassium inward rectifier 6.2 to the plasma membrane, and intracellular KATP channels localized in chromogranin-positive/insulin-negative dense-core granules. Our data suggest that glucose can recruit KATP channels to the β cell plasma membrane via non-insulin-containing dense-core granules in a Ca2+- and PKA-dependent manner.

                                                    摘自《生物谷》