Rapid glucose sensing by protein kinase A for insulin exocytosis in mouse pancreatic islets
Rapid glucose sensing by protein kinase A for insulin exocytosis in mouse pancreatic islets
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DOI：
10.1113/jphysiol.2005.096560
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发表时间：
2006-01-15
影响因子：
5.5
通讯作者：
Takahashi, N
中科院分区：
文献类型：
--
作者：
Hatakeyama, H;Kishimoto, T;Takahashi, N
用双光子激发小鼠胰岛细胞成像技术研究蛋白激酶A（PKA）在胰岛素胞吐中的作用。PKA抑制剂在葡萄糖诱导的胞吐（GIE）的第一阶段的初始期（< 250 s）选择性地减少胞吐事件的数量，而不影响完整胰岛或胰岛细胞的小簇的第二阶段。PKA抑制剂降低葡萄糖诱导的[Ca 2 +]增加的程度（i）。因此，研究了葡萄糖对钙诱导的胰岛素胞吐（CIE）中PKA的作用，该作用由笼状钙化合物引起，导致[Ca ~（2+）]（i）大量增加，从而绕过了ATP敏感的K ~+通道依赖的葡萄糖敏感机制。高浓度葡萄糖（20thmM）在1 min内增强CIE，这种作用可被PKA抑制剂阻断。这种PKA依赖的葡萄糖作用需要葡萄糖代谢，因为通过用毛喉素处理增加细胞内cAMP浓度仅在高葡萄糖浓度下增强CIE。最后，PKA似乎减少了“吻和运行”的胞吐事件的频率，并促进GIE期间的完全融合事件。这些数据表明，PKA依赖的葡萄糖传感机制，这是操作，甚至在PKA活性的基础水平，发挥了重要作用，特别是在第一阶段的GIE，他们建议，PKA的行动是介导的融合反应的水平。
The role of protein kinase A (PKA) in insulin exocytosis was investigated with the use of two-photon excitation imaging of mouse islets of Langerhans. Inhibitors of PKA selectively reduced the number of exocytic events during the initial period (< 250 s) of the first phase of glucose-induced exocytosis (GIE), without affecting the second phase, in intact islets or small clusters of islet cells. The PKA inhibitors de extent of the glucose-induced increase in [Ca2+](i). The actions of glucose andid not reduce th PKA in Ca2+-induced insulin exocytosis (CIE) trig photolysis ogered byf a caged-Ca2+ compound, which resulted in large increases in [Ca2+](i) and thereby bypassed the ATP-sensitive K+ channel-dependent mechanism of glucose sensing, were therefore studied. A high concentratmion (20 th mm) of glucose potentiated CIE within 1 min, andis effect was blocked by inhibitors of PKA. This PKA-dependent action of glucose required glucose metabolism, given that increasing the intracellular concentration of cAMP by treatment with forskolin potentiated CIE only at the high glucose concentration. Finally, PKA appeared to reduce the frequency of 'kiss-and-run' exocytic events and to promote full-fusion events during GIE. These data indicate that a PKA-dependent mechanism of glucose sensing, which is operative even at the basal level of PKA activity, plays an important role specifically in the first phase of GIE, and they suggest that the action of PKA is mediated at the level of the fusion reaction.