Robert Stempel College of Public Health and Social Work, Department of Environmental and Occupational Health, Florida International University, Miami, FL 33199, USA.
Life Sci. 2011 Jan 31;88(5-6):257-64. doi: 10.1016/j.lfs.2010.12.002. Epub 2010 Dec 10.
The voltage dependent calcium channel (VDCC) e.g., L-type VDCC plays critical roles in the spatio-temporal regulation of intracellular calcium concentration (Ca(2+)) and insulin secretion by β-cell. This study describes the involvement of 2.5 to 15mM glucose-induced spatial interactions between a calcium sensing receptor (CaR) and L-type VDCC in controlling Ca(2+) channel activity and insulin secretion in β-cells in association with the nuclear translocation of a transcription factor nuclear factor kappa B (NF-κB).
The insulin producing β-cells were exposed to 2.5, 5, 7.5, 10, and 15 mM glucose for 24 h at 37 °C. The confocal fluorescence imaging data was obtained by using antibodies against CaR and L-type VDCC. The nuclear translocation of NF-κB was measured by confocal fluorescence imaging using antibody against NF-κB. The insulin release was determined by enzyme-linked immunosorbent assay (ELISA).
The confocal imaging data showed 6 to 12-fold enhancement in the colocalization correlation coefficient between CaR and VDCC in β-cells exposed to glucose thereby indicating increased membrane delimited spatial interactions between these two membrane proteins. The confocal fluorescence imaging data showed that addition of glucose to β-cells led to 1.8 to 2.7-fold increase in the nuclear translocation of NF-κB. The insulin ELISA data showed a significant increase in the 1st phase of glucose-induced insulin secretion in β-cells exposed to increasing concentrations of glucose.
The results described in the present study further strengthen that VDCC and CaR can interact spatially to allow control over calcium channel activity and therefore glucose-induced insulin secretion by β-cells.
电压依赖性钙通道（VDCC），例如 L 型 VDCC，在细胞内钙离子浓度（Ca(2+)）的时空调节和β细胞胰岛素分泌中起着关键作用。本研究描述了钙敏感受体（CaR）和 L 型 VDCC 之间的 2.5 至 15mM 葡萄糖诱导的空间相互作用，如何控制钙通道活性和β细胞胰岛素分泌，并与转录因子核因子 kappa B（NF-κB）的核转位相关。
将胰岛素分泌β细胞在 37°C 下暴露于 2.5、5、7.5、10 和 15mM 葡萄糖中 24 小时。使用针对 CaR 和 L 型 VDCC 的抗体获得共聚焦荧光成像数据。使用针对 NF-κB 的抗体通过共聚焦荧光成像测量 NF-κB 的核转位。通过酶联免疫吸附测定（ELISA）测定胰岛素释放量。
共聚焦成像数据显示，暴露于葡萄糖的β细胞中 CaR 和 VDCC 之间的共定位相关系数增加了 6 至 12 倍，表明这两种膜蛋白之间的膜限域空间相互作用增加。共聚焦荧光成像数据显示，向β细胞中添加葡萄糖会导致 NF-κB 的核转位增加 1.8 至 2.7 倍。胰岛素 ELISA 数据显示，暴露于葡萄糖的β细胞中，葡萄糖诱导的胰岛素分泌的第一相显著增加。
本研究中描述的结果进一步证实了 VDCC 和 CaR 可以在空间上相互作用，以控制钙通道活性，从而控制β细胞的葡萄糖诱导胰岛素分泌。
