荧光生物传感器可揭示特定β细胞内体亚群中的钙水平。
Fluorescent biosensors illuminate calcium levels within defined beta-cell endosome subpopulations.
作者信息
Albrecht Tobias, Zhao Yongxin, Nguyen Trang Hai, Campbell Robert E, Johnson James D
机构信息
Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada.
Department of Chemistry, University of Alberta, Edmonton, AB, Canada.
出版信息
Cell Calcium. 2015 Apr;57(4):263-74. doi: 10.1016/j.ceca.2015.01.008. Epub 2015 Jan 28.
Live cell imaging has revealed that calcium ions (Ca(2+)) pass in and out of many cellular organelles. However, technical hurdles have limited measurements of Ca(2+) in acidic organelles, such as endosomes. Although evidence hints that endosomes play a role in Ca(2+) signaling, direct measurements within endosomal lumina represent one of the final frontiers in organelle imaging. To measure Ca(2+) in a TiVAMP-positive endosome sub-population, the pH-resistant ratiometric Ca(2+) biosensor GEM-GECO1 and the ratiometric pH biosensor mKeima were used. A positive correlation between acidic endosomal pH and higher Ca(2+) was observed within these Rab5a- and Rab7-positive compartments. Ca(2+) concentration in most endosomes was estimated to be below 2μM, lower than Ca(2+) levels in several other intracellular stores, indicating that endosomes may take up Ca(2+) during physiological stimulation. Indeed, endosomes accumulated Ca(2+) during glucose-stimulation, a condition where endosomal pH did not change. Our biosensors permitted the first measurements revealing a role for endosomes in cellular Ca(2+) homeostasis during physiological stimulation.
活细胞成像显示钙离子（Ca(2+)）可进出许多细胞器。然而，技术障碍限制了对酸性细胞器（如内体）中Ca(2+)的测量。尽管有证据表明内体在Ca(2+)信号传导中起作用，但在内体腔室内进行直接测量仍是细胞器成像的最后前沿领域之一。为了测量TiVAMP阳性内体亚群中的Ca(2+)，使用了抗pH的比率型Ca(2+)生物传感器GEM-GECO1和比率型pH生物传感器mKeima。在这些Rab5a和Rab7阳性区室中，观察到酸性内体pH与较高Ca(2+)之间存在正相关。大多数内体中的Ca(2+)浓度估计低于2μM，低于其他几个细胞内储存库中的Ca(2+)水平，这表明内体可能在生理刺激期间摄取Ca(2+)。事实上，在葡萄糖刺激期间内体积累了Ca(2+)，而在此条件下内体pH没有变化。我们的生物传感器首次测量揭示了内体在生理刺激期间细胞Ca(2+)稳态中的作用。
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