Melanopsin triggers the release of internal calcium stores in response to light
Melanopsin triggers the release of internal calcium stores in response to light
复制标题
DOI：
10.1562/2006-07-11-ra-964
复制
发表时间：
2007-03-01
影响因子：
3.3
通讯作者：
Provencio, I.
中科院分区：
文献类型：
--
作者：
Kumbalasiri, T.;Rollag, M. D.;Provencio, I.
黑视素是赋予内在光敏视网膜神经节细胞（ipRGC）光敏性的色素。视网膜神经节细胞的这一亚群占哺乳动物视网膜中所有RGC的不到2%。黑视素阳性细胞的缺乏使得对黑视素信号传导的研究难以在ipRGC中进行。为了解决这个问题，我们已经建立了几个细胞系组成的转化的人胚肾细胞系（HEK293）稳定表达人黑视素。利用这些细胞系，我们研究了黑视蛋白光激活后引发的细胞内钙升高。我们的人黑视素表达细胞表现出细胞内钙离子的辐射依赖性增加。表达人黑视素的对照细胞，其中席夫碱赖氨酸已突变为丙氨酸，显示对光无反应。螯合细胞外钙对光诱导的细胞内钙的增加没有影响，这表明钙是从细胞内商店动员。这种参与的细胞内存储已被证实，通过他们的消耗毒胡萝卜素，抑制随后的光诱导的细胞内钙的增加。添加非选择性阳离子通道阻断剂镧不会改变光诱导的细胞内钙升高，进一步支持黑视素触发从内部储存释放内部钙。稳定表达黑视素的HEK293细胞已被证明是研究黑视素启动的信号传导的有用工具。
Melanopsin is the photopigment that confers photosensitivity upon intrinsically photosensitive retinal ganglion cells (ipRGCs). This subset of retinal ganglion cells comprises less than 2% of all RGCs in the mammalian retina. The paucity of melanopsin-positive cells has made studies on melanopsin signaling difficult to pursue in ipRGCs. To address this issue, we have established several cell lines consisting of a transformed human embryonic kidney cell line (HEK293) stably expressing human melanopsin. With these cell lines, we have investigated the intracellular rise in calcium triggered upon light activation of melanopsin. Our human melanopsin-expressing cells exhibit an irradiance-dependent increase in intracellular calcium. Control cells expressing human melanopsin, where the Schiff-base lysine has been mutated to alanine, show no responses to light. Chelating extracellular calcium has no effect on the light-induced increase in intracellular calcium suggesting that calcium is mobilized from intracellular stores. This involvement of intracellular stores has been confirmed through their depletion by thapsigargin, which inhibits a subsequent light-induced increase in intracellular calcium. Addition of the nonselective cation channel blocker lanthanum does not alter light-induced rises in intracellular calcium, further supporting that melanopsin triggers a release of internal calcium from internal stores. HEK293 cells stably expressing melanopsin have proven to be a useful tool to study melanopsin-initiated signaling.