Photon capture and signalling by melanopsin retinal ganglion cells.
Photon capture and signalling by melanopsin retinal ganglion cells.
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DOI：
10.1038/nature07682
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发表时间：
2009-01-15
期刊：
影响因子：
64.8
通讯作者：
Yau, King-Wai
中科院分区：
文献类型：
--
作者：
Do, Michael Tri H.;Kang, Shin H.;Xue, Tian;Zhong, Haining;Liao, Hsi-Wen;Bergles, Dwight E.;Yau, King-Wai
最近发现视网膜神经节细胞的一个子集具有本质光敏性，以黑视蛋白为色素。这些细胞主要投射到大脑中心，以实现非图像形成视觉功能，例如瞳孔光反射和昼夜节律光诱导。它们如何有效地发出内在光吸收信号以驱动行为仍不清楚。在这里，我们报告了控制其固有光响应和相关尖峰生成的基本参数。黑视蛋白的膜密度比视杆细胞和视锥细胞色素的膜密度低 104 倍，导致光子捕获量非常低，并且仅在相对明亮的光线下发挥光转导作用。尽管如此，每个捕获的光子都会引起大量且非常长时间的响应，并且在已知的光感受器中具有独特的形状。值得注意的是，像杆状细胞一样，这些细胞能够发出单光子吸收信号。闪光在视网膜中引起数百个异构化黑视蛋白分子足以达到瞳孔对光反射的阈值。
A subset of retinal ganglion cells has recently been discovered to be intrinsically photosensitive, with melanopsin as the pigment. These cells project primarily to brain centers for non-image-forming visual functions such as the pupillary light reflex and circadian photoentrainment. How well they signal intrinsic light absorption to drive behavior remains unclear. Here we report fundamental parameters governing their intrinsic light responses and associated spike generation. The membrane density of melanopsin is 104-fold lower than that of rod and cone pigments, resulting in a very low photon-catch and a phototransducing role only in relatively bright light. Nonetheless, each captured photon elicits a large and extraordinarily prolonged response, with a unique shape among known photoreceptors. Remarkably, like rods, these cells are capable of signalling single-photon absorption. A flash causing a few hundred isomerized melanopsin molecules in a retina is sufficient for reaching threshold for the pupillary light reflex.
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