Melanopsin Tristability for Sustained and Broadband Phototransduction
Melanopsin Tristability for Sustained and Broadband Phototransduction
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DOI：
10.1016/j.neuron.2015.02.011
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发表时间：
2015-03-04
期刊：
影响因子：
16.2
通讯作者：
Do, Michael Tri Hoang
中科院分区：
文献类型：
--
作者：
Emanuel, Alan Joseph;Do, Michael Tri Hoang
哺乳动物依靠三种眼部感光细胞来感知光：视杆细胞、视锥细胞和本质光敏视网膜神经节细胞 (ipRGC)。视杆细胞和视锥细胞解析视觉场景中的细节。相反，ipRGC 在时间和空间上进行整合，主要是为了支持“非图像”视觉。ipRGC 的整合机制是神秘的，特别是因为这些细胞使用光转导基序，使果蝇等无脊椎动物能够以卓越的时间分辨率解析光。在这里，我们为允许 ipRGC 在时间和波长上整合的单一机制提供了证据。光将视觉色素黑视蛋白分布在三种状态，两种状态和一种状态。状态之间的光平衡维持了持续信号传导的色素可用性，信号传导状态的稳定性允许长达数分钟的时间求和，而沉默状态的适度光谱分离促进了跨波长的均匀激活。
Mammals rely upon three ocular photoreceptors to sense light: rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). Rods and cones resolve details in the visual scene. Conversely, ipRGCs integrate over time and space, primarily to support "non-image'' vision. The integrative mechanisms of ipRGCs are enigmatic, particularly since these cells use a phototransduction motif that allows invertebrates like Drosophila to parse light with exceptional temporal resolution. Here, we provide evidence for a single mechanism that allows ipRGCs to integrate over both time and wavelength. Light distributes the visual pigment, melanopsin, across three states, two silent and one signaling. Photoequilibration among states maintains pigment availability for sustained signaling, stability of the signaling state permits minutes-long temporal summation, and modest spectral separation of the silent states promotes uniform activation across wavelengths. By broadening the tuning of ipRGCs in both temporal and chromatic domains, melanopsin tristability produces signal integration for physiology and behavior.