Retinal melanopsin pathway: Signaling & Connectivity

描述（由申请人提供）：除了杆状/锥状通路外，现在已知在视网膜中存在黑视素相关的光接受通路。这一途径涉及一小部分视网膜神经节细胞，它们通过表达色素黑视素而具有内在光敏性（ipRGCs）。除了它们固有的光敏性外，这些细胞还接受来自杆状/锥状通路的突触输入。常规RGCs主要投射到大脑的图像形成视觉中心，而ipRGCs主要投射到非图像形成（辅助）视觉中心，后者控制昼夜节律光干扰和瞳孔光反射等功能。在亲本R01 EY14596资助的黑视素信号传导实验中，我们意外地发现，哺乳动物眼睛中存在一种内在的瞳孔光反射，显然也是由黑视素触发的。根据NOT-OD-09-058，我们建议仔细检查这一现象。具体来说，我们建议在父母补助金的现有目标1-4中增加新的目标5。这种新的Aim 5有几个组成部分。目的5a：探讨瞳孔固有光反射的敏感性、强效关系和动力学。目的5b是通过免疫细胞化学对WT动物、X-gal标记对taulacz敲入动物和我们之前产生的BAC转基因tdTomato动物的荧光检测来确定黑视素在小鼠虹膜中的位置。目标5c是筛选各种哺乳动物物种的虹膜，包括灵长类动物，以找出这种内在的瞳孔光敏性在物种间的普遍程度。目的5d是对潜在的光传导机制进行初步研究，这也将有助于我们理解尚不清楚的iprgc的光传导机制。总之，拟议的实验将增强我们对黑视素信号传导如何工作的整体理解，从而补充了父母资助的最初目的。预计拟议的实验可以在NOT-OD-09-058规定的2年时间窗口内完成。

DESCRIPTION (provided by applicant): Besides the rod/cone pathways, a melanopsin-associated photoreception pathway is now known to exist in the retina. This pathway involves a small subset of retinal ganglion cells that are intrinsically photosensitive (ipRGCs) by expressing the pigment melanopsin. Besides their intrinsic photosensitivity, these cells also receive synaptic inputs from the rod/cone pathways. Unlike the regular RGCs, which project predominantly to image-forming visual centers in the brain, the ipRGCs project primarily to non-image-forming (accessory) visual centers, which control functions such as circadian photoentrainment and pupillary light reflex. In the course of on-going experiments to study melanopsin-signaling supported by the parent grant R01 EY14596, we have unexpectedly found that there is an intrinsic pupillary light reflex in the mammalian eye apparently also triggered by melanopsin. Under NOT-OD-09-058, we propose to examine closely this phenomenon. Specifically, we propose to add a new Aim 5 to the existing Aims 1-4 in the parent grant. This new Aim 5 has several components. Aim 5a is to examine the sensitivity, intensity-response relation and kinetics of this intrinsic pupillary light reflex. Aim 5b is to identify the location of melanopsin in the mouse iris by using immunocytochemistry on WT animals, X-gal labeling on tauLacZ-knockin animals and fluorescence from BAC transgenic tdTomato animals that we have previously generated. Aim 5c is to screen the irises of various mammalian species, including primates, in order to find out how prevalent this intrinsic pupil photosensitivity is across species. Aim 5d is to make a first-pass study of the underlying phototransduction mechanism, which will also help us understand the still-unclear phototransduction mechanism in ipRGCs. Together, the proposed experiments will enhance our overall understanding of how melanopsin-signaling works, thus complementing the original Aims of the parent grant. It is anticipated that the proposed experiments can be completed in the 2-year time window as specified by NOT-OD-09-058. PUBLIC HEALTH RELEVANCE: The studies proposed in this Supplement to an existing R01 grant will enhance our overall understanding of the newly discovered non-rod/none-cone photoreception system in the eye. Any new information derived from these studies will be highly relevant to disease states affecting light detection by the eye.