Retinal melanopsin pathway: Signaling & Connectivity

描述(申请人提供)：除了视杆/视锥通路外，目前已知视网膜中还存在与黑素相关的光接收通路。这一途径涉及一小部分视网膜神经节细胞，这些细胞通过表达黑色素而具有内在的光敏性(IpRGCs)。除了其固有的光敏性，这些细胞还接受来自视杆/视锥通路的突触输入。与主要投射到大脑中成像视觉中心的常规RGC不同，ipRGC主要投射到非成像(辅助)视觉中心，后者控制着昼夜光携带和瞳孔光反射等功能。在研究黑素信号的实验过程中，我们意外地发现，哺乳动物的眼睛中存在一种内在的瞳孔光反射，显然也是由黑色素触发的。在NOT-OD-09-058中，我们建议仔细检查这一现象。具体来说，我们建议在现有的目标1至4的基础上，增加一项新的目标5。这款新的AIM 5有几个组成部分。目的5a是研究这种固有的瞳孔光反射的敏感性、强度-反应关系和动力学。目的5b是通过对WT动物的免疫细胞化学、tauLacZ敲击动物的X-Gal标记和我们以前培育的转BAC基因的tdTomato动物的荧光来鉴定黑素在小鼠虹膜中的位置。目的5c是为了筛选各种哺乳动物的虹膜，包括灵长类动物，以找出这种固有的瞳孔光敏性在不同物种中有多普遍。目的5d的目的是对ipRGCs的光传导机制进行初步研究，这也将有助于我们理解目前仍不清楚的ipRGCs的光传导机制。总之，拟议的实验将增强我们对黑素信号如何工作的整体理解，从而补充父母拨款的最初目标。预计拟议的实验可以在NOT-OD-09-058规定的两年时间窗口内完成。 公共卫生相关性：这项现有R01拨款的补编中提出的研究将加强我们对新发现的眼睛中的无杆/无锥体光接收系统的总体了解。从这些研究中获得的任何新信息都将与影响眼睛检测光线的疾病状态高度相关。

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.