Cephalochordate melanopsin: Evolutionary linkage between invertebrate visual cells and vertebrate photosensitive retinal ganglion cells
Cephalochordate melanopsin: Evolutionary linkage between invertebrate visual cells and vertebrate photosensitive retinal ganglion cells
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DOI：
10.1016/j.cub.2005.04.063
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发表时间：
2005-06-07
期刊：
影响因子：
9.2
通讯作者：
Terakita, A
中科院分区：
文献类型：
--
作者：
Koyanagi, M;Kubokawa, K;Terakita, A
动物感光细胞可以分为两种不同的类型，这取决于色素是附着在修饰的纤毛（纤毛型）还是顶端微绒毛（横纹肌型）的膜上[1]。睫状光感受器作为脊椎动物的视杆细胞和视锥细胞是众所周知的，并且也在几种无脊椎动物中发现。相比之下，横纹感光细胞是无脊椎动物视觉细胞的主要类型，但在脊椎动物中从未发现过形态学上可识别的横纹感光细胞。据推测，由于参与细胞分化的一些分子在其中是共同的，因此横纹肌感光细胞已经进化为脊椎动物昼夜光诱导的光敏视网膜神经节细胞[2-4][5]。我们专注于头索动物文昌鱼，因为它是最接近脊椎动物的活无脊椎动物，有趣的是，它具有横纹感光细胞，用于假定的非视觉功能[6]。在这里，我们表明，文昌鱼的黑视蛋白同系物[7-9]，在脊椎动物的感光视网膜神经节细胞的昼夜节律色素，是在文昌鱼的横纹感光细胞中表达，其生化和光化学性质，而不仅仅是其一级结构，是相当相似的视觉视紫红质在横纹感光细胞的高等无脊椎动物。头索动物的横纹感光器代表了无脊椎动物视觉感光器和脊椎动物昼夜节律感光器之间的进化联系。
Animal photoreceptor cells can be classified into two distinct types, depending on whether the photopigment is borne on the membrane of a modified cilium (ciliary type) or apical microvilli (rhabdomeric type) [1]. Ciliary photoreceptors are well known as vertebrate rods and cones and are also found in several invertebrates. The rhabdomeric photoreceptor, in contrast, is a predominant type of invertebrate visual cell, but morphologically identifiable rhabdomeric photoreceptors have never been found in vertebrates. It is hypothesized that the rhabdomeric photoreceptor cell had evolved to be the photosensitive retinal ganglion cell for the vertebrate circadian photoentrainment [2-4] owing to the fact that some molecules involved in cell differentiation are common among them [5]. We focused on the cephalochordate amphioxus because it is the closest living invertebrate to the vertebrates, and interestingly, it has rhabdomeric photoreceptor cells for putative nonvisual functions [6]. Here, we show that the amphioxus homolog of melanopsin [7-9], the circadian photopigment in the photosensitive retinal ganglion cells of vertebrates, is expressed in the rhabdomeric photoreceptor cells of the amphioxus and that its biochemical and photochemical properties, not just its primary structure, are considerably similar to those of the visual rhodopsins in the rhabdomeric photoreceptor cells of higher invertebrates. The cephalochordate rhabdomeric photoreceptor represents an evolutionary link between the invertebrate visual photoreceptor and the vertebrate circadian photoreceptor.