Two Opsin 3-Related Proteins in the Chicken Retina and Brain: A TMT-Type Opsin 3 Is a Blue-Light Sensor in Retinal Horizontal Cells, Hypothalamus, and Cerebellum.
Two Opsin 3-Related Proteins in the Chicken Retina and Brain: A TMT-Type Opsin 3 Is a Blue-Light Sensor in Retinal Horizontal Cells, Hypothalamus, and Cerebellum.
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DOI：
10.1371/journal.pone.0163925
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Ohuchi H
中科院分区：
文献类型：
--
作者：
Kato M;Sugiyama T;Sakai K;Yamashita T;Fujita H;Sato K;Tomonari S;Shichida Y;Ohuchi H
视蛋白家族基因编码G蛋白偶联的七跨膜蛋白，其在光感受中结合视网膜醛发色团。在这里，我们寻找潜在的尚未描述的鸟类视网膜光感受器，专注于鸡中的视蛋白3同系物。我们在鸡基因组中发现了两个视蛋白3相关基因：一个对应于哺乳动物的脑视蛋白/全视蛋白（Opn 3），另一个属于硬骨鱼多组织视蛋白（TMT）2组。生物发光成像和G蛋白激活试验表明，鸡TMT视蛋白（cTMT）作为蓝光传感器的功能时，强制表达在哺乳动物培养细胞。我们没有检测到鸡Opn 3（cOpn 3）的光敏感性的证据。原位杂交显示cTMT在视网膜内层分化细胞亚群中表达，随着发育的进展，主要定位于视网膜水平细胞（HC）。免疫组织化学（IHC）显示，cTMT在HC以及少量的细胞中的神经节和内核层的孵化后的鸡视网膜。相比之下，cOpn 3-IR细胞在内核层中的不同细胞亚群中被发现。cTMT-IR细胞也见于下丘脑的细胞亚群中。最后，我们发现cOpn 3和cTMT蛋白在小脑特定细胞中的差异分布。本研究结果表明，一种新的TMT型视蛋白3可能在鸡视网膜和大脑中起感光器的作用。
Opsin family genes encode G protein-coupled seven-transmembrane proteins that bind a retinaldehyde chromophore in photoreception. Here, we sought potential as yet undescribed avian retinal photoreceptors, focusing on Opsin 3 homologs in the chicken. We found two Opsin 3-related genes in the chicken genome: one corresponding to encephalopsin/panopsin (Opn3) in mammals, and the other belonging to the teleost multiple tissue opsin (TMT) 2 group. Bioluminescence imaging and G protein activation assays demonstrated that the chicken TMT opsin (cTMT) functions as a blue light sensor when forced-expressed in mammalian cultured cells. We did not detect evidence of light sensitivity for the chicken Opn3 (cOpn3). In situ hybridization demonstrated expression of cTMT in subsets of differentiating cells in the inner retina and, as development progressed, predominant localization to retinal horizontal cells (HCs). Immunohistochemistry (IHC) revealed cTMT in HCs as well as in small numbers of cells in the ganglion and inner nuclear layers of the post-hatch chicken retina. In contrast, cOpn3-IR cells were found in distinct subsets of cells in the inner nuclear layer. cTMT-IR cells were also found in subsets of cells in the hypothalamus. Finally, we found differential distribution of cOpn3 and cTMT proteins in specific cells of the cerebellum. The present results suggest that a novel TMT-type opsin 3 may function as a photoreceptor in the chicken retina and brain.