The signaling pathway in photoresponses that may be mediated by visual pigments in erythrophores of Nile tilapia
The signaling pathway in photoresponses that may be mediated by visual pigments in erythrophores of Nile tilapia
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DOI：
10.1111/j.1600-0749.2005.00267.x
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发表时间：
2005-10-01
期刊：
影响因子：
--
通讯作者：
Oshima, N
中科院分区：
文献类型：
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作者：
Ban, E;Kasai, A;Oshima, N
响应于光而增加色素的合成或改变色素的分布的能力是许多色素细胞的重要特征。与其他光敏色素细胞不同，尼罗罗非鱼的红细胞会根据入射光的峰值波长改变色素迁移的方向：365、400或600 nm附近的光诱导色素聚集，而500 nm处的光则会引起分散。这些现象是如何实现的，目前尚不清楚。本研究采用百日咳毒素、霍乱毒素、离子通道阻断剂、影响信号传导途径一系列步骤的各种化学物质和膜渗透性cAMP类似物，研究了500 nm光引起的色素分散或600 nm光引起的色素聚集中涉及的光转导。结果表明，光诱导的罗非鱼红细胞的双向运动可能是由细胞质cAMP水平通过Gi或GS型G蛋白控制。此外，RT-PCR首次证明了编码红色和绿色视蛋白的mRNA在罗非鱼鳍中的表达，只有在红细胞存在的地方。在这里，我们建议，多个锥型视色素可能存在于红细胞，和独特的级联反应，其中这样的视蛋白耦合到Gi或GS型G蛋白参与这些色素细胞的光反应。因此，罗非鱼红细胞系统似乎是一个很好的模型，了解细胞以外的视觉细胞的光响应。
The ability to increase the synthesis or vary the distribution of pigment in response to light is an important feature of many pigment cells. Unlike other light-sensitive pigment cells, erythrophores of Nile tilapia change the direction of pigment migration depending on the peak wavelength of incident light: light near 365, 400 or 600 nm induces pigment aggregation, while dispersion occurs in response to light at 500 nm. How these phenomena are achieved is currently unknown. In the present study, the phototransduction involved in the pigment dispersion caused by light at 500 nm or the aggregation by light at 600 nm was examined, using pertussis toxin, cholera toxin, blockers of ion channels, various chemicals affecting serial steps of signaling pathways and membrane-permeable cAMP analog. The results show that light-induced bidirectional movements in tilapia erythrophores may be controlled by cytosolic cAMP levels via Gi- or Gs-type G proteins. In addition, RT-PCR demonstrated for the first time the expression of mRNAs encoding red and green opsins in tilapia fins, only where erythrophores exist. Here, we suggest that multiple cone-type visual pigments may be present in the erythrophores, and that unique cascades in which such opsins couple to Gi or Gs-type G proteins are involved in the photoresponses in these pigment cells. Thus, tilapia erythrophore system seems to be a nice model for understanding the photoresponses of cells other than visual cells.