Division of Correlative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Neurosci Res. 2013 Jan;75(1):3-5. doi: 10.1016/j.neures.2012.07.010. Epub 2012 Sep 12.
Melanopsin (OPN4) is a photosensitive pigment originally found in a subtype of retinal ganglion cells and is a 7-transmembrane G-protein-coupled receptor (GPCR). Several previous reports showed that ectopic expression of OPN4 can be used as an optogenetic tool to control neural and cellular activities in various tissues. Compared with other optogenetic pigments, OPN4 is more sensitive to light, shows long-lasting activation, and can also control intracellular Ca(2+) dynamics. Here, we review how the ectopic expression of OPN4 enables the control of neural and cellular activities in vivo. In the retina, the ectopic expression of melanopsin in retinal ganglion cells successfully restored the vision of blind mice. It has also been reported that ectopic expression of melanopsin in orexin/hypocretin neurons enabled control of wakefulness in mice by blue light. In addition to neural activity, the ectopic expression of OPN4 has been reported to enable circuit control of the nuclear factor of activated T cells (NFAT) to enhance blood-glucose homeostasis in mice. We discuss the possibility of optogenetic control of other systems through the ectopic expression of OPN4.
黑视蛋白（OPN4）是最初在视网膜神经节细胞的一种亚型中发现的感光色素，是一种 7 次跨膜 G 蛋白偶联受体（GPCR）。有几项先前的报告表明，OPN4 的异位表达可用作光遗传学工具，以控制各种组织中的神经和细胞活动。与其他光遗传学色素相比，OPN4 对光更敏感，表现出持久的激活作用，还可以控制细胞内 Ca(2+)动力学。在这里，我们回顾了 OPN4 的异位表达如何能够控制体内的神经和细胞活动。在视网膜中，视网膜神经节细胞中黑视蛋白的异位表达成功地恢复了盲鼠的视力。也有报道称，在食欲素/下丘脑分泌素神经元中异位表达黑视蛋白，通过蓝光能够控制小鼠的觉醒。除了神经活动，据报道，OPN4 的异位表达还能够控制 T 细胞激活因子（NFAT）的核因子的回路控制，从而增强小鼠的血糖稳态。我们讨论了通过 OPN4 的异位表达对其他系统进行光遗传学控制的可能性。
