Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada.
Pigment Cell Melanoma Res. 2018 May;31(3):354-373. doi: 10.1111/pcmr.12678. Epub 2018 Jan 5.
Melanopsin photopigments, Opn4x and Opn4m, were evolutionary selected to "see the light" in systems that regulate skin colour change. In this review, we analyse the roles of melanopsins, and how critical evolutionary developments, including the requirement for thermoregulation and ultraviolet protection, the emergence of a background adaptation mechanism in land-dwelling amphibian ancestors and the loss of a photosensitive pineal gland in mammals, may have helped sculpt the mechanisms that regulate light-controlled skin pigmentation. These mechanisms include melanopsin in skin pigment cells directly inducing skin darkening for thermoregulation/ultraviolet protection; melanopsin-expressing eye cells controlling neuroendocrine circuits to mediate background adaptation in amphibians in response to surface-reflected light; and pineal gland secretion of melatonin phased to environmental illuminance to regulate circadian and seasonal variation in skin colour, a process initiated by melanopsin-expressing eye cells in mammals, and by as yet unknown non-visual opsins in the pineal gland of non-mammals.
黑视蛋白光色素，Opn4x 和 Opn4m，是为了在调节皮肤颜色变化的系统中“感知光线”而进化选择的。在这篇综述中，我们分析了黑视蛋白的作用，以及包括体温调节和紫外线保护的关键进化发展、陆地两栖动物祖先中背景适应机制的出现以及哺乳动物中感光松果体的丧失等因素，如何帮助塑造调节光控皮肤色素沉着的机制。这些机制包括皮肤色素细胞中的黑视蛋白直接诱导皮肤变暗以进行体温调节/紫外线保护；表达黑视蛋白的眼细胞控制神经内分泌回路，以响应表面反射光介导两栖动物的背景适应；以及松果腺分泌褪黑素与环境光照相适应，调节皮肤颜色的昼夜和季节性变化，这一过程由哺乳动物中表达黑视蛋白的眼细胞启动，而在非哺乳动物的松果腺中则由未知的非视觉视蛋白启动。
