期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：42
页码：13093-13098
DOI：10.1073/pnas.1516259112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThe behavioral circadian rhythms of mammals are synchronized to light/dark cycles through rods, cones, and melanopsin (OPN4)-expressing, intrinsically photosensitive ganglion cells in the retina. The molecular circadian rhythms in the mammalian retina are themselves synchronized to light/dark signals. We show here that this retinal photoentrainment, in an ex vivo setting, requires neuropsin (OPN5), an orphan opsin in mammals. Remarkably, the circadian clocks in the cornea are also photoentrained ex vivo in an OPN5-dependent manner. The molecular circadian clocks in the mammalian retina are locally synchronized by environmental light cycles independent of the suprachiasmatic nuclei (SCN) in the brain. Unexpectedly, this entrainment does not require rods, cones, or melanopsin (OPN4), possibly suggesting the involvement of another retinal photopigment. Here, we show that the ex vivo mouse retinal rhythm is most sensitive to short-wavelength light but that this photoentrainment requires neither the short-wavelength-sensitive cone pigment [S-pigment or cone opsin (OPN1SW)] nor encephalopsin (OPN3). However, retinas lacking neuropsin (OPN5) fail to photoentrain, even though other visual functions appear largely normal. Initial evidence suggests that OPN5 is expressed in select retinal ganglion cells. Remarkably, the mouse corneal circadian rhythm is also photoentrainable ex vivo, and this photoentrainment likewise requires OPN5. Our findings reveal a light-sensing function for mammalian OPN5, until now an orphan opsin.
