Neuropsin (OPN5)-mediated photoentrainment of local circadian oscillators in mammalian retina and cornea

The 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.