Abstract
Melanopsin (OPN4) is a photo-pigment found in a small subset of intrinsically photosensitive ganglion cells (ipRGCs) of the mammalian retina. These cells play a role in synchronizing the central circadian pacemaker to the astronomical day by conveying information about ambient light to the hypothalamic suprachiasmatic nucleus, the site of the master clock. We evaluated the effect of a heat stimulus (39.5 °C) on clock gene (Per1 and Bmal1) expression in cultured murine Melan-a melanocytes synchronized by medium changes, and in B16-F10 melanoma cells, in the presence of the selective OPN4 antagonist AA92593, or after OPN4 knockdown by small interfering RNA (siRNA). In addition, we evaluated the effects of heat shock on the localization of melanopsin by immunocytochemistry. In both cell lines melanopsin was found in a region capping the nucleus and heat shock did not affect its location. The heat-induced increase of Per1 expression was inhibited when melanopsin was pharmacologically blocked by AA92593 as well as when its protein expression was suppressed by siRNA in both Melan-a and B16-F10 cells. These data strongly suggest that melanopsin is required for thermo-reception, acting as a thermo-opsin that ultimately feeds the local circadian clock in mouse melanocytes and melanoma cells.
Highlights
IpRGC axons release glutamate at the SCN neurons, increasing Per transcripts which reset the clock gene machinery
Our group has shown that melanopsin and rhodopsin are expressed in murine melanocytes and melanoma cells where they may participate in a photo-sensitive system[15]
We questioned whether an opsin could function as a thermo-sensor in mammalian cells, conveying temperature information to the clock gene machinery of cutaneous melanocytes, cells known to be exposed to cycles of environmental light and temperature[16]
Summary
Maria Nathália Moraes[1], Leonardo Vinícius Monteiro de Assis[1], Keila Karoline MagalhãesMarques[1], Maristela Oliveira Poletini[2], Leonardo Henrique Ribeiro Graciani de Lima1 & Ana Maria de Lauro Castrucci[1,3]. The canonical role of melanopsin (OPN4) is to act as a photo-pigment in the mammalian intrinsically photosensitive retinal ganglion cells (ipRGCs)[1] These cells play a role in synchronizing the central circadian pacemaker[2] to the astronomical day by conveying information about ambient light to the hypothalamic suprachiasmatic nucleus (SCN), the site of the master clock[3]. Since the vascular physiology is under circadian control[14], one may suggest that melanopsin could act as sensor that feeds the local temporal controlling system Following this line, our group has shown that melanopsin and rhodopsin are expressed in murine melanocytes and melanoma cells where they may participate in a photo-sensitive system[15]. We questioned whether an opsin could function as a thermo-sensor in mammalian cells, conveying temperature information to the clock gene machinery of cutaneous melanocytes, cells known to be exposed to cycles of environmental light and temperature[16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
