Encephalopsin (OPN3) protein abundance in the adult mouse brain

Abstract

Encephalopsin belongs to the family of extraretinal opsins having a putative role in CNS tissue photosensitivity. Encephalopsin mRNA has earlier been localized in rodent brains, but expression and localization of the protein has not yet been reported. In this study, we aimed to define encephalopsin protein abundance and localization in the rodent brain. The distribution and localization of encephalopsin protein in a mouse brain and selected peripheral tissues were analysed in ten mice, using Western blotting and immunohistochemistry. The specificity of immunoreaction was validated by primary antibody omitting and immunizing peptide blocking experiment. We found encephalopsin protein abundant in the mouse brain, but not in the periphery. Encephalopsin protein was present in neurons of the mouse cerebral cortex, paraventricular area, and cerebellar cells. Our results show that encephalopsin is expressed at the protein level in different brain areas of the mouse. Therefore, the suggested idea that encephalopsin plays a role in non-visual photic processes seems to be applicable. Evidently, further investigations are needed to find out the signalling mechanisms, and the potential physiological role of encephalopsin in phototransduction due to the changes in ambient light.

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

“…We also tested for the involvement of two orphan pigments, encephalopsin (OPN3) (11) and neuropsin (OPN5) (12), both of which are expressed in mammalian retina and, when expressed heterologously, form light-sensitive pigments that activate G proteins (13)(14)(15)(16)(17). The function of OPN3 in mammals is unknown despite its widespread expression in neural tissues (18). OPN5 appears to be a deep-brain photopigment in the hypothalamus of birds and is thought to contribute to seasonal reproduction (19)(20)(21)(22); it has been immunolocalized to the mammalian inner retina (13, 16) (SI Text); however, to date, no retinal function for this mammalian pigment has been identified.…”

Transcranial Light Alters Melanopsin and Monoamine Production in Mouse (Mus musculus) Brain

“…The commonly acknowledged and best-known route for lightmediated effects is through the eye, where OPN4-containing ipRGCs gather light information and deliver it to the SCN via RHT [6,47,48]. Besides the retina, OPN4 is also found in the vertebrate brain [25,39] along with other opsins [10,12,13,39]. Additionally, OPN4 is considered to be an important molecule in adjusting the master clock and entraining the circadian rhythm [7][8][9]28], and light has been shown to act as a direct modulator for OPN4 actions [30].…”

“…It has been shown that mammalian brain consists of photosensitive opsin proteins also outside the RHT [10][11][12][13], and that light penetrates the mammalian skull [14][15][16][17]. It has been also proved that light is capable of phosphorylating OPN4, which inhibits the G protein-coupled activation [18], although only some OPN4 gene variants have been shown to affect the responses to light stimulus [19].…”

Optogenetic user s guide to Opto-GPCRs

“…The recently discovered blue-green light sensitive vertebrate encephalopsin is found in the brain and retina and believed to be at least partly involved in the regulation of the circadian melatonin production (44). The UV-sensitive vertebrate neuropsin is found throughout the body, but also in retinal ganglion, amacrine and horizontal cells where it was shown to couple to the Gi pathway (45).…”