Non-visual Opsins and Novel Photo-Detectors in the Vertebrate Inner Retina Mediate Light Responses Within the Blue Spectrum Region

GUIDO MARIO EDUARDO; MARCHESE NATALIA; MAXIMILIANO RIOS; MOERA LUIS P.; DIAZ, NICOLÁS; EDUARDO GARBARINO-PICO; MARIA ANA CONTIN.

CELLULAR AND MOLECULAR NEUROBIOLOGY.

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 2020

0272-4340

In recent decades, a number of novel non-visual opsin photopigments belonging to the family of G protein- coupled receptors,likely involved in a number of non-image-forming processes, have been identiied and characterized in cells of theinner retina of vertebrates. It is now known that the vertebrate retina is composed of visual photoreceptor cones and rodsresponsible for diurnal/color and nocturnal/black and white vision, and cells like the intrinsically photosensitive retinalganglion cells (ipRGCs) and photosensitive horizontal cells in the inner retina, both detecting blue light and expressing thephotopigment melanopsin (Opn4). Remarkably, these non-visual photopigments can continue to operate even in the absenceof vision under retinal degeneration. Moreover, inner retinal neurons and Müller glial cells have been shown to express otherphotopigments such as the photoisomerase retinal G protein-coupled receptor (RGR), encephalopsin (Opn3), and neuropsin(Opn5), all able to detect blue/violet light and implicated in chromophore recycling, retinal clock synchronization, neuronto-glia communication, and other activities. The discovery of these new photopigments in the inner retina of vertebratesis strong evidence of novel light-regulated activities. This review focuses on the features, localization, photocascade, andputative functions of these novel non-visual opsins in an attempt to shed light on their role in the inner retina of vertebratesand in the physiology of the whole organism.