Induction of stress granules in ganglion cells and the inner nuclear layer in a model of retinal degeneration caused by constant LED low-intensity light

PENAZZI, L GABRIELA; BENEDETTO, MARÍA M; MALCOM, MELISA; BRUERA, MANUEL G.; GUIDO, MARIO E.; CONTIN, MARÍA A; GARBARINO PICO, E

Mendoza

Congreso; LVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2022

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

The retina is a specialized light perception tissue that has evolved in an environment in which lightintensity values vary daily by several orders of magnitude as a consequence of the day/night cycle.During the day the retina is prepared to deal with the deleterious effects of light, but during the night, these protective mechanisms are diminished. Artificial light and the use of devices with luminous LED screens -such as cell phones, monitors or TVs- expose our retinas to light at times when the phototoxic effect cannot be avoided. In our laboratory we have developed a model of retinal degeneration caused by constant low intensity LED light in rats, in which accumulation of reactive oxygen species (ROS) and progressive cell death of cones and rods is observed. In the present work, considering that cellular stress induces the formation of stress granules (SGs), and that they have a protective role, we analyzed the presence of these ribonucleoprotein biocondensates in rat retinas maintained under constant light. SGs are formed in the cytoplasm as part of the integrated stress response, in which global protein synthesis is inhibited so that translation initiation complexes accumulate and give rise to liquid-liquid phase transitions giving origin to these biocondensates. Since they had not been described in this tissue, we first characterized them by immunohistochemistry (IHC) using two different antibodies (against eIF3 and G3BP1 markers) and by Fluorescence in situ hybridization (FISH), in control retinas and retinas treated with hydrogen peroxide or sodium arsenite (oxidative stress). We also did it on primary cultures of total retina. Once we were certain that we were detecting SGs, we proceeded to quantify them by IHC in the different retinal layers in control animals (kept under a 12 h light-12 h dark cycle, LD) and rats kept under constant LED light (LL) for 2-8 days (model of retinal degeneration). We found that retinas subjected to LL presented a significantly larger number of SGs. Notably, ganglion cells presented the highest number of SGs, cells of the inner nuclear layer also presented several granules, while the photoreceptor layer (cones and rods) presented almost no SGs. That is to say that the neurons that manage to survive during the first 8 days of LL are the ones that form more SGs, coinciding with the protective role attributed to them. This correlation has allowed us to propose the hypothesis that SGs would favor neuronal survival in the context of retinal photodamage.