Pentadecyl, an Active Component of Microalgae, Ameliorates Endoplasmic Reticulum Stress and Blue Light-Induced Cell Death in Mouse Retina-Derived 661W Cells

Abstract

Light stress is a risk factor leading to retinal diseases such as age-related macular degeneration. However, the mechanism underlying the stress response to light in the retina has yet to be elucidated. We have reported that exposure to blue light-emitting diode light induces excessive production of reactive oxygen species and activates the unfolded protein response, robustly increasing activating transcription factor 4 (ATF4) expression. These processes result in photoreceptor cell death. This study investigates the effects of Pentadecyl, a bioactive product obtained from Aurantiochytrium limacinum, on either chemical-induced or blue light-induced endoplasmic reticulum (ER) stress. Pentadecyl suppressed cell death induced by either thapsigargin or tunicamycin in a concentration-dependent manner. Pentadecyl also suppressed the expression of unfolded protein response target genes, including Atf4 and ER chaperones. Consistently, immunoblotting revealed that Pentadecyl suppressed the increased expression of ATF4 at the protein level. Pentadecyl also protected 661W cells from blue light-induced damage but did not protect against hydrogen peroxide (H₂O₂)-induced oxidative stress. These results indicated that Pentadecyl has a novel function that protects against ER stress induced by photodamage.