UV-B irradiation regulates apoptosis in yeast

Abstract

UV-B irradiation-induced reactive oxygen species (ROS) generates apoptosis. UV-B irradiation is known as an agent to modulate apoptosis in human cells as well as plants, but the mechanisms of apoptotic regulation of Saccharo-myces cerevisiae are not well established. The aim of our work is to evaluate the influence of continuous UV-B irradiation on defense mechanisms of antioxidants against cell death. To understand adaptive stress response during natural and artificially modulated (UV-B-induced) apoptosis, cells were adapted to sub-lethal dose of UV-B irradiation for 96 h or not. UV-B-induced apoptosis was revealed by cell death assay and DNA fragment assay. Oxidative damage induced by ROS was confirmed by SDS-PAGE. A sharply decrease of activity of antioxidant enzymes was appeared both in UV-B treated and control cells. By contrast, in continuous irradiated yeast cells, the level of SOD, CAT, and GR activity was increased by 1.1-, 1.1-, and 1.3-fold than those in control of 96 h, respectively. The contents of low-molecular weight antioxidants as trehalose and ergosterol increased but without significant changes in control. The results suggested that accumulation of antioxidants induced by UV-B would suppress apoptosis and played a main role to protect cells from death. © Springer-Verlag Berlin Heidelberg 2014.