Electrochemical measurements reveal reactive oxygen species in stress granules

Abstract

Stress granules (SGs) are membraneless organelles that assemble in the cytoplasm to organize cellular contents and promote rapid adaptation during stress. To understand how SGs contribute to physiological functions, we used electrochemical measurements to detect electroactive species in SGs. With amperometry, we discovered that reactive oxygen species (ROS) are encapsulated inside arseniteinduced SGs, and H2O2 is the main species. The release kinetics of H2O2 from single SGs and the number of H2O2 molecules were quantified. The discovery that SGs contain ROS implicates them as communicators of the cellular stresses rather than a simple endpoint. This may explain how SGs regulate cellular metabolism and stress responses.