Abstract
BACKGROUND: Within cells, there is a narrow concentration threshold that governs whether reactive oxygen species (ROS) induce toxicity or act as second messengers. SCOPE OF REVIEW: We discuss current understanding of how ROS arise, facilitate cell signaling, cause toxicities and disease related to abnormal cell differentiation and those (primarily) sulfur based pathways that provide nucleophilicity to offset these effects. PRIMARY CONCLUSIONS: Cellular redox homeostasis mediates a plethora of cellular pathways that determine life and death events. For example, ROS intersect with GSH based enzyme pathways to influence cell differentiation, a process integral to normal hematopoiesis, but also affecting a number of diverse cell differentiation related human diseases. Recent attempts to manage such pathologies have focused on intervening in some of these pathways, with the consequence that differentiation therapy targeting redox homeostasis has provided a platform for drug discovery and development. GENERAL SIGNIFICANCE: The balance between electrophilic oxidative stress and protective biomolecular nucleophiles predisposes the evolution of modern life forms. Imbalances of the two can produce aberrant redox homeostasis with resultant pathologies. Understanding the pathways involved provides opportunities to consider interventional strategies. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.