Tetrahydropteridines possess antioxidant roles to guard against glucose-induced oxidative stress in Dictyostelium discoideum

Abstract

Glucose effects on the vegetative growth of Dictyostelium discoideumAx2 were studied by examining oxidative stress and tetrahydropteridinesynthesis in cells cultured with different concentrations(0.5X, 7.7 g L-1; 1X, 15.4 g L-1; 2X, 30.8 g L-1) ofglucose. The growth rate was optimal in 1X cells (cells grown in1X glucose) but was impaired drastically in 2X cells, below thelevel of 0.5X cells. There were glucose-dependent increases inreactive oxygen species (ROS) levels and mitochondrial dysfunctionin parallel with the mRNA copy numbers of the enzymescatalyzing tetrahydropteridine synthesis and regeneration. Onthe other hand, both the specific activities of the enzymes andtetrahydropteridine levels in 2X cells were lower than those in1X cells, but were higher than those in 0.5X cells. Given the antioxidantfunction of tetrahydropteridines and both the beneficialand harmful effects of ROS, the results suggest glucose-inducedoxidative stress in Dictyostelium, a process that might originatefrom aerobic glycolysis, as well as a protective role of tetrahydropteridinesagainst this stress. [BMB Reports 2013; 46(2):86-91]

Keywords

• Dictyostelium
• Glucose
• Mitochondria
• Oxidative stress
• Tetrahydropteridines