Reactive oxygen species

Willems, Peter

Koopman, WernerIn collaboration with the Dept. of Pediatrics, Peter Willems  (left) and Werner Koopman (right) of the Dept. of Biochemistry (286) recently published a study in the Journal Antioxidants & Redox Signaling, which demonstrates how reactive oxygen species (ROS) act as signaling molecules in healthy cells.  Cell regulation by signaling ROS ("sROS") is often incorrectly studied through extracellular oxidant addition. Here we used the membrane-permeable antioxidant Trolox to examine the role of sROS in mitochondrial morphology, oxidative phosphorylation (OXPHOS) and cytosolic calcium (Ca2+) handling in healthy human skin fibroblasts. Trolox treatment reduced the levels of CM-H2DCF oxidizing ROS, lowered cellular lipid peroxidation and induced a less oxidized mitochondrial thiol redox state. This was paralleled by increased glutathione- and mitofusin-dependent mitochondrial filamentation, increased expression of fully-assembled mitochondrial complex I, elevated activity of citrate synthase and OXPHOS enzymes, and a higher cellular O2 consumption. In contrast, Trolox did not alter hydroethidium oxidation, cytosolic thiol redox state, mitochondrial NAD(P)H levels or mitochondrial membrane potential. Whole genome expression profiling revealed that Trolox did not trigger significant changes in gene expression, suggesting that Trolox acts downstream of this process. Cytosolic Ca2+ transients, induced by the hormone bradykinin, were of higher amplitude and decayed faster in Trolox-treated cells. These effects were dose-dependently antagonized by hydrogen peroxide. Our findings suggest that Trolox-sensitive sROS are upstream regulators of mitochondrial mitofusin levels, morphology and function in healthy human skin fibroblasts. This information not only facilitates interpretation of antioxidant effects in cell models (of oxidative-stress), but also contributes to a better understanding of ROS-related human pathologies including mitochondrial dysfunction.  

Distelmaier F., Valsecchi, F., Forkink, M., van Emst-de Vries, S., Swarts, H., Rodenburg, R., Verwiel, E., Smeitink, J., Willems, P.H.G.M., Koopman, W.J.H. (2012) Trolox-sensitive ROS regulate mitochondrial morphology, oxidative phosphorylation and cytosolic calcium handling in healthy cells. Antioxidants and redox signaling.  (in press)


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