Specific disintegration of complex II succinate:ubiquinone oxidoreductase links pH changes to oxidative stress for apoptosis induction

Stefan Grimm (1) , Anthony Lemarie (1) , Laurence Huc (2) , Evangelos Pazarentzos (1) , Anne-Laure Mahul-Mellier (1)

1 Experimental Medicine and Toxicology
2 ToxAlim-COMICS - Contaminants & Stress Cellulaire

The formation of reactive oxygen species (ROS) and the change of the intracellular pH are common phenomena during apoptosis. How they are interconnected, however, is poorly understood. Here we show that numerous anticancer drugs as well as cytokines such as FasL and TNFα provoke intracellular acidification and cause the formation of mitochondrial ROS. In parallel we found that the succinate:ubiquinone oxidoreductase (SQR) activity of the mitochondrial respiratory complex II is specifically impaired without affecting the second enzymatic activity of this complex as a succinate dehydrogenase (SDH). Only in this configuration is complex II an apoptosis mediator and generates superoxides for cell death. This is achieved by the pHi decline that leads to the specific dissociation of the SDHA/SDHB subunits, which encompass the SDH activity, from the membrane-bound components of complex II that are required for the SQR activity.

Mots clés: reactive oxygen species; respiratory chain; complex II

Domaines: Sciences du Vivant [q-bio]

Stefan Grimm, Anthony Lemarie, Laurence Huc, Evangelos Pazarentzos, Anne-Laure Mahul-Mellier. Specific disintegration of complex II succinate:ubiquinone oxidoreductase links pH changes to oxidative stress for apoptosis induction. Cell Death and Differentiation, 2010, 18 (2), pp.338-349. ⟨10.1038/cdd.2010.93⟩. ⟨hal-00565452⟩