Hall 2013 Biochim Biophys Acta
|Hall A, Larsen AK, Parhamifar L, Meyle KD, Wu LP, Moghimi SM (2013) High-resolution respirometry analysis of polyethylenimine-mediated mitochondrial energy crisis and cellular stress: Mitochondrial proton leak and inhibition of the electron transport system. Biochim Biophys Acta 1827:1213-25.|
Abstract: Polyethylenimines (PEIs) are highly efficient non-viral transfectants, but can induce cell death through poorly understood necrotic and apoptotic processes as well as autophagy. Through high-resolution respirometry studies in H1299 cells we demonstrate that the 25 kDa branched polyethylenimine (25k-PEI-B), in a concentration and time-dependent manner, facilitates mitochondrial proton leak and inhibits the electron transport system. These events were associated with gradual reduction of the mitochondrial membrane potential and mitochondrial ATP synthesis. The intracellular ATP levels further declined as a consequence of PEI-mediated plasma membrane damage and subsequent ATP leakage to the extracellular medium. Studies with freshly isolated mouse liver mitochondria corroborated with bioenergetic findings and demonstrated parallel polycation concentration- and time-dependent changes in State 2 and State 4o oxygen flux as well as lowered ADP phosphorylation (State 3) and mitochondrial ATP synthesis. Polycation-mediated reduction of electron transport system activity was further demonstrated in 'broken mitochondria' (freeze-thawed mitochondrial preparations). Moreover, by using both high-resolution respirometry and spectrophotometry analysis of cytochrome c oxidase activity we were able to identify Complex IV (cytochrome c oxidase) as a likely specific site of PEI mediated inhibition within the electron transport system. Unraveling the mechanisms of PEI-mediated mitochondrial energy crisis is central for combinatorial design of safer polymeric non-viral gene delivery systems.
• Keywords: Cell death, Cytochrome c oxidase, Electron transport system, Mitochondrial membrane potential, Mitochondrial uncoupling, Polyethylenimine
• O2k-Network Lab: DK Copenhagen Larsen A
Labels: MiParea: Respiration, Pharmacology;toxicology
Stress:Cell death Organism: Mouse Tissue;cell: Liver, Other cell lines Preparation: Isolated mitochondria, SMP
Regulation: Inhibitor, Uncoupler Coupling state: LEAK, ROUTINE, OXPHOS, ET Pathway: N, S, CIV, ROX HRR: Oxygraph-2k