High resolution respirometry analysis of polyethylenimine-mediated mitochondrial energy crisis and cellular stress: Mitochondrial proton leak and inhibition of the electron transport system

Arnaldur Hall, Anna K. Larsen, Ladan Parhamifar, Kathrine D. Meyle, Lin Ping Wu, S. Moein Moghimi

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

Polyethylenimines (PEIs) are highly efficient non-viral transfectants, but can induce cell death through poorly understood necrotic and apoptotic processes aswell 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 themitochondrial 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 concentrationand 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.

Original languageEnglish (US)
Pages (from-to)1213-1225
Number of pages13
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1827
Issue number10
DOIs
StatePublished - 2013

Keywords

  • Cell death
  • Cytochrome c oxidase
  • Electron transport system
  • Mitochondrial membrane potential
  • Mitochondrial uncoupling
  • Polyethylenimine

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology

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