IF1, the endogenous regulator of the F1Fo-ATPsynthase, defines mitochondrial volume fraction in HeLa cells by regulating autophagy

Michelangelo Campanella, Andreas Seraphim, Rosella Abeti, Edward Casswell, Pedro Echave, Michael R. Duchen

Research output: Contribution to journalArticle

Abstract

The protein IF1 limits mitochondrial ATP consumption when mitochondrial respiration is impaired by inhibiting the 'reverse' activity of the F1Fo-ATPsynthase. We have found that IF1 also increases F1Fo-ATPsynthase activity in respiring mitochondria, promoting its dimerization and increasing the density of mitochondrial cristae. We also noted that IF1 overexpression was associated with an increase in mitochondrial volume fraction that was conversely reduced when IF1 was knocked down using small interfering RNA (siRNA). The volume change did not correlate with the level of transcription factors involved in mitochondrial biogenesis. However, autophagy was dramatically increased in the IF1siRNA treated cells (-IF1), assessed by quantifying LC3-GFP translocation to autophagosomes, whilst levels of autophagy were low in IF1 overexpressing cells (+IF1). The increase in LC3-GFP labelled autophagosomes in -IF1 cells was prevented by the superoxide dismutase mimetic, manganese (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP). An increase in the basal rate of generation of reactive oxygen species (ROS) in -IF1 cells was demonstrated using the fluorescent probe dihydroethidium (DHE). Thus, IF1 appears to limit mitochondrial ROS generation, limiting autophagy which is increased by IF1 knockdown. Variations in IF1 expression level may therefore play a significant role in defining both resting rates of ROS generation and cellular mitochondrial content.

Original languageEnglish
Pages (from-to)393-401
Number of pages9
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1787
Issue number5
DOIs
Publication statusPublished - May 2009

Keywords

  • Autophagy
  • FF-ATPsynthase
  • IF1
  • Mitochondria
  • ROS

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology

Fingerprint Dive into the research topics of 'IF1, the endogenous regulator of the F1Fo-ATPsynthase, defines mitochondrial volume fraction in HeLa cells by regulating autophagy'. Together they form a unique fingerprint.

  • Cite this