title: Cholesterol impairs the adenine nucleotide translocator-mediated mitochondrial permeability transition through altered membrane fluidity.
abstract: Mitochondrial permeability transition (MPT) has been proposed to play a key role in cell death. Downstream MPT events include the release of apoptogenic factors that sets in motion the mitochondrial apoptosome leading to caspase activation. The current work examined the regulation of MPT by membrane fluidity modulated upon cholesterol enrichment. Mitochondria enriched in cholesterol displayed increased microviscosity resulting in impaired MPT induced by atractyloside, a c-conformation stabilizing ligand of the adenine nucleotide translocator (ANT). This effect was dependent on the dose of cholesterol loaded and reversed upon the fluidization of mitochondria by the fatty acid derivative A2C. Mitoplasts derived from cholesterol-enriched mitochondria responded to atractyloside in a similar fashion as intact mitochondria, indicating that a significant amount of cholesterol is still found in the inner membrane. The effects of cholesterol on MPT induced by atractyloside were mirrored by the release of intermembrane proteins, cytochrome c, Smac/Diablo, and apoptosis inducing factor. However, cholesterol loading did not affect the uptake rate of adenine nucleotide hence dissociating the function of ANT as a MPT-mediated protein from its adenine nucleotide exchange function. Thus, these findings indicate that the ability of atractyloside to induce MPT via ANT requires an appropriate membrane fluidity range.
authors.affiliation: Liver Unit, Institut de Malalties Digestives, Hospital Clínic y Provincial, Instituto Investigaciones Biomédicas August Pi Suñer, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Colell
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Ruiz
authors.forename: Josep M
authors.initials: JM
authors.lastname: Lluis
authors.forename: Olga
authors.initials: O
authors.lastname: Coll
authors.forename: Montse
authors.initials: M
authors.lastname: Mari
authors.forename: José C
authors.initials: JC
authors.lastname: Fernández-Checa
mesh_terms: D000225:Adenine / Q000737:chemistry; D033741:Adenine Nucleotide Translocator 1 / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001278:Atractyloside / Q000737:chemistry / Q000494:pharmacology; D001692:Biological Transport; D015153:Blotting, Western; D016923:Cell Death; D002784:Cholesterol / Q000378:metabolism / Q000502:physiology*; D003574:Cytochrome c Group / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D010539:Permeability; D010743:Phospholipids / Q000378:metabolism; D011487:Protein Conformation; D051381:Rats; D013997:Time Factors
chemical_list: D033741:Adenine Nucleotide Translocator 1; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D010743:Phospholipids; D001278:Atractyloside; D002784:Cholesterol; D000225:Adenine