On the mechanism by which 6‐ketocholestanol protects mitochondria against uncoupling‐induced Ca²⁺ efflux

Abstract

This work shows that 6-ketocholestanol (kCh) inhibits the effect of carbonyl cyanide-m-chlorophenyl hydrazone (CCP) on mitochondrial Ca 2÷ efflux. Such an effect proved to be caused by diminution of membrane fluidity, therefore, it is affected by the incubation temperature. Furthermore, kCh reversed CCPinduced Ca 2+ efflux depending on the accumulation of phosphate. It is also shown that kCh enhances the effect of carboxyatractyloside on membrane permeability transition.

FR58P1a; a new uncoupler of OXPHOS that inhibits migration in triple-negative breast cancer cells via Sirt1/AMPK/β1-integrin pathway

“…3f, no effect on the OCR induced by FR58P1a was observed. Then, to determine whether the uncoupling of mitochondria was mediated by protonophoric action of FR58P1a, we treated the isolated mitochondria with 6-ketocholestanol (6-Keto), a keto-derivative of cholesterol that decreases the membrane fluidity preventing uncoupling mediated by protonophores 27,28 . As shown in Fig.…”

Clofibrate-Induced Relocation of Phosphatidylcholine Transfer Protein to Mitochondria in Endothelial Cells

“…It is conceivable that relocation of PC-TP to mitochondria increases the amount of 16:0/PUFA-PC species in the mitochondrial membranes. The ensuing increase of membrane fluidity is reported to generate a number of responses, such as the enhancement of membrane-associated phospholipase A 2 activity [43], proton leakage [44,45], and Ca 2ϩ efflux [46]. Furthermore, changes in phospholipid fatty acid composition can alter the activity of carnitine palmitoyltransferase I [47,48] and of the pyruvate carrier [49,50].…”

Further studies on the recoupling effect of 6‐ketocholestanol upon oxidative phosphorylation in uncoupled liver mitochondria

“…Submitochondrial particles (SMP) were obtained by sonication of a suspension of thawed out rat liver mitochondria as described [13]. Fluorescence polarization was measured in SMP (1 mg protein/ml of IM) as reported in [10]. Oxygen consumption was recorded with a Clark‐type oxygen electrode.…”

“…After the control reading, 6‐kch was added. Calculations were carried out as indicated in [10]. All other experimental conditions are described in the corresponding figure legends.…”

“…The same coupling effect of 6‐kch was observed in rat liver mitochondria ATPase [7]and in plant mitochondria [8, 9]in the presence of uncouplers. In recent work, Chávez et al [10], demonstrated the inhibitory effect of 6‐kch on kidney mitochondria Ca 2+ efflux induced by CCCP, which proved to be caused by a diminution of the fluidity of the membrane, and depended on the accumulation of phosphate. Thus, the aim of this work was to make further studies on the effect of 6‐kch upon oxidative phosphorylation in rat liver mitochondria, and its behavior on an artificial system of cytochrome oxidase proteoliposomes and the uncoupler CCCP, in order to clarify its mechanism of action.…”