Modulation of F₀F₁‐ATP synthase activity by cyclophilin D regulates matrix adenine nucleotide levels

Abstract

Cyclophilin D was recently shown to bind to and decrease the activity of F 0 F 1 -ATP synthase in submitochondrial particles and permeabilized mitochondria [Giorgio V et al. (2009) J Biol Chem, 284, 33982-33988]. Cyclophilin D binding decreased both ATP synthesis and hydrolysis rates. In the present study, we reaffirm these findings by demonstrating that, in intact mouse liver mitochondria energized by ATP, the absence of cyclophilin D or the presence of cyclosporin A led to a decrease in the extent of uncoupler-induced depolarization. Accordingly, in substrate-energized mitochondria, an increase in F 0 F 1 -ATP synthase activity mediated by a relief of inhibition by cyclophilin D was evident in the form of slightly increased respiration rates during arsenolysis. However, the modulation of F 0 F 1 -ATP synthase by cyclophilin D did not increase the adenine nucleotide translocase (ANT)-mediated ATP efflux rate in energized mitochondria or the ATP influx rate in de-energized mitochondria. The lack of an effect of cyclophilin D on the ANT-mediated adenine nucleotide exchange rate was attributed to the $ 2.2-fold lower flux control coefficient of the F 0 F 1 -ATP synthase than that of ANT, as deduced from measurements of adenine nucleotide flux rates in intact mitochondria. These findings were further supported by a recent kinetic model of the mitochondrial phosphorylation system, suggesting that an $ 30% change in F 0 F 1 -ATP synthase activity in fully energized or fully de-energized mitochondria affects the ADP-ATP exchange rate mediated by the ANT in the range 1.38-1.7%. We conclude that, in mitochondria exhibiting intact inner membranes, the absence of cyclophilin D or the inhibition of its binding to F 0 F 1 -ATP synthase by cyclosporin A will affect only matrix adenine nucleotides levels. Structured digital abstractl F0F1-ATPase beta and CypD physically interact by cross-linking study (View interaction) Abbreviations ANT, adenine nucleotide translocase; CYPD, cyclophilin D; DSP, 3,3¢-dithiobis(sulfosuccinimidylpropionate); FCC, flux control coefficient; KO, knockout; MgG, magnesium green; P i, inorganic phopshate; PTP, permeability transition pore; WT, wild-type; DWm, mitochondrial membrane potential.

Role of the c subunit of the FOATP synthase in mitochondrial permeability transition

“…31 In addition, CYPD as well as two distinct anti-apoptotic members of the BCL-2 family, namely BCL-X L and MCL-1, have recently been reported to regulate mitochondrial ATP synthesis by physically interacting with the F 1 F O ATP synthase. [32][33][34][35] Driven by these observations and by the facts that: (1) a selective inhibitor of the F O subunit of ATP synthase, i.e., oligomycin, is able to prevent cell death as induced by tumor necrosis factor α (TNFα), 36 the multi-kinase inhibitor staurosporine 37 or BAX overexpression; 38 and that (2) the activity of both the PTPC and F 1 F O ATP synthase is modulated by Mg 2+ ions; 39,40 we decided to investigate the role of F O ATP synthase subunits in MPT.…”

Cyclophilin D and myocardial ischemia–reperfusion injury: A fresh perspective

“…This binding negatively regulates the catalytic activity of ATP synthase without impacting the assembly of ATP synthase as demonstrated in CypD KO mouse model [70]. Additionally, CypD ablation has been observed to increase matrix ATP levels with no influence on cytosolic fraction or ATP influx/efflux via ANT [71]. Interestingly, the recent demonstration of ATP synthase as a putative structural component of mPTP has revised classical model of the mPTP.…”

Phosphate is not an absolute requirement for the inhibitory effects of cyclosporin A or cyclophilin D deletion on mitochondrial permeability transition

“…Alternatively, under energized conditions, the mitochondrial ATP synthase would use the As i to create ADP–As adducts instead of ATP [28]. The non-enzymatic hydrolysis of these adducts would create a futile cycle between ADP and ADP–As [29]. This, coupled with a reduction in ATP, would reduce the inhibitory effects of adenine nucleotide levels on the MPT pore, thereby further sensitizing it to Ca 2+ .…”