Inhibition of complex I regulates the mitochondrial permeability transition through a phosphate-sensitive inhibitory site masked by cyclophilin D

Abstract

Inhibition of the mitochondrial permeability transition pore (PTP) has proved to be an effective strategy for preventing oxidative stress-induced cell death, and the pore represents a viable cellular target for drugs. Here, we report that inhibition of complex I by rotenone is more effective at PTP inhibition than cyclosporin A in tissues that express low levels of the cyclosporin A mitochondrial target, cyclophilin D; and, conversely, that tissues in which rotenone does not affect the PTP are characterized by high levels of expression of cyclophilin D and sensitivity to cyclosporin A. Consistent with a regulatory role of complex I in the PTP-inhibiting effects of rotenone, the concentrations of the latter required for PTP inhibition precisely match those required to inhibit respiration; and a similar effect is seen with the antidiabetic drug metformin, which partially inhibits complex I. Remarkably (i) genetic ablation of cyclophilin D or its displacement with cyclosporin A restored PTP inhibition by rotenone in tissues that are otherwise resistant to its effects; and (ii) rotenone did not inhibit the PTP unless phosphate was present, in striking analogy with the phosphate requirement for the inhibitory effects of cyclosporin A [Basso et al. (2008) J. Biol. Chem. 283, 26307-26311]. These results indicate that inhibition of complex I by rotenone or metformin and displacement of cyclophilin D by cyclosporin A affect the PTP through a common mechanism; and that cells can modulate their PTP response to complex I inhibition by modifying the expression of cyclophilin D, a finding that has major implications for pore modulation in vivo.

F-ATPase of Drosophila melanogaster Forms 53-Picosiemen (53-pS) Channels Responsible for Mitochondrial Ca2+-induced Ca2+ Release

“…Rotenone is a potent inhibitor of the mammalian PTP when succinate is used as the substrate (30), and inhibition of reverse electron flow at complex I provides a plausible mechanism for this inhibition because reactive oxygen species increase the probability of pore opening through thiol oxidation (31,32). Remarkably, rotenone increased nearly 4-fold the CRC of Drosophila mitochondria from both larvae and adults (Fig.…”

The beneficial effects of AMP kinase activation against oxidative stress are associated with prevention of PPARα-cyclophilin D interaction in cardiomyocytes

“…Notably, the inhibition of PTP opening might be due to a direct effect of metformin on complex I of the ETC, which, in turn, could block pore formation (34). Inhibition of complex I by rotenone or metformin and displacement of CypD by cyclosporin A have been proposed to affect the PTP through a common mechanism (33). However, a direct inhibitory effect of 10 mM metformin on complex I was observed only several hours after incubation with mitochondria because of low uptake rate of the drug (34 …”

TSPO ligand residence time influences human glioblastoma multiforme cell death/life balance

“…retention capacity (CRC) was determined as previously described [55] using Calcium Green-5N (k ex = 505 nm, k em = 535 nm), a low affinity membraneimpermeant probe that increases its fluorescence emission upon Ca 2? binding.…”