| Summary: | 博士 === 長庚大學 === 臨床醫學研究所 === 103 === The effects of F1F0-ATP synthase (F1F0-ATPase) defect on hypoxia/reoxygenetaion injury (H/RO) and hypoxic preconditioning (HPC) is unknown. Recently, the cyclophilin-D (cypD) component of the mitochondrial permeability transition pore (mPTP) has been shown to interact with and regulate the F1F0-ATPase. However, the precise role of the interaction between cypD and F1F0-ATPase in the mPTP and HPC remains uncertain.
The present study used mtDNA T8993G mutation (NARP) osteosarcoma 143B cybrids, a F1F0-ATPase defect cell model to investigate how F1F0-ATPase defect modulated H/RO and HPC. We administered cyclosporin A (CsA) to disrupt of the interaction between cypD and F1F0-ATPase and evaluated its effects on HPC. We showed that NARP augmented H/RO-induced mROS formation to significantly depolarize mitochondrial membrane potential (ΔΨm), enhance mitochondrial Ca2+ (mCa2+) accumulation, and deplete cardiolipin, thereby promoting permanent mPTP opening, retarded mitochondrial movement, and enhanced apoptosis. Melatonin markedly reduced NARP-augmented H/RO-induced mitochondrial dysfunction and improved cell survival. Moreover, we found a one-hour HPC improved cell survival following stimulation with different apoptotic inducers including H2O2, ionomycin, arachidonic acid (AA) in NARP cybrids. This HPC protected NARP cybrids against focal laser irradiation-induced oxidative stress by suppressing mitochondrial ROS (mROS) formation and preventing the depletion of cardiolipin. The protective functions of transient opening of mPTP can be augmented by HPC. Disruption of the interaction between cypD and F1F0-ATPase by CsA attenuated the mitochondrial protection induced by HPC in both NARP cybrids and wild-type 143B cells.
This study concluded that NARP-induced F1F0-ATPase defect augments H/RO and melatonin may have the potential to rescue patients with ischemia/reperfusion (I/R) injury. NARP-induced F1F0-ATPase defect did not disrupt the HPC-induced protection. The protective functions of transient opening of mPTP can be augmented by HPC. Furthermore, the interaction between cypD and F1F0-ATPase is important in the regulation of HPC-induced cell protection.
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