Asymmetric Opening of Mitochondrial Permeability Transition Pore in Mouse Brain Hemispheres: A Link to the Mitochondrial Calcium Uniporter Complex

Abstract The prolonged entry of large amounts of calcium into the mitochondria through the mitochondrial calcium uniporter complex (MCUC) may cause the permeability transition pore (mPTP) to open, which contributes to the pathogenesis of several diseases. Tissue-specific differences in mPTP opening due to variable expression of MCUC components may contribute to disease outcomes. We designed this study to determine differential mPTP opening in mitochondria isolated from different regions of mouse brain and kidney and to compare it with the expression of MCUC components. mPTP opening was measured using mitochondria isolated from the left/right brain hemispheres (LH/RH, respectively) and from kidney cortex/medulla, while the expression level of MCUC components was assessed from total cellular RNA. Interestingly, LH mitochondria showed less calcium-induced mPTP opening as compared to RH mitochondria at two different calcium concentrations. Conversely, mPTP opening was similar in the renal cortex and renal medulla mitochondria. However, the kidney mitochondria demonstrated bigger and faster mPTP opening as compared to the brain mitochondria. Furthermore, asymmetric mPTP opening in the LH and RH mitochondria was not associated with the expression of MCUC components. In brief, this study demonstrates thus far unreported asymmetric mPTP opening in mouse brain hemispheres that is not associated with the mRNA levels of MCUC components.

Kangxian Yixin Prescription Interferes with Mitochondrial Permeability Transition Pore to Inhibit Cardiomyocyte Apoptosis / 中国实验方剂学杂志

Objective:To explore the mechanism of Kangxian Yixin prescription in regulating mitochondrial permeability transition pore（mPTP）and inhibiting cardiomyocyte apoptosis. Method:H9c2 cardiomyocytes were cultured routinely. After 8 h of starvation，the cells were divided into the normal group，model group，Kangxian Yixin prescription（0.25 g·L^-1） group，and cyclosporin A（CsA，10 μmol·L^-1） group and treated with the corresponding drugs for 24 h for follow-up experiments. The H9c2 cardiomyocyte hypertrophy model was induced by norepinephrine（NE），whose optimal concentration was determined by real-time polymerase chain reaction （Real-time PCR）. The degree of mPTP opening was detected by flow cytometry， followed by the measurement of mRNA and protein expression levels of apoptosis-related factors cyclophilin D（Cyp-D），cytochrome C（Cyt-C），and cysteine aspartate-specific protease-3（Caspase-3） after mPTP opening and the quantification of mitochondrial membrane potential. Result:When the concentration of NE was 200 μmol·L^-1， the mRNA expression levels of atrial natriuretic peptide（ANP） and brain natriuretic peptide（BNP） were the highest， implying that it was the optimal concentration to induce H9c2 cell hypertrophy. Compared with the normal group，the model group exhibited excessive opening of mPTP，weakened relative fluorescence intensity in mitochondria， decreased mitochondrial membrane potential（<italic>P</italic><0.05，<italic>P</italic><0.01），and elevated mRNA and protein expression of Cyp-D，Cyt-C，and Caspase-3（<italic>P</italic><0.05）. Compared with the model group，both Kangxian Yixin prescription and CsA inhibited mPTP opening，enhanced the relative fluorescence intensity of mitochondria， increased mitochondrial membrane potential（<italic>P</italic><0.05，<italic>P</italic><0.01），and lowered the mRNA and protein expression of Cyp-D，Cyt-C，and Caspase-3 （<italic>P</italic><0.05）. Conclusion:Kangxian Yixin prescription inhibits cardiomyocyte apoptosis possibly by regulating mPTP opening and inhibiting the expression of apoptosis-related factors Cyp-D，Cyt-C， and Caspase-3.

Regulation mechanism and targeted drugs of mitochondrial permeability transition pore on programmed cell death:research advances / 国际药学研究杂志

Since its discovery in the 1970s,the mitochondrial permeability transition(mPT)has been proposed to be a strate?gic regulator of programmed cell death(PCD). The mPT denotes an increase in the mitochondrial inner membrane permeability to sol?utes with molecular masses up to about 1.5×103. It is presumed to be mediated by an opening of a channel,the mPT pore(mPTP), whose molecular nature remains a mystery. Intense research efforts have focused on elucidating the molecular components of the mPTP because it may help to better understand and treat various pathologies ranging from neurodegenerative and cardiac diseases to cancer. This article briefly reviews the new progress of mPTP structural models and its specific molecular mechanisms of regulating PCD , then demonstrates the feasibility of using the mPTP-targeting agents as a potential alternative strategy for effective management of PCD.

Regulation mechanism and targeted drugs of mitochondrial permeability transition pore on programmed cell death: Research advances / 国际药学研究杂志

Since its discovery in the 1970s, the mitochondrial permeability transition(mPT)has been proposed to be a strategic regulator of programmed cell death(PCD). The mPT denotes an increase in the mitochondrial inner membrane permeability to solutes with molecular masses up to about 1.5×103. It is presumed to be mediated by an opening of a channel, the mPT pore(mPTP), whose molecular nature remains a mystery. Intense research efforts have focused on elucidating the molecular components of the mPTP because it may help to better understand and treat various pathologies ranging from neurodegenerative and cardiac diseases to cancer. This article briefly reviews the new progress of mPTP structural models and its specific molecular mechanisms of regulating PCD, then demonstrates the feasibility of using the mPTP-targeting agents as a potential alternative strategy for effective management of PCD.

Effect of mitochondrial cytochrome c on hepatocyte apoptosis in non-alcoholic fatty liver disease in rabbits / 中国比较医学杂志

Objective To investigate the role of mitochondrial cytochrome c on hepatocyte apoptosis in non-alcoholic fatty liver disease in rabbits and its pathogenesis.Methods Forty Japanese white rabbits were randomly assigned to control group and model group.The model group was divided into three subgroups: 4-week, 6-week, and 8-week groups, with 10 rabbits in each group.The model groups were subcutaneously injected with peanut oil (1.2 mL/kg), twice a week for 4 weeks, 6 weeks or 8 weeks.The rabbits of all groups were killed at the right time.Serum samples were collected to detect the serum biochemical index levels.Liver tissue samples were taken for pathological observation using HE staining.The hepatocyte apoptosis index ( AI ) was measured by flow cytometry, and mitochondrial permeability transition pore ( MPTP) was evaluated by ultraviolet spectrophotometry.Immunohistochemistry was employed to detect the hepatic expressions of Bcl-2, Bax, CYT C and caspase-3.Western blot was performed to detect the changes of CYT C and caspase-3 protein expressions.Results The model groups showed hepatic injury and high level of TC, TG, CRP, IL-6 and TNF-αbeginning from 4 weeks.With the NAFLD process, the hepatocyte apoptosis index was significantly increased at 4-8 weeks and the MPTP was gradually increased.In the model group, hepatic Bcl-2, Bax, CYT C and caspase-3 expressions were increased steadily with the time passing.Conclusions NAFLD-induced liver damage is associated with apoptosis, and the mitochondrial cytochrome c-mediated apoptotic pathway plays a role in the occurrence of NAFLD.