Cyclophilin D (CypD) is a mitochondrial enzyme widely accepted as a regulator of the mitochondrial permeability transition pore (mPTP). Excessive opening of mPTP is associated with mitochondrial dysfunction and the development of various diseases; thus, suppression of mPTP opening through CypD inhibition presents a promising therapeutic approach. However, only a limited number of selective CypD inhibitors are currently available. In this study, 10 derivatives of 2-(benzyloxy)arylurea similar or identical to previously published CypD/mPTP inhibitors were synthesized. Unlike the original reports that assessed the opening of mPTP at the cellular level, the compounds were tested directly on the purified CypD enzyme to validate their putative mechanism of action. Additionally, the effect of the selected compounds was tested on isolated mitochondria. The obtained results show that the compounds are only weak inhibitors of CypD and mPTP opening, which is in contrast to previous conclusions drawn from the unspecific cellular JC-1 assay.
- Publikační typ
- časopisecké články MeSH
The mitochondrial permeability transition pore (MPTP) is a calcium-dependent, ion non-selective membrane pore with a wide range of functions. Although the MPTP has been studied for more than 50 years, its molecular structure remains unclear. Short-term (reversible) opening of the MPTP protects cells from oxidative damage and enables the efflux of Ca2+ ions from the mitochondrial matrix and cell signaling. However, long-term (irreversible) opening induces processes leading to cell death. Ca2+ ions, reactive oxygen species, and changes in mitochondrial membrane potential regulate pore opening. The sensitivity of the pore to Ca2+ ions changes as an organism ages, and MPTP opening plays a key role in the pathogenesis of many diseases. Most studies of the MPTP have focused on elucidating its molecular structure. However, understanding the mechanisms that will inhibit the MPTP may improve the treatment of diseases associated with its opening. To evaluate the functional state of the MPTP and its inhibitors, it is therefore necessary to use appropriate methods that provide reproducible results across laboratories. This review summarizes our current knowledge of the function and regulation of the MPTP. The latter part of the review introduces two optimized methods for evaluating the functional state of the pore under standardized conditions.
Mitochondria play an important role in the cell aging process. Changes in calcium homeostasis and/or increased reactive oxygen species (ROS) production lead to the opening of mitochondrial permeability transition pore (MPTP), depolarization of the inner mitochondrial membrane, and decrease of ATP production. Our work aimed to monitor age-related changes in the Ca2+ ion effect on MPTP and the ability of isolated rat liver mitochondria to accumulate calcium. The mitochondrial calcium retention capacity (CRC) was found to be significantly affected by the age of rats. Measurement of CRC values of the rat liver mitochondria showed two periods when 3 to 17-week old rats were tested. 3-week and 17-week old rats showed lower CRC values than 7-week old animals. Similar changes were observed while testing calcium-induced swelling of rat liver mitochondria. These findings indicate that the mitochondrial energy production system is more resistant to calcium-induced MPTP opening accompanied by the damaging effect of ROS in adult rats than in young and aged animals.
Values of the calcium retention capacity (CRC) of rat liver mitochondria are highly dependent on the experimental conditions used. When increasing amounts of added calcium chloride are used (1.25-10 nmol), the values of the CRC increase 3-fold. When calcium is added in 75 s intervals, the CRC values increase by 30 % compared with 150 s interval additions. CRC values are not dependent on the calcium/protein ratio in the measured sample in our experimental design. We also show that a more detailed evaluation of the fluorescence curves can provide new information about mitochondrial permeability transition pore opening after calcium is added.
- MeSH
- biologický transport MeSH
- jaterní mitochondrie metabolismus MeSH
- játra metabolismus MeSH
- krysa rodu rattus MeSH
- mitochondriální membrány metabolismus MeSH
- permeabilita MeSH
- přechodový pór mitochondriální permeability metabolismus MeSH
- transportní proteiny mitochondriální membrány metabolismus MeSH
- vápník metabolismus MeSH
- výzkumný projekt MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
By determining the calcium retention capacity (CRC) of rat liver mitochondria, we confirmed and extended previous observations describing the activation of mitochondrial swelling by phosphate and tert-butyl hydroperoxide (t-BHP). Using CRC measurements, we showed that both phosphate and t-BHP decrease the extent of calcium accumulation required for the full mitochondrial permeability transition pore (MPTP) opening to 35 % of control values and to only 15 % when both phosphate and t-BHP are present in the medium. When changes in fluorescence were evaluated at higher resolution, we observed that in the presence of cyclosporine A fluorescence values return after each Ca(2+) addition to basal values obtained before the Ca(2+) addition. This indicates that the MPTP remains closed. However, in the absence of cyclosporine A, the basal fluorescence after each Ca(2+) addition continuously increased. This increase was potentiated both by phosphate and t-BHP until the moment when the concentration of intramitochondrial calcium required for the full opening of the MPTP was reached. We conclude that in the absence of cyclosporine A, the MPTP is slowly opened after each Ca(2+) addition and that this rate of opening can be modified by various factors such as the composition of the media and the experimental protocol used.
- MeSH
- fosfáty farmakologie MeSH
- jaterní mitochondrie účinky léků metabolismus MeSH
- krysa rodu rattus MeSH
- potkani Wistar MeSH
- terc-butylhydroperoxid farmakologie MeSH
- transportní proteiny mitochondriální membrány metabolismus MeSH
- vápník metabolismus MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Klíčová slova
- mitochondriální pór přechodné propustnosti,
- MeSH
- akutní nekrotizující pankreatitida patologie MeSH
- Alzheimerova nemoc etiologie MeSH
- amyotrofická laterální skleróza etiologie MeSH
- buňky metabolismus MeSH
- Huntingtonova nemoc etiologie MeSH
- ionty chemie MeSH
- kardiovaskulární nemoci MeSH
- mitochondriální membrány patologie MeSH
- mitochondrie fyziologie patologie MeSH
- nealkoholová steatóza jater etiologie MeSH
- oxidační stres MeSH
- Parkinsonova nemoc etiologie MeSH
- reperfuzní poškození myokardu farmakoterapie MeSH
- Reyeův syndrom etiologie MeSH
- salicylany toxicita MeSH
- syndromy suchého oka etiologie MeSH
- vápník chemie metabolismus MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
CONTEXT: Acetaminophen (APAP) hepatotoxicity is often studied in primary cultures of hepatocytes of various species, but there are only few works comparing interspecies differences in susceptibility of hepatocytes to APAP in vitro. OBJECTIVES: The aim of our work was to compare hepatotoxicity of APAP in rat and mouse hepatocytes in primary cultures. MATERIALS AND METHODS: Hepatocytes isolated from male Wistar rats and C57Bl/6J mice were exposed to APAP for up to 24 h. We determined lactate dehydrogenase (LDH) activity in culture medium, activity of cellular dehydrogenases (WST-1) and activity of caspases 3 in cell lysate as markers of cell damage/death. We assessed content of intracellular reduced glutathione, production of reactive oxygen species (ROS) and malondialdehyde (MDA). Respiration of digitonin-permeabilized hepatocytes was measured by high resolution respirometry and mitochondrial membrane potential (MMP) was visualized (JC-1). RESULTS: APAP from concentrations of 2.5 and 0.75 mmol/L induced a decrease in viability of rat (p < 0.001) and mouse (p < 0.001) hepatocytes (WST-1), respectively. In contrast to rat hepatocytes, there was no activation of caspase-3 in mouse hepatocytes after APAP treatment. Earlier damage to plasma membrane and faster depletion of reduced glutathione were detected in mouse hepatocytes. Mouse hepatocytes showed increased glutamate + malate-driven respiration in state 4 and higher susceptibility of the outer mitochondrial membrane (OMM) to APAP-induced injury. CONCLUSION: APAP displayed dose-dependent toxicity in hepatocytes of both species. Mouse hepatocytes in primary culture however had approximately three-fold higher susceptibility to the toxic effect of APAP when compared to rat hepatocytes.
- MeSH
- biologické markery metabolismus MeSH
- buněčná membrána účinky léků metabolismus MeSH
- druhová specificita MeSH
- glutathion metabolismus MeSH
- hepatocyty cytologie účinky léků metabolismus MeSH
- jaterní mitochondrie účinky léků enzymologie metabolismus MeSH
- kultivované buňky MeSH
- membránový potenciál mitochondrií účinky léků MeSH
- mitochondriální membrány účinky léků metabolismus MeSH
- myši inbrední C57BL MeSH
- neopioidní analgetika škodlivé účinky MeSH
- oxidace-redukce MeSH
- oxidační stres účinky léků MeSH
- paracetamol škodlivé účinky MeSH
- peroxidace lipidů účinky léků MeSH
- potkani Wistar MeSH
- reaktivní formy kyslíku agonisté metabolismus MeSH
- viabilita buněk účinky léků MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
