Sodium‑calcium exchanger
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The sodium/calcium exchanger (NCX) type 1 has been well described in various cancers, but little is known about the other two NCX types (NCX2 and NCX3). In this study, we used the selective blocker of NCX3 - YM-244769 to investigate changes in apoptosis induction, migration, proliferation, intracellular calcium and ATP in four cancer cell lines - DLD1, HeLa, MDA-MB-231 and JIMT1. In all four cell lines we observed a concentration-dependent increase in the number of apoptotic cells, as well as reduced migration and proliferation. Induction of hypoxic conditions did not alter the response of these cells to YM-244769 in any of the above-mentioned parameters. These results indicate the role of NCX3 in cancer cell migration, proliferation and apoptosis, as inhibition of NCX1 by the specific blocker SEA0400 had no significant effect on these parameters. However, we verified the effect of NCX3 inhibition by using CRISPR/Cas9 to generate clones in which the SLC8A3 (NCX3) gene was deleted, and we obtained the same results. In addition, mitochondrial respiration was impaired in the clones with NCX3 knocked-out, suggesting that NCX3 also play a role in bioenergetics. In conclusion, we have clearly shown that NCX3 plays an important anti-apoptotic, pro-migratory and proliferative role in the cancer cells by affecting mitochondrial bioenergetics, thus supporting their survival and fate.
- MeSH
- apoptóza účinky léků MeSH
- lidé MeSH
- mitochondrie metabolismus účinky léků MeSH
- nádorové buněčné linie MeSH
- nádory * metabolismus patologie genetika MeSH
- pohyb buněk účinky léků MeSH
- proliferace buněk účinky léků MeSH
- pumpa pro výměnu sodíku a vápníku * metabolismus genetika antagonisté a inhibitory MeSH
- vápník metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The sarcolemmal Ca2+ efflux pathways, Na+-Ca2+-exchanger (NCX) and Ca2+-ATPase (PMCA), play a crucial role in the regulation of intracellular Ca2+ load and Ca2+ transient in cardiomyocytes. The distribution of these pathways between the t-tubular and surface membrane of ventricular cardiomyocytes varies between species and is not clear in human. Moreover, several studies suggest that this distribution changes during the development and heart diseases. However, the consequences of NCX and PMCA redistribution in human ventricular cardiomyocytes have not yet been elucidated. In this study, we aimed to address this point by using a mathematical model of the human ventricular myocyte incorporating t-tubules, dyadic spaces, and subsarcolemmal spaces. Effects of various combinations of t-tubular fractions of NCX and PMCA were explored, using values between 0.2 and 1 as reported in animal experiments under normal and pathological conditions. Small variations in the action potential duration (≤ 2%), but significant changes in the peak value of cytosolic Ca2+ transient (up to 17%) were observed at stimulation frequencies corresponding to the human heart rate at rest and during activity. The analysis of model results revealed that the changes in Ca2+ transient induced by redistribution of NCX and PMCA were mainly caused by alterations in Ca2+ concentrations in the subsarcolemmal spaces and cytosol during the diastolic phase of the stimulation cycle. The results suggest that redistribution of both transporters between the t-tubular and surface membranes contributes to changes in contractility in human ventricular cardiomyocytes during their development and heart disease and may promote arrhythmogenesis.
- MeSH
- akční potenciály MeSH
- biologické modely MeSH
- buněčná membrána metabolismus MeSH
- kardiomyocyty * metabolismus MeSH
- lidé MeSH
- modely kardiovaskulární MeSH
- pumpa pro výměnu sodíku a vápníku * metabolismus MeSH
- sarkolema * metabolismus MeSH
- srdeční komory * metabolismus MeSH
- vápník * metabolismus MeSH
- vápníková signalizace MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Sudden unexpected death in epilepsy (SUDEP) is a fatal complication experienced by otherwise healthy epilepsy patients. Dravet syndrome (DS) is an inherited epileptic disorder resulting from loss of function of the voltage-gated sodium channel, NaV 1.1, and is associated with particularly high SUDEP risk. Evidence is mounting that NaVs abundant in the brain also occur in the heart, suggesting that the very molecular mechanisms underlying epilepsy could also precipitate cardiac arrhythmias and sudden death. Despite marked reduction of NaV 1.1 functional expression in DS, pathogenic late sodium current (INa,L) is paradoxically increased in DS hearts. However, the mechanisms by which DS directly impacts the heart to promote sudden death remain unclear. OBJECTIVES: In this study, the authors sought to provide evidence implicating remodeling of Na+ - and Ca2+ -handling machinery, including NaV 1.6 and Na+/Ca2+exchanger (NCX) within transverse (T)-tubules in DS-associated arrhythmias. METHODS: The authors undertook scanning ion conductance microscopy (SICM)-guided patch clamp, super-resolution microscopy, confocal Ca2+ imaging, and in vivo electrocardiography studies in Scn1a haploinsufficient murine model of DS. RESULTS: DS promotes INa,L in T-tubular nanodomains, but not in other subcellular regions. Consistent with increased NaV activity in these regions, super-resolution microscopy revealed increased NaV 1.6 density near Ca2+release channels, the ryanodine receptors (RyR2) and NCX in DS relative to WT hearts. The resulting INa,L in these regions promoted aberrant Ca2+ release, leading to ventricular arrhythmias in vivo. Cardiac-specific deletion of NaV 1.6 protects adult DS mice from increased T-tubular late NaV activity and the resulting arrhythmias, as well as sudden death. CONCLUSIONS: These data demonstrate that NaV 1.6 undergoes remodeling within T-tubules of adult DS hearts serving as a substrate for Ca2+ -mediated cardiac arrhythmias and may be a druggable target for the prevention of SUDEP in adult DS subjects.
- MeSH
- epilepsie myoklonické * genetika MeSH
- kardiomyocyty metabolismus MeSH
- lidé MeSH
- myši knockoutované MeSH
- myši MeSH
- náhlá neočekávaná smrt při epilepsii MeSH
- napěťově řízený sodíkový kanál, typ 6 * genetika metabolismus MeSH
- pumpa pro výměnu sodíku a vápníku genetika metabolismus MeSH
- srdeční arytmie genetika MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Aspartate-glutamate carrier 2 (AGC2, citrin) is a mitochondrial carrier expressed in the liver that transports aspartate from mitochondria into the cytosol in exchange for glutamate. The AGC2 is the main component of the malate-aspartate shuttle (MAS) that ensures indirect transport of NADH produced in the cytosol during glycolysis, lactate oxidation to pyruvate, and ethanol oxidation to acetaldehyde into mitochondria. Through MAS, AGC2 is necessary to maintain intracellular redox balance, mitochondrial respiration, and ATP synthesis. Through elevated cytosolic Ca2+ level, the AGC2 is stimulated by catecholamines and glucagon during starvation, exercise, and muscle wasting disorders. In these conditions, AGC2 increases aspartate input to the urea cycle, where aspartate is a source of one of two nitrogen atoms in the urea molecule (the other is ammonia), and a substrate for the synthesis of fumarate that is gradually converted to oxaloacetate, the starting substrate for gluconeogenesis. Furthermore, aspartate is a substrate for the synthesis of asparagine, nucleotides, and proteins. It is concluded that AGC2 plays a fundamental role in the compartmentalization of aspartate and glutamate metabolism and linkage of the reactions of MAS, glycolysis, gluconeogenesis, amino acid catabolism, urea cycle, protein synthesis, and cell proliferation. Targeting of AGC genes may represent a new therapeutic strategy to fight cancer. [BMB Reports 2023; 56(7): 385-391].
- MeSH
- glukosa * metabolismus MeSH
- játra metabolismus MeSH
- kyselina asparagová * metabolismus MeSH
- kyselina glutamová metabolismus MeSH
- Publikační typ
- zprávy MeSH
Gluconeogenesis, a pathway for glucose synthesis from non-carbohydrate substances, begins with the synthesis of oxaloacetate (OA) from pyruvate and intermediates of citric acid cycle in hepatocyte mitochondria. The traditional view is that OA does not cross the mitochondrial membrane and must be shuttled to the cytosol, where most enzymes involved in gluconeogenesis are compartmentalized, in the form of malate. Thus, the possibility of transporting OA in the form of aspartate has been ignored. In the article is shown that malate supply to the cytosol increases only when fatty acid oxidation in the liver is activated, such as during starvation or untreated diabetes. Alternatively, aspartate synthesized from OA by mitochondrial aspartate aminotransferase (AST) is transported to the cytosol in exchange for glutamate via the aspartate-glutamate carrier 2 (AGC2). If the main substrate for gluconeogenesis is an amino acid, aspartate is converted to OA via urea cycle, therefore, ammonia detoxification and gluconeogenesis are simultaneously activated. If the main substrate is lactate, OA is synthesized by cytosolic AST, glutamate is transported to the mitochondria through AGC2, and nitrogen is not lost. It is concluded that, compared to malate, aspartate is a more suitable form of OA transport from the mitochondria for gluconeogenesis.
We compared the efficiency of real-time PCR analysis of FII (c.*97G>A, G20210A) and FV Leiden (c.1601G>A) thrombophilic mutations in the samples obtained from venous blood treated with various anti coagulant agents (EDTA, heparin, and sodium fluoride with potassium oxalate), or from clotted venous blood; one hundred samples of wild-type subjects were tested. Genomic DNA extracts and whole blood specimens modified by 90 °C heating were analysed by real-time PCR analysis; cycle threshold values were subsequently evaluated. Real-time PCR analysis for the FII gene assay performed in DNA extracts from EDTA blood samples revealed a median Ct value of 19.3. Similar Ct values were apparent in the DNA extracts obtained from the heparinized blood and sodium fluoride with potassium oxalatetreated samples: 18.5 and 18.9, respectively. Significantly higher Ct values were found in extracts from clotted blood with medians of 20.6 (tubes with inert separation gel) and 20.5 (tubes without the gel, both P < 0.001). The data on the FV real-time PCR analysis were very comparable to the FII assay. In the modified whole blood, the samples treated with heparin salts showed significantly lower Ct values (P < 0.001) in both assays when compared with the samples with EDTA, sodium fluoride with potassium oxalate, and with the samples with clotted blood. Our results indicate that real-time PCR analyses of thrombophilic mutations were not negatively influenced by the presence of heparin salts in collection tubes. Blood samples with various anticoagulants might be exchangeable for each other when DNA analysis of thrombophilic mutations is required.
- MeSH
- DNA MeSH
- EDTA farmakologie MeSH
- fluorid sodný MeSH
- heparin farmakologie MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- kyselina oxalová MeSH
- lidé MeSH
- mutace genetika MeSH
- soli * MeSH
- trombofilie * genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The ratio between Na+-Ca2+ exchange current densities in t-tubular and surface membranes of rat ventricular cardiomyocytes (JNaCa-ratio) estimated from electrophysiological data published to date yields strikingly different values between 1.7 and nearly 40. Possible reasons for such divergence were analysed by Monte Carlo simulations assuming both normal and log-normal distribution of the measured data. The confidence intervals CI95 of the mean JNaCa-ratios computed from the reported data showed an overlap of values between 1 and 3, and between 0.3 and 4.3 in the case of normal and log-normal distribution, respectively. Further analyses revealed that the published high values likely result from a large scatter of data due to transmural differences in JNaCa, dispersion of cell membrane capacitances and variability in incomplete detubulation. Taking into account the asymmetric distribution of the measured data, the reduction of mean current densities after detubulation and the substantially smaller CI95 of lower values of the mean JNaCa-ratio, the values between 1.6 and 3.2 may be considered as the most accurate estimates. This implies that 40 to 60% of Na+-Ca2+ exchanger is located at the t-tubular membrane of adult rat ventricular cardiomyocytes.
- MeSH
- kardiomyocyty * metabolismus MeSH
- krysa rodu rattus MeSH
- pumpa pro výměnu sodíku a vápníku MeSH
- sarkolema metabolismus MeSH
- sodík metabolismus MeSH
- srdeční komory metabolismus MeSH
- vápník * metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Neonatal hyperbilirubinemia or jaundice is associated with kernicterus, resulting in permanent neurological damage or even death. Conventional phototherapy does not prevent hyperbilirubinemia or eliminate the need for exchange transfusion. Here we investigated the potential of therapeutic bile acids ursodeoxycholic acid (UDCA) and obeticholic acid (OCA, 6-α-ethyl-CDCA), a farnesoid-X-receptor (FXR) agonist, as preventive treatment options for neonatal hyperbilirubinemia using the hUGT1*1 humanized mice and Ugt1a-deficient Gunn rats. Treatment of hUGT1*1 mice with UDCA or OCA at postnatal days 10-14 effectively decreased bilirubin in plasma (by 82% and 62%) and brain (by 72% and 69%), respectively. Mechanistically, our findings indicate that these effects are mediated through induction of protein levels of hUGT1A1 in the intestine, but not in liver. We further demonstrate that in Ugt1a-deficient Gunn rats, UDCA but not OCA significantly decreases plasma bilirubin, indicating that at least some of the hypobilirubinemic effects of UDCA are independent of UGT1A1. Finally, using the synthetic, non-bile acid, FXR-agonist GW4064, we show that some of these effects are mediated through direct or indirect activation of FXR. Together, our study shows that therapeutic bile acids UDCA and OCA effectively reduce both plasma and brain bilirubin, highlighting their potential in the treatment of neonatal hyperbilirubinemia.
- MeSH
- bilirubin krev MeSH
- ileum účinky léků metabolismus MeSH
- isoxazoly farmakologie MeSH
- játra účinky léků metabolismus MeSH
- kyselina chenodeoxycholová analogy a deriváty terapeutické užití MeSH
- kyselina ursodeoxycholová terapeutické užití MeSH
- myši MeSH
- novorozenecká hyperbilirubinemie krev farmakoterapie MeSH
- potkani Gunn MeSH
- receptory cytoplazmatické a nukleární agonisté metabolismus MeSH
- výsledek terapie MeSH
- žlučové kyseliny a soli terapeutické užití MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Several papers have reported that calcium channel blocking drugs were associated with increased breast cancer risk and worsened prognosis. One of the most common signs of breast tumors is the presence of small deposits of calcium, known as microcalcifications. Therefore, we studied the effect of dihydropyridine nifedipine on selected calcium transport systems in MDA-MB-231 cells, originating from triple negative breast tumor and JIMT1 cells that represent a model of HER2-positive breast cancer, which possesses amplification of HER2 receptor, but cells do not response to HER2 inhibition treatment with trastuzumab. Also, we compared the effect of nifedipine on colorectal DLD1 and ovarian A2780 cancer cells. Both, inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) and type 1 sodium calcium exchanger (NCX1) were upregulated due to nifedipine in DLD1 and A2780 cells, but not in breast cancer MDA-MB-231 and JIMT1 cells. On contrary to MDA-MB-231 and JIMT1 cells, in DLD1 and A2780 cells nifedipine induced apoptosis in a concentration-dependent manner. After NCX1 silencing and subsequent treatment with nifedipine, proliferation was decreased in MDA-MB-231, increased in DLD1 cells, and not changed in JIMT1 cells. Silencing of IP3R1 revealed increase in proliferation in DLD1 and JIMT1 cells, but caused decrease in proliferation in MDA-MB-231 cell line after nifedipine treatment. Interestingly, after nifedipine treatment migration was not significantly affected in any of tested cell lines after NCX1 silencing. Due to IP3R1 silencing, significant decrease in migration occurred in MDA-MB-231 cells after nifedipine treatment, but not in other tested cells. These results support different function of the NCX1 and IP3R1 in the invasiveness of various cancer cells due to nifedipine treatment.
- MeSH
- apoptóza účinky léků genetika MeSH
- blokátory kalciových kanálů farmakologie MeSH
- inositol-1,4,5-trisfosfát - receptory genetika metabolismus MeSH
- kolorektální nádory genetika metabolismus patologie MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádory prsu genetika metabolismus patologie MeSH
- nádory vaječníků genetika metabolismus patologie MeSH
- nifedipin farmakologie MeSH
- pohyb buněk účinky léků genetika MeSH
- proliferace buněk účinky léků genetika MeSH
- protinádorové látky imunologicky aktivní farmakologie MeSH
- pumpa pro výměnu sodíku a vápníku genetika metabolismus MeSH
- receptor erbB-2 genetika metabolismus MeSH
- regulace genové exprese u nádorů účinky léků MeSH
- RNA interference MeSH
- trastuzumab farmakologie MeSH
- triple-negativní karcinom prsu genetika metabolismus patologie MeSH
- vápníková signalizace účinky léků genetika MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The sodium/calcium exchanger (NCX) is a unique calcium transport system, generally transporting calcium ions out of the cell in exchange for sodium ions. Nevertheless, under special conditions this transporter can also work in a reverse mode, in which direction of the ion transport is inverted-calcium ions are transported inside the cell and sodium ions are transported out of the cell. To date, three isoforms of the NCX have been identified and characterized in humans. Majority of information about the NCX function comes from isoform 1 (NCX1). Although knowledge about NCX function has evolved rapidly in recent years, little is known about these transport systems in cancer cells. This review aims to summarize current knowledge about NCX functions in individual types of cancer cells.
- MeSH
- invazivní růst nádoru MeSH
- iontový transport MeSH
- lidé MeSH
- nádory metabolismus MeSH
- pumpa pro výměnu sodíku a vápníku metabolismus MeSH
- sodík metabolismus MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
