The Experts below are selected from a list of 17922 Experts worldwide ranked by ideXlab platform
Charles Steenbergen - One of the best experts on this subject based on the ideXlab platform.
-
cardioprotection and altered mitochondrial adenine Nucleotide Transport
Basic Research in Cardiology, 2009Co-Authors: Charles Steenbergen, Renee Wong, Samarjit Das, Elizabeth MurphyAbstract:It is becoming increasingly clear that mitochondrial dysfunction is critically important in myocardial ischemic injury, and that cardioprotective mechanisms must ultimately prevent or attenuate mitochondrial damage. Mitochondria are also essential for energy production, and therefore prevention of mitochondrial injury must not compromise oxidative phosphorylation during reperfusion. This review will focus on one mitochondrial mechanism of cardioprotection involving inhibition of adenine Nucleotide Transport across the outer mitochondria membrane under de-energized conditions. This slows ATP hydrolysis by the mitochondria, and would be expected to lower mitochondrial membrane potential during ischemia, to inhibit calcium uptake during ischemia, and potentially to reduce free radical generation during early reperfusion. Two interventions that similarly inhibit mitochondrial adenine Nucleotide Transport are Bcl-2 overexpression and GSK inhibition. A possible final common mechanism shared by both of these interventions is discussed.
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F1F0-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane s...
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Samarjit Das, Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F(1)F(0)-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane space. This assay requires adenine Nucleotide Transport across the outer but not the inner mitochondrial membrane, and we found that GSK inhibitors slow AMP production similar to their effect on ATP consumption. This suggests that GSK inhibitors are acting on outer mitochondrial membrane Transport. In sonicated mitochondria, GSK inhibition had no effect on ATP consumption or AMP production. In intact mitochondria, cyclosporin A had no effect, indicating that ATP consumption is not caused by opening of the mitochondrial permeability transition pore. Because GSK is a kinase, we assessed whether protein phosphorylation might be involved. Therefore, we performed Western blot and 1D/2D gel phosphorylation site analysis using phos-tag staining to indicate proteins that had decreased phosphorylation in hearts treated with GSK inhibitors. Liquid chromatographic-mass spectrometric analysis revealed 1 of these proteins to be VDAC2. Taken together, we found that GSK-mediated signaling modulates Transport through the outer membrane of the mitochondria. Both proteomics and adenine Nucleotide Transport data suggest that GSK regulates VDAC and that VDAC may be an important regulatory site in ischemia/reperfusion injury.
Elizabeth Murphy - One of the best experts on this subject based on the ideXlab platform.
-
cardioprotection and altered mitochondrial adenine Nucleotide Transport
Basic Research in Cardiology, 2009Co-Authors: Charles Steenbergen, Renee Wong, Samarjit Das, Elizabeth MurphyAbstract:It is becoming increasingly clear that mitochondrial dysfunction is critically important in myocardial ischemic injury, and that cardioprotective mechanisms must ultimately prevent or attenuate mitochondrial damage. Mitochondria are also essential for energy production, and therefore prevention of mitochondrial injury must not compromise oxidative phosphorylation during reperfusion. This review will focus on one mitochondrial mechanism of cardioprotection involving inhibition of adenine Nucleotide Transport across the outer mitochondria membrane under de-energized conditions. This slows ATP hydrolysis by the mitochondria, and would be expected to lower mitochondrial membrane potential during ischemia, to inhibit calcium uptake during ischemia, and potentially to reduce free radical generation during early reperfusion. Two interventions that similarly inhibit mitochondrial adenine Nucleotide Transport are Bcl-2 overexpression and GSK inhibition. A possible final common mechanism shared by both of these interventions is discussed.
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F1F0-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane s...
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Samarjit Das, Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F(1)F(0)-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane space. This assay requires adenine Nucleotide Transport across the outer but not the inner mitochondrial membrane, and we found that GSK inhibitors slow AMP production similar to their effect on ATP consumption. This suggests that GSK inhibitors are acting on outer mitochondrial membrane Transport. In sonicated mitochondria, GSK inhibition had no effect on ATP consumption or AMP production. In intact mitochondria, cyclosporin A had no effect, indicating that ATP consumption is not caused by opening of the mitochondrial permeability transition pore. Because GSK is a kinase, we assessed whether protein phosphorylation might be involved. Therefore, we performed Western blot and 1D/2D gel phosphorylation site analysis using phos-tag staining to indicate proteins that had decreased phosphorylation in hearts treated with GSK inhibitors. Liquid chromatographic-mass spectrometric analysis revealed 1 of these proteins to be VDAC2. Taken together, we found that GSK-mediated signaling modulates Transport through the outer membrane of the mitochondria. Both proteomics and adenine Nucleotide Transport data suggest that GSK regulates VDAC and that VDAC may be an important regulatory site in ischemia/reperfusion injury.
Renee Wong - One of the best experts on this subject based on the ideXlab platform.
-
cardioprotection and altered mitochondrial adenine Nucleotide Transport
Basic Research in Cardiology, 2009Co-Authors: Charles Steenbergen, Renee Wong, Samarjit Das, Elizabeth MurphyAbstract:It is becoming increasingly clear that mitochondrial dysfunction is critically important in myocardial ischemic injury, and that cardioprotective mechanisms must ultimately prevent or attenuate mitochondrial damage. Mitochondria are also essential for energy production, and therefore prevention of mitochondrial injury must not compromise oxidative phosphorylation during reperfusion. This review will focus on one mitochondrial mechanism of cardioprotection involving inhibition of adenine Nucleotide Transport across the outer mitochondria membrane under de-energized conditions. This slows ATP hydrolysis by the mitochondria, and would be expected to lower mitochondrial membrane potential during ischemia, to inhibit calcium uptake during ischemia, and potentially to reduce free radical generation during early reperfusion. Two interventions that similarly inhibit mitochondrial adenine Nucleotide Transport are Bcl-2 overexpression and GSK inhibition. A possible final common mechanism shared by both of these interventions is discussed.
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F1F0-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane s...
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Samarjit Das, Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F(1)F(0)-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane space. This assay requires adenine Nucleotide Transport across the outer but not the inner mitochondrial membrane, and we found that GSK inhibitors slow AMP production similar to their effect on ATP consumption. This suggests that GSK inhibitors are acting on outer mitochondrial membrane Transport. In sonicated mitochondria, GSK inhibition had no effect on ATP consumption or AMP production. In intact mitochondria, cyclosporin A had no effect, indicating that ATP consumption is not caused by opening of the mitochondrial permeability transition pore. Because GSK is a kinase, we assessed whether protein phosphorylation might be involved. Therefore, we performed Western blot and 1D/2D gel phosphorylation site analysis using phos-tag staining to indicate proteins that had decreased phosphorylation in hearts treated with GSK inhibitors. Liquid chromatographic-mass spectrometric analysis revealed 1 of these proteins to be VDAC2. Taken together, we found that GSK-mediated signaling modulates Transport through the outer membrane of the mitochondria. Both proteomics and adenine Nucleotide Transport data suggest that GSK regulates VDAC and that VDAC may be an important regulatory site in ischemia/reperfusion injury.
Xin Jie Chen - One of the best experts on this subject based on the ideXlab platform.
-
adenine Nucleotide translocase mitochondrial stress and degenerative cell death
Oxidative Medicine and Cellular Longevity, 2013Co-Authors: Yaxin Liu, Xin Jie ChenAbstract:Mitochondria are intracellular organelles involved in ATP synthesis, apoptosis, calcium signaling, metabolism, and the synthesis of critical metabolic cofactors. Mitochondrial dysfunction is associated with age-related degenerative diseases. How mitochondrial dysfunction causes cell degeneration is not well understood. Recent studies have shown that mutations in the adenine Nucleotide translocase (Ant) cause aging-dependent degenerative cell death (DCD) in yeast, which is sequentially manifested by inner membrane stress, mitochondrial DNA (mtDNA) loss, and progressive loss of cell viability. Ant is an abundant protein primarily involved in ADP/ATP exchange across the mitochondrial inner membrane. It also mediates basal proton leak and regulates the mitochondrial permeability transition pore. Missense mutations in the human Ant1 cause several degenerative diseases which are commonly manifested by fractional mtDNA deletions. Multiple models have been proposed to explain the Ant1-induced pathogenesis. Studies from yeast have suggested that in addition to altered Nucleotide Transport properties, the mutant proteins cause a global stress on the inner membrane. The mutant proteins likely interfere with general mitochondrial biogenesis in a dominant-negative manner, which secondarily destabilizes mtDNA. More recent work revealed that the Ant-induced DCD is suppressed by reduced cytosolic protein synthesis. This finding suggests a proteostatic crosstalk between mitochondria and the cytosol, which may play an important role for cell survival during aging.
-
dominant membrane uncoupling by mutant adenine Nucleotide translocase in mitochondrial diseases
Human Molecular Genetics, 2008Co-Authors: Xiaowen Wang, Kelly Salinas, Xiaoming Zuo, Blanka Kucejova, Xin Jie ChenAbstract:Adenine Nucleotide translocase (Ant) is the most abundant protein on the mitochondrial inner membrane (MIM) primarily involved in ADP/ATP exchange. Ant also possesses a discrete membrane uncoupling activity. Specific mis-sense mutations in the human Ant1 cause autosomal dominant Progressive External Ophthalmoplegia (adPEO), mitochondrial myopathy and cardiomyopathy, which are commonly manifested by fractional mitochondrial DNA (mtDNA) deletions. It is currently thought that the pathogenic mutations alter substrate preference (e.g. ATP versus ADP) thereby dominantly disturbing adenine Nucleotide homeostasis in mitochondria. This may interfere with mtDNA replication, consequently affecting mtDNA stability and oxidative phosphorylation. Here, we showed that the adPEO-type A128P, A106D and M114P mutations in the yeast Aac2p share the following common dominant phenotypes: electron Transport chain damage, intolerance to moderate over-expression, synthetic lethality with low Deltapsi(m) conditions, hypersensitivity to the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) and mtDNA instability. More interestingly, the aac2(A137D) allele mimicking ant1(A123D) in mitochondrial myopathy and cardiomyopathy exhibits similar dominant phenotypes. Because Aac2(A137D) is known to completely lack Transport activity, it is strongly argued that the dominant mitochondrial damages are not caused by aberrant Nucleotide Transport. The four pathogenic mutations occur in a structurally dynamic gating region on the cytosolic side. We provided direct evidence that the mutant alleles uncouple mitochondrial respiration. The pathogenic mutations likely enhance the intrinsic proton-conducting activity of Ant, which excessively uncouples the MIM thereby affecting energy transduction and mitochondrial biogenesis. mtDNA disintegration is a phenotype co-lateral to mitochondrial damages. These findings provide mechanistic insights into the pathogenesis of the Ant1-induced diseases.
-
Pleiotropic effects of the yeast Sal1 and Aac2 carriers on mitochondrial function via an activity distinct from adenine Nucleotide Transport
Molecular Genetics and Genomics, 2008Co-Authors: Blanka Kucejova, Xiaowen Wang, Li Li, Sergio Giannattasio, Xin Jie ChenAbstract:In Saccharomyces cerevisiae , SAL1 encodes a Ca^2+-binding mitochondrial carrier. Disruption of SAL1 is synthetically lethal with the loss of a specific function associated with the Aac2 isoform of the ATP/ADP translocase. This novel activity of Aac2 is defined as the V function (for Viability of aac2 sal1 double mutant), which is independent of the ATP/ADP exchange activity required for respiratory growth (the R function). We found that co-inactivation of SAL1 and AAC2 leads to defects in mitochondrial translation and mitochondrial DNA (mtDNA) maintenance. Additionally, sal1Δ exacerbates the respiratory deficiency and mtDNA instability of ggc1Δ , shy1Δ and mtg1Δ mutants, which are known to reduce mitochondrial protein synthesis or protein complex assembly. The V function is complemented by the human Short Ca^2+-binding Mitochondrial Carrier (SCaMC) protein, SCaMC-2, a putative ATP-Mg/P_i exchangers on the inner membrane. However, mitochondria lacking both Sal1p and Aac2p are not depleted of adenine Nucleotides. The Aac2^R252I and Aac2^R253I variants mutated at the R252-254 triplet critical for Nucleotide Transport retain the V function. Likewise, Sal1p remains functionally active when the R479I and R481I mutations were introduced into the structurally equivalent R479-T480-R481 motif. Finally, we found that the naturally occurring V^−R^+ Aac1 isoform of adenine Nucleotide translocase partially gains the V function at the expense of the R function by introducing the mutations P89L and A96 V. Thus, our data support the view that the V function is independent of adenine Nucleotide Transport associated with Sal1p and Aac2p and this evolutionarily conserved activity affects multiple processes in mitochondria.
Samarjit Das - One of the best experts on this subject based on the ideXlab platform.
-
cardioprotection and altered mitochondrial adenine Nucleotide Transport
Basic Research in Cardiology, 2009Co-Authors: Charles Steenbergen, Renee Wong, Samarjit Das, Elizabeth MurphyAbstract:It is becoming increasingly clear that mitochondrial dysfunction is critically important in myocardial ischemic injury, and that cardioprotective mechanisms must ultimately prevent or attenuate mitochondrial damage. Mitochondria are also essential for energy production, and therefore prevention of mitochondrial injury must not compromise oxidative phosphorylation during reperfusion. This review will focus on one mitochondrial mechanism of cardioprotection involving inhibition of adenine Nucleotide Transport across the outer mitochondria membrane under de-energized conditions. This slows ATP hydrolysis by the mitochondria, and would be expected to lower mitochondrial membrane potential during ischemia, to inhibit calcium uptake during ischemia, and potentially to reduce free radical generation during early reperfusion. Two interventions that similarly inhibit mitochondrial adenine Nucleotide Transport are Bcl-2 overexpression and GSK inhibition. A possible final common mechanism shared by both of these interventions is discussed.
-
glycogen synthase kinase 3 inhibition slows mitochondrial adenine Nucleotide Transport and regulates voltage dependent anion channel phosphorylation
Circulation Research, 2008Co-Authors: Samarjit Das, Renee Wong, Nishadi Rajapakse, Elizabeth Murphy, Charles SteenbergenAbstract:Inhibition of glycogen synthase kinase (GSK)-3 reduces ischemia/reperfusion injury by mechanisms that involve the mitochondria. The goal of this study was to explore possible molecular targets and mechanistic basis of this cardioprotective effect. In perfused rat hearts, treatment with GSK inhibitors before ischemia significantly improved recovery of function. To assess the effect of GSK inhibitors on mitochondrial function under ischemic conditions, mitochondria were isolated from rat hearts perfused with GSK inhibitors and were treated with uncoupler or cyanide or were made anoxic. GSK inhibition slowed ATP consumption under these conditions, which could be attributable to inhibition of ATP entry into the mitochondria through the voltage-dependent anion channel (VDAC) and/or adenine Nucleotide Transporter (ANT) or to inhibition of the F(1)F(0)-ATPase. To determine the site of the inhibitory effect on ATP consumption, we measured the conversion of ADP to AMP by adenylate kinase located in the intermembrane space. This assay requires adenine Nucleotide Transport across the outer but not the inner mitochondrial membrane, and we found that GSK inhibitors slow AMP production similar to their effect on ATP consumption. This suggests that GSK inhibitors are acting on outer mitochondrial membrane Transport. In sonicated mitochondria, GSK inhibition had no effect on ATP consumption or AMP production. In intact mitochondria, cyclosporin A had no effect, indicating that ATP consumption is not caused by opening of the mitochondrial permeability transition pore. Because GSK is a kinase, we assessed whether protein phosphorylation might be involved. Therefore, we performed Western blot and 1D/2D gel phosphorylation site analysis using phos-tag staining to indicate proteins that had decreased phosphorylation in hearts treated with GSK inhibitors. Liquid chromatographic-mass spectrometric analysis revealed 1 of these proteins to be VDAC2. Taken together, we found that GSK-mediated signaling modulates Transport through the outer membrane of the mitochondria. Both proteomics and adenine Nucleotide Transport data suggest that GSK regulates VDAC and that VDAC may be an important regulatory site in ischemia/reperfusion injury.
