scholarly journals ATP synthase K+- and H+-flux drive ATP synthesis and enable mitochondrial K+-uniporter function

2018 ◽  
Author(s):  
Magdalena Juhaszova ◽  
Evgeny Kobrinsky ◽  
Dmitry B. Zorov ◽  
H. Bradley Nuss ◽  
Yael Yaniv ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Single Molecule ◽  
Energy Supply ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Atp Synthesis ◽  
Mechanical Efficiency ◽  
Major Fraction ◽  
Isolated Mitochondria ◽  
Related Proteins

SummaryATP synthase (F1Fo) synthesizes daily our body’s weight in ATP, whose production-rate can be transiently increased several-fold. Using purified mammalian F1Fo-reconstituted proteoliposomes and isolated mitochondria, we show that F1Fo utilizes both H+- and K+-transport (because of >106-fold K+ excess vs H+) to drive ATP synthesis with the H+:K+ permeability of ~106:1. F1Fo can be upregulated by endogenous survival-related proteins (Bcl-xL, Mcl-1) and synthetic molecules (diazoxide, pinacidil) to increase its chemo-mechanical efficiency via IF1. Increasing K+- and H+-driven ATP synthesis enables F1Fo to operate as a primary mitochondrial K+-uniporter regulating energy supply-demand matching, and as the recruitable mitochondrial KATP-channel that can limit ischemia-reperfusion injury. Isolated mitochondria in the presence of K+ can sustain ~3.5-fold higher ATP-synthesis-flux (vs K+ absence) driven by a 2.7:1 K+:H+ stoichiometry with unaltered OxPhos coupling. Excellent agreement between F1Fo single-molecule and intact-mitochondria experiments is consistent with K+-transport through ATP synthase driving a major fraction of ATP synthesis.

scholarly journals ATP synthase K+- and H+-fluxes drive ATP synthesis and enable mitochondrial K+-‘uniporter’ function: I. Characterization of ion fluxes

Function ◽  
2021 ◽  
Author(s):  
Magdalena Juhaszova ◽  
Evgeny Kobrinsky ◽  
Dmitry B Zorov ◽  
H Bradley Nuss ◽  
Yael Yaniv ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Single Molecule ◽  
Chemical Potential ◽  
Atp Synthesis ◽  
Energy Utilization ◽  
Photon Detection ◽  
Isolated Mitochondria ◽  
Intact Mitochondrion ◽  
Atp Generation ◽  
K Transport

Abstract ATP synthase (F1Fo) synthesizes daily our body's weight in ATP, whose production-rate can be transiently increased several-fold to meet changes in energy utilization. Using purified mammalian F1Fo-reconstituted proteoliposomes and isolated mitochondria, we show F1Fo can utilize both ΔΨm-driven H+- and K+-transport to synthesize ATP under physiological pH = 7.2 and K+ = 140 mEq/L conditions. Purely K+-driven ATP synthesis from single F1Fo molecules measured by bioluminescence photon detection could be directly demonstrated along with simultaneous measurements of unitary K+ currents by voltage clamp, both blocked by specific Fo inhibitors. In the presence of K+, compared to osmotically-matched conditions in which this cation is absent, isolated mitochondria display 3.5-fold higher rates of ATP synthesis, at the expense of 2.6-fold higher rates of oxygen consumption, these fluxes being driven by a 2.7:1 K+:H+ stoichiometry. The excellent agreement between the functional data obtained from purified F1Fo single molecule experiments and ATP synthase studied in the intact mitochondrion under unaltered OxPhos coupling by K+ presence, is entirely consistent with K+ transport through the ATP synthase driving the observed increase in ATP synthesis. Thus, both K+ (harnessing ΔΨm) and H+ (harnessing its chemical potential energy, ΔµH) drive ATP generation during normal physiology.

scholarly journals Lnc-NEAT1 induces cell apoptosis and inflammation but inhibits proliferation in a cellular model of hepatic ischemia/reperfusion injury

2021 ◽  
Vol 49 (3) ◽  
pp. 030006051988725
Author(s):  
Liu Wang ◽  
Pan Qu ◽  
Wanling Yin ◽  
Jiao Sun
Keyword(s):  
Cell Proliferation ◽  
Cell Apoptosis ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Hepatocyte Proliferation ◽  
Western Blot Assay ◽  
Hepatic Ischemia ◽  
Hepatic Ischemia Reperfusion ◽  
Apoptosis And Inflammation ◽  
Related Proteins

Objective We aimed to investigate the effect of long non-coding RNA nuclear-enriched abundant transcript 1 (lnc-NEAT1) on regulating hepatocyte proliferation, apoptosis, and inflammation during hepatic ischemia/reperfusion (I/R) injury. Methods Human liver cells (HL-7702) were cultured under glucose-free and oxygen-free conditions to construct the I/R injury model. Expression of lnc-NEAT1 was detected in this model and in normal cells. Plasmids of control overexpression [NC(+)], lnc-NEAT1 overexpression [NEAT1(+)], control short hairpin (sh)RNA [NC(−)], and lnc-NEAT1 shRNA [NEAT1(−)] were transfected into HL-7702 cells and subsequently subjected to I/R treatment. Cell proliferation, apoptosis, apoptosis-related proteins, and inflammatory cytokines were assessed. Results Lnc-NEAT1 expression was elevated in the I/R group compared with the normal group. Cell proliferation was decreased in the NEAT1(+) group compared with the NC(+) group but increased in NEAT1(−) compared with NC(−). The apoptosis rate increased in the NEAT1(+) group compared with the NC(+) group but decreased in NEAT1(−) compared with NC(−). Western blot assay (detection of apoptosis-related proteins) showed similar results. Expression of interleukin-1β, interleukin-6, and tumor necrosis factor-α increased in the NEAT1(+) group compared with NC(+) but decreased in NEAT1(−) compared with NC(−). Conclusion Lnc-NEAT1 is overexpressed, induces cell apoptosis and inflammation, and inhibits proliferation during hepatic I/R injury.

scholarly journals Galangin Alleviates Liver Ischemia-Reperfusion Injury in a Rat Model by Mediating the PI3K/AKT Pathway

2018 ◽  
Vol 51 (3) ◽  
pp. 1354-1363 ◽  
Author(s):  
Yang Li ◽  
Liquan Tong ◽  
Jingyan Zhang ◽  
Yafeng Zhang ◽  
Feng  Zhang
Keyword(s):  
Oxidative Stress ◽  
Ischemia Reperfusion Injury ◽  
Hepatic Duct ◽  
Ischemia Reperfusion ◽  
Trauma Surgery ◽  
Liver Ischemia ◽  
Western Blots ◽  
Phosphorylated Akt ◽  
Related Proteins

Background/Aims: Liver ischemia-reperfusion (I/R) injury is a pathological process that often occurs during liver and trauma surgery. There are numerous causes of liver I/R injury, but the mechanism is unknown. Galangin (GA) is a flavonoid, a polyphenolic compound widely distributed in medicinal herbs that has anti-inflammatory, antioxidant, and antitumor activity. This study evaluated the protective effect of GA on hepatic I/R injury. Methods: An I/R model was created in male Wistar rats by clamping the hepatoportal vein, hepatic artery and hepatic duct for 30 min followed by reperfusion for 2 h. A hypoxia/restoration (H/R) model was established in buffalo rat liver (BRL) cells by hypoxia for 4 h followed by normoxic conditions for 10 h. The extent of liver injury was assayed by serum ALT/AST, hepatic histology, and MPO activity. Oxidative stress was assayed by serum superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA). Expression of apoptosis-related proteins in BRL cells was assayed in western blots. Expression of AKT and p-AKT proteins in vivo and vitro were assayed in western blots. Results: GA significantly decreased ALT/AST expression, reversed changes in oxidative stress markers induced by I/R, and mediated caspase-3 activity expression of apoptosis-related proteins in vivo and in vitro. Methylthiazol tetrazolium (MTT) assay, flow cytometry, and Hoechst 33258 staining confirmed that GA inhibited apoptosis of BRL cells. GA also increased the expression of phosphorylated AKT after H/R. Conclusion: GA reduced liver I/R injury both in vivo and vitro and inhibited BRL cell apoptosis. PI3K/AKT signaling have been involved. GA may protect against liver I/R and be a potential therapeutic candidate.

Abstract 10246: Hydroxychloroquine Pretreatment Reduces Myocardial Ischemia-Reperfusion Injury: Role of Cardiac Extracellular-Signal-Regulated Kinase 5 and Autophagy

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Feiyan Yang ◽  
Chang Yin ◽  
Lei Xi ◽  
Rakesh C Kukreja
Keyword(s):  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Beclin 1 ◽  
Myocardial Infarct Size ◽  
Western Blots ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Related Proteins

Background: Hydroxychloroquine (HCQ) is an antimalarial drug, which is also widely used to treat chronic rheumatologic diseases. Since HCQ was reported to inhibit cell autophagy and to activate extracellular-signal-regulated kinase 5 (ERK5) in vascular endothelial cells, we designed the current study to determine the effects of HCQ on cardiac ischemia-reperfusion (I-R) injury and post-I-R expression of ERK5 and autophagy marker proteins. Methods: Adult C57BL/6J mice of both genders were pretreated with HCQ (50 mg/kg, i.p.) 1 hour prior to isolation of the hearts, which were subjected to 30 min of no-flow global ischemia followed by 60 min of reperfusion in Langendorff mode. Ventricular function was continuously assessed and myocardial infarct size was determined at the end of I-R. Heart samples were collected following normoxic perfusion (no-ischemic controls), I-R, or I-R with HCQ for assessing ERK5 and autophagy-related proteins with Western blots. Results: HCQ pretreatment reduced infarct size significantly in the female hearts (P<0.05) as compared with the male hearts (Fig. A). Post-I-R cardiac function was better in HCQ-treated males (Fig. B). I-R resulted in a robust increase in total ERK5 (Fig. C) and phosphorylated ERK5 (Thr218/Tyr220) in both genders, which was abolished in HCQ-treated groups. Conversely, either I-R or HCQ did not affect the post-I-R cardiac expression of autophagy-related proteins (e.g., Atg5, Beclin-1, LC3II/LC3I ratio), except Beclin-1 phosphorylation was inhibited in HCQ-treated male hearts, but not females (Fig. D). Conclusions: Acute HCQ pretreatment affords cardioprotection against I-R injury in both genders. Interestingly, cardioprotective effects of HCQ are associated with a strong inhibitory effect on the induction of ERK5 following I-R in the heart, indicating a novel molecular mechanism underlying the HCQ-induced cardioprotection. However, the cardioprotective dose of HCQ has no major impact on cardiac autophagy.

scholarly journals Fluoxetine suppresses inflammatory reaction in microglia under OGD/R challenge via modulation of NF-κB signaling

2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Mouli Tian ◽  
Mei Yang ◽  
Zhenjie Li ◽  
Yiru Wang ◽  
Wei Chen ◽  
...  
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Glucose Deprivation ◽  
Cell Counting ◽  
Enzyme Linked Immunosorbent Assay ◽  
Oxygen Glucose Deprivation ◽  
Tnf Α ◽  
Anti Inflammatory ◽  
Related Proteins

Abstract We aimed to investigate the anti-inflammatory role of fluoxetine, a selective serotonin reuptake inhibitor, in microglia (MG) and the mechanisms under oxygen glucose deprivation/reoxygenation (OGD/R). An OGD/R model on BV-2 cells was used for the study of microglia under ischemia/reperfusion injury in ischemic stroke. Lentiviral transfection was applied to knock down IκB-α. Enzyme-linked immunosorbent assay (ELISA) was used for detecting levels of TNF-α, IL-1β, and IL-6, and real-time PCR was used to assess the expression of IκB-α protein. Western blotting was applied to analyze NF-κB-signaling related proteins and Cell Counting Kit-8 (CCK-8) was used for assessing cell viability. Molecular docking and drug affinity responsive target stability (DARTS) assay were used for the detection of the interaction between IκB-α and fluoxetine. We found that fluoxetine decreased the levels of TNF-α, IL-1β, and IL-6 in supernatant as well as NF-κB subunits p65 and p50 in BV-2 cells under OGD/R. Fluoxetine significantly increased the level of IκB-α through the inhibition of IκB-α ubiquitylation and promoted the bonding of IκB-α and fluoxetine in BV-2 cells under OGD/R. Knocking down IκB-α attenuated the decreasing effect of TNF-α, IL-1β, and IL-6 as well as p65 and p50 in BV-2 cells under OGD/R led to by fluoxetine. In conclusion, our present study demonstrated the anti-inflammatory role of fluoxetine and its mechanisms related to the modulation of NF-κB-related signaling in MG under ischemia/reperfusion challenge.

Effects of fatty acids in isolated mitochondria: implications for ischemic injury and cardioprotection

2003 ◽  
Vol 285 (1) ◽  
pp. H259-H269 ◽  
Author(s):  
Paavo Korge ◽  
Henry M. Honda ◽  
James N. Weiss
Keyword(s):  
Fatty Acids ◽  
Cytochrome C ◽  
Ischemia Reperfusion Injury ◽  
Adenine Nucleotide ◽  
Ischemia Reperfusion ◽  
Permeability Transition ◽  
Cytochrome C Release ◽  
Atp Production ◽  
Isolated Mitochondria ◽  
Long Chain

Fatty acids accumulate during myocardial ischemia and are implicated in ischemia-reperfusion injury and mitochondrial dysfunction. Because functional recovery after ischemia-reperfusion ultimately depends on the ability of the mitochondria to recover membrane potential (ΔΨm), we studied the effects of fatty acids on ΔΨm regulation, cytochrome c release, and Ca2+ handling in isolated mitochondria under conditions that mimicked aspects of ischemia-reperfusion. Long-chain but not short-chain free fatty acids caused a progressive and reversible (with BSA) increase in inner membrane leakiness (proton leak), which limited mitochondrial ability to support ΔΨm. In comparison, long-chain activated fatty acids promoted 1) a slower depolarization that was not reversible with BSA, 2) cytochrome c loss that was unrelated to permeability transition pore opening, and 3) inhibition of the adenine nucleotide translocator. Together, these results impaired both mitochondrial ATP production and Ca2+ handling. Diazoxide, a selective opener of mitochondrial ATP-dependent potassium (KATP) channels, partially protected against these effects. These findings indicate that long-chain fatty acid accumulation during ischemia-reperfusion may predispose mitochondria to cytochrome c loss and irreversible injury and identify a novel cardioprotective action of diazoxide.

Sign in / Sign up

Export Citation Format

Share Document