Zinc Overload Induces Damage to H9c2 Cardiomyocyte Through Mitochondrial Dysfunction and ROS-Mediated Mitophagy.

Zinc homeostasis is essential for maintaining redox balance, cell proliferation, and apoptosis. However, excessive zinc exposure is toxic and leads to mitochondrial dysfunction. In this study, we established a zinc overload model by treating rat cardiomyocyte H9c2 cells with Zn at different concentrations.

Resveratrol Inhibits Zinc Deficiency-Induced Mitophagy and Exerts Cardiac Cytoprotective Effects.

Resveratrol (Res) possesses various beneficial effects, including cardioprotective, anti-inflammatory, anti-aging, and antioxidant properties. However, the precise mechanism underlying these effects remains unclear. Here we investigated the protective effects of resveratrol on cardiomyocytes, focusing on the role of Zn and mitophagy.

Zn protect cardiac H9c2 cells from endoplasmic reticulum stress by preventing mPTP opening through MCU.

Zn regulates endoplasmic reticulum stress (ERS) and is essential for myocardial protection through gating the mitochondrial permeability transition pore (mPTP). However, the underlining mechanism of the mPTP opening remains uncertain. Cells under sustained ERS induce unfolded protein responses (UPR) and cell apoptosis.

Neuroprotection Effect of Astragaloside IV from 2-DG-Induced Endoplasmic Reticulum Stress.

Objective: Astragaloside IV shows neuroprotective activity, but its mechanism remains unclear. To investigate whether astragaloside IV protects from endoplasmic reticulum stress (ERS), we focus on the regulation of glycogen synthase kinase-3 (GSK-3) and mitochondrial permeability transition pore (mPTP) by astragaloside IV in neuronal cell PC12.

Methods And Results: PC12 cells treated with different concentrations of ERS inductor 2-deoxyglucose (2-DG) (25-500 M) showed a significant increase of glucose-regulated protein 78 (GRP 78) and GRP 94 expressions and a decrease of tetramethylrhodamine ethyl ester (TMRE) fluorescence intensity and mitochondrial membrane potential (∆m), with the peak effect seen at 50 M, indicating that 2-DG induces ERS and the mPTP opening.

Zn and mPTP mediate resveratrol-induced myocardial protection from endoplasmic reticulum stress.

Resveratrol displays cardioprotective activity; however, its mechanism of action remains unclear. In the current study, resveratrol-induced myocardial protection from endoplasmic reticulum stress (ERS) was investigated, focusing on the roles of Zn2+ and the mitochondrial permeability transition pore (mPTP). We found, using the MTT/LDH kit, that 2-DG-induced ERS significantly decreased H9c2 cell viability.

Roles of Endoplasmic Reticulum Stress in NECA-Induced Cardioprotection against Ischemia/Reperfusion Injury.

Objective: This study aimed to investigate whether the nonselective A2 adenosine receptor agonist NECA induces cardioprotection against myocardial ischemia/reperfusion (I/R) injury via glycogen synthase kinase 3 (GSK-3) and the mitochondrial permeability transition pore (mPTP) through inhibition of endoplasmic reticulum stress (ERS).

Methods And Results: H9c2 cells were exposed to HO for 20 minutes. NECA significantly prevented HO-induced TMRE fluorescence reduction, indicating that NECA inhibited the mPTP opening.

Tauroursodeoxycholic acid inhibits endoplasmic reticulum stress, blocks mitochondrial permeability transition pore opening, and suppresses reperfusion injury through GSK-3ß in cardiac H9c2 cells.

This study investigates whether inhibition of endoplasmic reticulum (ER) stress prevents opening of the mitochondrial permeability transition pore (mPTP) and evaluates the corresponding signaling pathways involved in this process. Exposure of cardiac H9c2 cells to 800 µM HO for 20 min opened mPTP in response to oxidative stress, as demonstrated by quenching of tetramethylrhodamine ethyl ester (TMRE) fluorescence. Oxidative stress-induced mPTP opening was rescued by the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) in a dose-dependent manner at low concentrations.

[Injurious effect of zinc deficiency on cardiomyocytes].

The aim of the present study was to investigate the effect of zinc deficiency on cardiomyocyte survival and the underlying mechanisms. Simulated zinc deficiency model was developed in H9c2 cardiac cells with zinc chelator N, N, N', N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN). MTT assay was used to evaluate cell viability.

Zn and mPTP Mediate Endoplasmic Reticulum Stress Inhibition-Induced Cardioprotection Against Myocardial Ischemia/Reperfusion Injury.

The purpose of this study was to determine whether Zn is involved in endoplasmic reticulum (ER) stress inhibition-induced cardioprotection against ischemia/reperfusion (I/R) injury by modulation of the mitochondrial permeability transition pore (mPTP) opening. Isolated rat hearts were subjected to 30-min regional ischemia followed by 2 h of reperfusion. Expression of glucose regulated protein 78 (GRP 78 or BIP), an ER homeostasis marker, was not increased during ischemia but was increased upon reperfusion, indicating that ER stress was initiated upon reperfusion but not during ischemia.

Lipopolysaccharides may aggravate apoptosis through accumulation of autophagosomes in alveolar macrophages of human silicosis.

Silica dust mainly attacks alveolar macrophages (AMs) and increases the apoptosis of AMs in silicosis patients. However, it is still unclear whether autophagy is affected. Autophagy mainly has defensive functions in response to stress, contributing to cell survival in adverse conditions, and conversely it has also been implicated in cell death.

[Effects of α1-PDX, a furin inhibitor, on growth, invasion, and tumorigenicity of cervical cancer HeLa cells].

Objective: To investigate the effects of the furin inhibitor α1-PDX on the growth, invasion, and tumorigenicity of cervical cancer cells and explore the mechanisms.

Methods: The changes in the growth, migration and invasion of α1-PDX-transfected HeLa cells were observed using MTT assay, Boyden migration and invasion assay. The protein levels of furin and MT1-MMP were measured using Western blotting and furin activity was detected by enzyme activity assay in the transfected cells.

[Resveratrol attenuates oxidant-induced mitochondrial damage in embryonic rat cardiomyocytes via inactivating GSK-3β].

Objective: To investigate the underlying mechanism of the protective effects of resveratrol on oxidant-induced mitochondrial damage in embryonic rat cardiomyocytes.

Methods: H9c2 cells, a permanent cell line derived from embryonic rat cardiac tissue, and then randomly divided into control group [PBS, cells exposed to H2O2 (600 µmol/L) for 20 min to induce mitochondrial oxidant damage], resveratrol group (0.01, 0.

Astragaloside IV inhibits oxidative stress-induced mitochondrial permeability transition pore opening by inactivating GSK-3β via nitric oxide in H9c2 cardiac cells.

Objective: This study aimed to investigate whether astragaloside IV modulates the mitochondrial permeability transition pore (mPTP) opening through glycogen synthase kinase 3β (GSK-3β) in H9c2 cells.

Methods: H9c2 cells were exposed to astragaloside IV for 20 min. GSK-3β (Ser(9)), Akt (Ser(473)), and VASP (Ser(239)) activities were determined with western blot.

Atrial natriuretic peptide prevents the mitochondrial permeability transition pore opening by inactivating glycogen synthase kinase 3β via PKG and PI3K in cardiac H9c2 cells.

The purpose of this study was to test if atrial natriuretic peptide (ANP) can prevent the mitochondrial permeability transition pore (mPTP) opening by inactivating glycogen synthase kinase 3β (GSK-3β). ANP prevented loss of mitochondrial membrane potential (ΔΨ(m)) caused by H(2)O(2) in a dose-dependent manner. Similarly, cyclosporin A, an inhibitor of the mPTP opening, could also preserve ΔΨ(m).

The molecular mechanism underlying morphine-induced Akt activation: roles of protein phosphatases and reactive oxygen species.

Although Akt is reported to play a role in morphine's cardioprotection, little is known about the mechanism underlying morphine-induced Akt activation. This study aimed to define the molecular mechanism underlying morphine-induced Akt activation and to determine if the mechanism contributes to the protective effect of morphine on ischemia/reperfusion injury. In cardiac H9c2 cells, morphine increased Akt phosphorylation at Ser(473), indicating that morphine upregulates Akt activity.

The critical role of intracellular zinc in adenosine A(2) receptor activation induced cardioprotection against reperfusion injury.

Exogenous zinc can protect cardiac cells from reperfusion injury, but the exact roles of endogenous zinc in the pathogenesis of reperfusion injury and in adenosine A(2) receptor activation-induced cardioprotection against reperfusion injury remain unknown. Adenosine A(1)/A(2) receptor agonist 5'-(N-ethylcarboxamido) adenosine (NECA) given at reperfusion reduced infarct size in isolated rat hearts subjected to 30min ischemia followed by 2h of reperfusion. This effect of NECA was partially but significantly blocked by the zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN), and ZnCl(2) given at reperfusion mimicked the effect of NECA by reducing infarct size.

Morphine prevents the mitochondrial permeability transition pore opening through NO/cGMP/PKG/Zn2+/GSK-3beta signal pathway in cardiomyocytes.

The aim of this study was to test whether morphine prevents the mitochondrial permeability transition pore (mPTP) opening through Zn(2+) and glycogen synthase kinase 3beta (GSK-3beta). Fluorescence dyes including Newport Green Dichlorofluorescein (DCF), 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM), and tetramethylrhodamine ethyl ester (TMRE) were used to image free Zn(2+), nitric oxide (NO), and mitochondrial membrane potential (DeltaPsi(m)), respectively. Fluorescence images were obtained with confocal microscopy.

Adenosine A2A and A2B receptors work in concert to induce a strong protection against reperfusion injury in rat hearts.

We aimed to test if stimulation of both adenosine A2A and A2B receptors is required to produce an effective cardioprotection against reperfusion injury. Isolated rat hearts were subjected to 30-min regional ischemia followed by 2 h of reperfusion. The adenosine A1/A2 receptor agonist 5'-(N-ethylcarboxamido) adenosine (NECA) given at reperfusion reduced infarct size, an effect that was reversed by both the adenosine A2A antagonist SCH58261 and the A2B antagonist MRS1706.

Mechanism for resveratrol-induced cardioprotection against reperfusion injury involves glycogen synthase kinase 3beta and mitochondrial permeability transition pore.

Resveratrol pretreatment can protect the heart by inducing pharmacological preconditioning. Whether resveratrol protects the heart when applied at reperfusion remains unknown. We examined the effect of resveratrol on myocardial infarct size when given at reperfusion and investigated the mechanism underlying the effect.

Ethanol prevents oxidant-induced mitochondrial permeability transition pore opening in cardiac cells.

Aims: The purpose of this study was to determine if ethanol prevents the mitochondrial permeability transition pore (mPTP) opening via glycogen synthase kinase 3beta (GSK-3beta).

Methods: Cardiac H9c2 cells were exposed to ethanol (10-1000 microM) for 20 min. GSK-3beta activity was determined by measuring its phosphorylation at Ser(9).

Exogenous zinc protects cardiac cells from reperfusion injury by targeting mitochondrial permeability transition pore through inactivation of glycogen synthase kinase-3beta.

The purpose of this study was to determine whether exogenous zinc prevents cardiac reperfusion injury by targeting the mitochondrial permeability transition pore (mPTP) via glycogen synthase kinase-3beta (GSK-3beta). The treatment of cardiac H9c2 cells with ZnCl2 (10 microM) in the presence of zinc ionophore pyrithione for 20 min significantly enhanced GSK-3beta phosphorylation at Ser9, indicating that exogenous zinc can inactivate GSK-3beta in H9c2 cells. The effect of zinc on GSK-3beta activity was blocked by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY-294002 but not by the mammalian target of rapamycin (mTOR) inhibitor rapamycin or the PKC inhibitor chelerythrine, implying that PI3K but not mTOR or PKC accounts for the action of zinc.

Postconditioning prevents reperfusion injury by activating delta-opioid receptors.

Background: While postconditioning has been proposed to protect the heart by targeting the mitochondrial permeability transition pore (mPTP), the detailed mechanism underlying this action is unknown. The authors hypothesized that postconditioning stimulates opioid receptors, which in turn protect the heart from reperfusion injury by targeting the mPTP.

Methods: Rat hearts (both in vivo and in vitro) were subjected to 30 min of ischemia and 2 h of reperfusion.

Cardioprotection against reperfusion injury: updated mechanisms and strategies.

Early restoration of blood flow to the ischemic myocardium not only saves myocardium but also induces reperfusion injury. While no specific therapy to reduce reperfusion injury has yet been established, recent laboratory studies have shown that G protein-coupled receptor (GPCR) agonists, insulin, and postconditioning can effectively prevent reperfusion injury in various experimental settings and animal species. The potential mechanisms underlying the cardioprotection initiated by these interventions may include activation of the reperfusion injury salvage kinase (RISK) pathway, inactivation of glycogen synthase kinase 3beta (GSK-3beta), and modulation of mitochondrial permeability transition pore (mPTP) opening.

NO mobilizes intracellular Zn2+ via cGMP/PKG signaling pathway and prevents mitochondrial oxidant damage in cardiomyocytes.

Objective: Our aim was to determine if NO prevents mitochondrial oxidant damage by mobilizing intracellular free zinc (Zn(2+)).

Methods: Zn(2+) levels were determined by imaging enzymatically isolated adult rat cardiomyocytes loaded with Newport Green DCF. Mitochondrial membrane potential (DeltaPsi(m)) was assessed by imaging cardiomyocytes loaded with tetramethylrhodamine ethyl ester (TMRE).