Journal of molecular and cellular cardiology
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J. Mol. Cell. Cardiol. · Jun 2014
Aldehyde dehydrogenase 2 ameliorates doxorubicin-induced myocardial dysfunction through detoxification of 4-HNE and suppression of autophagy.
Mitochondrial aldehyde dehydrogenase (ALDH2) protects against cardiac injury via reducing production of 4-hydroxynonenal (4-HNE) and ROS. This study was designed to examine the impact of ALDH2 on doxorubicin (DOX)-induced cardiomyopathy and mechanisms involved with a focus on autophagy. 4-HNE and autophagic markers were detected by Western blotting in ventricular tissues from normal donors and patients with idiopathic dilated cardiomyopathy. Cardiac function, 4-HNE and levels of autophagic markers were detected in WT, ALDH2 knockout or ALDH2 transfected mice treated with or without DOX. ⋯ Our data further revealed downregulated ALDH2 and upregulated autophagy levels in the hearts from patients with dilated cardiomyopathy. Taken together, our findings suggest that inhibition of 4-HNE and autophagy may be a plausible mechanism underscoring ALDH2-offered protection against DOX-induced cardiac defect. This article is part of a Special Issue entitled "Protein Quality Control, the Ubiquitin Proteasome System, and Autophagy".
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J. Mol. Cell. Cardiol. · Mar 2014
Cardioprotection by remote ischemic preconditioning of the rat heart is mediated by extracellular vesicles.
Remote ischemic preconditioning (RIPC) of the heart is exerted by brief ischemic insults affected on a remote organ or a remote area of the heart before a sustained cardiac ischemia. To date, little is known about the inter-organ transfer mechanisms of cardioprotection by RIPC. Exosomes and microvesicles/microparticles are vesicles of 30-100 nm and 100-1000 nm in diameter, respectively (collectively termed extracellular vesicles [EVs]). ⋯ Administration of coronary perfusate from IPC donor hearts attenuated infarct size in non-preconditioned recipient hearts (12.9 ± 1.6% vs. 25.0 ± 2.7%), similarly to cardioprotection afforded by IPC (7.3 ± 2.7% vs. 22.1 ± 2.9%) on the donor hearts. Perfusates of IPC hearts depleted of EVs failed to exert cardioprotection in recipient hearts (22.0 ± 2.3%). This is the first demonstration that EVs released from the heart after IPC are necessary for cardioprotection by RIPC, evidencing the importance of vesicular transfer mechanisms in remote cardioprotection.
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J. Mol. Cell. Cardiol. · Feb 2014
Focal adhesion kinase antagonizes doxorubicin cardiotoxicity via p21(Cip1.).
Clinical application of potent anthracycline anticancer drugs, especially doxorubicin (DOX), is limited by a toxic cardiac side effect that is not fully understood and preventive strategies are yet to be established. Studies in genetically modified mice have demonstrated that focal adhesion kinase (FAK) plays a key role in regulating adaptive responses of the adult myocardium to pathological stimuli through activation of intracellular signaling cascades that facilitate cardiomyocyte growth and survival. The objective of this study was to determine if targeted myocardial FAK activation could protect the heart from DOX-induced de-compensation and to characterize the underlying mechanisms. ⋯ DOX treatment induced proteasomal degradation of p21, which exacerbated mitochondrial dysfunction and cardiomyocyte apoptosis. FAK was both necessary and sufficient for maintaining p21 levels following DOX treatment and depletion of p21 compromised FAK-dependent protection from DOX. These findings identify p21 as a key determinant of DOX resistance downstream of FAK in cardiomyocytes and indicate that cardiac-restricted enhancement of the FAK/p21 signaling axis might be an effective strategy to preserve myocardial function in patients receiving anthracycline chemotherapy.
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J. Mol. Cell. Cardiol. · Jan 2014
Zinc plays a critical role in the cardioprotective effect of postconditioning by enhancing the activation of the RISK pathway in rat hearts.
This study investigated if zinc plays a role in postconditioning-induced cardioprotection in rat hearts. Isolated rat hearts were subjected to 30 min regional ischemia followed by 2h of reperfusion. Postconditioning was elicited by 6 cycles of 10s reperfusion and 10s ischemia. ⋯ Knockdown of the zinc transporter Zip2 inhibited the protective effect of postconditioning on hypoxia/reoxygenation injury in H9c2 cells. These results suggest that zinc plays an important role in the cardioprotective effect of postconditioning presumably by enhancing the activation of the RISK pathway. Zip2 and inactivation of PP2A by zinc may, at least in part, account for the activation of the RISK pathway.
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J. Mol. Cell. Cardiol. · Jan 2014
Sarcoplasmic reticulum Ca2+ cycling protein phosphorylation in a physiologic Ca2+ milieu unleashes a high-power, rhythmic Ca2+ clock in ventricular myocytes: relevance to arrhythmias and bio-pacemaker design.
Basal phosphorylation of sarcoplasmic reticulum (SR) Ca(2+) proteins is high in sinoatrial nodal cells (SANC), which generate partially synchronized, spontaneous, rhythmic, diastolic local Ca(2+) releases (LCRs), but low in ventricular myocytes (VM), which exhibit rare diastolic, stochastic SR-generated Ca(2+) sparks. We tested the hypothesis that in a physiologic Ca(2+) milieu, and independent of increased Ca(2+) influx, an increase in basal phosphorylation of SR Ca(2+) cycling proteins will convert stochastic Ca(2+) sparks into periodic, high-power Ca(2+) signals of the type that drives SANC normal automaticity. We measured phosphorylation of SR-associated proteins, phospholamban (PLB) and ryanodine receptors (RyR), and spontaneous local Ca(2+) release characteristics (LCR) in permeabilized single, rabbit VM in physiologic [Ca(2+)], prior to and during inhibition of protein phosphatase (PP) and phosphodiesterase (PDE), or addition of exogenous cAMP, or in the presence of an antibody (2D12), that specifically inhibits binding of the PLB to SERCA-2. ⋯ When the kinetics of Ca(2+) pumping into the SR were increased by an increase in PLB phosphorylation (via PDE and PP inhibition or addition of cAMP) or by 2D12, self-organized, "clock-like" local Ca(2+) releases, partially synchronized in space and time (Ca(2+) wavelets), emerged, and the ensemble of these rhythmic local Ca(2+) wavelets generated a periodic high-amplitude Ca(2+) signal. Thus, a Ca(2+) clock is not specific to pacemaker cells, but can also be unleashed in VM when SR Ca(2+) cycling increases and spontaneous local Ca(2+) release becomes partially synchronized. This unleashed Ca(2+) clock that emerges in a physiological Ca(2+) milieu in VM has two faces, however: it can provoke ventricular arrhythmias; or if harnessed, can be an important feature of novel bio-pacemaker designs.