Hagenbuchner J.,Tyrolean Cancer Research Institute |
Kuznetsov A.,Cardiac Research Laboratory |
Hausott B.,Innsbruck Medical University |
Obexer P.,Tyrolean Cancer Research Institute |
Ausserlechner M.J.,Tyrolean Cancer Research Institute
Journal of Cell Science | Year: 2012
FOXO transcription factors induce apoptosis and regulate cellular production of reactive oxygen species (ROS). To identify the sequence of molecular events underlying FOXO3 (FKHRL1)-induced apoptosis, we studied the regulation and function of FOXO3 by expressing an ECFP-tagged FOXO3 or a 4OH-tamoxifen (4OHT)-inducible FOXO3-ERtm fusion protein in SH-EP and STA-NB15 neuronal cells. After knockdown of FOXO3 or expression of a dominant-negative FOXO3 mutant we observed that etoposide- and doxorubicin-induced elevation of cellular ROS depends on FOXO3 activation and induction of its transcriptional target BCL2L11 (Bim). Activation of FOXO3 on its own induced two sequential ROS waves as measured by reduced MitoTrackerRed in live cell microscopy. Induction of Bim by FOXO3 is essential for this phenomenon because Bim knockdown or ectopic expression of BCL2L1 (BclxL) prevented FOXO3-mediated overproduction of ROS and apoptosis. Tetracycline-controlled expression of Bim impaired mitochondrial respiration and caused ROS production, suggesting that FOXO3 induces uncoupling of mitochondrial respiration through Bim. FOXO3 also activated a ROS rescue pathway by inducing the peroxiredoxin SESN3 (Sestrin3), which is responsible for the biphasic ROS accumulation. Knockdown of SESN3 caused an increase of FOXO3-induced ROS and accelerated apoptosis. The combined data clearly demonstrate that FOXO3 activates overproduction of ROS as a consequence of Bim-dependent impairment of mitochondrial respiration in neuronal cells, which leads to apoptosis. © 2012.
Divald A.,Yeshiva University |
Kivity S.,Cardiac Research Laboratory |
Wang P.,Yeshiva University |
Hochhauser E.,Cardiac Research Laboratory |
And 2 more authors.
Circulation Research | Year: 2010
Rationale: The ubiquitin proteasome system (UPS) becomes dysfunctional as a result of ischemia/reperfusion (I/R), which may lead to dysregulation of signaling pathways. Ischemic preconditioning (IPC) may prevent dysregulation by preventing UPS dysfunction through inhibition of oxidative damage. Objective: Examine the hypothesis that early IPC preserves postischemic UPS function thus facilitating prosurvival signaling events. Methods and results: I/R decreased proteasome chymotryptic activity by 50% in isolated rat heart and an in vivo murine left anterior descending coronary artery occlusion model. Following IPC, proteasome activity was decreased 25% (P<0.05) in isolated heart and not different from baseline in the murine model. Enriched 26S proteasome was prepared and analyzed for protein carbonyl content. Increased (P<0.05) carbonylation in a 53-kDa band following I/R was diminished by IPC. Immunoprecipitation studies indicated that the 53-kDa carbonylation signal was of proteasomal origin. Two-dimensional gel electrophoresis resolved the 53-kDa band into spots analyzed by liquid chromatography/tandem mass spectrometry containing Rpt3/Rpt5 both of which could be immunoprecipitated conjugated to dinitrophenylhydrazine (DNPH). Higher amounts of DNPH-tagged Rpt5 were immunoprecipitated from the I/R samples and less from the IPC samples. I/R increased Bax levels by 63% (P<0.05) which was decreased by IPC. Lactacystin (lac) pretreatment of preconditioned hearts increased Bax by 140% (P<0.05) and also increased ubiquitinated proteins. Pretreatment of hearts with a proteasome inhibitor reversed the effects of IPC on postischemic Rpt5 carbonylation, cardiac function, morphology and morphometry, and ubiquitinated and signaling proteins. Conclusions: These studies suggest that IPC protects function of the UPS by diminishing oxidative damage to 19S regulatory particle subunits allowing this complex to facilitate degradation of proapoptotic proteins. © 2010 American Heart Association, Inc.
Ben-Ari Z.,Liver Disease Center |
Ben-Ari Z.,Cardiac Research Laboratory |
Ben-Ari Z.,Tel Aviv University |
Avlas O.,Cardiac Research Laboratory |
And 7 more authors.
Cellular Physiology and Biochemistry | Year: 2012
Background/Aims: Toll-like receptor 4 (TLR4) is expressed on hepatic non-parenchymal cells and hepatocytes. Hepatic signaling through TLR4 is critical in the pathogenesis of ischemia reperfusion injury (IRI) and leads to the release of cytokines. The role of bone marrow-derived TLR4 in the early reperfusion stage is unclear. Methods: We used wild type mice (WT), TLR4deficient (TLR4ko) mice and chimeras to dissociate between the role of TLR4 expression in the liver (TLR4ko/WT) and in the immuno-hematopoietic system (WT/TLR4ko) in mouse hepatic IR injury model. Mice were subjected to in vivo partial IRI (70% for 60 min). Results: Compared with WT IR livers, TLR4ko IRI mice (4 hours) showed a significant reduction in serum liver enzyme, hepatic TNF-α and interleukin-1β levels. Fewer apoptotic hepatocytes cells were identified by morphological criteria and immunohistochemistry for caspase-3. In TLR4ko mice, decreased hepatic CJUN and NF-κB expression during IRI was noted compared with WT mice. Chimeric mice having either TLR4 bone-marrow or non-bone marrow derived cells following IRI exhibited almost similar hepatic injury as WT mice in the immediate reperfusion stage. Conclusion: Both TLR4 bone marrow-derived and non-bone marrow-derived cells are necessary in the initial process of hepatic injury. Activating TLR4-dependent signaling is required for IRI. The absence of the TLR4 gene plays a pivotal role in reducing hepatic IR injury. © 2012 S. Karger AG, Basel.
Waldman M.,Cardiac Research Laboratory |
Hochhauser E.,Cardiac Research Laboratory |
Hochhauser E.,Tel Aviv University |
Fishbein M.,Adelson Center for the Biology of Addictive Diseases |
And 6 more authors.
Biochemical Pharmacology | Year: 2013
Tetrahydrocannabinol (THC), the major psychoactive component of marijuana, is a cannabinoid agonist that exerts its effects by activating at least two specific receptors (CB1 and CB2) that belong to the seven transmembrane G-protein coupled receptor (GPCR) family. Both CB1 and CB2 mRNA and proteins are present in the heart. THC treatment was beneficial against hypoxia in neonatal cardiomyocytes in vitro. We also observed a neuroprotective effect of an ultra low dose of THC when applied to mice before brain insults. The present study was aimed to test and characterize the cardioprotective effects of a very low dose (0.002 mg/kg) of THC which is 3-4 orders of magnitude lower than the conventional doses, administered before myocardial infarction in mice in vivo. Three regimens of THC administration were tested: single THC application 2 h or 48 h before the induction of infarct, or 3 weeks continuous treatment before MI. All protocols of THC administration were found to be beneficial. In the case of THC treatment 2 h before MI, fractional shortening was elevated (37 ± 4% vs. 42 ± 1%, p < 0.04), troponin T leakage to the blood was reduced (14 ± 3 ng/ml vs. 10 ± 4 ng/ml, p < 0.008), infarct size decreased (29 ± 4% vs. 23 ± 4%, p < 0.02), and the accumulation of neutrophils to the infarct area declined (36 ± 10 cells/field vs. 19 ± 4 cells/field, p < 0.007) in THC- compared to vehicle-pretreated mice, 24 h after MI. ERK1/2 phosphorylation following infarct was also inhibited by pre-treatment with THC (p < 0.01). Conclusion A single ultra low dose of THC before ischemia is a safe and effective treatment that reduces myocardial ischemic damage. © 2013 Elsevier Inc. All rights reserved.
Emanuelov A.K.,Bar - Ilan University |
Shainberg A.,Bar - Ilan University |
Chepurko Y.,Cardiac Research Laboratory |
Kaplan D.,Israel Institute for Biological Research |
And 4 more authors.
Biochemical Pharmacology | Year: 2010
Cardiotoxicity associated with doxorubicin (DOX) treatment limits the therapeutic efficiency of this drug against cancer. 2-Chloro-N(6)-(3-iodobenzyl)adenosine-5′-N-methyluronamide (Cl-IB-MECA), a selective agonist of A3 adenosine receptor (A3R), reduces DOX toxicity in newborn rat cultured cardiomyocytes. The study's aim was to determine whether the protection demonstrated by Cl-IB-MECA attenuates cardiac depression in vivo. In addition, we wished to examine whether this protective pathway affects the sarcoplasmic reticulum (SR) calcium uptake and release, as well as intramitochondrial Ca2+ accumulation induced by DOX. Rats were injected every alternate day (6 times) with (1) saline, (2) 2.5 mg/kg i.p. DOX, (3) 33 μg/kg i.v. Cl-IB-MECA, (4) DOX + Cl-IB-MECA. Left ventricular functions were assessed by invasive (pressure) and non-invasive (echocardiography) techniques at the end of the injection period and 4 weeks later. Cytosolic and intramitochondrial calcium levels were measured with indo-1 and rhod-2 probes. SR Ca2+ content was determined by exposing cultured rat cardiomyocytes to caffeine. Echocardiography data demonstrate left ventricular wall thinning (23%), an increase in the end systolic dimension (170%) and decreased fractional shortening (35 ± 5% vs. 54 ± 5%, p < 0.01) in DOX-treated animals, compared to the control group. DOX increased Ca2+ levels in the cytosol and in mitochondria by diminishing the SR Ca2+ uptake. Pretreatment with Cl-IB-MECA attenuated left ventricular dysfunction, improved SR calcium storage capacity and prevented mitochondrial Ca2+ overload. We conclude that the adenosine A3 receptor agonist is effective in vivo against DOX cardiotoxicity via the restoration of Ca2+ homeostasis and prevention of mitochondrial damage that occurs as a result of Ca2+ overload. © 2009 Elsevier Inc. All rights reserved.
Pappo O.,Beilinson Hospital |
Ben-Ari Z.,Beilinson Hospital |
Shevtsov E.,Beilinson Hospital |
Shevtsov E.,Cardiac Research Laboratory |
And 5 more authors.
Canadian Journal of Physiology and Pharmacology | Year: 2010
Ischemia-reperfusion injury (I/R) is the main cause of primary graft nonfunction. Our aim was to evaluate the effect of excessive versus acute administration of erythropoietin (EPO) in attenuating the hepatic injury induced by I/R in mice. The effect of segmental (70%) hepatic ischemia was evaluated in a transgenic mouse line with constitutive overexpression of human EPO cDNA and in wild-type (WT) mice. Mice were randomly allocated to 5 main experimental groups: (i) WT-sham, (ii) WT ischemia, (iii) WT ischemia + recombinant human erythropoietin (rhEPO), (iv) transgenic-sham, and (v) transgenic ischemia. The EPO-pretreated mice showed a significant reduction in liver enzyme levels and intrahepatic caspase-3 activity and fewer apoptotic hepatocytes (p < 0.05 for all) compared with the WT untreated I/R group. EPO decreased c-Jun N-terminal kinase (JNK) phosphorylation and nuclear factor-kB (NF-kB) expression during I/R. In transgenic I/R livers, baseline histology showed diffused hepatic injury, and no significant beneficial effect was noted between the WT untreated and the transgenic I/R mice. In conclusion, acute pretreatment with EPO in WT mice attenuated in vivo I/R liver injury. However, in excessive EPO overexpression, the initial liver injury abolished the beneficial effect of EPO. These findings have important implications for the potential use of acute EPO in I/R injury during liver transplantation.
Avlas O.,Bar - Ilan University |
Avlas O.,Cardiac Research Laboratory |
Fallach R.,Bar - Ilan University |
Fallach R.,Cardiac Research Laboratory |
And 3 more authors.
Antioxidants and Redox Signaling | Year: 2011
Toll-like receptors (TLRs) have been identified as primary innate immune receptors for the recognition of pathogen-associated molecular patterns by immune cells, initiating a primary response toward invading pathogens and recruitment of the adaptive immune response. TLRs, especially Toll-like receptor 4 (TLR4), can also be stimulated by host-derived molecules and are expressed in the cardiovascular system, thus acting as a possible key link between cardiovascular diseases and the immune system. TLR4 is involved in the acute myocardial dysfunction caused by septic shock and myocardial ischemia. We used wild-type (WT) mice, TLR4-deficient (TLR4-knockout [ko]) mice, and chimeras that underwent myeloablative bone marrow transplantation to dissociate between TLR4 expression in the heart (TLR4-ko/WT) and the immunohematopoietic system (WT/TLR4-ko). Following lipopolysaccharide (LPS) challenge (septic shock model) or coronary artery ligation, myocardial ischemia (MI) model, we found WT/TLR4-ko mice challenged with LPS or MI displayed reduced cardiac function, increased myocardial levels of interleukin-1β and tumor necrosis factor-α, and upregulation of mRNA encoding TLR4 prior to myocardial leukocyte infiltration. The cardiac function of TLR4-ko or WT/TLR4-ko mice was less affected by LPS and demonstrated reduced suppression by MI compared with WT. These results suggest that TLR4 expressed in the cardiomyocytes plays a key role in this acute phenomenon. © 2011 Mary Ann Liebert, Inc.