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Mazen Zakariya Kurdi

Full professor
Chemistry - Biochemistry department - Section I - Hadath
Speciality: Biochemistry
Specific Speciality: Pharmacology
Interests: Gym (workout). Sports
Skills: Management skills

Teaching 7 Taught Courses
(2014-2015) CVPH 502 - Molecular Cardiology

M2 Cardiovascular Phamacology

(2014-2015) CVPH 506 - Cellular and Animal models in Cardiovascular Research

M2 Cardiovascular Phamacology

(2014-2015) Bioc 409 - Pharmacology and General Toxicology

M1 Biochemistry

(2014-2015) Bioc 300 - Enzymology

BS Biochemistry

(2014-2015) Bioc 331 - Modulation of Protein function

BS Biochemistry

(2014-2015) Bioc 380 - Metabolic Biochemistry

BS Earth and life sciences

(2014-2015) Bioc 303 - Metabolic Biochemistry

BS Biochemistry

Education
Ph.D.

Claude Bernard University, Lyon, France.
Pharmacology

DEA

Claude Bernard University, Lyon, France.
Biochemistry

Maitrise

Lebanese University, Faculty of Sciences, Section 1.
Biochemistry

High school

Saint-Elie Btina School, Beirut, Lebanon.
Life Sciences

Publications 35 publications
Zouein FA, Kurdi M, Booz GW, Fuseler JW. Applying fractal dimension and image analysis to quantify fibrotic collagen deposition and organization in the normal and hypertensive heart. Microscopy and Microanalysis 2014

Hearts of mice with reduction of function mutation in STAT3 (SA/SA) develop fibrotic collagen foci and reduced systolic function with hypertension. This model was used to determine if fractal dimension and image analysis can provide a quantitative description of myocardial fibrosis using routinely prepared trichome-stained material. Collagen was characterized by relative density [integrated optical density/area (IOD/A)] and fractal dimension (D), an index of complexity. IOD/A of collagen in wild type mice increased with hypertension while D decreased, suggesting tighter collagen packing that could eventually stiffen the myocardium as in diastolic heart failure. Reduced STAT3 function caused modest collagen fibrosis with increased IOD/A and D, indicating more tightly packed, but more disorganized collagen than normotensive and hypertensive controls. Hypertension in SA/SA mice resulted in large regions where myocytes were lost and replaced by fibrotic collagen characterized by decreased density and increased disorder. This indicates that collagen associated with reparative fibrosis in SA/SA hearts experiencing hypertension was highly disorganized and more space filling. Loss of myocytes and their replacement by disordered collagen fibers may further weaken the myocardium leading to systolic heart failure. Our findings highlight the utility of image analysis in revealing importance of a cellular protein for normal and reparative extracellular matrix deposition.

Kurdi M, Booz GW. Carvedilol protects the infarcted heart by upregulating miR-133: First evidence that disease state affects β-adrenergic arrestin-biased signaling? J Mol Cell Cardiol. 2014

Zouein FA, Duhé RJ, Arany I, Shirey K, Hosler JP, Liu H, Saad I, Kurdi M, Booz GW. Loss of STAT3 in mouse embryonic fibroblasts reveals its Janus-like actions on mitochondrial function and cell viability. Cytokine 2014

STAT3 has been implicated in mitochondrial function; however, the physiological relevance of this action is not established. Here we studied the importance of STAT3 to the cellular response to stimuli, TNFα and serum deprivation, which increase mitochondrial reactive oxygen species (ROS) formation. Experiments were performed using wild type (WT) and STAT3 knockout (KO) mouse embryonic fibroblasts (MEF). Both WT and STAT3 KO MEF expressed similar levels of tumor necrosis factor receptor 1 (TNFR1) and exhibited comparable IκBα degradation with TNFα. However, in the absence of STAT3 nuclear accumulation of NFκB p65 with TNFα was attenuated and induction of the survival protein c-FLIPL was eliminated. Nonetheless, WT MEF were more sensitive to TNFα-induced death which was attributed to necrosis. Deletion of STAT3 decreased ROS formation induced by TNFα and serum deprivation. STAT3 deletion was associated with lower levels of complex I and rates of respiration. Relative to WT cells, mitochondria of STAT3 KO cells released significantly more cytochrome c in response to oxidative stress and had greater caspase 3 cleavage due to serum deprivation. Our findings are consistent with STAT3 being important for mitochondrial function and cell viability by ensuring mitochondrial integrity and the expression of pro-survival genes.

Zouein FA, Kurdi M, Booz GW. Dancing rhinos in stilettos: The amazing saga of the genomic and nongenomic actions of STAT3 in the heart. JAKSTAT 2013

A substantial body of evidence has shown that signal transducer and activator of transcription 3 (STAT3) has an important role in the heart in protecting the myocardium from ischemia and oxidative stress. These actions are attributed to STAT3 functioning as a transcription factor in upregulating cardioprotective genes. Loss of STAT3 has been implicated as well in the pathogenesis of heart failure and, in that context and in addition to the loss of a cardioprotective gene program, nuclear STAT3 has been identified as a transcriptional repressor important for the normal functioning of the ubiquitin-proteasome system for protein degradation. The later finding establishes a genomic role for STAT3 in controlling cellular homeostasis in cardiac myocytes independent of stress. Surprisingly, although a well-studied area, very few downstream gene targets of STAT3 in the heart have been definitively identified. In addition, STAT3 is now known to induce gene expression by noncanonical means that are not well characterized in the heart. On the other hand, recent evidence has shown that STAT3 has important nongenomic actions in cardiac myocytes that affect microtubule stability, mitochondrial respiration, and autophagy. These extranuclear actions of STAT3 involve protein-protein interactions that are incompletely understood, as is their regulation in both the healthy and injured heart. Moreover, how the diverse genomic and nongenomic actions of STAT3 crosstalk with each other is unchartered territory. Here we present an overview of what is and is not known about both the genomic and nongenomic actions of STAT3 in the heart from a structure-function perspective that focuses on the impact of posttranslational modifications and oxidative stress in regulating the actions and interactions of STAT3. Even though we have learnt a great deal about the role played by STAT3 in the heart, much more awaits to be discovered.

Zouein FA, Kurdi M, Booz GW. HSPA12B and repairing the heart: beauty in simplicity. Cardiovasc Res. 2013

Werner T, Dombrowski SM, Zgheib C, Zouein FA, Keen HL, Kurdi M, Booz GW. Elucidating functional context within microarray data by integrated transcription factor-focused gene-interaction and regulatory network analysis. Eur Cytokine Netw. 2013

Microarrays do not yield direct evidence for functional connections between genes. However, transcription factors (TFs) and their binding sites (TFBSs) in promoters are important for inducing and coordinating changes in RNA levels, and thus represent the first layer of functional interaction. Similar to genes, TFs act only in context, which is why a TF/TFBS-based promoter analysis of genes needs to be done in the form of gene(TF)-gene networks, not individual TFs or TFBSs. In addition, integration of the literature and various databases (e.g. GO, MeSH, etc) allows the adding of genes relevant for the functional context of the data even if they were initially missed by the microarray as their RNA levels did not change significantly. Here, we outline a TF-TFBSs network-based strategy to assess the involvement of transcription factors in agonist signaling and demonstrate its utility in deciphering the response of human microvascular endothelial cells (HMEC-1) to leukemia inhibitory factor (LIF). Our strategy identified a central core of eight TFs, of which only STAT3 had previously been definitively linked to LIF in endothelial cells. We also found potential molecular mechanisms of gene regulation in HMEC-1 upon stimulation with LIF that allow for the prediction of changes of genes not used in the analysis. Our approach, which is readily applicable to a wide variety of expression microarray and next generation sequencing RNA-seq results, illustrates the power of a TF-gene networking approach for elucidation of the underlying biology.

Zouein FA, de Castro Brás LE, da Costa DV, Lindsey ML, Kurdi M, Booz GW. Heart Failure with Preserved Ejection Fraction: Emerging Drug Strategies. J Cardiovasc Pharmacol. 2013

Approximately half of heart failure patients have a normal ejection fraction, a condition designated as heart failure with preserved ejection fraction (HFpEF). This heart failure subtype disproportionately affects women and the elderly and is commonly associated with other cardiovascular comorbidities, such as hypertension and diabetes. HFpEF is increasing at a steady rate and is predicted to become the leading cause of heart failure within a decade. HFpEF is characterized by impaired diastolic function, thought to be due to concentric remodeling of the heart along with increased stiffness of both the extracellular matrix and myofilaments. In addition, oxidative stress and inflammation are thought to have a role in HFpEF progression, along with endothelial dysfunction and impaired nitric oxide-cyclic guanosine monophosphate-protein kinase G signaling. Surprisingly a number of clinical studies have failed to demonstrate any benefit of drugs effective in heart failure with systolic dysfunction in HFpEF patients. Thus, HFpEF is one of the largest unmet needs in cardiovascular medicine, and there is a substantial need for new therapeutic approaches and strategies that target mechanisms specific for HFpEF. This conclusion is underscored by the recently reported disappointing results of the RELAX trial, which assessed the use of phosphodiesterase-5 inhibitor sildenafil for treating HFpEF. In animal models, endothelial nitric oxide synthase activators and If current inhibitors have shown benefit in improving diastolic function, and there is a rationale for assessing matrix metalloproteinase 9 inhibitors and nitroxyl donors. LCZ696, a combination drug of angiotensin II receptor blocker and neprilysin inhibitor, and the aldosterone receptor antagonist spironolactone are currently in clinical trial for treating HFpEF. Here we present an overview of the etiology and diagnosis of HFpEF that segues into a discussion of new therapeutic approaches emerging from basic research and drugs currently in clinical trial that primarily target diastolic dysfunction or imbalanced ventricular-arterial coupling.

Zouein FA, Kurdi M, Booz GW. LIF and the heart: Just Another Brick in the Wall? Eur Cytokine Netw. 2013

Multiple studies have shown that the cytokine leukemia inhibitory factor (LIF) is protective of the myocardium in the acute stress of ischemia-reperfusion. All three major intracellular signaling pathways that are activated by LIF in cardiac myocytes have been linked to actions that protect against oxidative stress and cell death, either at the level of the mitochondrion or via nuclear transcription. In addition, LIF has been shown to contribute to post-myocardial infarction cardiac repair and regeneration, by stimulating the homing of bone marrow-derived cardiac progenitors to the injured myocardium, the differentiation of resident cardiac stem cells into endothelial cells, and neovascularization. Whether LIF offers protection to the heart under chronic stress such as hypertension-induced cardiac remodeling and heart failure is not known. However, mice with cardiac myocyte restricted knockout of STAT3, a principal transcription factor activated by LIF, develop heart failure with age, and cardiac STAT3 levels are reported to be decreased in heart failure patients. In addition, endogenously produced LIF has been implicated in the cholinergic transdiffrentiation that may serve to attenuate sympathetic overdrive in heart failure and in the peri-infarct region of the heart after myocardial infarction. Surprisingly, therapeutic strategies to exploit the beneficial actions of LIF on the injured myocardium have received scant attention. Nor is it established whether the purported so-called adverse effects of LIF observed in isolated cardiac myocytes have physiological relevance in vivo. Here we present an overview of the actions of LIF in the heart with the goal of stimulating further research into the translational potential of this pleiotropic cytokine.

Zouein FA, Zgheib C, Hamza S, Fuseler JW, Hall JE, Soljancic A, Lopez-Ruiz A, Kurdi M, Booz GW. Role of STAT3 in angiotensin II-induced hypertension and cardiac remodeling revealed by mice lacking STAT3 serine 727 phosphorylation. Hypertens Res. 2013

STAT3 is involved in protection of the heart provided by ischemic preconditioning. However, the role of this transcription factor in the heart in chronic stresses such as hypertension has not been defined. We assessed whether STAT3 is important in hypertension-induced cardiac remodeling using mice with reduced STAT3 activity due to a S727A mutation (SA/SA). Wild type (WT) and SA/SA mice received angiotensin (ANG) II or saline for 17 days. ANG II increased mean arterial and systolic pressure in SA/SA and WT mice, but cardiac levels of cytokines associated with heart failure were increased less in SA/SA mice. Unlike WT mice, hearts of SA/SA mice showed signs of developing systolic dysfunction as evidenced by reduction in ejection fraction and fractional shortening. In the left ventricle of both WT and SA/SA mice, ANG II induced fibrosis. However, fibrosis in SA/SA mice appeared more extensive and was associated with loss of myocytes. Cardiac hypertrophy as indexed by heart to body weight ratio and left ventricular anterior wall dimension during diastole was greater in WT mice. In WT+ANG II mice there was an increase in the mass of individual myofibrils. In contrast, cardiac myocytes of SA/SA+ANG II mice showed a loss in myofibrils and myofibrillar mass density was decreased during ANG II infusion. Our findings reveal that STAT3 transcriptional activity is important for normal cardiac myocyte myofibril morphology. Loss of STAT3 may impair cardiac function in the hypertensive heart due to defective myofibrillar structure and remodeling that may lead to heart failure.

Zgheib C, Zouein FA, Kurdi M, Booz GW. Chronic treatment of mice with leukemia inhibitory factor does not cause adverse cardiac remodeling but improves heart function. Eur Cytokine Netw. 2012

Recent evidence suggests that the IL-6 family cytokine, leukemia inhibitory factor (LIF) is produced by cardiac cells under stress conditions including myocardial infarction and heart failure. Additionally, short-term delivery of LIF has been shown to have preconditioning effects on the heart and to limit infarct size. However, cell culture studies have suggested that LIF may exert harmful effects on cardiac myocytes, including pathological hypertrophy and contractile dysfunction. Long-term effects of LIF on the heart in vivo have not been reported and were the focus of this study. Adult male mice were injected daily with LIF (2 μg/30 g) or saline for 10 days. LIF treatment caused an approximate 11% loss in body weight. Cardiac function as assessed by echocardiography was improved in LIF-treated mice. Ejection fraction and fractional shortening were increased by 21% and 32%, respectively. No cardiac hypertrophy was seen on histology in LIF-treated mice,, there was no change in the heart-to-tibia length ratio, and no cardiac fibrosis was observed. STAT3 was markedly activated by LIF in the left ventricle. Different effects of LIF were seen in protein levels of genes associated with STAT3 in the left ventricle: levels of SOD2 and Bcl-xL were unchanged, but levels of total STAT3 and MCP-1 were increased. There was a trend towards increased expression of miR-17, miR-21, and miR-199 in the left ventricle of LIF-treated mice, but these changes were not statistically significant. In conclusion, effects of chronic LIF treatment on the heart, although modest, were positive for systolic function: adverse cardiac remodeling was not observed. Our findings thus lend further support to recent proposals that LIF may have therapeutic utility in preventing injury to or repairing the myocardium.

Kurdi M, Sivakumarand V, Duhé RJ, Aond MA, Paoloccid N, Booz GW. Depletion of cellular glutathione modulates LIF-induced JAK1-STAT3 signaling in cardiac myocytes. Int J Biochem Cell Biol. 2012

Previously we reported that the sesquiterpene lactone parthenolide induces oxidative stress in cardiac myocytes, which blocks Janus kinase (JAK) activation by the interleukin 6 (IL-6)-type cytokines. One implication suggested by this finding is that IL-6 signaling is dependent upon cellular anti-oxidant defenses or redox status. Therefore, the present study was undertaken to directly test the hypothesis that JAK1 signaling by the IL-6-type cytokines in cardiac myocytes is impaired by glutathione (GSH) depletion, since this tripeptide is one of the major anti-oxidant molecules and redox-buffers in cells. Cardiac myocytes were pretreated for 6h with l-buthionine-sulfoximine (BSO) to inhibit GSH synthesis. After 24h, cells were dosed with the IL-6-like cytokine, leukemia inhibitory factor (LIF). BSO treatment decreased GSH levels and dose-dependently attenuated activation of JAK1, Signal Transducer and Activator of Transcription 3 (STAT3), and extracellular signal regulated kinases 1 and 2 (ERK1/2). Addition of glutathione monoethyl ester, which is cleaved intracellularly to GSH, prevented attenuation of LIF-induced JAK1 and STAT3 activation, as did the reductant N-acetyl-cysteine. Unexpectedly, LIF-induced STAT1 activation was unaffected by GSH depletion. Evidence was found that STAT3 is more resistant than STAT1 to intermolecular disulfide bond formation under oxidizing conditions and more likely to retain the monomeric form, suggesting that conformational differences explain the differential effect of GSH depletion on STAT1 and STAT3. Overall, our findings indicate that activation of both JAK1 and STAT3 is redox-sensitive and the character of IL-6 type cytokine signaling in cardiac myocytes is sensitive to changes in the cellular redox status. In cardiac myocytes, activation of STAT1 may be favored over STAT3 under oxidizing conditions due to GSH depletion and/or augmented reactive oxygen species production, such as in ischemia-reperfusion and heart failure.

Zgheib C, Kurdi M, Zouein FA, Gunter BW, Stanley BA, Zgheib J, Romero DG, King SB, Paolocci N, Booz GW. Acyloxy Nitroso Compounds Inhibit LIF Signaling in Endothelial Cells and Cardiac Myocytes: Evidence That STAT3 Signaling Is Redox-Sensitive. PLoS One. 2012

We previously showed that oxidative stress inhibits leukemia inhibitory factor (LIF) signaling by targeting JAK1, and the catalytic domains of JAK 1 and 2 have a cysteine-based redox switch. Thus, we postulated that the NO sibling and thiophylic compound, nitroxyl (HNO), would inhibit LIF-induced JAK-STAT3 activation. Pretreatment of human microvascular endothelial cells (HMEC-1) or neonatal rat cardiomyocytes with the HNO donors Angeli's salt or nitrosocyclohexyl acetate (NCA) inhibited LIF-induced STAT3 activation. NCA pretreatment also blocked the induction of downstream inflammatory genes (e.g. intercellular adhesion molecule 1, CCAAT/enhancer binding protein delta). The related 1-nitrosocyclohexyl pivalate (NCP; not a nitroxyl donor) was equally effective in inhibiting STAT3 activation, suggesting that these compounds act as thiolate targeting electrophiles. The JAK1 redox switch is likely not a target of acyloxy nitroso compounds, as NCA had no effect on JAK1 catalytic activity and only modestly affected JAK1-induced phosphorylation of the LIF receptor. However, pretreatment of recombinant human STAT3 with NCA or NCP reduced labeling of free sulfhydryl residues. We show that NCP in the presence of diamide enhanced STAT3 glutathionylation and dimerization in adult mouse cardiac myocytes and altered STAT3 under non-reducing conditions. Finally, we show that monomeric STAT3 levels are decreased in the Gαq model of heart failure in a redox-sensitive manner. Altogether, our evidence indicates that STAT3 has redox-sensitive cysteines that regulate its activation and are targeted by HNO donors and acyloxy nitroso compounds. These findings raise the possibility of new therapeutic strategies to target STAT3 signaling via a redox-dependent manner, particularly in the context of cardiac and non-cardiac diseases with prominent pro-inflammatory signaling.

Alturkmani HJ, Zgheib C, Zouein FA, Alshaaer NE, Kurdi M, Booz GW. Selenate enhances STAT3 transcriptional activity in endothelial cells: differential actions of selenate and selenite on LIF cytokine signaling and cell viability. J Inorg Biochem. 2012

Sodium selenate may have utility in treating Alzheimer's disease and diabetes; however, its impact on the associated proinflammatory cytokine signaling of endothelial cells has not been investigated. We report that treatment of human microvascular endothelial cells with sodium selenate at a pharmacological dose (100 μM) enhanced tyrosine phosphorylation of nuclear STAT3 on Y705 in response to IL-6-type cytokine, leukemia inhibitory factor (LIF), indicative of enhanced STAT3 activity. Accordingly, STAT3 nuclear binding to DNA was increased, as well as LIF-induced gene expression of chemokine (C-C motif) ligand 2 (CCL2). CCL2 plays a key role in inflammatory processes associated with neuronal degenerative and vascular diseases. The enhancing action of selenate on LIF-induced STAT3 Y705 phosphorylation was replicated by vanadate and a specific inhibitor of protein tyrosine phosphatase, non-receptor type 1 (PTP1B). Moreover, we observed that selenite, the cellular reduction bioproduct of selenate but not selenate itself, inhibited enzymatic activity of human recombinant PTP1B. Our findings support the conclusion that in human microvascular endothelial cells selenate has a vanadate-like effect in inhibiting PTP1B and enhancing proinflammatory STAT3 activation. These findings raise the possibility that beneficial actions of supranutritional levels of selenate for treating Alzheimer's and diabetes may be offset by a proinflammatory action on endothelial cells.

Zgheib C, Zouein FA, Chidiac R, Kurdi M, Booz GW. Calyculin a reveals serine/threonine phosphatase protein phosphatase 1 as a regulatory nodal point in canonical signal transducer and activator of transcription 3 signaling of human microvascular endothelial cells. J Interferon Cytokine Res. 2012

Vascular inflammation is initiated by stimuli acting on endothelial cells. A clinical feature of vascular inflammation is increased circulating interleukin 6 (IL-6) type cytokines such as leukemia inhibitory factor (LIF), but their role in vascular inflammation is not fully defined. IL-6 type cytokines activate transcription factor signal transducer and activator of transcription 3 (STAT3), which has a key role in inflammation and the innate immune response. Canonical STAT3 gene induction is due to phosphorylation of (1) Y705, leading to STAT3 dimerization and DNA binding and (2) S727, enhancing homodimerization and DNA binding by recruiting p300/CBP. We asked whether enhancing S727 STAT3 phosphorylation using the protein phosphatase 1 (PP1) inhibitor, calyculin A, would enhance LIF-induced gene expression in human microvascular endothelial cells (HMEC-1). Cotreatment with calyculin A and LIF markedly increased STAT3 S727 phosphorylation, without affecting the increase in the nuclear fraction of STAT3 phosphorylated on Y705. PP2A inhibitors, okadaic acid and fostriecin, did not enhance STAT3 S727 phosphorylation. Surprisingly, calyculin A eliminated LIF-induced gene expression: (1) calyculin A reduced binding of nuclear extracts to a STAT3 consensus site, thereby reducing the overall level of binding observed with LIF; and (2) calyculin A caused p300/CBP phosphorylation, thus resulting in reduced acetylation activity and degradation. Together, these findings reveal a pivotal role of a protein serine/threonine phosphatases that is likely PP1 in HMEC in controlling STAT3 transcriptional activity.

Zgheib C, Zouein FA, Kurdi M, Booz GW. Differential STAT3 signaling in the heart: Impact of concurrent signals and oxidative stress. JAKSTAT 2012

Multiple lines of evidence suggest that the transcription factor STAT3 is linked to a protective and reparative response in the heart. Thus, increasing duration or intensity of STAT3 activation ought to minimize damage and improve heart function under conditions of stress. Two recent studies using genetic mouse models, however, report findings that appear to refute this proposition. Unfortunately, studies often approach the question of the role of STAT3 in the heart from the perspective that all STAT3 signaling is equivalent, particularly when it comes to signaling by IL-6 type cytokines, which share the gp130 signaling protein. Moreover, STAT3 activation is typically equated with phosphorylation of a critical tyrosine residue. Yet, STAT3 transcriptional behavior is subject to modulation by serine phosphorylation, acetylation, and redox status of the cell. Unphosphorylated STAT3 is implicated in gene induction as well. Thus, how STAT3 is activated and also what other signaling events are occurring at the same time is likely to impact on the outcome ultimately linked to STAT3. Notably STAT3 may serve as a scaffold protein allowing it to interact with other singling pathways. In this context, canonical gp130 cytokine signaling may function to integrate STAT3 signaling with a protective PI3K/AKT signaling network via mutual involvement of JAK tyrosine kinases. Differences in the extent of integration may occur between those cytokines that signal through gp130 homodimers and those through heterodimers of gp130 with a receptor α chain. Signal integration may have importance not only for deciding the particular gene profile linked to STAT3, but for the newly described mitochondrial stabilization role of STAT3 as well. In addition, disruption of integrated gp130-related STAT3 signaling may occur under conditions of oxidative stress, which negatively impacts on JAK catalytic activity. For these reasons, understanding the importance of STAT3 signaling to heart function requires a greater appreciation of the plasticity of this transcription factor in the context in which it is investigated.

Kurdi M, Booz GW. Focus on mitochondria dysfunction and dysregulation in heart failure: towards new therapeutic strategies to improve heart function. Congest Heart Fail. 2011

Kurdi M. and Booz G.W. New take on the role of angiotensin II in cardiac hypertrophy and fibrosis. Hypertension 2011

Kurdi M. and Booz G.W. Three 4-letter words of hypertension-related cardiac hypertrophy: TRPC, mTOR, and HDAC. J Mol Cell Cardiol. 2011

Left ventricular hypertrophy due to hypertension represents a major risk factor for adverse cardiovascular events and death. In recent years, the prevalence of cardiac hypertrophy has increased due to obesity and an aging population. Notably, a significant number of individuals have persistent cardiac hypertrophy in the face of blood pressure that is normalized by drug treatment. Thus, a better understanding of the processes underlying the cardiac remodeling events that are set into play by hypertension is needed. At the level of the cardiac myocytes, hypertrophic growth is often described as physiological, as occurs with exercise, or pathological, as seen with hypertension. Here we discuss recent developments in three areas that are fundamental to pathological hypertrophic growth of cardiac myocytes. These areas are the transient receptor potential canonical (TRPC) channels, mammalian target of rapamycin (mTOR) complexes, and histone deacetylase (HDAC) enzymes. In the last several years, studies in each of these areas have yielded new and exciting discoveries into the genesis of pathological growth of cardiac myocytes. The phosphoinositide 3-kinase-Akt signaling network may be the common denominator that links these areas together. Defining the interrelationship among TRPC channels, mTOR signaling, and HDAC enzymes is a promising, but challenging area of research. Such knowledge will undoubtedly lead to new drugs that better prevent or reverse left ventricular hypertension.

Kurdi M. and Booz GW. Deciphering STAT3 signaling in the heart: plasticity and vascular inflammation. Congest Heart Fail. 2010

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that plays a critical role in heart development and protection. New developments in understanding its molecular chemistry have revealed the importance of STAT3 in controlling mitochondrial respiration, independent of its function as a transcription factor, and in modulating inflammatory signaling through interactions with other transcription factors and cofactors. The purpose of this article is 2-fold. First, the authors summarize some recent insights into the function of STAT3. Second, the authors seek to illustrate the complexity of targeting a particular cellular protein for therapeutic purposes and the need to consider context when attempting to decipher the role of a particular signaling pathway in the heart. In this case, inflammation, aging, hypertrophy, and heart failure provide new environments that certainly impact on the functioning of STAT3 and on the gene profile linked to its activation.

Kurdi M., Chidiac R., Hoemann C., Zouein F., Zgheib C., Booz GW. Hydrogels as a Platform for Stem Cell Delivery to the Heart. Congest Heart Fail. 2010

Stem cell therapy offers great promise to repair the injured or failing heart. The outcomes of clinical trials to date, however, have shown that the actual benefit realized falls far short of the promise. A number of factors may explain why that is the case, but poor stem cell retention and engraftment in the hostile environment of the injured heart would seem to be a major factor. Improving stem cell retention and longevity once delivered would seem a logical means to enhance their reparative function. One way to accomplish this goal may be injectable hydrogels, which would serve to fix stem cells in place while providing a sheltering environment. Hydrogels also provide a means to allow for the paracrine factors produced by encapsulated stem cells to diffuse into the injured myocardium. Alternatively, hydrogels themselves can be used for the sustained delivery of reparative factors. Here the authors discuss chitosan-based hydrogels.

Kurdi M. and Booz G.W. JAK Redux - A Second Look at the Regulation and Role of JAKs in the Heart. Am J Physiol Heart Circ Physiol. 2009

A number of type 1 receptor cytokine family members protect the heart from acute and chronic oxidative stress. This protection involves activation of two intracellular signaling cascades: the reperfusion injury salvage kinase (RISK) pathway, which entails activation of phosphatidylinositol 3-kinase (PI3-kinase) and ERK1/2, and JAK-STAT signaling, which involves activation of transcription factor signal transducer and activator of transcription 3 (STAT3). Obligatory for activation of both RISK and STAT3 by nearly all of these cytokines are the kinases JAK1 and JAK2. Yet surprisingly little is known about how JAK1 and JAK2 are regulated in the heart or how they couple to PI3-kinase activation. Although the JAKs are linked to antioxidative stress programs in the heart, we recently reported that these kinases are inhibited by oxidative stress in cardiac myocytes. In contrast, others have reported that cardiac JAK2 is activated by acute oxidative stress by an undefined process. Here we summarize recent insights into the regulation of JAK1 and JAK2. Besides oxidative stress, inhibitory regulation involves phosphorylation, nitration, and intramolecular restraints. Stimulatory regulation involves phosphorylation and adaptor proteins. The net effect of stress on JAK activity in the heart likely represents the sum of both inhibitory and stimulatory processes, along with their dynamic interaction. Thus the regulation of JAKs in the heart, once touted as the paragon of simplicity, is proving rather complicated indeed, requiring a second look. It is our contention that a better understanding of the regulation of this kinase family that is implicated in cardiac protection could translate into effective therapeutic strategies for preventing myocardial damage or repairing the injured heart.

Chouabe C., Ricci E., Kurdi M., Legrand C., Bricca G., Bonvallet R. Evaluation of remodeling in left and right ventricular myocytes from heterozygous (mRen2)27 transgenic rats. Gen Physiol Biophys. 2009

Cardiac remodeling was assessed both in the pressure-overloaded left ventricle and in the normotensive right ventricle of hypertensive transgenic rats (mRen2)27 (TGR27). The present study combined histology, electrophysiology, molecular biology and biochemistry techniques. A significant increase in action potential (AP) duration was recorded both in right and left ventricular myocytes wheareas only in the latter ones were hypertrophic. The increase in AP duration is mainly supported by the reduction of the transient outward K current (I(to)) density since no significant modification was observed for the L-type calcium current (I(Ca,L)), the sodium-calcium exchange current (I(NCX)), the delayed rectifier current (I(K)) and the inward rectifier current (I(K1)). The lower amplitude of I(to) current was associated with a lower Kv4.3 protein expression both in right and left ventricles while Kv4.3 mRNA levels was decreased only in left ventricle. Thus, a differential ventricular remodeling takes place in the TGR27 model. The possible cause of electrical remodeling in right ventricular myocytes of TGR27 is discussed.

Kurdi M. and Booz GW. Growing hearts by the bushel. Congest Heart Fail. 2008

Kurdi M. and Booz G.W. G-CSF-based stem cell therapy for the heart--unresolved issues part B: Stem cells, engraftment, transdifferentiation, and bioengineering. Congest Heart Fail. 2007

The authors extend their coverage of recent developments in stem cell-based therapy for repairing the heart to cover the basic questions of what stem cells should be used and how best to favor their survivability within the injured heart. The authors focus their attention on those adult stem/progenitor cells that have been best investigated in animal studies for repairing the infarcted heart and are the focus of completed or ongoing clinical trials. In addition, they discuss the promise that resident cardiac stem cells offer and the recent identification of specialized architecturally defined niches within the heart to nurse their development. Bioengineering approaches employing off-the-shelf mesenchymal stem cell patches may soon provide a way to recreate these niches in the scarred heart. Conceivably, these patches might also be seeded with prescribed mixtures of culturally expanded autologous stem/progenitor cells that would lead to new blood vessel and cardiac myocyte formation. The convergence of bioengineering and molecular biology on stem cell therapy would seem to make what was once unimaginable, cardiac regeneration, a clinical reality in less than one generation.

Kurdi M. and Booz G.W. G-CSF-based stem cell therapy for the heart-unresolved issues part A: paracrine actions, mobilization, and delivery. Congest Heart Fail. 2007

The results of large-scale clinical trials involving granulocyte colony-stimulating factor (G-CSF)-based mobilization of bone marrow stem cells to improve cardiac remodeling and function after acute myocardial infarction have been disappointing. These trials came about as the result of an explosion of animal studies reporting dramatic successes with this therapeutic approach and small-scale nonrandomized, nonblinded clinical trials suggesting beneficial effects in humans as well. It would be rash to conclude, however, that G-CSF-based stem cell therapies for repairing the injured or failing heart are not worth pursuing. Recent advances in basic science not only help explain the failure of the larger clinical trials but have revitalized interest into using G-CSF-based or G-CSF-related therapies for the injured heart. This article will provide an overview of recent advances that have been made in the direct protective actions of G-CSF on cardiac cells, the mobilization of stem cells from the bone marrow, and the delivery of these cells to the heart. Such knowledge could be readily exploited to make G-CSF-based therapy a reality for the clinician.

Kurdi M. and Booz G.W. Can the Protective Actions of JAK-STAT in the Heart be Exploited Therapeutically? Parsing the Regulation of IL-6-Type Cytokine Signaling. J Cardiovasc Pharmacol. 2007

Activation of the transcription factor signal transducers and activators of transcription (STAT) 3 is a defining feature of the interleukin (IL)-6 family of cytokines, which include IL-6, leukemia inhibitory factor, and cardiotrophin-1. These cytokines, as well as STAT3 activation, have been shown to be protective for cardiac myocytes and necessary for ischemia preconditioning. However, the mechanisms that regulate IL-6-type cytokine signaling in cardiac myocytes are largely unexplored. We propose that the protective character of IL-6-type cytokine signaling in cardiac myocytes is determined principally by three mechanisms: redox status of the nonreceptor tyrosine kinase Janus kinase 1 (JAK) 1 that activates STAT3, phosphorylation of STAT3 within the transcriptional activation domain on serine 727, and STAT3-mediated induction of suppressor of cytokine signaling (SOCS) 3 that terminates IL-6-type cytokine signaling. Moreover, we hypothesize that hyperactivation of the JAK kinases, particularly JAK2, mismatched STAT3 serine-tyrosine phosphorylation or heightened STAT3 transcriptional activity, and SOCS3 induction may ultimately prove detrimental. Here we summarize recent evidence that supports this hypothesis, as well as additional possible mechanisms of JAK-STAT regulation. Understanding how IL-6-type cytokine signaling is regulated in cardiac myocytes has great significance for exploiting the therapeutic potential of these cytokines and the phenomenon of preconditioning.

Kurdi M. and Booz G.W. Evidence that IL-6-type cytokine signaling in cardiomyocytes is inhibited by oxidative stress: Parthenolide targets JAK1 activation by generating ROS. J Cell Physiol. 2007

Parthenolide, an anti-inflammatory compound, was reported to inhibit signal transducer and activator of transcription 3 (STAT3) activation by the interleukin (IL)-6-type cytokines by an undefined process, which was the focus of our study. Here we report that parthenolide reduced both basal and leukemia inhibitory factor (LIF)-induced STAT3 tyrosine 705 (Y705) phosphorylation in cardiomyocytes in a dose-dependent manner, but stimulated the MAP kinase signaling pathways. Activation of Janus kinase 1 (JAK1) tyrosine kinase was markedly reduced by parthenolide. Pretreatment with parthenolide inhibited JAK1-mediated phosphorylation of the LIF receptor subunits LIF receptor (LIFR) alpha and glycoprotein 130 (gp130), and reduced the LIF-induced increase in JAK1 association with both components. In addition, we documented that parthenolide, over the same concentration range, does not have a direct inhibitory effect on JAK1 autophosphorylation. However, we observed that parthenolide increased intracellular reactive oxygen species (ROS). Pretreatment with the antioxidant, N-acetyl-L-cysteine, completely suppressed the effect of parthenolide on JAK1 and STAT3. From these results, we conclude ROS generation in cardiomyocytes blocks STAT3 signaling of the IL-6-type cytokines by targeting JAK1. The finding that signaling by the IL-6-type cytokine may be redox-sensitive defines a novel mechanism of regulation that has implications for exploiting their therapeutic potential.

Kurdi M., Bowers M.C., Dado J., and Booz G.W. Parthenolide induces a distinct pattern of oxidative stress in cardiac myocytes. Free Radic Biol Med. 2007

Although parthenolide was reported to reduce cardiovascular damage in endotoxic shock and have beneficial effects in myocardial ischemia, its actions on cardiac myocytes have not been reported. Because parthenolide possesses an alpha-methylene-gamma-lactone ring and epoxide residue, we hypothesized that it would induce oxidative stress in cardiac myocytes. Superoxide production and sources, viability, glutathione levels, and mitochondrial membrane potential were studied in neonatal rat ventricular myocytes treated with parthenolide. Parthenolide, dose dependently, induced oxidase activity as assessed by superoxide generation in cell lysates. Superoxide formation was increased more than 4-fold with 50 microM parthenolide. At concentrations >5 microM, parthenolide decreased cell viability in a dose-and time-dependent manner, and activated the stress MAP kinases JNK and p38. Over 6 h, parthenolide at concentrations >5 microM markedly depleted intracellular glutathione and led to collapse of the mitochondrial membrane potential. At lower parthenolide concentrations (<5 microM) the source of superoxide was mitochondria; at higher concentrations (>5 microM) the primary source was NADPH oxidase. We conclude that parthenolide causes oxidative stress in cardiac myocytes by inducing superoxide formation by mitochondrial and NADPH oxidase in a dose-dependent manner. Parthenolide may be a useful tool for studying the roles of oxidative stress and mitochondrial dysfunction in the pathogenesis of cardiac hypertrophy and failure.

Kurdi M. and Booz G.W. Jak inhibition, but not Stat1 knockdown, blocks the synergistic effect of IFN-gamma on Fas-induced apoptosis of A549 human non-small cell lung cancer cells. J Interferon Cytokine Res. 2007

Non-small cell lung cancer (NSCLC) is highly resistant to chemotherapy and radiation. Because these treatments induce apoptosis, efforts are underway to define molecular events opposing cell death in NSCLC cells. The transcription factor Stat3 was reported recently to promote growth of several human NSCLC cell lines, including A549. Because Stat1 and Stat3 often elicit opposite effects, we assessed whether Stat1 would couple to A549 cell apoptosis. Interferon-gamma (IFN-gamma) markedly induced Jak1 and Stat1 activation in cells cultured under optimal growth conditions. IFN-gamma also activated Stat3. IFN-gamma inhibited proliferation but did not induce apoptosis; however, IFN-gamma synergized with activation of Fas to induce apoptosis, as indexed by cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP), as well as DNA laddering. Knockdown of Stat1 or Stat3 with small interfering RNA (siRNA), separately or together, did not inhibit apoptosis, although a paninhibitor of Jak1 did. Our findings suggest that the proapoptotic actions of IFN-gamma in A549 cells occur downstream of Jak1 activation by a noncanonical pathway that does not involve the Jak1 target, Stat1.

Cerutti C., Kurdi M., Bricca G., Hodroj W., Paultre C., Randon J., Gustin M.P. Transcriptional alterations in the left ventricle of three hypertensive rat models. Physiol Genomics. 2006

Left ventricular hypertrophy (LVH) is commonly associated with hypertension and represents an independent cardiovascular risk factor. The aim of this study was to test the hypothesis that the cardiac overload related to hypertension is associated to a specific gene expression pattern independently of genetic background. Gene expression levels were obtained with microarrays for 15,866 transcripts from RNA of left ventricles from 12-wk-old rats of three hypertensive models [spontaneously hypertensive rat (SHR), Lyon hypertensive rat (LH), and heterozygous TGR(mRen2)27 rat] and their respective controls. More than 60% of the detected transcripts displayed significant changes between the three groups of normotensive rats, showing large interstrain variability. expression data were analyzed with respect to hypertension, LVH, and chromosomal distribution. Only four genes had significantly modified expression in the three hypertensive models among which a single gene, coding for sialyltransferase 7A, was consistently overexpressed. Correlation analysis between expression data and left ventricular mass index (LVMI) over all rats identified a larger set of genes whose expression was continuously related with LVMI, including known genes associated with cardiac remodeling. Positioning the detected transcripts along the chromosomes pointed out high-density regions mostly located within blood pressure and cardiac mass quantitative trait loci. Although our study could not detect a unique reprogramming of cardiac cells involving specific genes at early stage of LVH, it allowed the identification of some genes associated with LVH regardless of genetic background. This study thus provides a set of potentially important genes contained within restricted chromosomal regions involved in cardiovascular diseases.

Kurdi M., De Mello W.C., Booz G.W. Working outside the system: an update on the unconventional behavior of the renin-angiotensin system components. Int J Biochem Cell Biol. 2005

The renin-angiotensin system (RAS) plays an important role in regulating arterial pressure, blood volume, thirst, cardiac function, and cellular growth. Both a circulating and multiple tissue-localized systems have been identified, and are generally portrayed as a series of reactions that occur sequentially with a single outcome: angiotensinogen is cleaved by renin to form angiotensin I, which in turn is processed by angiotensin-converting enzyme (ACE) to angiotensin II, which then activates either the AT1 or the AT2 plasma membrane receptor. Evidence has emerged, however, showing that some RAS components play important roles outside of this canonical scheme. This article provides an overview of some recently identified extra-system functions. In addition to forming angiotensin II, ACE is a multifunctional enzyme equally important in the metabolism of vasodilator and antifibrotic peptides. As the membrane-bound form, ACE functions as a "receptor" that initiates intracellular signaling leading to gene expression. Both angiotensin I and II may lead to actions that are independent of, or even oppose, those of the RAS via their metabolism by the novel ACE-homologue ACE2. The two angiotensin II receptor types have ligand-independent roles that influence cellular signaling and growth, some of which may result from the ability to form hetero-dimers with other 7-transmembrane receptors. Finally, intracellular angiotensin II has been demonstrated to have actions on cell-communication, gene expression, and cellular growth, through both receptor-dependent and independent means. A greater understanding of these extra-system functions of the RAS components may aid in the development of novel treatments for hypertension, myocardial ischemia, and heart failure.

Kurdi M., Randon J., Cerutti C., Bricca G. Increased expression of IL-6 and LIF in the hypertrophied left ventricle of TGR(mRen2)27 and SHR rats. Mol Cell Biochem. 2005

Cytokines from the interleukin-6 (IL-6) family have been reported to play an important synergistic role with angiotensin II in the development of pathological cardiac hypertrophy. Whether their expression pattern changes in vivo, in an angiotensin I-dependent hypertrophied myocardium has not been reported. In this study, we addressed that issue using two animal models of angiotensin II-dependent cardiac hypertrophy. Heterozygous transgenic TGR(mRen2)27 (TGR) with an overactive cardiac renin angiotensin system and the closely related spontaneously hypertensive rats (SHR) were compared to their respective control rats. The mRNA levels of IL-6, leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF) and cardiotrophin-1 (CT-1) as well as their receptor subunits, glycoprotein 130 (gp130), IL-6 receptor (IL-6R), LIFR, and CNTFR, were measured by semi-quantitative RT-PCR. The protein levels of IL-6, LIF and CT-1 were investigated by western blot. TGR and SHR both displayed significant over expression of mRNA and protein levels for IL-6 and LIF. In TGR, the increased level of LIF was accompanied by a decrease in mRNA levels for LIFR and CNTFR. In SHR, a higher level of mRNA IL-6R was observed. By contrast, the mRNA and protein levels for CT-1 and the mRNA level for gp130 did not vary in these two models. These findings suggest that IL-6 and LIF, but not CT-1, contribute to angiotensin II-dependent left ventricular hypertrophy in the two hypertensive rat models, TGR(mRen2)27 and SHR.

Kurdi M., Cerutti C., Randon J., McGregor L., Bricca G. Macroarray analysis in the hypertrophic left ventricle of renin-dependent hypertensive rats: identification of target genes for renin. J Renin Angiotensin Aldosterone Syst. 2004

INTRODUCTION: aim of this work was to identify new renin target genes in left ventricular hypertrophy during hypertension. MATERIALS AND METHODS: We compared left ventricle gene expression from four transgenic TGR(mRen2)27 (TG+/-) rats and four non-transgenic littermates (TG-/-) using cDNA macroarray. Hybridisation signals were quantified with a phosphorimager, and normalised to an external scale. Data analysis was performed with Statistical Analysis for Microarrays (SAM 1.21) software. The mRNA levels of candidate genes were determined by semi-quantitative RT-PCR in three different hypertensive rats: TG+/-, spontaneously hypertensive (SHR) and genetically Lyon hypertensive (LH) rats, compared to their respective controls (TG-/-, Wistar-Kyoto, Lyon low blood pressure rats). RESULTS: Out of 1,200 genes present on the macroarray, 233 were reliably measured and only three were overexpressed (Biglycan, beta1-adenosine monophosphate-activated protein kinase [AMPK] and amyloid precursor like protein 2 [APLP2]) and 19 were underexpressed in the left ventricle of TG+/- compared with TG-/-. APLP2 is a member of the amyloid precursor protein (APP) family. APLP2 and APP mRNA levels were increased in TGR(mRen2)27 but significantly decreased in LH rats, while only APP was increased in SHR rats. CONCLUSIONS: We report new genes associated with renin-dependent left ventricular hypertrophy. Moreover, this work shows for the first time that the APP family gene expression could be altered in response to high renin activity and this effect is independent of cardiac remodelling and hypertension.

Bricca G., Randon J., Paultre C., Legedz L., Kurdi M., Gustin M.P., Cerutti C. Transcriptome myocardique : une approche de la complexité du remodelage cardiaque. Médecine Thérapeutique Cardiologie. 2004

Le transcriptome représente une mesure de l’échantillon le plus large possible des ARN présents à un instant donné dans une cellule ou un tissu. Appliquée au myocarde, l’analyse du transcriptome a permis de prendre la mesure de la complexité des phénomènes transcriptomiques qui surviennent dans le myocarde tant au cours du fonctionnement physiologique que dans les situations pathologiques et leurs traitements. Cette revue rappelle les principes et les contraintes de la méthode. Sur la base des études publiées et de nos travaux, nous examinerons l’impact des différents facteurs impliqués dans le remodelage cardiaque qui aboutissent à l’hypertrophie ventriculaire gauche comme première étape vers les pathologies constituées comme l’insuffisance cardiaque ou l’infarctus du myocarde.

Kurdi M., Dizerens N., Cerutti C., Bricca G., Randon J. Expression des cytokines et de leurs récepteurs dans le ventricule gauche hypertrophique du rat TGR(mRen2)27. Arch Mal Coeur Vaiss. 2003

Variations in the expression of cytokines from the interleukin-6 (IL-6) family: ciliary neurotrophic factor (CNTF), leukaemia inhibitory factor (LIF), and cardiotrophin 1 (CT-1) were studied during cardiac remodelling leading to left ventricular hypertrophy (LVH) in TGR(mRen2)27 rats at the age of 8 and 20 weeks. The cytokines mRNA levels within the free wall of the left ventricle were measured by semi-quantitative RT-PCR standardised with 18S. They were compared between heterozygous rats for the mRen2 transgene (TG+/-) and control rats (TG-/-). No significant difference was observed between results obtained at 8 and 20 weeks of age. At 20 weeks of age, TGR(mRen2)27 rats showed higher levels of mRNA LIF and IL-6 respectively by 52 and 55% compared to the control rats [LIF TG+/-: 3.17 +/- 0.21, TG-/-: 2.09 +/- 0.03; p < 0.001; n = 5; and IL-6 TG+/-: 1.53 +/- 0.13; TG-/-: 0.99 +/- 0.17; p < 0.05; n = 5]. By contrast, no variation of mRNAs levels of CT-1 and gp 130 genes was observed between control and transgenic rats. Concerning the cytokine receptors, the levels of mRNA for IL-6R did not vary while those of receptor subunits LIFR and CNTFR were decreased respectively by 48 and 42% in transgenic rats vs controls [LIFR TG+/-: 0.48 +/- 0.01; TG-/-: 0.92 +/- 0.08 p < 0.001; n = 5; and CNTFR TG+/-: 1.07 +/- 0.08; TG-/-: 1.85 +/- 0.18; p < 0.01; n = 5]. Therefore, these results show a specific pattern of activation of the cytokines pathway in the LVH of the TGR(mRen2)27 rat.

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