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Wei Liu,
Min Zi,
Ronald Naumann,
Susanne Ulm,
Jiawei Jin,
Domenico M Taglieri, Sukhpal Prehar,
Junhong Gui,
Hoyee Tsui,
Rui-Ping Xiao,
Ludwig Neyses,
R John Solaro,
Yunbo Ke,
Elizabeth J Cartwright,
Ming Lei,
Xin Wang
[show abstract]
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ABSTRACT: Stress-induced hypertrophic remodeling is a critical pathogenetic process leading to heart failure. Although many signal transduction cascades are demonstrated as important regulators to facilitate the induction of cardiac hypertrophy, the signaling pathways for suppressing hypertrophic remodeling remain largely unexplored. In this study, we identified p21-activated kinase 1 (Pak1) as a novel signaling regulator that antagonizes cardiac hypertrophy.
Hypertrophic stress applied to primary neonatal rat cardiomyocytes (NRCMs) or murine hearts caused the activation of Pak1. Analysis of NRCMs expressing constitutively active Pak1 or in which Pak1 was silenced disclosed that Pak1 played an antihypertrophic role. To investigate the in vivo role of Pak1 in the heart, we generated mice with a cardiomyocyte-specific deletion of Pak1 (Pak1(cko)). When subjected to 2 weeks of pressure overload, Pak1(cko) mice developed greater cardiac hypertrophy with attendant blunting of JNK activation compared with controls, and these knockout mice underwent the transition into heart failure when prolonged stress was applied. Chronic angiotensin II infusion also caused increased cardiac hypertrophy in Pak1(cko) mice. Moreover, we discovered that the Pak1 activator FTY720, a sphingosine-like analog, was able to prevent pressure overload-induced hypertrophy in wild-type mice without compromising their cardiac functions. Meanwhile, FTY720 failed to exert such an effect on Pak1(cko) mice, suggesting that the antihypertrophic effect of FTY720 likely acts through Pak1 activation.
These results, for the first time, establish Pak1 as a novel antihypertrophic regulator and suggest that it may be a potential therapeutic target for the treatment of cardiac hypertrophy and heart failure.
Circulation 11/2011; 124(24):2702-15. · 14.74 Impact Factor
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Tamer M A Mohamed,
Delvac Oceandy,
Min Zi, Sukhpal Prehar,
Nasser Alatwi,
Yanwen Wang,
Mohamed A Shaheen,
Riham Abou-Leisa,
Celine Schelcher,
Zeinab Hegab,
Florence Baudoin,
Michael Emerson,
Mamas Mamas,
Giulietta Di Benedetto,
Manuela Zaccolo,
Ming Lei,
Elizabeth J Cartwright,
Ludwig Neyses
[show abstract]
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ABSTRACT: Identification of the signaling pathways that regulate cyclic nucleotide microdomains is essential to our understanding of cardiac physiology and pathophysiology. Although there is growing evidence that the plasma membrane Ca(2+)/calmodulin-dependent ATPase 4 (PMCA4) is a regulator of neuronal nitric-oxide synthase, the physiological consequence of this regulation is unclear. We therefore tested the hypothesis that PMCA4 has a key structural role in tethering neuronal nitric-oxide synthase to a highly compartmentalized domain in the cardiac cell membrane. This structural role has functional consequences on cAMP and cGMP signaling in a PMCA4-governed microdomain, which ultimately regulates cardiac contractility. In vivo contractility and calcium amplitude were increased in PMCA4 knock-out animals (PMCA4(-/-)) with no change in diastolic relaxation or the rate of calcium decay, showing that PMCA4 has a function distinct from beat-to-beat calcium transport. Surprisingly, in PMCA4(-/-), over 36% of membrane-associated neuronal nitric-oxide synthase (nNOS) protein and activity was delocalized to the cytosol with no change in total nNOS protein, resulting in a significant decrease in microdomain cGMP, which in turn led to a significant elevation in local cAMP levels through a decrease in PDE2 activity (measured by FRET-based sensors). This resulted in increased L-type calcium channel activity and ryanodine receptor phosphorylation and hence increased contractility. In the heart, in addition to subsarcolemmal calcium transport, PMCA4 acts as a structural molecule that maintains the spatial and functional integrity of the nNOS signaling complex in a defined microdomain. This has profound consequences for the regulation of local cyclic nucleotide and hence cardiac β-adrenergic signaling.
Journal of Biological Chemistry 09/2011; 286(48):41520-9. · 4.77 Impact Factor
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Min Zi,
Tomomi E. Kimura,
Wei Liu,
Jiawei Jin,
Jonathan Higham,
Sanjay Kharche,
Guoliang Hao,
Ying Shi,
Weijian Shen, Sukhpal Prehar,
Aleksandr Mironov,
Ludwig Neyses,
Marti F. A. Bierhuizen,
Mark R. Boyett,
Henggui Zhang,
Ming Lei,
Elizabeth J. Cartwright,
Xin Wang
[show abstract]
[hide abstract]
ABSTRACT: Connexin 43 (Cx43) is the predominant isoform of gap junction proteins in the working myocardium. In the heart, mitogen-activated
protein (MAP) kinases are implicated in regulating Cx43 remodeling; however, their precise roles remain obscure. Mitogen-activated
protein kinase kinase 4 (MKK4) is a critical component of the stress-activated MAP kinase signaling pathway. We have previously
demonstrated that MKK4 antagonizes cardiomyocyte hypertrophy. Herein, we investigate the role of MKK4 in regulating Cx43 expression
in cardiomyocytes. We found that knockdown of MKK4 expression or inhibition of its kinase activity in neonatal rat cardiomyocytes
(NRCMs) significantly reduced phenylephrine-induced Cx43 expression. Furthermore, two activator protein-1 (AP-1) binding elements
in the Cx43 promoter region were identified as being responsible for the MKK4-regulated Cx43 expression. Consistently, we
also detected heterogeneously reduced Cx43 expression and attenuated zonula occludens-1 (ZO-1) content in the hearts of MKK4
cardiomyocyte-specific knockout mice (MKK4cko) following pressure overload. To test whether heterogeneously reduced Cx43 expression
contributes to ventricular arrhythmic vulnerability, MKK4cko and control mice were subjected to pressure overload followed
by programmed electrical stimulation (PES). 6 of 13 MKK4cko mice, but none of the controls, developed ventricular tachycardia.
Epicardial activation mapping recorded from the MKK4cko hypertrophied heart showed ventricular activation delay. Mathematical
models have simulated that the spatially heterogeneous decrease in Cx43 causes slowed ventricular conduction and fragmented
wave propagations leading to re-entrant excitations. Collectively, these data reveal a novel role for MKK4 in regulating Cx43
expression and preventing hypertrophy-associated arrhythmogenesis.
Journal of Biological Chemistry 03/2011; · 4.77 Impact Factor
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Min Zi,
Tomomi E Kimura,
Wei Liu,
Jiawei Jin,
Jonathan Higham,
Sanjay Kharche,
Guoliang Hao,
Ying Shi,
Weijian Shen, Sukhpal Prehar,
Aleksandr Mironov,
Ludwig Neyses,
Marti F A Bierhuizen,
Mark R Boyett,
Henggui Zhang,
Ming Lei,
Elizabeth J Cartwright,
Xin Wang
[show abstract]
[hide abstract]
ABSTRACT: Connexin 43 (Cx43) is the predominant isoform of gap junction proteins in the working myocardium. In the heart, mitogen-activated protein (MAP) kinases are implicated in regulating Cx43 remodeling; however, their precise roles remain obscure. Mitogen-activated protein kinase kinase 4 (MKK4) is a critical component of the stress-activated MAP kinase signaling pathway. We have previously demonstrated that MKK4 antagonizes cardiomyocyte hypertrophy. Herein, we investigate the role of MKK4 in regulating Cx43 expression in cardiomyocytes. We found that knockdown of MKK4 expression or inhibition of its kinase activity in neonatal rat cardiomyocytes (NRCMs) significantly reduced phenylephrine-induced Cx43 expression. Furthermore, two activator protein-1 (AP-1) binding elements in the Cx43 promoter region were identified as being responsible for the MKK4-regulated Cx43 expression. Consistently, we also detected heterogeneously reduced Cx43 expression and attenuated zonula occludens-1 (ZO-1) content in the hearts of MKK4 cardiomyocyte-specific knockout mice (MKK4cko) following pressure overload. To test whether heterogeneously reduced Cx43 expression contributes to ventricular arrhythmic vulnerability, MKK4cko and control mice were subjected to pressure overload followed by programmed electrical stimulation (PES). 6 of 13 MKK4cko mice, but none of the controls, developed ventricular tachycardia. Epicardial activation mapping recorded from the MKK4cko hypertrophied heart showed ventricular activation delay. Mathematical models have simulated that the spatially heterogeneous decrease in Cx43 causes slowed ventricular conduction and fragmented wave propagations leading to re-entrant excitations. Collectively, these data reveal a novel role for MKK4 in regulating Cx43 expression and preventing hypertrophy-associated arrhythmogenesis.
Journal of Biological Chemistry 03/2011; 286(20):17821-30. · 4.77 Impact Factor
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[show abstract]
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ABSTRACT: There is little doubt that members of mitogen-activated protein kinase (MAPK) families play key roles in the transition from adaptive hypertrophic remodeling to heart failure. Mitogen-activated protein kinase kinase 7 (MKK7) is a critical component of stress-activated MAP kinase signaling pathway. The role of MKK7 plays in mediating cardiac remodeling in response to load stress has yet to be defined. Herein, we investigate the role of MKK7 in regulating cardiac remodeling in response to pressure overload. We generated and examined the phenotype of mice with cardiomyocyte-specific deletion of the mkk7 gene (MKK7(cko)). Following one week of pressure overload, MKK7(cko) mice exhibited characteristic phenotypes of heart failure evidenced by deterioration in ventricular function and pulmonary congestion. Cell death assays revealed an increased prevalence of cardiomyocyte apoptosis in the MKK7(cko) heart, in which elevated p53 levels and attenuated expression of manganese superoxide dismutase (MnSOD) were found. Moreover, extensive interstitial fibrosis was discovered in the knockout heart likely attributable to upregulation of transforming growth factor β (TGF-β) signaling. These results reveal an essential role of MKK7 in cardiomyocytes for protecting the heart from hypertrophic insults thereby preventing the transition to heart failure.
Journal of Molecular and Cellular Cardiology 01/2011; 50(4):702-11. · 5.17 Impact Factor
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Tomomi E Kimura,
Jiawei Jin,
Min Zi, Sukhpal Prehar,
Wei Liu,
Delvac Oceandy,
Jun-ichi Abe,
Ludwig Neyses,
Arthur H Weston,
Elizabeth J Cartwright,
Xin Wang
[show abstract]
[hide abstract]
ABSTRACT: Mitogen-activated protein kinase (MAPK) pathways provide a critical connection between extrinsic and intrinsic signals to cardiac hypertrophy. Extracellular signal-regulated protein kinase (ERK)5, an atypical MAPK is activated in the heart by pressure overload. However, the role of ERK5 plays in regulating hypertrophic growth and hypertrophy-induced apoptosis is not completely understood.
Herein, we investigate the in vivo role and signaling mechanism whereby ERK5 regulates cardiac hypertrophy and hypertrophy-induced apoptosis.
We generated and examined the phenotypes of mice with cardiomyocyte-specific deletion of the erk5 gene (ERK5(cko)). In response to hypertrophic stress, ERK5(cko) mice developed less hypertrophic growth and fibrosis than controls. However, increased apoptosis together with upregulated expression levels of p53 and Bad were observed in the mutant hearts. Consistently, we found that silencing ERK5 expression or specific inhibition of its kinase activity using BIX02189 in neonatal rat cardiomyocytes (NRCMs) reduced myocyte enhancer factor (MEF)2 transcriptional activity and blunted hypertrophic responses. Furthermore, the inhibition of MEF2 activity in NRCMs using a non-DNA binding mutant form of MEF2 was found to attenuate the ERK5-regulated hypertrophic response.
These results reveal an important function of ERK5 in cardiac hypertrophic remodeling and cardiomyocyte survival. The role of ERK5 in hypertrophic remodeling is likely to be mediated via the regulation of MEF2 activity.
Circulation Research 03/2010; 106(5):961-70. · 9.49 Impact Factor
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Delvac Oceandy,
Adam Pickard, Sukhpal Prehar,
Min Zi,
Tamer M A Mohamed,
Peter J Stanley,
Florence Baudoin-Stanley,
Raja Nadif,
Stella Tommasi,
Gerd P Pfeifer,
Angel L Armesilla,
Elizabeth J Cartwright,
Ludwig Neyses
[show abstract]
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ABSTRACT: Ras signaling regulates a number of important processes in the heart, including cell growth and hypertrophy. Although it is known that defective Ras signaling is associated with Noonan, Costello, and other syndromes that are characterized by tumor formation and cardiac hypertrophy, little is known about factors that may control it. Here we investigate the role of Ras effector Ras-association domain family 1 isoform A (RASSF1A) in regulating myocardial hypertrophy.
A significant downregulation of RASSF1A expression was observed in hypertrophic mouse hearts, as well as in failing human hearts. To further investigate the role of RASSF1A in cardiac (patho)physiology, we used RASSF1A knock-out (RASSF1A(-)(/)(-)) mice and neonatal rat cardiomyocytes with adenoviral overexpression of RASSF1A. Ablation of RASSF1A in mice significantly enhanced the hypertrophic response to transverse aortic constriction (64.2% increase in heart weight/body weight ratio in RASSF1A(-)(/)(-) mice compared with 32.4% in wild type). Consistent with the in vivo data, overexpression of RASSF1A in cardiomyocytes markedly reduced the cellular hypertrophic response to phenylephrine stimulation. Analysis of molecular signaling events in isolated cardiomyocytes indicated that RASSF1A inhibited extracellular regulated kinase 1/2 activation, likely by blocking the binding of Raf1 to active Ras.
Our data establish RASSF1A as a novel inhibitor of cardiac hypertrophy by modulating the extracellular regulated kinase 1/2 pathway.
Circulation 09/2009; 120(7):607-16. · 14.74 Impact Factor
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Wei Liu,
Min Zi,
Jiawei Jin, Sukhpal Prehar,
Delvac Oceandy,
Tomomi E Kimura,
Ming Lei,
Ludwig Neyses,
Arthur H Weston,
Elizabeth J Cartwright,
Xin Wang
[show abstract]
[hide abstract]
ABSTRACT: Mitogen-activated protein kinase kinase (MKK)4 is a critical member of the mitogen-activated protein kinase family. It is able to activate the c-Jun NH(2)-terminal protein kinase (JNK) and p38 mitogen-activated protein kinase in response to environmental stresses. JNK and p38 are strongly implicated in pathological cardiac hypertrophy and heart failure; however, the regulatory mechanism whereby the upstream kinase MKK4 activates these signaling cascades in the heart is unknown. To elucidate the biological function of MKK4, we generated mice with a cardiac myocyte-specific deletion of mkk4 (MKK4(cko) mice). In response to pressure overload or chronic beta-adrenergic stimulation, upregulated NFAT (nuclear factor of activated T-cell) transcriptional activity associated with exacerbated cardiac hypertrophy and the appearance of apoptotic cardiomyocytes were observed in MKK4(cko) mice. However, when subjected to swimming exercise, MKK4(cko) mice displayed a similar level of physiological cardiac hypertrophy compared to controls (MKK4(f/f)). In addition, we also discovered that MKK4 expression was significantly reduced in heart failure patients. In conclusion, this study demonstrates for the first time that MKK4 is a key mediator which prevents the transition from an adaptive response to maladaptive cardiac hypertrophy likely involving the regulation of the NFAT signaling pathway.
Circulation Research 04/2009; 104(7):905-14. · 9.49 Impact Factor
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ABSTRACT: Although, it is accepted that there is an excess of cardiovascular mortality in acromegaly, it is uncertain whether this is due to the direct effects of growth hormone-induced-cardiomyopathy or is a consequence of atherosclerosis secondary to the metabolic syndrome often observed in this condition. Direct comparison of a mouse model of acromegaly to a mouse model of Laron's syndrome allowed us to carry out detailed phenotyping and better understand the role GH plays in the circulatory system.
Transgenic mice that overexpress the growth hormone gene (GH) developed gigantism, including insulin resistance and higher blood pressures commensurate with increased body mass. In these giant mice, the hearts were hypertrophied but haemodynamic studies suggested contractile function was normal. Segments of small arteries mounted in a pressure myograph showed vascular wall hypertrophy but a preserved lumen diameter. Vascular contractile function was normal. Mice in which the GH receptor gene was disrupted or 'knocked out' were dwarf and had low blood pressure, small hearts and blood vessels but a normally functioning circulation. Correlations of body mass with cardiovascular parameters suggested that blood pressure and structural characteristics develop in line with body size.
In this transgenic mouse model of acromegaly, there is cardiac and vascular hypertrophy commensurate with GH excess but normal function. Our findings support the contention that the excess mortality in this condition may be due to the development of hypertrophic cardiomyopathy rather than increased rates of atherosclerotic coronary artery disease.
Growth hormone & IGF research: official journal of the Growth Hormone Research Society and the International IGF Research Society 04/2009; 19(5):413-9. · 2.35 Impact Factor
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Tamer M A Mohamed,
Delvac Oceandy, Sukhpal Prehar,
Nasser Alatwi,
Zeinab Hegab,
Florence M Baudoin,
Adam Pickard,
Aly O Zaki,
Raja Nadif,
Elizabeth J Cartwright,
Ludwig Neyses
[show abstract]
[hide abstract]
ABSTRACT: The cardiac neuronal nitric-oxide synthase (nNOS) has been described as a modulator of cardiac contractility. We have demonstrated previously that isoform 4b of the sarcolemmal calcium pump (PMCA4b) binds to nNOS in the heart and that this complex regulates beta-adrenergic signal transmission in vivo. Here, we investigated whether the nNOS-PMCA4b complex serves as a specific signaling modulator in the heart. PMCA4b transgenic mice (PMCA4b-TG) showed a significant reduction in nNOS and total NOS activities as well as in cGMP levels in the heart compared with their wild type (WT) littermates. In contrast, PMCA4b-TG hearts showed an elevation in cAMP levels compared with the WT. Adult cardiomyocytes isolated from PMCA4b-TG mice demonstrated a 3-fold increase in Ser(16) phospholamban (PLB) phosphorylation as well as Ser(22) and Ser(23) cardiac troponin I (cTnI) phosphorylation at base line compared with the WT. In addition, the relative induction of PLB phosphorylation and cTnI phosphorylation following isoproterenol treatment was severely reduced in PMCA4b-TG myocytes, explaining the blunted physiological response to the beta-adrenergic stimulation. In keeping with the data from the transgenic animals, neonatal rat cardiomyocytes overexpressing PMCA4b showed a significant reduction in nitric oxide and cGMP levels. This was accompanied by an increase in cAMP levels, which led to an increase in both PLB and cTnI phosphorylation at base line. Elevated cAMP levels were likely due to the modulation of cardiac phosphodiesterase, which determined the balance between cGMP and cAMP following PMCA4b overexpression. In conclusion, these results showed that the nNOS-PMCA4b complex regulates contractility via cAMP and phosphorylation of both PLB and cTnI.
Journal of Biological Chemistry 03/2009; 284(18):12091-8. · 4.77 Impact Factor
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Delvac Oceandy,
Elizabeth J Cartwright,
Michael Emerson, Sukhpal Prehar,
Florence M Baudoin,
Min Zi,
Nasser Alatwi,
Luigi Venetucci,
Kai Schuh,
Judith C Williams,
Angel L Armesilla,
Ludwig Neyses
[show abstract]
[hide abstract]
ABSTRACT: Neuronal nitric oxide synthase (nNOS) has recently been shown to be a major regulator of cardiac contractility. In a cellular system, we have previously shown that nNOS is regulated by the isoform 4b of plasma membrane calcium/calmodulin-dependent ATPase (PMCA4b) through direct interaction mediated by a PDZ domain (PSD 95, Drosophilia Discs large protein and Zona occludens-1) on nNOS and a cognate ligand on PMCA4b. It remains unknown, however, whether this interaction has physiological relevance in the heart in vivo.
We generated 2 strains of transgenic mice overexpressing either human PMCA4b or PMCA ct120 in the heart. PMCA ct120 is a highly active mutant form of the pump that does not interact with or modulate nNOS function. Calcium was extruded normally from PMCA4b-overexpressing cardiomyocytes, but in vivo, overexpression of PMCA4b reduced the beta-adrenergic contractile response. This attenuated response was not observed in ct120 transgenic mice. Treatment with a specific nNOS inhibitor (N omega-propyl-L-arginine) reduced the beta-adrenergic response in wild-type and ct120 transgenic mice to levels comparable to those of PMCA4b transgenic animals. No differences in lusitropic response were observed in either transgenic strain compared with wild-type littermates.
These data demonstrate the physiological relevance of the interaction between PMCA4b and nNOS and suggests its signaling role in the heart.
Circulation 02/2007; 115(4):483-92. · 14.74 Impact Factor
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[show abstract]
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ABSTRACT: The cytokines IL-1 and IL-6 are able to induce prostaglandin (PG)-dependent activation of the hypothalamo-pituitary-adrenal axis (HPAA) and are thought to play key roles in immune-neuroendocrine interactions during inflammation. The present study shows that inflammation induced by im injection of turpentine (TPS) in the hind limb of mice causes an increase in the plasma concentration of IL-6, but not that of IL-1 alpha or IL-1 beta, together with a prolonged (>18-h) activation of the HPAA. IL-6 plays a causal role in the TPS-induced elevation in HPAA activity, because the sustained (8-18 h) increases in 1) plasma corticosterone, 2) plasma ACTH, and 3) induction of c-Fos in the hypothalamic paraventricular nucleus are all markedly blunted in IL-6-deficient (IL-6(-/-)) mice. Peripheral administration of a neutralizing IL-6 antiserum inhibited the plasma corticosterone response of normal (C57BL/6) mice to hind limb inflammation to an extent similar to that seen in IL-6(-/-) mice, suggesting that the IL-6 responsible for the increased HPAA activity is produced, or acts, on the blood side of the blood-brain barrier. We also show that IL-6 in the circulation is induced almost exclusively at the local inflammatory site, where IL-1 beta is produced. Induction of IL-6 and activation of the HPAA are dependent upon prior activation of an IL-1 type I receptor, as both are inhibited in type I IL-1 receptor-deficient mice. Furthermore, hind limb inflammation induced cyclooxygenase-2 protein expression around the cerebrovasculature of normal (IL-6(+/+)), but not IL-6(-/-), mice. Based on these data, we propose that IL-6 is produced at the local inflammatory site under the control of IL-1 beta and is the circulating afferent signal that is in part responsible for elevated HPAA activity, possibly acting via eicosanoid production within the cerebrovasculature.
Endocrinology 05/2003; 144(5):1894-906. · 4.46 Impact Factor
