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ABSTRACT: Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of matrix metalloproteinases (MMPs). While TIMP2 and TIMP3 inhibit MMPs, TIMP3 also inhibits activation of pro-MMP2, whereas TIMP2 promotes it. Here we assessed the differential role of TIMP2 and TIMP3 in renal injury using the unilateral ureteral obstruction model. Gene microarray assay showed that post obstruction, the lack of TIMP3 had a greater impact on gene expression of intermediate, late injury- and repair-induced transcripts, kidney selective transcripts, and solute carriers. Renal injury in TIMP3(-/-), but not in TIMP2(-/-), mice increased the expression of collagen type I/III, connective tissue growth factor, transforming growth factor-β, and the downstream Smad2/3 pathway. Interestingly, ureteral obstruction markedly increased MMP2 activation in the kidneys of TIMP3(-/-) mice, which was completely blocked in the kidneys of TIMP2(-/-) mice. These changes are consistent with enhanced renal tubulointerstitial fibrosis in TIMP3(-/-) and its reduction in TIMP2(-/-) mice. The activities of tumor necrosis factor-α-converting enzyme, caspase-3, and mitogen-activated kinases were elevated in the kidneys of TIMP3(-/-) mice but not TIMP2(-/-) mice, suggesting enhanced activation of apoptotic and pathological signaling pathways only in the obstructed kidney of TIMP3(-/-) mice. Thus, TIMP2 and TIMP3 play differential and contrasting roles in renal injury: TIMP3 protects from damage, whereas TIMP2 promotes injury through MMP2 activation.Kidney International advance online publication, 12 June 2013; doi:10.1038/ki.2013.225.
Kidney International 06/2013; · 6.61 Impact Factor
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Vaibhav B Patel,
Zuocheng Wang,
Dong Fan,
Pavel Zhabyeyev,
Ratnadeep Basu,
Subhash K Das,
Wang Wang,
Jessica L Desaulniers,
Steven M Holland, Zamaneh Kassiri,
Gavin Y Oudit
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ABSTRACT: Rationale: The classical phagocyte NADPH oxidase (gp91(phox) or Nox2) is expressed in the heart. Nox2 activation requires membrane translocation of the p47(phox) subunit and is linked to heart failure. We hypothesized that loss of p47(phox) subunit will result in decreased ROS production and resistance to heart failure. Objective: To define the role of p47(phox) in pressure-overload induced biomechanical stress. Methods and Results: Eight weeks old male p47(phox) null (p47(phox)KO), Nox2 null (Nox2KO) and wildtype (WT) mice were subjected to transverse aortic constriction (TAC)-induced pressure-overload. Contrary to our hypothesis, p47(phox)KO mice showed markedly worsened systolic dysfunction in response to pressure-overload at 5 weeks and 9 weeks post-TAC compared to WT-TAC mice. We found that biomechanical stress upregulated N-cadherin and β-catenin in p47(phox)KO hearts but disrupted the actin filament cytoskeleton and reduced phosphorylation of FAK. p47(phox) interacts with cytosolic cortactin by co-immunoprecipitation and double immunofluorescence staining in murine and human hearts and translocated to the membrane upon biomechanical stress where cortactin interacted with N-cadherin resulting in adaptive cytoskeletal remodeling. However, p47(phox)KO hearts showed impaired interaction of cortactin with N-cadherin resulting in loss of biomechanical stress-induced actin polymerization and cytoskeletal remodeling. In contrast, Nox2 does not interact with cortactin and Nox2 deficient hearts were protected from pressure-overload induced adverse myocardial and intracellular cytoskeletal remodeling. Conclusions: We showed a novel role of p47(phox) subunit beyond and independent of NADPH oxidase activity, as a regulator of cortactin and adaptive cytoskeletal remodeling leading to a paradoxical enhanced susceptibility to biomechanical stress and heart failure.
Circulation Research 04/2013; · 9.49 Impact Factor
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ABSTRACT: AIMS: Hypertension is accompanied by structural remodeling of vascular extracellular matrix. Tissue inhibitor of metalloproteinases (TIMPs) inhibit matrix metalloproteinases (MMPs) that degrade the matrix structural proteins. In response to a hypertensive stimulus, the balance between MMPs and TIMPs is altered. We examined the role of TIMPs in agonist-induced hypertension.Methods and ResultsWe subjected TIMP-knockout mice to Angiotensin II (Ang II) infusion, and found that Ang II-induced hypertension in TIMP1(-/-), TIMP2(-/-) and TIMP4(-/-) mice was comparable to wildtype mice, but significantly suppressed in TIMP3(-/-) mice. Ex vivo pressure myography analyses on carotid and mesenteric arteries revealed that Ang II-infused TIMP3(-/-) arteries were more distensible with impaired elastic recoil compared to the wildtype group. The acute response to vasoconstriction and vasodilation was intact in TIMP3(-/-) mesenteric and carotid arteries. Mesenteric arteries from TIMP3(-/-)-Ang II mice exhibited a reduced media-to-lumen ratio, suppressed collagen and elastin levels, elevated elastase and gelatinase proteolytic activities compared to WT-Ang II. TIMP3(-/-)-Ang II carotid arteries also showed adverse structural remodeling. Treatment of mice with Doxycycline, a matrix metalloproteinase inhibitor, improved matrix integrity in mesenteric and carotid arteries in TIMP3(-/-)-Ang II and differentially regulated elastin and collagen levels in WT-Ang II versus TIMP3(-/-)-Ang II.Conclusion.Our study demonstrates a critical role for TIMP3, among all TIMPs, is preserving arterial extracellular matrix in response to Ang-- II. It is critical to acknowledge that the suppressed Ang II-induced hypertension in TIMP3(-/-) mice is not a protective mechanism but due to adverse remodeling in arterial matrix.
Cardiovascular research 03/2013; · 5.80 Impact Factor
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ABSTRACT: AIMS: Development of heart failure is known to be associated with changes in energy substrate metabolism. Information on the changes in energy substrate metabolism that occur in heart failure is limited and results vary depending on the methods employed. Our aim is to characterize the changes in energy substrate metabolism associated with pressure overload and ischemia-reperfusion injury.Methods and ResultsWe used transverse aortic constriction (TAC) in mice to induce pressure overload-induced heart failure. Metabolic rates were measured in isolated working hearts perfused at physiological afterload (80 mmHg) using (3)H or (14)C labeled substrates. As a result of pressure-overload injury, murine hearts exhibited: (1) hypertrophy, systolic and diastolic dysfunctions; (2) reduction in LV work, (3) reduced rates of glucose and lactate oxidations, with no change in glycolysis or fatty acid oxidation and a small decrease in triacylglycerol oxidation, and (4) increased phosphorylation of AMPK and a reduction in malonyl-CoA levels. Sham hearts produced more acetyl CoA from carbohydrates than from fats, whereas TAC hearts showed a reverse trend. Ischemia-reperfusion (I/R) in sham group produced a metabolic switch analogous to the TAC-induced shift to fatty acid oxidation, whereas I/R in TAC hearts greatly exacerbated the existing imbalance, and was associated with a poorer recovery during reperfusion. CONCLUSIONS: Pressure overload-induced heart failure and I/R shift the preference of substrate oxidation from glucose and lactate to fatty acid due to a selective reduction in carbohydrate oxidation. Normalizing the balance between metabolic substrate utilization may alleviate pressure-overload induced heart failure and ischemia.
Cardiovascular research 12/2012; · 5.80 Impact Factor
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ABSTRACT: Aortic aneurysm is dilation of the aorta primarily due to degradation of the aortic wall extracellular matrix (ECM). Tissue inhibitor of metalloproteinases (TIMPs) inhibit MMPs, the proteases that degrade the ECM. TIMP3 is the only ECM-bound TIMP and its levels are altered in the aorta from patients with abdominal aortic aneurysm (AAA). We investigated the causal role of TIMP3 in AAA formation. Infusion of angiotensin II (Ang II), using micro-osmotic (Alzet) pumps, in TIMP3-/- male mice, but not in wild type control mice, led to adverse remodeling of the abdominal aorta, reduced collagen and elastin proteins but not mRNA, and elevated proteolytic activities suggesting excess protein degradation within 2 weeks that led to formation of AAA by 4 weeks. Intriguingly, despite early upregulation of MMP2 in TIMP3-/--AngII aortas, additional deletion of MMP2 in these mice (TIMP3-/-/MMP2-/-) resulted in exacerbated AAA, compromised survival due to aortic rupture, and inflammation in the abdominal aorta. Reconstitution of WT bone marrow in TIMP3-/-/MMP2-/- mice reduced inflammation and prevented AAA in these animals following Ang II infusion. Treatment with a broad-spectrum MMP inhibitor (PD166793) prevented the Ang II-induced AAA in TIMP3-/- and in TIMP3-/-/MMP2-/- mice. Our study demonstrates that the regulatory function of TIMP3 is critical in preventing adverse vascular remodeling and AAA. Hence, replenishing TIMP3, a physiological inhibitor of a number of metalloproteinases, could serve as a therapeutic approach in limiting AAA development or expansion.
Journal of Biological Chemistry 11/2012; · 4.77 Impact Factor
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ABSTRACT: Fibroblasts comprise the largest cell population in the myocardium. In heart disease, the number of fibroblasts is increased either by replication of the resident myocardial fibroblasts, migration and transformation of circulating bone marrow cells, or by transformation of endothelial/epithelial cells into fibroblasts and myofibroblasts. The primary function of fibroblasts is to produce structural proteins that comprise the extracellular matrix (ECM). This can be a constructive process; however, hyperactivity of cardiac fibroblasts can result in excess production and deposition of ECM proteins in the myocardium, known as fibrosis, with adverse effects on cardiac structure and function. In addition to being the primary source of ECM proteins, fibroblasts produce a number of cytokines, peptides, and enzymes among which matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitor of metalloproteinases (TIMPs), directly impact the ECM turnover and homeostasis. Function of fibroblasts can also in turn be regulated by MMPs and TIMPs. In this review article, we will focus on the function of cardiac fibroblasts in the context of ECM formation, homeostasis and remodeling in the heart. We will discuss the origins and multiple roles of cardiac fibroblasts in myocardial remodeling in different types of heart disease in patients and in animal models. We will further provide an overview of what we have learned from experimental animal models and genetically modified mice with altered expression of ECM regulatory proteins, MMPs and TIMPs.
Fibrogenesis & Tissue Repair 09/2012; 5(1):15.
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Ratnadeep Basu,
Jiwon Lee,
Zuocheng Wang,
Vaibhav B Patel,
Dong Fan,
Subhash K Das,
George C Liu,
Rohan John,
James W Scholey,
Gavin Y Oudit, Zamaneh Kassiri
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ABSTRACT: Diabetic nephropathy is the most common cause of end-stage renal disease. Polymorphism in the TIMP3 gene, and ECM-bound inhibitor of metalloproteinases (MMPs), has been linked to diabetic nephropathy in humans. In order to elucidate the mechanism we generated double mutant mice in which the TIMP3 gene was deleted in the genetic diabetic Akita mouse background. The aggravation of diabetic injury occurred in the absence of worsening of hypertension or hyperglycemia. In fact, myocardial TIMP3 levels were not affected and cardiac diastolic and systolic function remained unchanged in the double mutant mice. However, TIMP3 levels increased in Akita kidneys and deletion of TIMP3 exacerbated the diabetic renal injury in the Akita mouse, characterized by increased albuminuria, mesangial matrix expansion and kidney hypertrophy. The progression of diabetic renal injury was accompanied by the upregulation of fibrotic and inflammatory markers, increased production of reactive oxygen species and NADPH oxidase activity, and elevated activity of TACE (TNF-alpha converting enzyme) in the TIMP3(-/-)/Akita kidneys. Moreover, while the elevated phospho-Akt (S473 and T308) and phospho-ERK1/2 in the Akita mice was not detected in the TIMP3(-/-)/Akita kidneys, PKCβ1 (but not PKCα) was markedly elevated in the double mutant kidneys. Our data provide definitive evidence for a critical and selective role of TIMP3 in diabetic renal injury consistent with gene expression findings from human diabetic kidneys.
AJP Renal Physiology 08/2012; · 4.42 Impact Factor
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ABSTRACT: Activation of the renin-angiotensin and sympathetic nervous systems may alter the cardiac energy substrate preference, thereby contributing to the progression of heart failure with normal ejection fraction. We assessed the qualitative and quantitative effects of angiotensin II (Ang II) and the α-adrenergic agonist, phenylephrine (PE), on cardiac energy metabolism in experimental models of hypertrophy and diastolic dysfunction and the role of the Ang II type 1 receptor.
Ang II (1.5 mg·kg(-1)·day(-1)) or PE (40 mg·kg(-1)·day(-1)) was administered to 9-week-old male C57/BL6 wild-type mice for 14 days via implanted microosmotic pumps. Echocardiography showed concentric hypertrophy and diastolic dysfunction, with preserved systolic function in Ang II- and PE-treated mice. Ang II induced marked reduction in cardiac glucose oxidation and lactate oxidation, with no change in glycolysis and fatty acid β-oxidation. Tricarboxylic acid acetyl coenzyme A production and ATP production were reduced in response to Ang II. Cardiac pyruvate dehydrogenase kinase 4 expression was upregulated by Ang II and PE, resulting in a reduction in the pyruvate dehydrogenase activity, the rate-limiting step for carbohydrate oxidation. Pyruvate dehydrogenase kinase 4 upregulation correlated with the activation of the cyclin/cyclin-dependent kinase-retinoblastoma protein-E2F pathway in response to Ang II. Ang II type 1 receptor blockade normalized the activation of the cyclin/cyclin-dependent kinase-retinoblastoma protein-E2F pathway and prevented the reduction in glucose oxidation but increased fatty acid oxidation.
Ang II- and PE-induced hypertrophy and diastolic dysfunction is associated with reduced glucose oxidation because of the cyclin/cyclin-dependent kinase-retinoblastoma protein-E2F-induced upregulation of pyruvate dehydrogenase kinase 4, and targeting these pathways may provide novel therapy for heart failure with normal ejection fraction.
Circulation Heart Failure 06/2012; 5(4):493-503. · 6.29 Impact Factor
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ABSTRACT: Loss of angiotensin (Ang)-converting enzyme 2 (ACE2) and inability to metabolize Ang II to Ang 1-7 perpetuate the actions of Ang II after biomechanical stress and exacerbate early adverse myocardial remodeling. Ang receptor blockers are known to antagonize the effect of Ang II by blocking Ang II type 1 receptor (AT(1)R) and also by upregulating the ACE2 expression. We directly compare the benefits of AT(1)R blockade versus enhancing Ang 1-7 action in pressure-overload-induced heart failure in ACE2 knockout mice. AT(1)R blockade and Ang 1-7 both resulted in marked recovery of systolic dysfunction in pressure-overloaded ACE2-null mice. Similarly, both therapies attenuated the increase in NADPH oxidase activation by downregulating the expression of Nox2 and p47(phox) subunits and also by limiting the p47(phox) phosphorylation. Biomechanical stress-induced increase in protein kinase C-α expression and phosphorylation of extracellular signal-regulated kinase 1/2, signal transducer and activator of transcription 3, Akt, and glycogen synthase kinase 3β were normalized by irbesartan and Ang 1-7. Ang receptor blocker and Ang 1-7 effectively reduced matrix metalloproteinase 2 activation and matrix metalloproteinase 9 levels. Ang II-mediated cellular effects in cultured adult cardiomyocytes and cardiofibrolasts isolated from pressure-overloaded ACE2-null hearts were inhibited to similar degree by AT(1)R blockade and stimulation with Ang 1-7. Thus, treatment with the AT(1)R blocker irbesartan and Ang 1-7 prevented the cardiac hypertrophy and improved cardiac remodeling in pressure-overloaded ACE2-null mice by suppressing NADPH oxidase and normalizing pathological signaling pathways.
Hypertension 04/2012; 59(6):1195-203. · 6.21 Impact Factor
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Vaibhav B Patel,
Sreedhar Bodiga,
Ratnadeep Basu,
Subhash K Das,
Wang Wang,
Zuocheng Wang,
Jennifer Lo,
Maria B Grant,
JiuChang Zhong, Zamaneh Kassiri,
Gavin Y Oudit
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ABSTRACT: Diabetic cardiovascular complications are reaching epidemic proportions. Angiotensin-converting enzyme-2 (ACE2) is a negative regulator of the renin-angiotensin system. We hypothesize that loss of ACE2 exacerbates cardiovascular complications induced by diabetes.
To define the role of ACE2 in diabetic cardiovascular complications.
We used the well-validated Akita mice, a model of human diabetes, and generated double-mutant mice using the ACE2 knockout (KO) mice (Akita/ACE2(-/y)). Diabetic state was associated with increased ACE2 in Akita mice, whereas additional loss of ACE2 in these mice leads to increased plasma and tissue angiotensin II levels, resulting in systolic dysfunction on a background of impaired diastolic function. Downregulation of SERCA2 and lipotoxicity were equivalent in Akita and Akita/ACE2KO hearts and are likely mediators of the diastolic dysfunction. However, greater activation of protein kinase C and loss of Akt and endothelial nitric oxide synthase phosphorylation occurred in the Akita/ACE2KO hearts. Systolic dysfunction in Akita/ACE2KO mice was linked to enhanced activation of NADPH oxidase and metalloproteinases, resulting in greater oxidative stress and degradation of the extracellular matrix. Impaired flow-mediated dilation in vivo correlated with increased vascular oxidative stress in Akita/ACE2KO mice. Treatment with the AT1 receptor blocker, irbesartan rescued the systolic dysfunction, normalized altered signaling pathways, flow-mediated dilation, and the increased oxidative stress in the cardiovascular system.
Loss of ACE2 disrupts the balance of the renin-angiotensin system in a diabetic state and leads to an angiotensin II/AT1 receptor-dependent systolic dysfunction and impaired vascular function. Our study demonstrates that ACE2 serves as a protective mechanism against diabetes-induced cardiovascular complications.
Circulation Research 04/2012; 110(10):1322-35. · 9.49 Impact Factor
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Hai-Yan Jin,
Bei Song,
Gavin Y Oudit,
Sandra T Davidge,
Hui-Min Yu,
Yan-Yan Jiang,
Ping-Jin Gao,
Ding-Liang Zhu,
Guang Ning, Zamaneh Kassiri,
Josef M Penninger,
Jiu-Chang Zhong
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ABSTRACT: Inflammation and oxidative stress play a crucial role in angiotensin (Ang) II-mediated vascular injury. Angiotensin-converting enzyme 2 (ACE2) has recently been identified as a specific Ang II-degrading enzyme but its role in vascular biology remains elusive. We hypothesized that loss of ACE2 would facilitate Ang II-mediated vascular inflammation and peroxynitrite production. 10-week wildtype (WT, Ace2(+/y)) and ACE2 knockout (ACE2KO, Ace2(-/y)) mice received with mini-osmotic pumps with Ang II (1.5 mg.kg⁻¹.d⁻¹) or saline for 2 weeks. Aortic ACE2 protein was obviously reduced in WT mice in response to Ang II related to increases in profilin-1 protein and plasma levels of Ang II and Ang-(1-7). Loss of ACE2 resulted in greater increases in Ang II-induced mRNA expressions of inflammatory cytokines monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-1β, and IL-6 without affecting tumor necrosis factor-α in aortas of ACE2KO mice. Furthermore, ACE2 deficiency led to greater increases in Ang II-mediated profilin-1 expression, NADPH oxidase activity, and superoxide and peroxynitrite production in the aortas of ACE2KO mice associated with enhanced phosphorylated levels of Akt, p70S6 kinase, extracellular signal-regulated kinases (ERK1/2) and endothelial nitric oxide synthase (eNOS). Interestingly, daily treatment with AT1 receptor blocker irbesartan (50 mg/kg) significantly prevented Ang II-mediated aortic profilin-1 expression, inflammation, and peroxynitrite production in WT mice with enhanced ACE2 levels and the suppression of the Akt-ERK-eNOS signaling pathways. Our findings reveal that ACE2 deficiency worsens Ang II-mediated aortic inflammation and peroxynitrite production associated with the augmentation of profilin-1 expression and the activation of the Akt-ERK-eNOS signaling, suggesting potential therapeutic approaches by enhancing ACE2 action for patients with vascular diseases.
PLoS ONE 01/2012; 7(6):e38502. · 4.09 Impact Factor
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AHA scientific sessions 2011, Orlando, Florida, USA; 11/2011
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American Heart Association Scientific Sessions 2011, Orlando, Florida; 11/2011
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ABSTRACT: Remodeling of the extracellular matrix (ECM) is a key aspect of myocardial response to biomechanical stress and heart failure. Tissue inhibitors of metalloproteinases (TIMPs) regulate the ECM turnover through negative regulation of matrix metalloproteinases (MMPs), which degrade the ECM structural proteins. Tissue inhibitor of metalloproteinases 2 is unique among TIMPs in activating pro-MMP2 in addition to inhibiting a number of MMPs. Given this dual role of TIMP2, we investigated whether TIMP2 serves a critical role in heart disease.
Pressure overload by transverse aortic constriction (TAC) in 8-week-old male mice resulted in greater left ventricular hypertrophy, fibrosis, dilation, and dysfunction in TIMP2-deficient (TIMP2(-/-)) compared with wild-type mice at 2 weeks and 5 weeks post-TAC. Despite lack of MMP2 activation, total collagenase activity and specific membrane type MMP activity were greater in TIMP2(-/-)-TAC hearts. Loss of TIMP2 resulted in a marked reduction of integrin β1D levels and compromised focal adhesion kinase phosphorylation, resulting in impaired adhesion of cardiomyocytes to ECM proteins, laminin, and fibronectin. Nonuniform ECM remodeling in TIMP2(-/-)-TAC hearts revealed degraded network structure as well as excess fibrillar deposition. Greater fibrosis in TIMP2(-/-)-TAC compared with wild-type TAC hearts was due to higher levels of SPARC (secreted protein acidic and rich in cysteine) and posttranslational stabilization of collagen fibers rather than increased collagen synthesis. Inhibition of MMPs including membrane type MMP significantly reduced left ventricular dilation and dysfunction, hypertrophy, and fibrosis in TIMP2(-/-)-TAC mice.
Lack of TIMP2 leads to exacerbated cardiac dysfunction and remodeling after pressure overload because of excess activity of membrane type MMP and loss of integrin β1D, leading to nonuniform ECM remodeling and impaired myocyte-ECM interaction.
Circulation 11/2011; 124(19):2094-105. · 14.74 Impact Factor
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ABSTRACT: Remodeling of the myocardium and the extracellular matrix (ECM) occurs in heart failure irrespective of its initial cause. The ECM serves as a scaffold to provide structural support as well as housing a number of cytokines and growth factors. Hence, disruption of the ECM will result in structural instability as well as activation of a number of signaling pathways that could lead to fibrosis, hypertrophy, and apoptosis. The ECM is a dynamic entity that undergoes constant turnover, and the integrity of its network structure is maintained by a balance in the function of matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs). In heart disease, levels of MMPs and TIMPs are altered resulting in an imbalance between these two families of proteins. In this review, we will discuss the structure, function, and regulation of TIMPs, their MMP-independent functions, and their role in heart failure. We will review the knowledge that we have gained from clinical studies and animal models on the contribution of TIMPs in the development and progression of heart disease. We will further discuss how ECM molecules and regulatory genes can be used as biomarkers of disease in heart failure patients.
Heart Failure Reviews 06/2011; 17(4-5):693-706. · 3.20 Impact Factor
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Christina Luong,
Juliana Rey-Perra,
Arul Vadivel,
Greg Gilmour,
Yves Sauve,
Debby Koonen,
Don Walker,
Kathryn G Todd,
Pierre Gressens, Zamaneh Kassiri,
Khurram Nadeem,
Beverly Morgan,
Farah Eaton,
Jason R Dyck,
Stephen L Archer,
Bernard Thébaud
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ABSTRACT: Lung hypoplasia and persistent pulmonary hypertension of the newborn limit survival in congenital diaphragmatic hernia (CDH). Unlike other diseases resulting in persistent pulmonary hypertension of the newborn, infants with CDH are refractory to inhaled nitric oxide (NO). Nitric oxide mediates pulmonary vasodilatation at birth in part via cyclic GMP production. Phosphodiesterase type 5 (PDE5) limits the effects of NO by inactivation of cyclic GMP. Because of the limited success in postnatal management of CDH, we hypothesized that antenatal PDE5 inhibition would attenuate pulmonary artery remodeling in experimental nitrofen-induced CDH.
Nitrofen administered at embryonic day 9.5 to pregnant rats resulted in a 60% incidence of CDH in the offspring and recapitulated features seen in human CDH, including structural abnormalities (lung hypoplasia, decreased pulmonary vascular density, pulmonary artery remodeling, right ventricular hypertrophy), and functional abnormalities (decreased pulmonary artery relaxation in response to the NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide). Antenatal sildenafil administered to the pregnant rat from embryonic day 11.5 to embryonic day 20.5 crossed the placenta, increased fetal lung cyclic GMP and decreased active PDE5 expression. Antenatal sildenafil improved lung structure, increased pulmonary vessel density, reduced right ventricular hypertrophy, and improved postnatal NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide-induced pulmonary artery relaxation. This was associated with increased lung endothelial NO synthase and vascular endothelial growth factor protein expression. Antenatal sildenafil had no adverse effect on retinal structure/function and brain development.
Antenatal sildenafil improves pathological features of persistent pulmonary hypertension of the newborn in experimental CDH and does not alter the development of other PDE5-expressing organs. Given the high mortality/morbidity of CDH, the potential benefit of prenatal PDE5 inhibition in improving the outcome for infants with CDH warrants further studies.
Circulation 05/2011; 123(19):2120-31. · 14.74 Impact Factor
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ABSTRACT: Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase capable of metabolizing angiotensin (Ang) II into Ang 1 to 7. We hypothesized that ACE2 is a negative regulator of Ang II signaling and its adverse effects on the kidneys. Ang II infusion (1.5 mg/kg⁻¹/d⁻¹) for 4 days resulted in higher renal Ang II levels and increased nicotinamide adenine dinucleotide phosphate oxidase activity in ACE2 knockout (Ace2(-/y)) mice compared to wild-type mice. Expression of proinflammatory cytokines, interleukin-1β and chemokine (C-C motif) ligand 5, were increased in association with greater activation of extracellular-regulated kinase 1/2 and increase of protein kinase C-α levels. These changes were associated with increased expression of fibrosis-associated genes (α-smooth muscle actin, transforming growth factor-β, procollagen type Iα1) and increased protein levels of collagen I with histological evidence of increased tubulointerstitial fibrosis. Ang II-infused wild-type mice were then treated with recombinant human ACE2 (2 mg/kg⁻¹/d⁻¹, intraperitoneal). Daily treatment with recombinant human ACE2 reduced Ang II-induced pressor response and normalized renal Ang II levels and oxidative stress. These changes were associated with a suppression of Ang II-mediated activation of extracellular-regulated kinase 1/2 and protein kinase C pathway and Ang II-mediated renal fibrosis and T-lymphocyte-mediated inflammation. We conclude that loss of ACE2 enhances renal Ang II levels and Ang II-induced renal oxidative stress, resulting in greater renal injury, whereas recombinant human ACE2 prevents Ang II-induced hypertension, renal oxidative stress, and tubulointerstitial fibrosis. ACE2 is an important negative regulator of Ang II-induced renal disease and enhancing ACE2 action may have therapeutic potential for patients with kidney disease.
Hypertension 02/2011; 57(2):314-22. · 6.21 Impact Factor
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Sreedhar Bodiga,
Jiu Chang Zhong,
Wang Wang,
Ratnadeep Basu,
Jennifer Lo,
George C Liu,
Danny Guo,
Steven M Holland,
James W Scholey,
Josef M Penninger, Zamaneh Kassiri,
Gavin Y Oudit
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ABSTRACT: Angiotensin-converting enzyme 2 (ACE2) is an important negative regulator of the renin-angiotensin system. Loss of ACE2 enhances the susceptibility to heart disease but the mechanism remains elusive. We hypothesized that ACE2 deficiency activates the NADPH oxidase system in pressure overload-induced heart failure.
Using the aortic constriction model, we subjected wild-type (Ace2(+/y)), ACE2 knockout (ACE2KO, Ace2(-/y)), p47(phox) knockout (p47(phox)KO, p47(phox-)(/-)), and ACE2/p47(phox) double KO mice to pressure overload. We examined changes in peptide levels, NADPH oxidase activity, gene expression, matrix metalloproteinases (MMP) activity, pathological signalling, and heart function. Loss of ACE2 resulted in enhanced susceptibility to biomechanical stress leading to eccentric remodelling, increased pathological hypertrophy, and worsening of systolic performance. Myocardial angiotensin II (Ang II) levels were increased, whereas Ang 1-7 levels were lowered. Activation of Ang II-stimulated signalling pathways in the ACE2-deficient myocardium was associated with increased expression and phosphorylation of p47(phox), NADPH oxidase activity, and superoxide generation, leading to enhanced MMP-mediated degradation of the extracellular matrix. Additional loss of p47(phox) in the ACE2KO mice normalized the increased NADPH oxidase activity, superoxide production, and systolic dysfunction following pressure overload. Ang 1-7 supplementation suppressed the increased NADPH oxidase and rescued the early dilated cardiomyopathy in pressure-overloaded ACE2KO mice.
In the absence of ACE2, biomechanical stress triggers activation of the myocardial NAPDH oxidase system with a critical role of the p47(phox) subunit. Increased production of superoxide, activation of MMP, and pathological signalling leads to severe adverse myocardial remodelling and dysfunction in ACE2KO mice.
Cardiovascular research 02/2011; 91(1):151-61. · 5.80 Impact Factor
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ABSTRACT: The heart is a mechanosensitive organ that adapts its morphology to changing hemodynamic conditions via a process named mechanotransduction, which is the primary means of detecting mechanical stress in the extracellular environment. In the heart, mechanical signals are propagated into the intracellular space primarily via cell adhesion complexes and are subsequently transmitted from cell to cell via paracrine signaling. Enhanced excitation-contraction coupling increases myocardial contractility in various experimental models. However, these animal models routinely show increased susceptibility to biomechanical stress with the development of early ventricular dilation and reduced systolic function in the setting of adverse myocardial remodeling. The enhanced susceptibility of the PI3Kγ knockout mice to biomechanical stress is linked to a cAMP-dependent up-regulation of matrix metalloproteinase with a loss of N-cadherin mediated cell adhesion. Enhancing cell-cell adhesion and cell-ECM interaction will promote the salutary effects of enhanced intracellular Ca(2+) cycling on whole heart function and booster the therapeutic potential of normalizing intracellular Ca(2+) cycling in patients with heart failure.
Journal of Molecular and Cellular Cardiology 01/2011; 50(4):606-12. · 5.17 Impact Factor
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ABSTRACT: The heart is a mechanosensitive organ that adapts its morphology to changing hemodynamic conditions via a process named mechanotransduction,
which is the primary means of detecting mechanical stress in the extracellular environment. In the heart, mechanical signals
are propagated into the intracellular space primarily via integrin-linked complexes, and are subsequently transmitted from
cell to cell via paracrine signaling. The biochemical signals derived from mechanical stimuli activate both acute phosphorylation
of signaling cascades, such as in the PI3K, FAK, and ILK pathways, and long-term morphological modifications via intracellular
cytoskeletal reorganization and extracellular matrix remodelling. Mechanotransduction plays a fundamental role in cardiac
(and vascular) function and involves interaction between extracellular matrix and intracellular cytoskeletal proteins via
cell adhesion complexes, which are modulated by PI3Ks. Loss of PI3K signaling enhances the susceptibility to biomechanical
stress while the loss of its negative regulator, PTEN, is associated with a wide variety of adaptive mechanisms necessary
to resist the progression of maladaptive ventricular remodelling and heart failure. In this chapter, we discuss several of
the key players involved in mechanotransduction in the heart.
KeywordsMechanotransduction-ECM-Integrin-ILK-FAK-Dystrophin-PI3K-PTEN-Cadherin-Remodelling
12/2010: pages 141-166;
