Effect of AT2 blockade on cardiac hypertrophy as induced by high dietary salt in the proatrial natriuretic peptide (ANP) gene-disrupted mouse

2006 ◽  
Vol 84 (6) ◽  
pp. 625-634 ◽  
Author(s):  
Ekaterini Angelis ◽  
M. Yat Tse ◽  
Michael A. Adams ◽  
Stephen C. Pang

The role of the angiotensin II type 2 receptor (AT2) during alterations in cardiac size remains largely unclear. Through employment of an AT2 antagonist, the present study explored a possible involvement of the AT2 receptor during salt-induced cardiac hypertrophy in the proatrial natriuretic peptide gene-disrupted mouse (ANP−/−). ANP−/− mice received either saline solution or the AT2 antagonist, PD123319, and were then placed on a high salt diet (8.0% NaCl) for 3 weeks. Cardiac and pulmonary size, expression of the renin–angiotensin system (RAS), and the behaviour of various hypertrophy marker genes were assessed. PD123319 caused enhanced expression of the systemic RAS, yet the cardiac RAS was largely unaffected. Although AT2 blockade did not alter whole cardiac mass, right ventricle mass, as well as pulmonary mass-to-body mass ratios were significantly decreased. Collagen type I was decreased in the latter tissues, likely contributing to the regression in mass. Several players essential in the maintenance of myocardial extracellular matrix homeostasis including B-type natriuretic peptide, matrix metalloproteinase-2, tumour necrosis factor, and transforming growth factor were also significantly altered by PD123319. These data suggest that AT2 blockade is involved in significant changes in myocardial extracellular matrix components translating into decreases in tissue mass in the salt-sensitive ANP−/− animal.

2013 ◽  
Vol 126 (4) ◽  
pp. 275-288 ◽  
Author(s):  
Hangxiang Zhang ◽  
Jing Wu ◽  
Hailong Dong ◽  
Shaukat A. Khan ◽  
Mon-Li Chu ◽  
...  

AngII (angiotensin II) is a potent neurohormone responsible for cardiac hypertrophy, in which TGF (transforming growth factor)-β serves as a principal downstream mediator. We recently found that ablation of fibulin-2 in mice attenuated TGF-β signalling, protected mice against progressive ventricular dysfunction, and significantly reduced the mortality after experimental MI (myocardial infarction). In the present study, we investigated the role of fibulin-2 in AngII-induced TGF-β signalling and subsequent cardiac hypertrophy. We performed chronic subcutaneous infusion of AngII in fibulin-2 null (Fbln2−/−), heterozygous (Fbln2+/−) and WT (wild-type) mice by a mini-osmotic pump. After 4 weeks of subpressor dosage of AngII infusion (0.2 μg/kg of body weight per min), WT mice developed significant hypertrophy, whereas the Fbln2−/− showed no response. In WT, AngII treatment significantly up-regulated mRNAs for fibulin-2, ANP (atrial natriuretic peptide), TGF-β1, Col I (collagen type I), Col III (collagen type III), MMP (matrix metalloproteinase)-2 and MMP-9, and increased the phosphorylation of TGF-β-downstream signalling markers, Smad2, TAK1 (TGF-β-activated kinase 1) and p38 MAPK (mitogen-activated protein kinase), which were all unchanged in AngII-treated Fbln2−/− mice. The Fbln2+/− mice consistently displayed AngII-induced effects intermediate between WT and Fbln2−/−. Pressor dosage of AngII (2 mg/kg of body weight per min) induced significant fibrosis in WT but not in Fbln2−/− mice with comparable hypertension and hypertrophy in both groups. Isolated CFs (cardiac fibroblasts) were treated with AngII, in which direct AngII effects and TGF-β-mediated autocrine effects was observed in WT. The latter effects were totally abolished in Fbln2−/− cells, suggesting that fibulin-2 is essential for AngII-induced TGF-β activation. In conclusion our data indicate that fibulin-2 is essential for AngII-induced TGF-β-mediated cardiac hypertrophy via enhanced TGF-β activation and suggest that fibulin-2 is a potential therapeutic target to inhibit AngII-induced cardiac remodelling.


1998 ◽  
Vol 9 (11) ◽  
pp. 2040-2047
Author(s):  
O Lenz ◽  
L J Striker ◽  
T A Jacot ◽  
S J Elliot ◽  
P D Killen ◽  
...  

Mesangial sclerosis is a major feature of progressive renal disease. The mesangium contains mesangial cells and is bounded by the peripheral glomerular basement membrane and endothelial cells. Mesangial cells synthesize and degrade extracellular matrix. Whereas both mesangial and endothelial cells synthesize extracellular matrix components, the degradative pathway, well studied in the former, has not been investigated in endothelial cells. This study examines lines of all three glomerular cell types derived from female B6SJLF1/J mice, as well as mRNA levels for collagens alpha1(I), alpha1(IV), alpha3 (IV), alpha5 (IV), and alpha1 (VI), laminin, tenascin, matrix metalloproteinase-2 (MMP-2), and MMP-9. Type I and IV collagen synthesis was confirmed by enzyme-linked immunosorbent assay. MMP-2 and MMP-9 enzyme activity was measured by zymography. It was found that glomerular endothelial cells are a significant source of collagens, laminin, and tenascin. However, they express only low levels of MMP-2 and no detectable MMP-9. Stimulation with exogenous transforming growth factor-beta1 leads to a significant increase in collagen I, tissue inhibitors of metalloproteinase-1, and MMP-9 in conditioned media. These data suggest that glomerular endothelial cells may play an active role in extracellular matrix remodeling in glomerular disease.


1995 ◽  
Vol 108 (6) ◽  
pp. 2153-2162 ◽  
Author(s):  
J.F. Talts ◽  
A. Weller ◽  
R. Timpl ◽  
M. Ekblom ◽  
P. Ekblom

We have here studied the composition and regulation of stromal extracellular matrix components in an experimental tumor model. Nude mice were inoculated with WCCS-1 cells, a human Wilms' tumor cell line. In the formed tumors the stroma was found to contain mesenchymal extracellular matrix proteins such as tenascin-C, fibulins-1 and 2 and fibronectin, but no nidogen. Nidogen was confined to basement membranes of tumor blood vessels. Since glucocorticoids have been shown to downregulate tenascin-C expression in vitro, we tested whether dexamethasone can influence biosynthesis of extracellular matrix components during tumor formation in vivo. A downregulation of tenascin-C mRNA and an upregulation of fibronectin mRNA expression by dexamethasone was noted. Transforming growth factor-beta 1 mRNA levels were unaffected by the dexamethasone treatment. Glucocorticoids can thus downregulate tenascin-C synthesis although local stimulatory growth factors are present. The competition between a negative and a positive extrinsic factor on synthesis of stromal extracellular matrix components was studied in a fibroblast/preadipocyte cell line. Transforming growth factor-beta 1 stimulated tenascin-C synthesis but did not affect fibronectin or fibulin-2 synthesis. Dexamethasone at high concentrations could completely suppress the effect of transforming growth factor-beta 1 on tenascin-C mRNA expression. Transforming growth factor-beta 1 could in turn overcome the downregulation of tenascin-C mRNA expression caused by a lower concentration of dexamethasone. We therefore suggest that the limited expression of tenascin-C in part is due to a continuous suppression by physiological levels of glucocorticoids, which can be overcome by local stimulatory growth factors when present in sufficient amounts.


Endocrinology ◽  
2021 ◽  
Vol 162 (11) ◽  
Author(s):  
Tsai-Der Chuang ◽  
Derek Quintanilla ◽  
Drake Boos ◽  
Omid Khorram

Abstract The objective of this study was to determine the expression and functional role of a long noncoding RNA (lncRNA) MIAT (myocardial infarction–associated transcript) in leiomyoma pathogenesis. Leiomyoma compared with myometrium (n = 66) expressed significantly more MIAT that was independent of race/ethnicity and menstrual cycle phase but dependent on MED12 (mediator complex subunit 12) mutation status. Leiomyomas bearing the MED12 mutation expressed higher levels of MIAT and lower levels of microRNA 29 family (miR-29a, -b, and -c) compared with MED12 wild-type leiomyomas. Using luciferase reporter activity and RNA immunoprecipitation analysis, MIAT was shown to sponge the miR-29 family. In a 3-dimensional spheroid culture system, transient transfection of MIAT siRNA in leiomyoma smooth muscle cell (LSMC) spheroids resulted in upregulation of miR-29 family and downregulation of miR-29 targets, collagen type I (COL1A1), collagen type III (COL3A1), and TGF-β3 (transforming growth factor β-3). Treatment of LSMC spheroids with TGF-β3 induced COL1A1, COL3A1, and MIAT levels, but repressed miR-29 family expression. Knockdown of MIAT in LSMC spheroids blocked the effects of TGF-β3 on the induction of COL1A1 and COL3A1 expression. Collectively, these results underscore the physiological significance of MIAT in extracellular matrix accumulation in leiomyoma.


Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Karien J Rodriguez ◽  
Kristyn S Masters

Calcification is the leading cause of bioprosthetic and native aortic valve failure, but relatively little is known regarding the factors that contribute to the progression of valvular calcification. Because extracellular matrix (ECM) disarray is often observed in explanted diseased valves, we have investigated the role of individual ECM components in the in vitro calcification of valvular interstitial cells (VICs). The transformation of VICs to an osteoblast-like phenotype was quantified in VICs cultured on different types of ECM coatings. The results show that the number and size of calcific nodules formed in VIC cultures, as well as the expression of mineralization markers alkaline phosphatase (ALP) and CBFa1, were highly dependent upon the composition of the culture surface. In fact, VICs cultured on certain ECM components, namely collagen (Coll) and fibronectin (FN), were resistant to calcification, even upon treatment with potent mineralization-inducing growth factors, such as transforming growth factor beta1 (TGFb1). Meanwhile, VIC cultures on fibrin (FB), laminin, and heparin not only had a high number of calcified nodules (p<0.001 vs. Coll, FN), but also elevated levels of ALP and CBFa1 (p<0.02), and the number of nodules on these ‘pro-calcific’ coatings significantly increased upon treatment with exogenous TGFb1 (p<0.05). To explain the ECM-dependence of calcification, the endogenous production of a pro-mineralization factor (TGFb1) was assessed in VICs on anti-calcific (Coll) and pro-calcific (FB) substrates. Quantification of TGFb1 mRNA revealed that VICs on Coll surfaces expressed a significantly lower amount of TGFb1 mRNA than VICs on FB (p<0.01). Furthermore, treatment with a neutralizing antibody to TGFb1 decreased TGFb1 mRNA expression by VICs on Coll in comparison to VICs on FB or polystyrene controls (p<0.02). Thus, we have discovered a strong correlation between VIC calcification and ECM composition. Our findings show that the ECM plays an important role in controlling TGFb1 expression and subsequent calcification of VICs, which may significantly impact the design of biomaterials for valve tissue engineering, understanding of valvular disease, and the development of preventative treatments for valve calcification.


2018 ◽  
Vol 46 (05) ◽  
pp. 1021-1044 ◽  
Author(s):  
Simei Sun ◽  
Tianyi Li ◽  
Li Jin ◽  
Zhe Hao Piao ◽  
Bin Liu ◽  
...  

An extract of Dendropanax morbifera branch exerts antioxidant, anti-inflammatory, antithrombotic, and anticancer activities. The purpose of this study was to investigate the effect of the extract in isoproterenol-induced cardiac hypertrophy. Phalloidin staining showed that treatment with the extract dramatically prevents isoproterenol-induced H9c2 cell enlargement and the expression of cardiac hypertrophic marker genes, including atrial natriuretic peptide (ANP) and B-type brain natriuretic peptide (BNP). Further, pretreatment with the extract decreased isoproterenol-induced GATA4 and Sp1 expression in H9c2 cells. Overexpression of Sp1 induced the expression of GATA4. The forced expression of Sp1 or its downstream target GATA4, as well as the co-transfection of Sp1 and GATA4 increased the expression of ANP, which was decreased by treatment with the extract. To further elucidate the regulation of the Sp1/GATA4-mediated expression of ANP, knockdown experiments were performed. Transfection with small interfering RNAs (siRNAs) for Sp1 or GATA4 decreased ANP expression. The extract did not further inhibit the expression of ANP reduced by the transfection of GATA4 siRNA. Sp1 knockdown did not affect the expression of ANP that was induced by the overexpression of GATA4; however, GATA4 knockdown abolished the expression of ANP that had been induced by Sp1 overexpression. The extract treatment also attenuated the isoproterenol-induced activation of p38 MAPK, ERK1/2, and JNK1. Hesperidin, catechin, 2,5-dihydroxybenzoic acid, and salicylic acid are the main phenolic compounds present in the extract as observed by high performance liquid chromatography. Hesperidin and 2,5-dihydroxybenzoic acid attenuated isoproterenol-induced cardiac hypertrophy. These findings suggest that the D. morbifera branch extract prevents cardiac hypertrophy by downregulating the activation of Sp1/GATA4 and MAPK signaling pathways.


2001 ◽  
Vol 276 (50) ◽  
pp. 46707-46713 ◽  
Author(s):  
Neil A. Bhowmick ◽  
Roy Zent ◽  
Mayshan Ghiassi ◽  
Maureen McDonnell ◽  
Harold L. Moses

Transforming growth factor-β (TGF-β) can induce epithelial to mesenchymal transdifferentiation (EMT) in mammary epithelial cells. TGF-β-meditated EMT involves the stimulation of a number of signaling pathways by the sequential binding of the type II and type I serine/threonine kinase receptors, respectively. Integrins comprise a family of heterodimeric extracellular matrix receptors that mediate cell adhesion and intracellular signaling, hence making them crucial for EMT progression. In light of substantial evidence indicating TGF-β regulation of various β1integrins and their extracellular matrix ligands, we examined the cross-talk between the TGF-β and integrin signal transduction pathways. Using an inducible system for the expression of a cytoplasmically truncated dominant negative TGF-β type II receptor, we blocked TGF-β-mediated growth inhibition, transcriptional activation, and EMT progression. Dominant negative TGF-β type II receptor expression inhibited TGF-β signaling to the SMAD and AKT pathways, but did not block TGF-β-mediated p38MAPK activation. Interestingly, blocking integrin β1function inhibited TGF-β-mediated p38MAPK activation and EMT progression. Limiting p38MAPK activity through the expression of a dominant negative-p38MAPK also blocked TGF-β-mediated EMT. In summary, TGF-β-mediated p38MAPK activation is dependent on functional integrin β1, and p38MAPK activity is required but is not sufficient to induce EMT.


2007 ◽  
Vol 293 (5) ◽  
pp. F1678-F1690 ◽  
Author(s):  
Alexis Dixon ◽  
Christine Maric

We previously showed that supplementation with 17β-estradiol (E2) from the onset of diabetes attenuates the development of diabetic renal disease. The aim of the present study was to examine whether E2 can also attenuate the disease process once it has developed. The present study was performed in nondiabetic and streptozotocin-induced diabetic Sprague-Dawley rats. E2 supplementation began after 9 wk of diabetes and continued for 8 wk. Diabetes was associated with an increase in urine albumin excretion, glomerulosclerosis, tubulointerstitial fibrosis, renal cortical collagen type I and IV, laminin, plasminogen activator inhibitor-1, tissue inhibitors of metalloproteinase-1 and -2, transforming growth factor (TGF)-β, TGF-β receptor type I and II, Smad2/3, phosphorylated Smad2/3, and Smad4 protein expression, and CD68-positive cell abundance. Decreases in matrix metalloproteinase (MMP)-2 protein expression and activity and decreases in Smad6 and Smad7 protein expression were also associated with diabetes. E2 supplementation completely or partially attenuated all these changes, except Smad4 and fibronectin, on which E2 supplementation had no effect. These data suggest that E2 attenuates the progression of diabetic renal disease once it has developed by regulating extracellular matrix, TGF-β, and expression of its downstream regulatory proteins. These findings support the notion that sex hormones in general, and E2 in particular, are important regulators of renal function and may be novel targets for the treatment and prevention of diabetic renal disease.


2006 ◽  
Vol 396 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Concetta Ambrosino ◽  
Tomoko Iwata ◽  
Claudio Scafoglio ◽  
Massimo Mallardo ◽  
Rüdiger Klein ◽  
...  

p38 MAPKs (mitogen-activated protein kinases) play important roles in the regulation of cellular responses to environmental stress. Recently, this signalling pathway has also been implicated in the regulation of processes unrelated to stress, for example, in T lymphocytes and cardiomyocytes. In order to identify molecular targets responsible for the housekeeping functions of p38 MAPKs, we have analysed the differences in the transcriptomes of normally proliferating wild-type and p38α knockout immortalized embryonic cardiomyocytes. Interestingly, many potential components of the myocardium extracellular matrix were found to be upregulated in the absence of p38α. Further analysis of the microarray data identified TEF-1 (transcriptional enhancer factor-1), a known regulator of heart-specific gene expression, and C/EBPβ (CCAAT/enhancer-binding protein β), as the two transcription factors the binding sites of which were most enriched in the promoters of p38α-regulated genes. We have focused on the study of the extracellular matrix component COL1A1 (α1 chain of type I collagen) and found evidence for the involvement of both TEF-1 and C/EBPβ in the p38α-dependent inhibition of COL1A1 transcription. Our data therefore show that p38 MAPKs regulate TEF-1 and C/EBPβ transcriptional activity in the absence of environmental stress and suggests a role for p38α in the expression of extracellular matrix components that maintain organ architecture.


1990 ◽  
Vol 110 (4) ◽  
pp. 1405-1415 ◽  
Author(s):  
C H Streuli ◽  
M J Bissell

Reconstituted basement membranes and extracellular matrices have been demonstrated to affect, positively and dramatically, the production of milk proteins in cultured mammary epithelial cells. Here we show that both the expression and the deposition of extracellular matrix components themselves are regulated by substratum. The steady-state levels of the laminin, type IV collagen, and fibronectin mRNAs in mammary epithelial cells cultured on plastic dishes and on type I collagen gels have been examined, as has the ability of these cells to synthesize, secrete, and deposit laminin and other, extracellular matrix proteins. We demonstrate de novo synthesis of a basement membrane by cells cultured on type I collagen gels which have been floated into the medium. Expression of the mRNA and proteins of basement membranes, however, are quite low in these cultures. In contrast, the levels of laminin, type IV collagen, and fibronectin mRNAs are highest in cells cultured on plastic surfaces, where no basement membrane is deposited. It is suggested that the interaction between epithelial cells and both basement membrane and stromally derived matrices exerts a negative influence on the expression of mRNA for extracellular matrix components. In addition, we show that the capacity for lactational differentiation correlates with conditions that favor the deposition of a continuous basement membrane, and argue that the interaction between specialized epithelial cells and stroma enables them to create their own microenvironment for accurate signal transduction and phenotypic function.


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