scholarly journals Angiotensin II impairs endothelial function via tyrosine phosphorylation of the endothelial nitric oxide synthase

2009 ◽  
Vol 206 (13) ◽  
pp. 2889-2896 ◽  
Author(s):  
Annemarieke E. Loot ◽  
Judith G. Schreiber ◽  
Beate Fisslthaler ◽  
Ingrid Fleming
Keyword(s):  
Angiotensin Ii ◽  
Endothelial Dysfunction ◽  
Tyrosine Phosphorylation ◽  
Dominant Negative ◽  
No Production ◽  
Dependent Manner ◽  
Ang Ii ◽  
Wild Type ◽  
Tyrosine Kinase 2

Proline-rich tyrosine kinase 2 (PYK2) can be activated by angiotensin II (Ang II) and reactive oxygen species. We report that in endothelial cells, Ang II enhances the tyrosine phosphorylation of endothelial NO synthase (eNOS) in an AT1-, H2O2-, and PYK2-dependent manner. Low concentrations (1–100 µmol/liter) of H2O2 stimulated the phosphorylation of eNOS Tyr657 without affecting that of Ser1177, and attenuated basal and agonist-induced NO production. In isolated mouse aortae, 30 µmol/liter H2O2 induced phosphorylation of eNOS on Tyr657 and impaired acetylcholine-induced relaxation. Endothelial overexpression of a dominant-negative PYK2 mutant protected against H2O2-induced endothelial dysfunction. Correspondingly, carotid arteries from eNOS−/− mice overexpressing the nonphosphorylatable eNOS Y657F mutant were also protected against H2O2. In vivo, 3 wk of treatment with Ang II considerably increased levels of Tyr657-phosphorylated eNOS in the aortae of wild-type but not Nox2y/− mice, and this was again associated with a clear impairment in endothelium-dependent vasodilatation in the wild-type but not in the Nox2y/− mice. Collectively, endothelial PYK2 activation by Ang II and H2O2 causes the phosphorylation of eNOS on Tyr657, attenuating NO production and endothelium-dependent vasodilatation. This mechanism may contribute to the endothelial dysfunction observed in cardiovascular diseases associated with increased activity of the renin–angiotensin system and elevated redox stress.

Abstract 229: TNF Receptor 1 Signaling Is Critically Involved in Mediating Angiotensin II-Induced Cardiac Fibrosis and Dysfunction

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Sandra B Haudek ◽  
Jeff Crawford ◽  
Erin Reineke ◽  
Alberto A Allegre ◽  
George E Taffet ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Cardiac Fibrosis ◽  
Smooth Muscle Actin ◽  
Protein A ◽  
Ang Ii ◽  
Wild Type ◽  
Monocyte Chemoattractant Protein 1 ◽  
Reactive Fibrosis

Angiotensin-II (Ang-II) plays a key role in the development of cardiomyopathies, as it is associated with many conditions involving heart failure and pathologic hypertrophy. Using a murine model of Ang-II infusion, we found that Ang-II induced the synthesis of monocyte chemoattractant protein 1 (MCP-1) that mediated the uptake of CD34 + /CD45 + monocytic cells into the heart. These precursor cells differentiated into collagen-producing fibroblasts and were responsible for the Ang-II-induced development of reactive fibrosis. Preliminary in vitro data using our monocyte-to-fibroblast differentiation model, suggested that Ang-II required the presence of TNF to induce fibroblast maturation from monocytes. In vivo, they indicated that in mice deficient of both TNF receptors (TNFR1 and TNFR2), Ang-II-induced fibrosis was absent. We now assessed the hypothesis that specific TNFR1 signaling is necessary for Ang-II-mediated cardiac fibrosis. Mice deficient in either TNFR1 (TNFR1-KO) or TNFR2 (TNFR2-KO) were subjected to continuous infusion of Ang-II for 1 to 6 weeks (n=6-8/group). Compared to wild-type, we found that in TNFR1-KO, but not in TNFR2-KO mouse hearts, collagen deposition was attenuated, as was cardiac α-smooth muscle actin protein (a marker for activated fibroblasts). When we isolated viable cardiac fibroblasts and characterized them by flow cytometry, we found that Ang-II infusion in TNFR1-KO, but not in TNFR2-KO, resulted in a marked decrease of CD34 + /CD45 + cells. Quantitative RT-PCR demonstrated a striking reduction of type 1 and 3 collagen, as well of MCP-1 mRNA expression in TNFR1-KO mouse hearts. Further measurements of cardiovascular parameters indicated that TNFR1-KO animals developed lesser Ang-II-mediated LV remodeling, smaller changes in E-linear deceleration times/rates over time, and displayed a lower Tei index (a heart rate independent marker of cardiac function), indicating less stiffness in TNFR1-KO hearts compared to wild-type and TNFR2-KO hearts. The data suggest that Ang-II-dependent cardiac fibrosis requires TNF and its signaling through TNFR1 which enhances the induction of MCP-1 and uptake of monocytic fibroblast precursors that are associated with reactive fibrosis and cardiac remodeling and function.

Abstract 257: Oxidative Stress Induces Endothelial Dysfunction: Role of Ubiquitin-Proteasome System

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jian Xu ◽  
Shuangxi Wang ◽  
Yong Wu ◽  
Ping Song ◽  
Miao Zhang ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
De Novo ◽  
Ex Vivo ◽  
Umbilical Vein ◽  
Proteasome Inhibitors ◽  
Dominant Negative ◽  
26S Proteasome ◽  
No Production ◽  
Ang Ii ◽  
Enos Uncoupling

Endothelial Nitric oxide (NO) production is dependent on adequate cellular tetrahydrobiopterin (BH 4 ), a key cofactor for endothelial NO syntheses (eNOS). Reduction of BH 4 levels is reported in diseased vessels and plays a causal role in the development of eNOS uncoupling. However, the mechanisms that lead to BH 4 reduction are not entirely understood. Here we report that angiotensin-II (Ang II) reduced tetrahydrobiopterin (BH 4 ) and eNOS uncoupling by peroxynitrite ONOO − )-triggered proteasome activation. Compared to control, exposure of human umbilical vein endothelial cells (HUVEC) to angiotensin II (Ang II, 100nM) for 6h significantly decreased the levels of total biopterins (BH 4 plus BH 2 ) and BH 4 (−22.0 4.6%, n= 3, p<0.01), indicating decreased synthesis of biopterins. In parallel, Ang II but not vehicle significantly reduced the levels of GTP-cyclohydrolase (GTPCH), a rate-limiting enzyme for de novo synthesis of biopterins, and dihydrofolate reductase (DHFR), a crucial enzyme for BH 4 recycle from BH 2 . Ang II but not vehicle significantly increased the 26S proteasome activity. In addition, administration of proteasome inhibitors, MG132, abolished the Ang II-induced reduction of both GTPCH and DHFR. While Ang II significantly increased O 2 − , the scavenging of O 2 − by Tempol (SOD mimetic), or inhibition of NOS with N -nitro-L-arginine methyl ester hydrochloride (L-NAME) (1mM) significantly attenuated Ang II-induced both 26S proteasome activation and the reduction of both GTPCH and DHFR, suggesting that Ang II via endogenous ONOO − causes 26S proteasome-dependent degradation of both GTPCH and DHFR. Moreover, inhibition of NAD(P)H oxidase with either apocynin or by overexpression of p67 phox -dominant negative mutants ablated Ang II-induced proteasome activation and degradation of both GTPCH and DHFR. Finally, treatment of mice aorta ex vivo with MG132 (0.5 μM for 1h followed by Ang II for 12h) reversed the Ang II-induced reduction of GTPCH, DHFR and BH 4 , and increased acetylcholine-induced endothelium-dependent relaxation. We conclude that Ang II activates NAD(P)H oxidase to release O 2 . − and ONOO − , which activate 26S proteasome resulting in increased degradation of both GTPCH and DHFR, two key enzymes in controlling the levels of BH 4 .

Angiotensin II decreases inducible nitric oxide synthase expression in rat astroglial cultures

1995 ◽  
Vol 268 (3) ◽  
pp. C700-C707 ◽  
Author(s):  
L. J. Chandler ◽  
K. Kopnisky ◽  
E. Richards ◽  
F. T. Crews ◽  
C. Sumners
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Nitric Oxide Synthase ◽  
Receptor Antagonist ◽  
Maximal Response ◽  
No Production ◽  
Dependent Manner ◽  
Ang Ii ◽  
Subsequent Formation ◽  
Oxide Synthase

Consistent with stimulation of expression of an inducible form of nitric oxide synthase (iNOS), exposure of rat astroglial cultures to lipopolysaccharide (LPS) caused a time-dependent increase in the accumulation of nitrite in the culture media. Addition of the peptide angiotensin II (ANG II) with LPS decreased subsequent formation of nitrite in a concentration-dependent manner (concentration inhibiting 50% of maximal response approximately 1 nM). The ANG II effect could be blocked by the ANG II type 1 (AT1 receptor antagonist losartan but not by the ANG II type 2 (AT2) receptor antagonist PD-123177. ANG II had no effect on nitrite formation stimulated by a combination of inflammatory cytokines (interleukin-1 beta, tumor necrosis factor-alpha, and interferon-gamma). A brief 10-min exposure to ANG II was sufficient to cause an approximately 30% inhibition of the LPS response, with maximal inhibition of approximately 65% after 3 h, and occurred only when ANG II was added during the iNOS induction phase. Consistent with partial inhibition of LPS-stimulated expression of iNOS, ANG II reduced the levels of both iNOS mRNA and iNOS protein. These results demonstrate that ANG II can decrease LPS-stimulated NO production in astroglia by inhibiting induction of iNOS expression.

scholarly journals Interference with PPARγ in endothelium accelerates angiotensin II-induced endothelial dysfunction

2016 ◽  
Vol 48 (2) ◽  
pp. 124-134 ◽  
Author(s):  
Chunyan Hu ◽  
Ko-Ting Lu ◽  
Masashi Mukohda ◽  
Deborah R. Davis ◽  
Frank M. Faraci ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Endothelial Dysfunction ◽  
Vascular Function ◽  
Carotid Arteries ◽  
Pressor Response ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Ang Ii ◽  
Specific Expression ◽  
Stress Dependent

The ligand activated nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) in the endothelium regulates vascular function and blood pressure (BP). We previously reported that transgenic mice (E-V290M) with selectively targeted endothelial-specific expression of dominant negative PPARγ exhibited endothelial dysfunction when treated with a high-fat diet, and exhibited an augmented pressor response to angiotensin II (ANG II). We hypothesize that interference with endothelial PPARγ would exacerbate ANG II-induced endothelial dysfunction. Endothelial function was examined in E-V290M mice infused with a subpressor dose of ANG II (120 ng·kg−1·min−1) or saline for 2 wk. ANG II infusion significantly impaired the responses to the endothelium-dependent agonist acetylcholine both in basilar and carotid arteries from E-V290M but not NT mice. This impairment was not due to increased BP, which was not significantly different in ANG II-infused E-V290M compared with NT mice. Superoxide levels, and expression of the pro-oxidant Nox2 gene was elevated, whereas expression of the anti-oxidant genes Catalase and SOD3 decreased in carotid arteries from ANG II-infused E-V290M mice. Increased p65 and decreased Iκ-Bα suggesting increased NF-κB activity was also observed in aorta from ANG II-infused E-V290M mice. The responses to acetylcholine were significantly improved both in basilar and carotid arteries after treatment with Tempol (1 mmol/l), a scavenger of superoxide. These findings provide evidence that interference with endothelial PPARγ accelerates ANG II-mediated endothelial dysfunction both in cerebral and conduit arteries through an oxidative stress-dependent mechanism, suggesting a role for endothelial PPARγ in protecting against ANG II-induced endothelial dysfunction.

scholarly journals Angiotensin II stimulates superoxide production in the thick ascending limb by activating NOX4

2012 ◽  
Vol 303 (7) ◽  
pp. C781-C789 ◽  
Author(s):  
Katherine J. Massey ◽  
Nancy J. Hong ◽  
Jeffrey L. Garvin
Keyword(s):  
Angiotensin Ii ◽  
Nadph Oxidase ◽  
Knockout Mice ◽  
Thick Ascending Limb ◽  
Ang Ii ◽  
Wild Type ◽  
Outer Medulla ◽  
Catalytic Subunits ◽  
In The Wild

Angiotensin II (ANG II) stimulates production of superoxide (O2−) by NADPH oxidase (NOX) in medullary thick ascending limbs (TALs). There are three isoforms of the catalytic subunit (NOX1, 2, and 4) known to be expressed in the kidney. We hypothesized that NOX2 mediates ANG II-induced O2− production by TALs. To test this, we measured NOX1, 2, and 4 mRNA and protein by RT-PCR and Western blot in TAL suspensions from rats and found three catalytic subunits expressed in the TAL. We measured O2− production using a lucigenin-based assay. To assess the contribution of NOX2, we measured ANG II-induced O2− production in wild-type and NOX2 knockout mice (KO). ANG II increased O2− production by 346 relative light units (RLU)/mg protein in the wild-type mice ( n = 9; P < 0.0007 vs. control). In the knockout mice, ANG II increased O2− production by 290 RLU/mg protein ( n = 9; P < 0.007 vs. control). This suggests that NOX2 does not contribute to ANG II-induced O2− production ( P < 0.6 WT vs. KO). To test whether NOX4 mediates the effect of ANG II, we selectively decreased NOX4 expression in rats using an adenovirus that expresses NOX4 short hairpin (sh)RNA. Six to seven days after in vivo transduction of the kidney outer medulla, NOX4 mRNA was reduced by 77%, while NOX1 and NOX2 mRNA was unaffected. In control TALs, ANG II stimulated O2− production by 96%. In TALs transduced with NOX4 shRNA, ANG II-stimulated O2− production was not significantly different from the baseline. We concluded that NOX4 is the main catalytic isoform of NADPH oxidase that contributes to ANG II-stimulated O2− production by TALs.

scholarly journals Angiotensin II modulates mouse skeletal muscle resting conductance to chloride and potassium ions and calcium homeostasis via the AT1 receptor and NADPH oxidase

2014 ◽  
Vol 307 (7) ◽  
pp. C634-C647 ◽  
Author(s):  
Anna Cozzoli ◽  
Antonella Liantonio ◽  
Elena Conte ◽  
Maria Cannone ◽  
Ada Maria Massari ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Nadph Oxidase ◽  
Calcium Homeostasis ◽  
Potassium Conductance ◽  
Mdx Mouse ◽  
Dependent Manner ◽  
Ang Ii ◽  
Concentration Dependent Manner

Angiotensin II (ANG II) plays a role in muscle wasting and remodeling; however, little evidence shows its direct effects on specific muscle functions. We presently investigated the acute in vitro effects of ANG II on resting ionic conductance and calcium homeostasis of mouse extensor digitorum longus (EDL) muscle fibers, based on previous findings that in vivo inhibition of ANG II counteracts the impairment of macroscopic ClC-1 chloride channel conductance (gCl) in the mdx mouse model of muscular dystrophy. By means of intracellular microelectrode recordings we found that ANG II reduced gCl in the nanomolar range and in a concentration-dependent manner (EC50 = 0.06 μM) meanwhile increasing potassium conductance (gK). Both effects were inhibited by the ANG II receptors type 1 (AT1)-receptor antagonist losartan and the protein kinase C inhibitor chelerythrine; no antagonism was observed with the AT2 antagonist PD123,319. The scavenger of reactive oxygen species (ROS) N-acetyl cysteine and the NADPH-oxidase (NOX) inhibitor apocynin also antagonized ANG II effects on resting ionic conductances; the ANG II-dependent gK increase was blocked by iberiotoxin, an inhibitor of calcium-activated potassium channels. ANG II also lowered the threshold for myofiber and muscle contraction. Both ANG II and the AT1 agonist L162,313 increased the intracellular calcium transients, measured by fura-2, with a two-step pattern. These latter effects were not observed in the presence of losartan and of the phospholipase C inhibitor U73122 and the in absence of extracellular calcium, disclosing a Gq-mediated calcium entry mechanism. The data show for the first time that the AT1-mediated ANG II pathway, also involving NOX and ROS, directly modulates ion channels and calcium homeostasis in adult myofibers.

scholarly journals Angiotensin II-induced vascular endothelial dysfunction through RhoA/Rho kinase/p38 mitogen-activated protein kinase/arginase pathway

2011 ◽  
Vol 300 (5) ◽  
pp. C1181-C1192 ◽  
Author(s):  
Alia Shatanawi ◽  
Maritza J. Romero ◽  
Jennifer A. Iddings ◽  
Surabhi Chandra ◽  
Nagavedi S. Umapathy ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Endothelial Dysfunction ◽  
P38 Mapk ◽  
Gene Knockout ◽  
Rho Kinase ◽  
Arginase Activity ◽  
No Production ◽  
Vascular Endothelial ◽  
Ang Ii ◽  
Vascular Endothelial Dysfunction

Enhanced vascular arginase activity impairs endothelium-dependent vasorelaxation by decreasing l-arginine availability to endothelial nitric oxide (NO) synthase, thereby reducing NO production. Elevated angiotensin II (ANG II) is a key component of endothelial dysfunction in many cardiovascular diseases and has been linked to elevated arginase activity. We determined signaling mechanisms by which ANG II increases endothelial arginase function. Results show that ANG II (0.1 μM, 24 h) elevates arginase activity and arginase I expression in bovine aortic endothelial cells (BAECs) and decreases NO production. These effects are prevented by the arginase inhibitor BEC (100 μM). Blockade of ANG II AT1 receptors or transfection with small interfering RNA (siRNA) for Gα12 and Gα13 also prevents ANG II-induced elevation of arginase activity, but siRNA for Gαq does not. ANG II also elevates active RhoA levels and induces phosphorylation of p38 MAPK. Inhibitors of RhoA activation (simvastatin, 0.1 μM) or Rho kinase (ROCK) (Y-27632, 10 μM; H1152, 0.5 μM) block both ANG II-induced elevation of arginase activity and phosphorylation of p38 MAPK. Furthermore, pretreatment of BAECs with p38 inhibitor SB-202190 (2 μM) or transfection with p38 MAPK siRNA prevents ANG II-induced increased arginase activity/expression and maintains NO production. Additionally, inhibitors of p38 MAPK (SB-203580, 5 μg·kg−1·day−1) or arginase (ABH, 8 mg·kg−1·day−1) or arginase gene knockout in mice prevents ANG II-induced vascular endothelial dysfunction and associated enhancement of arginase. These results indicate that ANG II increases endothelial arginase activity/expression through Gα12/13 G proteins coupled to AT1 receptors and subsequent activation of RhoA/ROCK/p38 MAPK pathways leading to endothelial dysfunction.

Abstract P011: Novel Roles Of Global, Intestinal, And Kidney Proximal Tubule Sodium And Hydrogen Exchanger 3 In Angiotensin Ii-induced Hypertension

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Jia L Zhuo ◽  
Liang Zhang ◽  
Ana Leite ◽  
Xiao C Li
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Proximal Tubule ◽  
Pressor Response ◽  
Dependent Manner ◽  
Ang Ii ◽  
Wild Type ◽  
Salt Wasting ◽  
Arterial Blood ◽  
Induced Hypertension

The present study used global ( Nhe3 -/- ), kidney-selective (tg Nhe3 -/- ), and proximal tubule-specific Na + /H + exchanger 3 (NHE3)-deficient mice (PT- Nhe3 -/- ) to test the hypothesis that NHE3 is required for the full development of angiotensin II (Ang II)-induced hypertension in mice. Four groups of adult male, age-matched wild-type (WT), global Nhe3 -/- , kidney-selective tg Nhe3 -/- and proximal tubule-specific Nhe3 -/- mice were infused with: a) saline; b) Ang II (10 pmol/min, i.v.); Ang II via an osmotic minipump for 2 weeks (1.5 mg/kg/day, i.p.); or treated with Ang II and losartan concurrently for 2 weeks (20 mg/kg/day, p.o.). Under basal conditions, global Nhe3 -/- , kidney-selective tg Nhe3 -/- and proximal tubule-specific Nhe3 -/- mice all showed significantly lower systolic, diastolic, and mean arterial pressure than wild-type mice (~15 ± 3 mmHg, P <0.01). The hypotensive phenotype in both global Nhe3 -/- and kidney-selective tg Nhe3 -/- mice was associated with abnormal intestinal structures, diarrhea, increased 24 h fecal Na + excretion, and salt wasting ( P <0.01). By contrast, there were no differences in intestinal structures and fecal Na + excretion between wild-type and PT- Nhe3 -/- mice. PT- Nhe3 -/- mice showed significant diuretic and natriuretic responses compared with wild-type mice ( P <0.01). Acute infusion of Ang II markedly increased arterial blood pressure in a time-dependent manner in wild-type mice, as expected ( P <0.01), but the pressure response was attenuated in global Nhe3 -/- , kidney-selective tg Nhe3 -/- , and PT- Nhe3 -/- mice ( P <0.01). Furthermore, the chronic pressor response to 2-week Ang II infusion was also significantly attenuated in Nhe3 -/- , tgNhe3 -/- , and PT- Nhe3 -/- mice, compared with wild-type mice ( P <0.01). Finally, concurrent treatment with losartan completely blocked the acute and chronic pressor responses to Ang II in wild-type, Nhe3 -/- , tg Nhe3 -/- , and PT- Nhe3 -/- mice (p<0.01). Taken together, these data support the proof of concept that NHE3 in the small intestines and the proximal tubules of the kidney is required for maintaining basal blood pressure homeostasis and for the development of Ang II-induced hypertension. Supported by NIH grants, 2R01DK102429-03A1, 1R56HL130988-01, and 2R01DK067299-10A1.

scholarly journals Angiotensin II Induces Oxidative Stress and Endothelial Dysfunction in Mouse Ophthalmic Arteries via Involvement of AT1 Receptors and NOX2

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1238
Author(s):  
Michael Birk ◽  
Ewa Baum ◽  
Jenia Kouchek Zadeh ◽  
Caroline Manicam ◽  
Norbert Pfeiffer ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Endothelial Dysfunction ◽  
Vascular Function ◽  
Point Of View ◽  
Ang Ii ◽  
Ocular Diseases ◽  
Underlying Mechanisms ◽  
Ophthalmic Arteries

Angiotensin II (Ang II) has been implicated in the pathophysiology of various age-dependent ocular diseases. The purpose of this study was to test the hypothesis that Ang II induces endothelial dysfunction in mouse ophthalmic arteries and to identify the underlying mechanisms. Ophthalmic arteries were exposed to Ang II in vivo and in vitro to determine vascular function by video microscopy. Moreover, the formation of reactive oxygen species (ROS) was quantified and the expression of prooxidant redox genes and proteins was determined. The endothelium-dependent artery responses were blunted after both in vivo and in vitro exposure to Ang II. The Ang II type 1 receptor (AT1R) blocker, candesartan, and the ROS scavenger, Tiron, prevented Ang II-induced endothelial dysfunction. ROS levels and NOX2 expression were increased following Ang II incubation. Remarkably, Ang II failed to induce endothelial dysfunction in ophthalmic arteries from NOX2-deficient mice. Following Ang II incubation, endothelium-dependent vasodilation was mainly mediated by cytochrome P450 oxygenase (CYP450) metabolites, while the contribution of nitric oxide synthase (NOS) and 12/15-lipoxygenase (12/15-LOX) pathways became negligible. These findings provide evidence that Ang II induces endothelial dysfunction in mouse ophthalmic arteries via AT1R activation and NOX2-dependent ROS formation. From a clinical point of view, the blockade of AT1R signaling and/or NOX2 may be helpful to retain or restore endothelial function in ocular blood vessels in certain ocular diseases.

Abstract 52: PPAR-γ Targeted by MicroRNA-130a Regulates Angiotensin II-Induced Cardiac Fibrosis

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Sudhiranjan Gupta ◽  
Li Li
Keyword(s):  
Angiotensin Ii ◽  
Cardiac Fibrosis ◽  
Myocardial Dysfunction ◽  
Critical Role ◽  
Pressure Overload ◽  
Underlying Mechanism ◽  
Dominant Negative ◽  
Protective Mechanism ◽  
Ang Ii

Aims: Cardiac fibrosis which occurs due to disruption of extracellular matrix network resulted in the accumulation of excess collagens and other matrix components leading to myocardial dysfunction. Angiotensin II (Ang II), a critical effector of this system has been implicated in the development of hypertension-induced cardiac fibrosis. In recent years, miRNAs have identified as an attractive targets for therapeutic intervention in various disease pathologies including cardiac fibrosis. However, the exact effect and underlying mechanism of miRNAs in cardiac fibrosis remains unclear. Here, we sought to investigate and test our hypothesis that miR-130a plays a critical role in the development of myocardial fibrosis by restoring PPARγ level. Methods and Results: We have identified a panel of novel miRNAs via miRNA array in Ang II infused mice heart. Among them, we found that miR-130a was upregulated both in pressure overload and Ang II infused models targeting PPARγ. Overexpressing miR-130a in cardiac fibroblast promoted the pro-fibrotic gene expression (collagen I/III, fibronectin and CTGF) and myofibroblasts differentiation. Inhibition miR-130a reversed the process and weakened these activities. Using luciferase-linked constitutive and dominant negative constructs of PPARγ, we determined the underlying mechanism of cardiac fibrosis occurred via targeting PPARγ. The in vivo inhibition of miR-130a by subcutaneous injections of LNA-based anti-miR-130a in mice subjected to Ang II infusion significantly reduced the severity of cardiac fibrosis, hypertrophy. The protective mechanism is associated with restoration of PPARγ level, reduction of pro-fibrotic genes and apoptosis; reversion of myofibroblasts differentiation and improved cardiac function. Conclusions: Our findings provide evidence that miR-130a plays a critical role in the progression of cardiac fibrosis by directly targeting PPARγ, and that inhibition of miR-130a reversed the cardiac fibrosis. We conclude that miR-130a may be a new marker for cardiac fibrosis and inhibition of miR-130a would be a promising strategy in the treatment of cardiac fibrosis.

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