1
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Sung JH, Song A, Park T, Kim E, Lee S. The Different Expression Patterns of HSP22, a Late Embryogenesis Abundant-like Protein, in Hypertrophic H9C2 Cells Induced by NaCl and Angiotensin II. Electrolyte Blood Press 2018; 16:1-10. [PMID: 30046328 PMCID: PMC6051945 DOI: 10.5049/ebp.2018.16.1.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 05/25/2018] [Indexed: 11/05/2022] Open
Abstract
Background High-NaCl diet is a contributing factor for cardiac hypertrophy. The role of HSP22 as a protective protein during cardiac hypertrophy due to hypernatremia is unclear. Accordingly, this study aimed to establish a cellular hypernatremic H9C2 model and to compare the expression of HSP22 in Ca2+ homeostasis between a high-NaCl and angiotensin II-induced hypertrophic cellular H9C2 model. Methods Real-time PCR was performed to compare the mRNA expression. Flow cytometry and confocal microscopy were used to analyze the cells. Results The addition of 30 mM NaCl for 48 h was the most effective condition for the induction of hypertrophic H9C2 cells (termed the in vitro hypernatremic model). Cardiac cellular hypertrophy was induced with 30 mM NaCl and 1 µM angiotensin II for 48 h, without causing abnormal morphological changes or cytotoxicity of the culture conditions. HSP22 contains a similar domain to that found in the consensus sequences of the late embryogenesis abundant protein group 3 from Artemia. The expression of HSP22 gradually decreased in the in vitro hypernatremic model. In contrast to the in vitro hypernatremic model, HSP22 increased after exposure to angiotensin II for 48 h. Intracellular Ca2+ decreased in the angiotensin II model and further decreased in the in vitro hypernatremic model. Impaired intracellular Ca2+ homeostasis was more evident in the in vitro hypernatremic model. Conclusion The results showed that NaCl significantly decreased HSP22. Decreased HSP22, due to the hypernatremic condition, affected the Ca2+ homeostasis in the H9C2 cells. Therefore, hypernatremia induces cellular hypertrophy via impaired Ca2+ homeostasis. The additional mechanisms of HSP22 need to be explored further.
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Affiliation(s)
- Jae Hwi Sung
- Integrated Biomedical and Life Science, College of Health Science, Korea University, Seoul, Korea
| | - Ahran Song
- Integrated Biomedical and Life Science, College of Health Science, Korea University, Seoul, Korea
| | - Taegun Park
- Integrated Biomedical and Life Science, College of Health Science, Korea University, Seoul, Korea
| | - Eunyoung Kim
- Integrated Biomedical and Life Science, College of Health Science, Korea University, Seoul, Korea
| | - Seunggwan Lee
- Integrated Biomedical and Life Science, College of Health Science, Korea University, Seoul, Korea
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2
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Park BM, Cha SA, Lee SH, Kim SH. Angiotensin IV protects cardiac reperfusion injury by inhibiting apoptosis and inflammation via AT4R in rats. Peptides 2016; 79:66-74. [PMID: 27038740 DOI: 10.1016/j.peptides.2016.03.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/17/2016] [Accepted: 03/29/2016] [Indexed: 02/07/2023]
Abstract
Angiotensin IV (Ang IV) is formed by aminopeptidase N from Ang III by removing the first N-terminal amino acid. Previously, we reported that Ang III has some cardioprotective effects against global ischemia in Langendorff heart. However, it is not clear whether Ang IV has cardioprotective effects. The aim of the present study was to evaluate the effect of Ang IV on myocardial ischemia-reperfusion (I/R) injury in rats. Before ischemia, male Sprague-Dawley rats received Ang IV (1mg/kg/day) for 3 days. Anesthetized rats were subjected to 45min of ischemia by ligation of left anterior descending coronary artery followed by reperfusion and then, sacrificed 1 day or 1 week after reperfusion. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations, and infarct size were measured. Quantitative analysis of apoptotic and inflammatory proteins in ventricles were performed using Western blotting. Pretreatment with Ang IV attenuated I/R-induced increases in plasma CK and LDH levels, and infarct size, which were blunted by Ang IV receptor (AT4R) antagonist and but not by antagonist for AT1R, AT2R, or Mas receptor. I/R increased Bax, caspase-3 and caspase-9 protein levels, and decreased Bcl-2 protein level in ventricles, which were blunted by Ang IV. I/R-induced increases in TNF-α, MMP-9, and VCAM-1 protein levels in ventricles were also blunted by Ang IV. Ang IV increased the phosphorylation of Akt and mTOR. These effects were attenuated by co-treatment with AT4R antagonist or inhibitors of downstream signaling pathway. Myocardial dysfunction after reperfusion was improved by Ang IV. These results suggest that Ang IV has cardioprotective effect against I/R injury by inhibiting apoptosis via AT4R and PI3K-Akt-mTOR pathway.
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Affiliation(s)
- Byung Mun Park
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Seung Ah Cha
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Sun Hwa Lee
- Internal Medicine, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Suhn Hee Kim
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju, Republic of Korea.
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3
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Yang H, Zeng XJ, Wang HX, Zhang LK, Dong XL, Guo S, Du J, Li HH, Tang CS. Angiotensin IV protects against angiotensin II-induced cardiac injury via AT4 receptor. Peptides 2011; 32:2108-15. [PMID: 21963909 DOI: 10.1016/j.peptides.2011.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 09/15/2011] [Accepted: 09/15/2011] [Indexed: 10/17/2022]
Abstract
Angiotensin II (Ang II) is an important regulator of cardiac function and injury in hypertension. The novel Ang IV peptide/AT4 receptor system has been implicated in several physiological functions and has some effects opposite to those of Ang II. However, little is known about the role of this system in Ang II-induced cardiac injury. Here we studied the effect of Ang IV on Ang II-induced cardiac dysfunction and injury using isolated rat hearts, neonatal cardiomyocytes and cardiac fibroblasts. We found that Ang IV significantly improved Ang II-induced cardiac dysfunction and injury in the isolated heart in response to ischemia/reperfusion (I/R). Moreover, Ang IV inhibited Ang II-induced cardiac cell apoptosis, cardiomyocyte hypertrophy, and proliferation and collagen synthesis of cardiac fibroblasts; these effects were mediated through the AT4 receptor as confirmed by siRNA knockdown. These findings suggest that Ang IV may have a protective effect on Ang II-induced cardiac injury and dysfunction and may be a novel therapeutic target for hypertensive heart disease.
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MESH Headings
- Angiotensin II/analogs & derivatives
- Angiotensin II/metabolism
- Angiotensin II/pharmacology
- Animals
- Cell Proliferation
- Cells, Cultured
- Fibroblasts/cytology
- Fibroblasts/drug effects
- Fibroblasts/physiology
- Heart/drug effects
- Hypertrophy
- Male
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/physiology
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/metabolism
- Reperfusion Injury/metabolism
- Reperfusion Injury/pathology
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Affiliation(s)
- Hui Yang
- The Key Laboratory of Remodeling-related Cardiovascular Diseases, Department of Pathology School of Basic Medical Sciences, Capital Medical University, Beijing, China
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4
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Schlüter KD, Wenzel S. Angiotensin II: a hormone involved in and contributing to pro-hypertrophic cardiac networks and target of anti-hypertrophic cross-talks. Pharmacol Ther 2008; 119:311-25. [PMID: 18619489 DOI: 10.1016/j.pharmthera.2008.05.010] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 05/30/2008] [Indexed: 12/23/2022]
Abstract
Angiotensin II (Ang II) plays a major role in the progression of myocardial hypertrophy to heart failure. Inhibiting the angiotensin converting enzyme (ACE) or blockade of the corresponding Ang II receptors is used extensively in clinical practice, but there is scope for refinement of this mode of therapy. This review summarizes the current understanding of the direct effects of Ang II on cardiomyocytes and then focus particularly on interaction of components of the renin-angiotensin system with other hormones and cytokines. New findings described in approximately 400 papers identified in the PubMed database and published during the 2.5 years are discussed in the context of previous relevant literature. The cardiac action of Ang II is influenced by the activity of different isoforms of ACE leading to different amounts of Ang II by comparison with other angiotensinogen-derived peptides. The effect of Ang II is mediated by at least two different AT receptors that are differentially expressed in cardiomyocytes from neonatal, adult and failing hearts. The intracellular effects of Ang II are influenced by nitric oxide (NO)/cGMP-dependent cross talk and are mediated by the release of autocrine factors, such as transforming growth factor (TGF)-beta1 and interleukin (IL)-6. Besides interactions with cytokines, Ang II is involved in systemic networks including aldosterone, parathyroid hormone and adrenomedullin, which have their own effects on cardiomyocytes that modify, amplify or antagonize the primary effect of Ang II. Finally, hyperinsulemia and hyperglycaemia influence Ang II-dependent processes in diabetes and its cardiac sequelae.
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Affiliation(s)
- K-D Schlüter
- Physiologisches Institut, Justus-Liebig-Universität Giessen, Germany.
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5
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Ryckwaert F, Colson P, Guillon G, Foëx P. Cumulative effects of AT1 and AT2 receptor blockade on ischaemia–reperfusion recovery in rat hearts. Pharmacol Res 2005; 51:497-502. [PMID: 15829428 DOI: 10.1016/j.phrs.2004.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/10/2004] [Indexed: 11/28/2022]
Abstract
Though ischaemia/reperfusion injury induces renin-angiotensin systemic (RAS) activation and increased heart angiotensin production, the effects of blockade of the two main angiotensin II receptors, AT1 and AT2, are not definitively established. Using a Langendorff heart preparation, effects of Valsartan 10(-7)M (AT1 receptor blocker), PD 123319 10(-7)M (AT2 receptor blocker) or both in the presence of a controlled concentration of angiotensin II (10(-8)M) in order to reproduce systemic RAS activation were studied in adult male Wistar rat hearts submitted to ischaemia/reperfusion. Ischaemia/reperfusion impaired both systolic and diastolic function through a no-reflow phenomenon. Presence of a controlled concentration of angiotensin in the perfusate, enough to produce a significant AT1-induced vasoconstriction before ischaemia, has no relevant influence on ischaemia/reperfusion injury. Only blockade of both AT1 and AT2 receptors significantly improved recovery from ischaemia; better ventricle function paralleled better perfusion. The results suggest that blockade of angiotensin II receptors is cumulative since blockade of AT1 and AT2 receptors is more effective than blockade of just one of them.
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6
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Caron AZ, Arguin G, Guillemette G. Angiotensin IV interacts with a juxtamembrane site on AT(4)/IRAP suggesting an allosteric mechanism of enzyme modulation. REGULATORY PEPTIDES 2003; 113:9-15. [PMID: 12686456 DOI: 10.1016/s0167-0115(02)00294-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Angiotensin IV (Ang IV), the 3-8 fragment of angiotensin II, binds to a specific receptor (AT(4)) that has recently been identified as the transmembrane aminopeptidase insulin-regulated aminopeptidase (IRAP) based on the fact that the two proteins share several pharmacological and biochemical properties. Our binding studies indicated that bovine heart expresses relatively large amounts (1.2 pmol/mg protein) of high-affinity binding sites for Ang IV (K(d)=1.8 nM). A photoaffinity-labeling approach combined with mild trypsin digestion revealed that the AT(4) receptor of bovine heart is a single transmembrane domain protein (153 kDa) with a large extracellular fragment (143 kDa). After alkaline denaturation of the AT(4) receptor, trypsin digestion produced two small membrane-associated fragments (16.9 and 6.6 kDa). These results suggest that Ang IV interacts with a juxtamembrane domain of AT(4) receptor. The location of the juxtamembrane site of contact was different from that of the active site of IRAP, suggesting that Ang IV uses an allosteric mechanism to modulate the activity of the AT(4)/IRAP.
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Affiliation(s)
- Annabelle Z Caron
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, 3001 12th Avenue North, Sherbrooke, Quebec, Canada J1H 5N4
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7
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Mustafa T, Lee JH, Chai SY, Albiston AL, McDowall SG, Mendelsohn FA. Bioactive angiotensin peptides: focus on angiotensin IV. J Renin Angiotensin Aldosterone Syst 2001; 2:205-10. [PMID: 11881124 DOI: 10.3317/jraas.2001.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- T Mustafa
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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8
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Ibrahim J, Hughes AD, Sever PS. Action of angiotensin II on DNA synthesis by human saphenous vein in organ culture. Hypertension 2000; 36:917-21. [PMID: 11082167 DOI: 10.1161/01.hyp.36.5.917] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II (Ang II), an effector peptide of the renin-angiotensin system, has been reported to stimulate growth of blood vessels in vivo and smooth muscle cells in culture. In this study, the effect of Ang II on DNA synthesis was examined in deendothelialized human saphenous vein in organ culture. After 7 days' exposure to medium containing 0.4% fetal calf serum plus Ang II, there was a marked increase in DNA synthesis. The effect of Ang II was comparable to the response to platelet-derived growth factor. Responses to Ang II were partially inhibited by the AT(1) receptor antagonist candesartan. An AT(2) receptor antagonist, PD123319, had no effect on Ang II-induced DNA synthesis, either alone or in combination with candesartan. The Ang II peptide analogues [Sar(1), Ile(8)]-Ang II (saralasin) and [Sar(1),Thr(8)]-Ang II (sarthran) acted as agonists, increasing DNA synthesis. In the presence of saralasin, responses to Ang II were inhibited. Tyrphostin-23, a tyrosine kinase inhibitor, prevented Ang II-induced DNA synthesis and reduced DNA synthesis in tissues incubated in medium containing only 0.4% fetal calf serum. In conclusion, Ang II stimulates DNA synthesis in human saphenous vein in organ culture. The effect of Ang II was more marked than has been previously reported in isolated cultured saphenous vein smooth muscle cells, and this effect is mediated in part by an angiotensin type 1 receptor. It is possible that an undefined receptor for Ang II may also be involved in the stimulation of DNA synthesis in this preparation.
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Affiliation(s)
- J Ibrahim
- Clinical Pharmacology, National Heart and Lung Institute, Imperial College School of Medicine, St Mary's Hospital, London, UK
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9
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Moeller I, Clune EF, Fennessy PA, Bingley JA, Albiston AL, Mendelsohn FA, Chai SY. Up regulation of AT4 receptor levels in carotid arteries following balloon injury. REGULATORY PEPTIDES 1999; 83:25-30. [PMID: 10498341 DOI: 10.1016/s0167-0115(99)00047-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Angiotensin IV, (V-Y-I-H-P-F), binds to AT4 receptors in blood vessels to induce vasodilatation and proliferation of cultured bovine endothelial cells. This latter effect may be important not only in developing tissues but also in injured vessels undergoing remodelling. In the present study, using normal rabbit carotid arteries, we detected AT4 receptors in vascular smooth muscle cells and in the vasa vasorum of the adventitia. Very low receptor levels were observed in the endothelial cells. In keeping with the described binding specificity of AT4 receptors, unlabelled angiotensin IV competed for [125I]angiotensin IV binding in the arteries, with an IC50 of 1.4 nM, whereas angiotensin II and angiotensin III were weaker competitors. Within the first week following endothelial denudation of the carotid artery by balloon catheter, AT4 receptor binding in the media increased to approximately 150% of control tissue. AT4 receptor binding further increased in the media, large neointima and re-endothelialized cell layer to 223% at 20 weeks after injury. In view of the known trophic effects of angiotensin IV, the elevated expression of AT4 receptors, in both the neointima and media of arteries, following balloon injury to the endothelium, suggests a role for the peptide in the adaptive response and remodelling of the vascular wall following damage.
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Affiliation(s)
- I Moeller
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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10
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Gesualdo L, Ranieri E, Monno R, Rossiello MR, Colucci M, Semeraro N, Grandaliano G, Schena FP, Ursi M, Cerullo G. Angiotensin IV stimulates plasminogen activator inhibitor-1 expression in proximal tubular epithelial cells. Kidney Int 1999; 56:461-70. [PMID: 10432384 DOI: 10.1046/j.1523-1755.1999.00578.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Angiotensin II (Ang II) has been shown to be implicated in the development of renal fibrosis in several forms of chronic glomerulonephritides, but the precise mechanisms of its effects remain unclear. It has recently been reported that Ang II stimulates the expression of plasminogen activator inhibitor-1 (PAI-1) in several cell lines. PAI-1 is a major physiological inhibitor of the plasminogen activator/plasmin system, a key regulator of fibrinolysis and extracellular matrix (ECM) turnover. PAI-1 induction by Ang II in endothelial cells seems to be mediated by Ang IV via a receptor that is different from Ang II type 1 and 2 receptors (AT1 and AT2). METHODS In this study, we sought to evaluate the effects of Ang IV on PAI-1 gene and protein expression in a well-characterized and immortalized human proximal tubular cell line (HK2) by Northern blot and enzyme-linked immunosorbent assay. RESULTS Ang IV stimulated PAI-1 mRNA expression, whereas it did not induce a significant increase in tritiated thymidine uptake after 24 hours of incubation. This effect was dose and time dependent. Ang IV (10 nM) induced a 7.8 +/- 3.3-fold increase in PAI-1 mRNA expression. The PAI-1 antigen level was significantly higher in conditioned media and the ECM of cells treated with Ang II and Ang IV than in control cells (both P < 0.02). Although Ang II induced a 4.2 +/- 2. 1-fold increase in PAI-1 mRNA expression, its effect underwent a dose-dependent reduction when amastatin, a potent inhibitor of the endopeptidases that catalyzes the conversion of Ang II to Ang IV, was added. In contrast, amastatin was not able to prevent the expression of PAI-1 mRNA induced by Ang IV. Finally, pretreatment of HK2 cells with losartan and N-Nicotinoyl-Tyr-N3-(Nalpha-CBZ-Arg)-Lys-His-Pro-Ile, the specific antagonists of AT1 and AT2 receptors, failed to modify PAI-1 mRNA expression as induced by Ang II. CONCLUSIONS Our results demonstrate that Ang II stimulates PAI-1 mRNA expression and the production of its protein in human proximal tubular cells. This is mainly-if not exclusively-due to Ang IV, which acts on a receptor that is different than AT1 or AT2. Therefore, it can be hypothesized that the induction of PAI-1 by Ang IV may be implicated in the pathogenesis of renal interstitial fibrosis in several forms of chronic glomerulonephritides.
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MESH Headings
- Angiotensin II/analogs & derivatives
- Angiotensin II/pharmacology
- Angiotensin Receptor Antagonists
- Anti-Bacterial Agents/pharmacology
- Antihypertensive Agents/pharmacology
- Blotting, Northern
- Cell Division/drug effects
- Cell Line, Transformed
- Epithelial Cells/cytology
- Epithelial Cells/drug effects
- Epithelial Cells/enzymology
- Fibrosis
- Gene Expression/drug effects
- Humans
- Kidney Diseases/enzymology
- Kidney Diseases/etiology
- Kidney Diseases/pathology
- Kidney Tubules, Proximal/cytology
- Kidney Tubules, Proximal/drug effects
- Kidney Tubules, Proximal/physiology
- Losartan/pharmacology
- Peptides
- Plasminogen Activator Inhibitor 1/genetics
- Protease Inhibitors/pharmacology
- RNA, Messenger/analysis
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Tissue Plasminogen Activator/genetics
- Transforming Growth Factor beta/genetics
- Urokinase-Type Plasminogen Activator/genetics
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Affiliation(s)
- L Gesualdo
- Dipartimento dell'Emergenza e dei Trapianti di Organi, Sezione di Nefrologia, Policlinico, Bari, Italy.
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11
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Moeller I, Albiston AL, Lew RA, Mendelsohn FA, Chai SY. A globin fragment, LVV-hemorphin-7, induces [3H]thymidine incorporation in a neuronal cell line via the AT4 receptor. J Neurochem 1999; 73:301-8. [PMID: 10386983 DOI: 10.1046/j.1471-4159.1999.0730301.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The AT4 receptor was characterized initially as a specific binding site for angiotensin IV, a C-terminal fragment of the vasoactive peptide angiotensin II. Recently, we found that LVV-hemorphin-7, a fragment of beta globin, is an abundant peptide in the brain and binds to the AT4 receptor with high affinity and specificity. In the neuroblastoma/glioma hybrid cell line, NG108-15, LVV-hemorphin-7 and angiotensin IV competed for 125I-angiotensin IV binding in a biphasic fashion with IC50 values of 1.2 x 10(-10) and 1.1 x 10(-9) M for the high-affinity site, respectively, and 6.7 x 10(-8) and 1.5 x 10(-8) M for the low-affinity site, respectively. Both peptides were internalized rapidly by the cells. However, LVV-hemorphin-7, but not angiotensin IV, elicited a 1.8-fold increase in DNA synthesis in a dose-dependent manner. Furthermore, co-incubation of the cells with an excess of angiotensin IV (10(-6) M) inhibited LVV-hemorphin-7-stimulated DNA synthesis. Therefore, whereas LVV-hemorphin-7 and angiotensin IV were capable of binding to the AT4 receptor, only LVV-hemorphin-7 elicited [3H]thymidine incorporation in NG108-15 cells. In contrast, angiotensin IV behaved as an antagonist. The current finding suggests that LVV-hemorphin-7 is a functional peptide in the central nervous system and in view of its abundance in neural tissue, compared with angiotensin IV, may be of significant physiological importance.
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Affiliation(s)
- I Moeller
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia
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12
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Abstract
The role of the renin-angiotensin system in hypertension and end organ damage has long been recognized. Recent advances in genetic models and newly available pharmacologic tools have allowed dissection of the mechanisms of actions of the renin-angiotensin system in hypertensive kidney disease. The newly cloned AT(2) receptor is now recognized to oppose many of the AT(1) receptor"s actions. The renin-angiotensin system is now recognized to be linked to induction of plasminogen activator inhibitor-1 (PAI-1), possibly via the AT(4) receptor, thus promoting both thrombosis and fibrosis. Interactions of the renin-angiotensin system with aldosterone and bradykinin may have impact on both blood pressure and tissue injury. The effects of angiotensin 1 converting enzyme inhibitors versus those of the newly available AT(1) receptor antagonists on blood pressure and organ damage are undergoing evaluation in clinical trials. Finally, polymorphisms of genes relevant to the renin-angiotensin system appear to affect response to treatment, although this effect varies in different populations.
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Affiliation(s)
- A B Fogo
- MCN C3310, Department of Pathology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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13
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Vinson GP, Saridogan E, Puddefoot JR, O'Mahony OA, Mahmood T, Djahanbakhch O. Renin-angiotensin systems and reproduction. Gynecol Endocrinol 1999; 13:56-70. [PMID: 10368799 DOI: 10.1080/09513599909167532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- G P Vinson
- Division of Biomedical Sciences, St Bartholomew's, London, UK
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14
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Krishnan R, Hanesworth JM, Wright JW, Harding JW. Structure-binding studies of the adrenal AT4 receptor: analysis of position two- and three-modified angiotensin IV analogs. Peptides 1999; 20:915-20. [PMID: 10503768 DOI: 10.1016/s0196-9781(99)00081-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Amino acid substitutions in positions two and three of angiotensin IV (VYIHPF) were carried out to determine which structural features of the side-chains were important for achieving high-affinity binding to bovine adrenal receptors. These studies demonstrated that an activated aromatic ring in the second position side-chain resulted in the highest-affinity binding. Position three required a hydrophobic amino acid to achieve high-affinity binding. Both aliphatic and aromatic side-chains were sufficient to yield high-affinity binding.
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Affiliation(s)
- R Krishnan
- Department of VCAPP, Washington State University, Pullman 99164-6520, USA
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15
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Moeller I, Chai SY, Smith I, Lew R, Mendelsohn FA. Haemorphin peptides may be endogenous ligands for brain angiotensin AT4 receptors. CLINICAL AND EXPERIMENTAL PHARMACOLOGY & PHYSIOLOGY. SUPPLEMENT 1998; 25:S68-71. [PMID: 9809196 DOI: 10.1111/j.1440-1681.1998.tb02304.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. Angiotensin IV (AngIV), the (3-8) fragment of AngII, was previously believed to be an inactive metabolite. However, specific binding sites, termed AT4 receptors, have been identified in the brain and peripheral organs and the peptide has been reported to enhance memory recall in passive avoidance studies and to dilate pial and renal cortical vessels. 2. AT4 receptors are distinct from AngII AT1 and AT2 receptors with respect to function, ligand specificity and distribution. 3. In the brain, AT4 receptors are abundant in cerebral and cerebellar cortex, hippocampal formation and cholinergic systems, as well as sensory and motor systems. However, the peptide AngIV is low or undetectable in the central nervous system. This led us to search for an alternative peptide ligand of the AT4 receptor. 4. The decapeptide LVVYPWTQRF was isolated from cerebral cortex and binds with high affinity to brain AT4 receptors. This peptide sequence corresponds to an internal sequence of beta-globin and has previously been named LVV-haemorphin 7. 5. Haemorphin may represent a new class of endogenous neuropeptides, some of which interact potently with the brain AT4 receptor to elicit a range of actions.
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Affiliation(s)
- I Moeller
- Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria, Australia.
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16
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Kramár EA, Krishnan R, Harding JW, Wright JW. Role of nitric oxide in angiotensin IV-induced increases in cerebral blood flow. REGULATORY PEPTIDES 1998; 74:185-92. [PMID: 9712180 DOI: 10.1016/s0167-0115(98)00039-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The present study investigated the effects of three newly synthesized AngIV analogs (Lysine1-AngIV, Norleucine1-AngIV, and Norleucinal) on cerebral blood flow (CBF) in anesthetized Sprague-Dawley rats utilizing laser-Doppler flowmetry. The results indicate that internal carotid infusions of AngIV, Norleucine1-AngIV, Norleucinal, and Lysine1-AngIV increased CBF above baseline by 25, 32, 33 and 44%, respectively, without changing systemic arterial blood pressure. In a second experiment separate groups of rats were pretreated with nitric oxide (NO) synthase inhibitor, Nw-nitro-L-arginine methyl ester (L-NAME) or saline, followed by AngIV or Norleucinal for the purpose of evaluating the hypothesis that the mechanism of action of these compounds is linked to the release of NO. Pretreatment with saline followed by AngIV and Norleucinal increased CBF by 29 and 39%, respectively, while pretreatment with L-NAME blocked the vasodilatory effects of AngIV and Norleucinal, suggesting that the increment in blood flow induced by these compounds is dependent upon the synthesis and release of NO from vascular endothelial cells.
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Affiliation(s)
- E A Kramár
- Department of Psychology, Washington State University, Pullman 99164-4820, USA
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