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Polo CC, Fonseca-Alaniz MH, Chen JH, Ekman A, McDermott G, Meneau F, Krieger JE, Miyakawa AA. Three-dimensional imaging of mitochondrial cristae complexity using cryo-soft X-ray tomography. Sci Rep 2020; 10:21045. [PMID: 33273629 PMCID: PMC7713364 DOI: 10.1038/s41598-020-78150-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are dynamic organelles that change morphology to adapt to cellular energetic demands under both physiological and stress conditions. Cardiomyopathies and neuronal disorders are associated with structure-related dysfunction in mitochondria, but three-dimensional characterizations of the organelles are still lacking. In this study, we combined high-resolution imaging and 3D electron density information provided by cryo-soft X-ray tomography to characterize mitochondria cristae morphology isolated from murine. Using the linear attenuation coefficient, the mitochondria were identified (0.247 ± 0.04 µm-1) presenting average dimensions of 0.90 ± 0.20 µm in length and 0.63 ± 0.12 µm in width. The internal mitochondria structure was successfully identified by reaching up the limit of spatial resolution of 35 nm. The internal mitochondrial membranes invagination (cristae) complexity was calculated by the mitochondrial complexity index (MCI) providing quantitative and morphological information of mitochondria larger than 0.90 mm in length. The segmentation to visualize the cristae invaginations into the mitochondrial matrix was possible in mitochondria with MCI ≥ 7. Altogether, we demonstrated that the MCI is a valuable quantitative morphological parameter to evaluate cristae modelling and can be applied to compare healthy and disease state associated to mitochondria morphology.
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Affiliation(s)
- Carla C Polo
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, 13083-970, Brazil.
| | - Miriam H Fonseca-Alaniz
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
| | - Jian-Hua Chen
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Anatomy, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Axel Ekman
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Gerry McDermott
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Florian Meneau
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, 13083-970, Brazil
| | - José E Krieger
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
| | - Ayumi A Miyakawa
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil.
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Miyakawa AA, Girão-Silva T, Krieger JE, Edelman ER. Rapamycin activates TGF receptor independently of its ligand: implications for endothelial dysfunction. Clin Sci (Lond) 2018; 132:437-447. [PMID: 29343616 PMCID: PMC6301009 DOI: 10.1042/cs20171457] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 01/12/2018] [Accepted: 01/16/2018] [Indexed: 01/06/2023]
Abstract
Rapamycin, the macrolide immunosuppressant and active pharmaceutic in drug-eluting stents (DES), has a well-recognized antiproliferative action that involves inhibition of the mTOR pathway after binding to the cytosolic protein FKBP12. TGF receptor-type I (TGFRI) spontaneous activation is inhibited by the association with FKBP12. We hypothesized that rapamycin, in addition to inhibition of mTOR signaling, activates TGFRI independent of TGFβ. Human umbilical vein endothelial cells (HUVECs) were treated with rapamycin (10 nmol/l) and/or TGFβ RI kinase inhibitor (TGFRIi, 100 nmol/l) for 24 h. Rapamycin induced SMAD phosphorylation (SMAD1, SMAD2, and SMAD5) and PAI-1 up-regulation, which was specifically abrogated by SMAD2 knockdown. TGFRIi efficiently blocked phosphorylation of SMAD2, but not SMAD1/5. Interestingly, the inhibitor did not alter cell proliferation arrest induced by rapamycin. Active TGFβ secretion was not affected by the treatment. Neutralizing TGFβ experiments did not influence SMAD2 phosphorylation or PAI-1 expression indicating that activation of this pathway is independent of the ligand. In addition, rapamycin induction of endothelial-to-mesenchymal transition (EndMT) was potentiated by IL-1β and efficiently blocked by TGFRIi. In vivo, the prothrombogenic effects of rapamycin and up-regulation of PAI-1 in murine carotid arteries were reduced by TGFRIi treatment. In conclusion, we provide evidence that rapamycin activates TGF receptor independent of its ligand TGFβ, in concert with promotion of PAI-1 expression and changes in endothelial phenotype. These undesirable effects, the prothrombogenic state, and activation of EndMT are SMAD2-dependent and independent of the therapeutic rapamycin-induced cell proliferation arrest.
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Affiliation(s)
- Ayumi A Miyakawa
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, U.S.A.
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor, HCFMUSP), Sao Paulo, SP 054003, Brazil
| | - Thais Girão-Silva
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor, HCFMUSP), Sao Paulo, SP 054003, Brazil
| | - Jose E Krieger
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor, HCFMUSP), Sao Paulo, SP 054003, Brazil
| | - Elazer R Edelman
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, U.S.A
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A
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Barauna VG, Magalhaes FC, Campos LCG, Reis RI, Kunapuli SP, Costa-Neto CM, Miyakawa AA, Krieger JE. Shear stress-induced Ang II AT1 receptor activation: G-protein dependent and independent mechanisms. Biochem Biophys Res Commun 2013; 434:647-52. [PMID: 23583236 DOI: 10.1016/j.bbrc.2013.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 04/04/2013] [Indexed: 01/14/2023]
Abstract
Mechanotransduction enables cells to sense and respond to stimuli, such as strain, pressure and shear stress (SS), critical for maintenance of cardiovascular homeostasis or pathological states. The angiotensin II type 1 receptor (AT1R) was the first G protein-coupled receptor described to display stretch-induced activation in cardiomyocytes independent of its ligand Ang II. Here, we assessed whether SS (15 dynes/cm(2), 10 min), an important mechanical force present in the cardiovascular system, activates AT1R independent of its ligand. SS induced extracellular signal-regulated kinase (ERK) activation, used as a surrogate of AT1R activation, in Chinese hamster ovary cells expressing the AT1R (CHO+AT1) but not in wild type cells (CHO). AT1R dependent SS-induced ERK activation involves Ca(2+) inflow and activation of Gαq since Ca(2+) chelator EGTA or Gαq-specific inhibitor YM-254890 decreased SS-induced ERK activation. On the other hand, the activation of JAK-2 and Src, two intracellular signaling molecules independent of G protein activation, were not differently modulated in the presence of AT1R. Also, ERK activation by SS was observed in CHO cells expressing the mutated AT1R DRY/AAY, which has impaired ability to activate Gαq dependent intracellular signaling. Altogether we provided evidence that SS activates AT1R in the absence of its ligand by both a G protein-dependent and -independent pathways. The biological relevance of these observations deserves to be further investigated since the novel mechanisms described extend the knowledge of the activation of GPCRs independent of its traditional ligand.
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Affiliation(s)
- Valerio G Barauna
- Laboratory of Genetics and Molecular Cardiology, Heart Institute, InCor, University of São Paulo Medical School, São Paulo 05403-000, Brazil
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Ferreira NE, Omae S, Pereira A, Rodrigues MV, Miyakawa AA, Campos LC, Santos PC, Dallan LA, Martinez TL, Santos RD, Mill JG, Krieger JE, Pereira AC. Thioredoxin interacting protein genetic variation is associated with diabetes and hypertension in the Brazilian general population. Atherosclerosis 2012; 221:131-6. [DOI: 10.1016/j.atherosclerosis.2011.12.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 11/03/2011] [Accepted: 12/06/2011] [Indexed: 12/17/2022]
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Neukamm B, Miyakawa AA, Fukada SY, de Andrade CR, Pacheco FP, da Silva TG, Ramalho LNZ, de Oliveira AM, Krieger JE. Local TAT-p27Kip1 fusion protein inhibits cell proliferation in rat carotid arteries. Ther Adv Cardiovasc Dis 2009; 2:129-36. [PMID: 19124416 DOI: 10.1177/1753944708090170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
INTRODUCTION p27(Kip1) is a cyclin kinase inhibitor that induces cell cycle arrest. In this study, the efficacy of fusion protein TAT- p27(Kip1) to inhibit cell proliferation in rat perivascular injured carotid arteries was tested. METHODS The cDNA of p27(Kip1) and GFP (green fluorescein protein) fused to the TAT epitope, which allows cell penetration, yielded TAT-p27 (Kip1) and TAT-GFP fusion proteins. In vitro biological activity on cell proliferation was evaluated by [(3)H] thymidine DNA incorporation in rabbit aortic endothelial cells (REC). An in vivo model used a silicone collar filled with saline positioned around the carotid vessel for 14 days to produce an increased adventitia cross-sectional area. RESULTS TAT-p27(Kip1) inhibited REC proliferation in vitro using either 100, 200, and 500 nM compared to control (88.2 +/- 4.4, 81.3 +/- 7, 71.9 +/- 4.2 vs. 100 +/- 6.7%, N = 3, respectively, p < 0.05). This response was stable for purified proteins stored at -20*C for at least 23 days. In vivo , TAT-p27(Kip1) solution reduced adventitia cross-sectional area in a dose-dependent manner compared to TAT-GFP (area in mm(2) - TAT-p27(Kip1): 200 nM, 0.160 +/- 0.018; 500 nM, 0.050 +/- 0.005 vs. TAT-GFP: 500 nM, 0.595 +/- 0.066 vs. the contralateral: 0.047 +/- 0.005, N = 7, p < 0.01). CONCLUSION Taken together, these results provide evidence that TAT-p27(Kip1) can inhibit vascular cells proliferation. It is the first successful demonstration that the cell permeable TAT-p27(Kip1) has potential as a vascular anti-proliferative agent.
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Affiliation(s)
- Birgit Neukamm
- Heart Institute (InCor)/LIM 13, University of Sao Paulo Medical School, Sao Paulo, Brazil
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Bassaneze V, Miyakawa AA, Krieger JE. A quantitative chemiluminescent method for studying replicative and stress-induced premature senescence in cell cultures. Anal Biochem 2008; 372:198-203. [DOI: 10.1016/j.ab.2007.08.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/01/2007] [Accepted: 08/14/2007] [Indexed: 01/06/2023]
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Pereira AC, Miyakawa AA, Lopes NHM, Soares PR, de Oliveira SA, Cesar LAM, Ramires JF, Hueb W, Krieger JE. Dynamic regulation of MTHFR mRNA expression and C677T genotype modulate mortality in coronary artery disease patients after revascularization. Thromb Res 2007; 121:25-32. [PMID: 17604826 DOI: 10.1016/j.thromres.2007.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 03/01/2007] [Accepted: 03/06/2007] [Indexed: 12/13/2022]
Abstract
INTRODUCTION A large body of evidence links plasma homocysteine (Hcy) concentrations and cardiovascular disease. A common MTHFR polymorphism (C677T) leads to a variant with reduced activity and associated with increased Hcy levels. Coronary surgery precipitates a significant and sustained increase in the blood concentrations of Hcy and elevated levels of plasma Hcy have been associated to saphenous vein (SV) graft disease after CABG. However, the effects of MTHFR genotypes in the incidence of cardiovascular events after CABG have not been investigated prospectively. Here, we investigate whether MTHFR gene variants are associated with an increased cardiovascular risk in individuals submitted to CABG. We also propose a molecular mechanism to explain our findings. METHODS We performed MTHFR C677T genotypes in 558 patients with two or three vessel-disease and normal left ventricular function prospectively followed in the MASS II Trial, a randomized study to compare treatments for multivessel CAD and preserved left ventricle function. Follow-up time was 5 years. Survival curves were calculated with the Kaplan-Meier method, and evaluated with the log-rank statistic. We assessed the relationship between baseline variables and the composite end-point of death, myocardial infarction and refractory angina using a Cox proportional hazards survival model. Finally, using an ex-vivo organ culture we have reproduced the arterialization of SV implants by culturing human SV either under venous hemodynamic condition (flow: 5 mL/min; no pressure) or arterial hemodynamic condition (flow: 50 mL/min; pressure: 80 mm Hg) for 1 day. MTHFR gene expression was quantified by real time RT-PCR in 15 SV from different individuals in both experimental conditions. RESULTS There were no significant differences among individuals within each genotype group for baseline clinical characteristics. A statistically significant association between the TT genotype, associated with increased serum levels of Hcy, and cardiovascular mortality after 5 years was verified (p=0.007) in individuals submitted to CABG surgery. In addition, MTHFR TT genotype was still significantly associated with a 4.4 fold increased risk in cardiovascular outcomes (p=0.01) even after adjustment of a Cox multivariate model for age, sex, hypertension, diabetes, LDL, HDL, triglycerides, and number of diseased vessels in this population. Finally, a significant reduction in MTHFR gene expression was demonstrated in human SV when submitted to an arterial hemodynamic condition (p=0.02). CONCLUSIONS There is a dynamic regulation of MTHFR gene expression during the arterialization process of human saphenous vein grafts resulting in lower levels of gene expression when in an arterial hemodynamic condition. In addition, the C677T MTHFR functional variant is associated with a worse outcome in individuals submitted to CABG. Taken together, these data suggest an important role of Hcy metabolism in individuals after CABG.
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Dallan LA, Miyakawa AA, Lisboa LA, Borin TF, Abreu Filho CA, Campos LC, Krieger JE, Oliveira SA. Ação inibitória da Interleucina - 1ß sobre a proliferação de células musculares lisas cultivadas a partir de veias safenas humanas. Braz J Cardiovasc Surg 2005. [DOI: 10.1590/s0102-76382005000200004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Dallan LA, Miyakawa AA, Lisboa LA, Borin TF, Abreu Filho CA, Campos LC, Krieger JE, Oliveira SA. <![CDATA[<B>Inhibitory action of the Interleukin 1� over the cellular proliferation of smooth muscle cells cultivated from human saphenous veins</B>]]>. Braz J Cardiovasc Surg 2005. [DOI: 10.1590/s1678-97412005000200004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Xavier-Neto J, Pereira AC, Oliveira EM, Miyakawa AA, Junqueira ML, Krieger JE. Control of the rat angiotensin I converting enzyme gene by CRE-like sequences. Braz J Med Biol Res 2004; 37:1441-53. [PMID: 15448864 DOI: 10.1590/s0100-879x2004001000002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We characterized the role of potential cAMP-responsive elements (CRE) in basal and in induced angiotensin converting enzyme (ACE) gene promoter activity in order to shed light on the regulation of somatic ACE expression. We identified stimulators and repressors of basal expression between 122 and 288 bp and between 415 and 1303 bp upstream from the transcription start site, respectively, using a rabbit endothelial cell (REC) line. These regions also contained elements associated with the response to 8BrcAMP. When screening for CRE motifs we found pCRE, a proximal sequence between 209 and 222 bp. dCRE, a distal tandem of two CRE-like sequences conserved between rats, mice and humans, was detected between 834 and 846 bp. Gel retardation analysis of nuclear extracts of REC indicated that pCRE and dCRE bind to the same protein complexes as bound by a canonical CRE. Mutation of pCRE and dCRE in REC established the former as a positive element and the latter as a negative element. In 293 cells, a renal cell line, pCRE and dCRE are negative regulators. Co-transfection of ATF-2 or ATF-2 plus c-Jun repressed ACE promoter activity, suggesting that the ACE gene is controlled by cellular stress. Although mapping of cAMP responsiveness was consistent with roles for pCRE and dCRE, mutation analysis indicated that they were not required for cAMP responsiveness. We conclude that the basal activity of the somatic ACE promoter is controlled by proximal and distal CREs that can act as enhancers or repressors depending on the cell context.
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Affiliation(s)
- J Xavier-Neto
- Laboratório de Genética e Cardiologia Molecular, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas C. Aguiar 44, 05403-000 São Paulo, SP, Brazil
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Dallan LAO, Miyakawa AA, Lisboa LA, Abreu Filho CA, Campos L, Borin T, Krieger JE, Oliveira SAD. Alterações estruturais e moleculares (cDNA) precoces em veias safenas humanas cultivadas sob regime pressórico arterial. Braz J Cardiovasc Surg 2004. [DOI: 10.1590/s0102-76382004000200006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Dallan LAO, Miyakawa AA, Lisboa LA, Abreu Filho CA, Campos L, Borin T, Krieger JE, Oliveira SA. Precocious structural and molecular (cDNA) changes in the human saphenous veins cultivated under arterial hemodynamic conditions]]>. Braz J Cardiovasc Surg 2004. [DOI: 10.1590/s1678-97412004000200006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Costa-Neto CM, Miyakawa AA, Pesquero JB, Oliveira L, Hjorth SA, Schwartz TW, Paiva AC. Erratum: Interaction of a non-peptide agonist with angiotensin II AT1 receptor mutants. Can J Physiol Pharmacol 2003. [DOI: 10.1139/y03-109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Pertrini CM, Miyakawa AA, Laurindo FRM, Krieger JE. Nitric oxide regulates angiotensin-I converting enzyme under static conditions but not under shear stress. Braz J Med Biol Res 2003; 36:1175-8. [PMID: 12937782 DOI: 10.1590/s0100-879x2003000900005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical forces including pressure and shear stress play an important role in vascular homeostasis via the control of the production and release of a variety of vasoactive factors. An increase in vascular shear stress is accompanied by nitric oxide (NO) release and NO synthase activation. Previously, we have demonstrated that shear stress induces angiotensin-I converting enzyme (ACE) down-regulation in vivo and in vitro. In the present study, we determined whether NO participates in the shear stress-induced ACE suppression response. Rabbit aortic endothelial cells were evaluated using the NO synthase inhibitor L-NAME, and two NO donors, diethylamine NONOate (DEA/NO) and sodium nitroprusside (SNP). Under static conditions, incubation of endothelial cells with 1 mM L-NAME for 18 h increased ACE activity by 27% (from 1.000 +/- 0.090 to 1.272 +/- 0.182) while DEA/NO and SNP (0.1, 0.5 and 1 mM) caused no change in ACE activity. Interestingly, ACE activity was down-regulated similarly in the presence or absence of L-NAME (delta(0 mM) = 0.26 0.055, delta(0.1 mM) = 0.21 +/- 0.22, delta(1 mM) = 0.36 +/- 0.13) upon 18 h shear stress activation (from static to 15 dyn/cm2 ). Taken together, these results indicate that NO can participate in the maintenance of basal ACE levels in the static condition but NO is not associated with the shear stress-induced inactivation of ACE.
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Affiliation(s)
- C M Pertrini
- Laboratório de Genética e Cardiologia Molecular, Instituto do Coração (InCor), Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
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Costa-Neto CM, Miyakawa AA, Pesquero JB, Oliveira L, Hjorth SA, Schwartz TW, Paiva ACM. Interaction of a non-peptide agonist with angiotensin II AT1 receptor mutants. Can J Physiol Pharmacol 2002; 80:413-7. [PMID: 12056547 DOI: 10.1139/y02-058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To identify residues of the rat AT1A angiotensin II receptor involved with signal transduction and binding of the non-peptide agonist L-162,313 (5,7-dimethyl-2-ethyl-3-[[4-[2(n-butyloxycarbonylsulfonamido)-5-isobutyl-3-thienyl]phenyl]methyl]imidazol[4,5,6]-pyridine) we have performed ligand binding and inositol phosphate turnover assays in COS-7 cells transiently transfected with the wild-type and mutant forms of the receptor. Mutant receptors bore modifications in the extracellular region: T88H, Y92H, G1961, G196W, and D278E. Compound L-162,313 displaced [125I]-Sar1,Leu8-AngII from the mutants G196I and G196W with IC50 values similar to that of the wild-type. The affinity was, however, slightly affected by the D278E mutation and more significantly by the T88H and Y92H mutations. In inositol phosphate turnover assays, the ability of L-162,313 to trigger the activation cascade was compared with that of angiotensin II. These assays showed that the G196W mutant reached a relative maximum activation exceeding that of the wild-type receptor; the efficacy was slightly reduced in the G1961 mutant and further reduced in the T88H, Y92H, and D278E mutants. Our data suggest that residues of the extracellular domain of the AT1 receptor are involved in the binding of the non-peptide ligand, or in a general receptor activation phenomenon that involves conformational modifications for a preferential binding of agonists or antagonists.
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Affiliation(s)
- Claudio M Costa-Neto
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, SP, Brazil
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Costa-Neto CM, Miyakawa AA, Oliveira L, Hjorth SA, Schwartz TW, Paiva ACM. Mutational analysis of the interaction of the N- and C-terminal ends of angiotensin II with the rat AT(1A) receptor. Br J Pharmacol 2000; 130:1263-8. [PMID: 10903964 PMCID: PMC1572190 DOI: 10.1038/sj.bjp.0703430] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. The role of different residues of the rat AT(1A) receptor in the interaction with the N- and C-terminal ends of angiotensin II (AngII) was studied by determining ligand binding and production of inositol phosphates (IP) in COS-7 cells transiently expressing the following AT(1A) mutants: T88H, Y92H, G196I, G196W and D278E. 2. G196W and G196I retained significant binding and IP-production properties, indicating that bulky substituents in position 196 did not affect the interaction of AngII's C-terminal carboxyl with Lys(199) located three residues below. 3. Although the T88A mutation did not affect binding, the T88H mutant had greatly decreased affinity for AngII, suggesting that substitution of Thr(88) by His might hinder binding through an indirect effect. 4. The Y92H mutation caused loss of affinity for AngII that was much less pronounced than that reported for Y92A, indicating that His in that position can fulfil part of the requirements for binding. 5. Replacing Asp(278) by Glu caused a much smaller reduction in affinity than replacing it by Ala, indicating the importance of Asp's beta-carboxyl group for AngII binding. 6. Mutations in residues Thr(88), Tyr(92) and Asp(278) greatly reduced affinity for AngII but not for Sar(1) Leu(8)-AngII, suggesting unfavourable interactions between these residues and AngII's aspartic acid side-chain or N-terminal amino group, which might account for the proposed role of the N-terminal amino group of AngII in the agonist-induced desensitization (tachyphylaxis) of smooth muscles.
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Affiliation(s)
- Claudio M Costa-Neto
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, 04023-062 São Paulo, SP, Brazil
- Laboratory for Molecular Pharmacology, Panun Institute, University of Copenhagen, Copenhagen, Denmark
| | - Ayumi A Miyakawa
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, 04023-062 São Paulo, SP, Brazil
| | - Laerte Oliveira
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, 04023-062 São Paulo, SP, Brazil
| | - Siv A Hjorth
- Laboratory for Molecular Pharmacology, Panun Institute, University of Copenhagen, Copenhagen, Denmark
| | - Thue W Schwartz
- Laboratory for Molecular Pharmacology, Panun Institute, University of Copenhagen, Copenhagen, Denmark
| | - Antonio C M Paiva
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, 04023-062 São Paulo, SP, Brazil
- Author for correspondence:
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Perlman S, Costa-Neto CM, Miyakawa AA, Schambye HT, Hjorth SA, Paiva AC, Rivero RA, Greenlee WJ, Schwartz TW. Dual agonistic and antagonistic property of nonpeptide angiotensin AT1 ligands: susceptibility to receptor mutations. Mol Pharmacol 1997; 51:301-11. [PMID: 9203636 DOI: 10.1124/mol.51.2.301] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Two nonpeptide ligands that differ chemically by only a single methyl group but have agonistic (L-162,782) and antagonistic (L-162,389) properties in vivo were characterized on the cloned angiotensin AT1 receptor. Both compounds bound with high affinity (K(I) = 8 and 28 nM, respectively) to the AT1 receptor expressed transiently in COS-7 cells as determined in radioligand competition assays. L-162,782 acted as a powerful partial agonist, stimulating phosphatidylinositol turnover with a bell-shaped dose-response curve to 64% of the maximal level reached in response to angiotensin II. Surprisingly, L-162,389 also stimulated phosphatidylinositol turnover, albeit only to a small percentage of the angiotensin response. The prototype nonpeptide AT1 agonist L-162,313 gave a response of approximately 50%. The apparent EC50 values for all three compounds in stimulating phosphatidylinositol turnover were similar, approximately 30 nM, corresponding to their binding affinity. Each of the three compounds also acted as angiotensin antagonists, yet in this capacity the compounds differed markedly, with IC50 values ranging from 1.05 x 10(-7) M for L-162,389 to 6.5 x 10(-6) for L-162,782. A series of point mutations in the transmembrane segments (TMs) of the AT1 receptor had only minor effect on the binding affinity of the nonpeptide compounds, with the exception of A104V at the top of TM III, which selectively impaired the binding of L-162,782 and L-162,389. Substitutions in the middle of TM III, VI, or VII, which did not affect the binding affinity of the compounds, impaired or eliminated the agonistic efficacy of the nonpeptides but with only minor or no effect on the angiotensin potency or efficacy. Thus, in the N295D rat AT1 construct, L-162,782, L-162,313, and L-162,389 all antagonized the angiotensin-induced phosphatidylinositol turnover with surprisingly similar IC50 values (90-180 nM), and they all bound with unaltered, high affinity (22-36 nM). However, L-162,313 and L-162,782 could stimulate phosphatidylinositol turnover to only 20% of that of angiotensin. It is concluded that minor chemical modifications of either the compound or the receptor can dramatically alter the agonistic efficacy of biphenyl imidazole compounds on the AT1 receptor without affecting their affinity, as determined in binding assays, and that a number of substitutions in the middle of the TM segments affect the efficacy of nonpeptide agonists as opposed to angiotensin.
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Affiliation(s)
- S Perlman
- Laboratory for Molecular Pharmacology, University Department of Clinical Pharmacology, Rigshospitalet, Copenhagen, Denmark
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