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1.
Life Sci ; 235: 116796, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31470003

RESUMO

AIM: Depressor arm of the renin-angiotensin system (RAS) exerts reno-protective effects in chronic kidney diseases like diabetic nephropathy. However, same is still elusive under AKI and hyperglycaemia comorbidity. Hence, the present study delineates the role of angiotensin-II type 2 receptor (AT2R) and angiotensin-converting enzyme 2 (ACE2) in AKI under normal and hyperglycaemia condition. METHODS: Non-diabetic (ND) and Streptozotocin-induced diabetes mellitus (DM) rats were subjected to ischemic renal injury (IRI). Rats underwent IRI were treated with an AT2R agonist, C21 (0.3 mg/kg/day, i.p.) or ACE2 activator, Dize, (5 mg/kg/day, p.o.) either alone or as combination therapy. Renal histopathology and immunohistochemistry, proximal tubular fraction isolation, ELISA, immunoblotting and qRT-PCR were performed for subsequent analysis. KEY FINDINGS: Rats subjected to IRI displayed an increase in plasma ACE, AT1R, AT2R, Ang II, and reduction in ACE2, Ang-(1-7) expressions, with augmented renal inflammation and apoptosis. These changes were more prominent in diabetic rats with IRI. Co-administration of C21 and Dize augmented ACE2, Ang-(1-7), AT2R and MasR expressions, and attenuated tubular injury in both DM and ND rats. CONCLUSION: We demonstrated that pharmacological activation of AT2R and ACE2 protects DM and ND rats from IRI by preventing oxidative stress, inflammation and apoptosis-mediated tubular damage.


Assuntos
Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Tipo 1/complicações , Nefropatias Diabéticas/etiologia , Peptidil Dipeptidase A/metabolismo , Receptor Tipo 2 de Angiotensina/metabolismo , Traumatismo por Reperfusão/fisiopatologia , Animais , Apoptose , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/patologia , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/patologia , Inflamação/etiologia , Inflamação/metabolismo , Inflamação/patologia , Masculino , Estresse Oxidativo , Peptidil Dipeptidase A/química , Ratos , Ratos Wistar , Receptor Tipo 2 de Angiotensina/química
2.
Nat Struct Mol Biol ; 25(7): 570-576, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29967536

RESUMO

Angiotensin II (AngII) plays a central role in regulating human blood pressure, which is mainly mediated by interactions between AngII and the G-protein-coupled receptors (GPCRs) AngII type 1 receptor (AT1R) and AngII type 2 receptor (AT2R). We have solved the crystal structure of human AT2R binding the peptide ligand [Sar1, Ile8]AngII and its specific antibody at 3.2-Å resolution. [Sar1, Ile8]AngII interacts with both the 'core' binding domain, where the small-molecule ligands of AT1R and AT2R bind, and the 'extended' binding domain, which is equivalent to the allosteric modulator binding site of muscarinic acetylcholine receptor. We generated an antibody fragment to stabilize the extended binding domain that functions as a positive allosteric modulator. We also identified a signature positively charged cluster, which is conserved among peptide-binding receptors, to locate C termini at the bottom of the binding pocket. The reported results should help with designing ligands for angiotensin receptors and possibly to other peptide GPCRs.


Assuntos
Angiotensina II/análogos & derivados , Receptor Tipo 2 de Angiotensina/química , Sítio Alostérico , Sequência de Aminoácidos , Angiotensina II/química , Angiotensina II/metabolismo , Cristalografia por Raios X , Endotelina-1/química , Endotelina-1/metabolismo , Humanos , Fragmentos de Imunoglobulinas , Cinética , Ligantes , Modelos Moleculares , Conformação Proteica , Receptor Tipo 2 de Angiotensina/genética , Receptor Tipo 2 de Angiotensina/metabolismo , Transdução de Sinais , Eletricidade Estática
3.
Appl Physiol Nutr Metab ; 42(12): 1254-1263, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28772089

RESUMO

The adipose tissue renin-angiotensin system (RAS) is proposed to be a pathophysiological link between adipose tissue dysregulation and metabolic disorders induced by a fructose-rich diet (FRD). RAS can act intracellularly. We hypothesized that adipocyte nuclear membranes possess angiotensin receptor types 1 and 2 (AT1R and AT2R), which couple to nuclear signaling pathways and regulate oxidative gene expression under FRD conditions. We analyzed the effect of consumption of 10% fructose solution for 9 weeks on biochemical parameters, adipocyte morphology, and expression of AT1R, AT2R, AT1R-associated protein (ATRAP), NADPH oxidase 4 (NOX4), matrix metalloproteinase-9 (MMP-9), and manganese superoxide dismutase (MnSOD) in adipose tissue of Wistar rats. We detected AT1R and AT2R in the nuclear fraction. FRD reduced the level of angiotensin receptors in the nucleus, while increased AT1R and decreased AT2R levels were observed in the plasma membrane. FRD increased the ATRAP mRNA level and decreased MnSOD mRNA and protein levels. No significant differences were observed for MMP-9 and NOX4 mRNA levels. These findings coincided with hyperleptinemia, elevated blood pressure and triglycerides, and unchanged visceral adipose tissue mass and morphology in FRD rats. Besides providing evidence for nuclear localization of angiotensin receptors in visceral adipose tissue, this study demonstrates the different effects of FRD on AT1R expression in different cellular compartments. Elevated blood pressure and decreased antioxidant capacity in visceral fat of fructose-fed rats were accompanied by an increased AT1R level in the plasma membrane, while upregulation of ATRAP and a decrease of nuclear membrane AT1R suggest an increased capacity for attenuation of excessive AT1R signaling and visceral adiposity.


Assuntos
Membrana Celular/química , Núcleo Celular/metabolismo , Carboidratos da Dieta , Frutose/farmacologia , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/metabolismo , Adipócitos/química , Adipócitos/metabolismo , Animais , Peso Corporal , Núcleo Celular/química , Frutose/administração & dosagem , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 2 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/genética , ATPase Trocadora de Sódio-Potássio/genética , ATPase Trocadora de Sódio-Potássio/metabolismo
4.
Nature ; 544(7650): 327-332, 2017 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-28379944

RESUMO

The angiotensin II receptors AT1R and AT2R serve as key components of the renin-angiotensin-aldosterone system. AT1R has a central role in the regulation of blood pressure, but the function of AT2R is unclear and it has a variety of reported effects. To identify the mechanisms that underlie the differences in function and ligand selectivity between these receptors, here we report crystal structures of human AT2R bound to an AT2R-selective ligand and to an AT1R/AT2R dual ligand, capturing the receptor in an active-like conformation. Unexpectedly, helix VIII was found in a non-canonical position, stabilizing the active-like state, but at the same time preventing the recruitment of G proteins or ß-arrestins, in agreement with the lack of signalling responses in standard cellular assays. Structure-activity relationship, docking and mutagenesis studies revealed the crucial interactions for ligand binding and selectivity. Our results thus provide insights into the structural basis of the distinct functions of the angiotensin receptors, and may guide the design of new selective ligands.


Assuntos
Modelos Moleculares , Receptor Tipo 2 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/metabolismo , Bloqueadores do Receptor Tipo 2 de Angiotensina II/química , Bloqueadores do Receptor Tipo 2 de Angiotensina II/metabolismo , Sítios de Ligação/genética , Cristalografia por Raios X , Desenho de Drogas , Proteínas Heterotriméricas de Ligação ao GTP/química , Proteínas Heterotriméricas de Ligação ao GTP/metabolismo , Humanos , Ligantes , Simulação de Acoplamento Molecular , Mutação , Ligação Proteica , Conformação Proteica , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/agonistas , Receptor Tipo 2 de Angiotensina/genética , Transdução de Sinais , Relação Estrutura-Atividade , Especificidade por Substrato/genética , beta-Arrestinas/metabolismo
5.
Nucleic Acids Res ; 44(W1): W455-62, 2016 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-27166369

RESUMO

GPCR-ModSim (http://open.gpcr-modsim.org) is a centralized and easy to use service dedicated to the structural modeling of G-protein Coupled Receptors (GPCRs). 3D molecular models can be generated from amino acid sequence by homology-modeling techniques, considering different receptor conformations. GPCR-ModSim includes a membrane insertion and molecular dynamics (MD) equilibration protocol, which can be used to refine the generated model or any GPCR structure uploaded to the server, including if desired non-protein elements such as orthosteric or allosteric ligands, structural waters or ions. We herein revise the main characteristics of GPCR-ModSim and present new functionalities. The templates used for homology modeling have been updated considering the latest structural data, with separate profile structural alignments built for inactive, partially-active and active groups of templates. We have also added the possibility to perform multiple-template homology modeling in a unique and flexible way. Finally, our new MD protocol considers a series of distance restraints derived from a recently identified conserved network of helical contacts, allowing for a smoother refinement of the generated models which is particularly advised when there is low homology to the available templates. GPCR- ModSim has been tested on the GPCR Dock 2013 competition with satisfactory results.


Assuntos
Internet , Modelos Moleculares , Receptores Acoplados a Proteínas-G/química , Software , Algoritmos , Regulação Alostérica , Sequência de Aminoácidos , Humanos , Ligantes , Simulação de Dinâmica Molecular , Receptor Tipo 2 de Angiotensina/química
6.
Bioorg Med Chem Lett ; 26(4): 1355-9, 2016 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-26810314

RESUMO

Agonists of the angiotensin II receptor type 2 (AT2), a G-protein coupled receptor, promote tissue protective effects in cardiovascular and renal diseases, while antagonists reduce neuropathic pain. We here report detailed molecular models that explain the AT2 receptor selectivity of our recent series of non-peptide ligands. In addition, minor structural changes of these ligands that provoke different functional activity are rationalized at a molecular level, and related to the selectivity for the different receptor conformations. These findings should pave the way to structure based drug discovery of AT2 receptor ligands.


Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/química , Receptor Tipo 2 de Angiotensina/metabolismo , Sequência de Aminoácidos , Bloqueadores do Receptor Tipo 1 de Angiotensina II/metabolismo , Sítios de Ligação , Ligantes , Simulação de Acoplamento Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/agonistas , Receptor Tipo 2 de Angiotensina/química , Alinhamento de Sequência
7.
Chem Commun (Camb) ; 52(8): 1645-8, 2016 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-26660361

RESUMO

We describe herein the design, synthesis and conformational investigation of Pro-Amb (proline-3-amino-2-methoxybenzoic acid) incorporated Angiotensin II and its truncated analogues. Solution-state NMR and CD studies suggest γ-turn-like conformation in Pro-Amb analogs in aqueous solution. Furthermore, Pro-Amb analogs have been shown to act as AT2 receptor agonists.


Assuntos
Angiotensina II/farmacologia , Receptor Tipo 2 de Angiotensina/agonistas , Linhagem Celular , Humanos , Receptor Tipo 2 de Angiotensina/química
8.
Interdiscip Sci ; 6(3): 197-207, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25205497

RESUMO

A QSAR study has been performed on a series of pyridines derivatives with potent angiotensin II AT1 receptor antagonists. Structural features responsible for the activity of the compounds were characterized by using topological, electrotopological, group based and 3D descriptors, calculated from the Molecular Design Suite software (V-life MDS 3.5). To elucidate the structural properties required for antihypertensive activity, four different molecular modeling techniques; two-dimensional, Group-based (G-QSAR), k-nearest neighbour and pharmacophore approach. A suitable set of molecular descriptors was calculated and stepwise - partial component regression (SW-PCR) was employed to select the descriptors that resulted in the models with the best fit to the data. This study was performed with twenty two compounds using sphere exclusion algorithm method for the division of the data set into training and test set. The statistically significant 2D QSAR model having r(2) = 0.8407 and q(2) = 0.7395 with pred_r(2) = 0.7971 was developed by stepwise-partial component regression (SW-PCR) and best Group based QSAR model having R(2) = 0.8132 and Q(2) = 0.6804 with pred_r(2) = 0.7661 was developed by SW-PCR. The analyzed k-nearest neighbour MFA model revealed a good fit, having q(2) value of 0.7635. The predictive power of the model generated was validated using a test set molecules with pred _r(2) value of 0.7314. The generated k-nearest neighbour models suggest that steric and electrostatic interactions play an important role in describing the variation in binding affinity. Additionally the pharmacophore model well corraborated with k-nearest neighbour studies as the contours of later were in good agreement with the 3D orientation of the pharmacophoric features. The present analysis has shown that the antihypertensive activity can be improved with the presence of specific steric substituent and electro-donating and electro-withdrawing groups nearby the pyridine moiety. The Pharmacophore information shows that the four features used were two AroC feature, one HAc, one AlaC features. The structural variations in the molecular fields at particular regions in the space provide underlying structural requirements and 3D-QSAR models generated give good predictive ability and aid in the design of potent antihypertensive activity.


Assuntos
Antagonistas de Receptores de Angiotensina/química , Modelos Moleculares , Piridinas/química , Relação Quantitativa Estrutura-Atividade , Algoritmos , Desenho de Drogas , Imagem Tridimensional , Receptor Tipo 2 de Angiotensina/química , Eletricidade Estática
9.
ACS Chem Biol ; 9(7): 1420-5, 2014 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-24787922

RESUMO

GPCR subtypes possess distinct functional and pharmacological profiles, and thus development of subtype-selective ligands has immense therapeutic potential. This is especially the case for the angiotensin receptor subtypes AT1R and AT2R, where a functional negative control has been described and AT2R activation highlighted as an important cancer drug target. We describe a strategy to fine-tune ligand selectivity for the AT2R/AT1R subtypes through electronic control of ligand aromatic-prolyl interactions. Through this strategy an AT2R high affinity (Ki = 3 nM) agonist analogue that exerted 18,000-fold higher selectivity for AT2R versus AT1R was obtained. We show that this compound is a negative regulator of AT1R signaling since it is able to inhibit MCF-7 breast carcinoma cellular proliferation in the low nanomolar range.


Assuntos
Angiotensina II/análogos & derivados , Antineoplásicos/química , Receptor Tipo 2 de Angiotensina/agonistas , Receptor Tipo 2 de Angiotensina/metabolismo , Angiotensina II/metabolismo , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Desenho de Drogas , Feminino , Humanos , Ligantes , Simulação de Acoplamento Molecular , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/química
10.
Int J Mol Sci ; 14(12): 24029-45, 2013 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-24336063

RESUMO

The exact molecular mechanism that mediates hypoxia-induced pulmonary fibrosis needs to be further clarified. The aim of this study was to explore the effect and underlying mechanism of angiotensin II (Ang II) on collagen synthesis in hypoxic human lung fibroblast (HLF) cells. The HLF-1 cell line was used for in vitro studies. Angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin II type 1 receptor (AT1R) and angiotensin II type 2 receptor (AT2R) expression levels in human lung fibroblasts were analysed using real-time polymerase chain reaction (RT-PCR) after hypoxic treatment. Additionally, the collagen type I (Col-I), AT1R and nuclear factor κappaB (NF-κB) protein expression levels were detected using Western blot analysis, and NF-κB nuclear translocation was measured using immunofluorescence localization analysis. Ang II levels in HLF-1 cells were measured with an enzyme-linked immunosorbent assay (ELISA). We found that hypoxia increased Col-I mRNA and protein expression in HLF-1 cells, and this effect could be inhibited by an AT1R or AT2R inhibitor. The levels of NF-κB, RAS components and Ang II production in HLF-1 cells were significantly increased after the hypoxia exposure. Hypoxia or Ang II increased NF-κB-p50 protein expression in HLF-1 cells, and the special effect could be inhibited by telmisartan (TST), an AT1R inhibitor, and partially inhibited by PD123319, an AT2R inhibitor. Importantly, hypoxia-induced NF-κB nuclear translocation could be nearly completely inhibited by an AT1R or AT2R inhibitor. Furthermore pyrrolidine dithiocarbamate (PDTC), a NF-κB blocker, abolished the expression of hypoxia-induced AT1R and Col-I in HLF-1 cells. Our results indicate that Ang II-mediated NF-κB signalling via ATR is involved in hypoxia-induced collagen synthesis in human lung fibroblasts.


Assuntos
Angiotensina II/metabolismo , Hipóxia Celular , Colágeno Tipo I/metabolismo , Angiotensina II/análise , Angiotensinogênio/genética , Angiotensinogênio/metabolismo , Benzimidazóis/farmacologia , Benzoatos/farmacologia , Linhagem Celular , Colágeno Tipo I/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Imidazóis/farmacologia , Pulmão/citologia , Pulmão/metabolismo , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/metabolismo , Piridinas/farmacologia , Pirrolidinas/farmacologia , RNA Mensageiro/metabolismo , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/genética , Receptor Tipo 2 de Angiotensina/metabolismo , Telmisartan , Tiocarbamatos/farmacologia
11.
PLoS One ; 8(6): e65307, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23755216

RESUMO

The renin-angiotensin system is involved in multiple conditions ranging from cardiovascular disorders to cancer. Components of the pathway, including ACE, renin and angiotensin receptors are targets for disease treatment. This study addresses three receptors of the pathway: AT1, AT2, and MAS and how the receptors are similar and differ in activation by angiotensin peptides. Combining biochemical and amino acid variation data with multiple species sequence alignments, structural models, and docking site predictions allows for visualization of how angiotensin peptides may bind and activate the receptors; allowing identification of conserved and variant mechanisms in the receptors. MAS differs from AT1 favoring Ang-(1-7) and not Ang II binding, while AT2 recently has been suggested to preferentially bind Ang III. A new model of Ang peptide binding to AT1 and AT2 is proposed that correlates data from site directed mutagenesis and photolabled experiments that were previously considered conflicting. Ang II binds AT1 and AT2 through a conserved initial binding mode involving amino acids 111 (consensus 325) of AT1 (Asn) interacting with Tyr (4) of Ang II and 199 and 256 (consensus 512 and 621, a Lys and His respectively) interacting with Phe (8) of Ang II. In MAS these sites are not conserved, leading to differential binding and activation by Ang-(1-7). In both AT1 and AT2, the Ang II peptide may internalize through Phe (8) of Ang II propagating through the receptors' conserved aromatic amino acids to the final photolabled positioning relative to either AT1 (amino acid 294, Asn, consensus 725) or AT2 (138, Leu, consensus 336). Understanding receptor activation provides valuable information for drug design and identification of other receptors that can potentially bind Ang peptides.


Assuntos
Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Proteínas Proto-Oncogênicas/química , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/química , Receptores Acoplados a Proteínas-G/química , Sequência de Aminoácidos , Angiotensina I/química , Angiotensina II/química , Angiotensina III/química , Humanos , Dados de Sequência Molecular , Peptídeos/química , Peptidil Dipeptidase A/química , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Transporte Proteico , Renina/química , Alinhamento de Sequência , Homologia Estrutural de Proteína
12.
J Pediatr Gastroenterol Nutr ; 57(5): 562-9, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23783021

RESUMO

BACKGROUND AND AIM: We have previously shown that angiotensin II (ANGII) plays an important role in the regulation of the apoptosis of intestinal epithelial cells (IECs). In this study, we investigated the pathway by which ANGII modulates apoptosis of the IECs. METHODS: Epithelial cells (HT-29) were cultured; the ANGII receptor type-1 (AT1R) inhibitor (Losartan) and ANGII receptor type-2 (AT2R) inhibitor (PD123319) were used separately to block the ANGII receptor. Flow cytometry was used to detect the apoptosis of the IECs. In the in vivo study, Sprague-Dawley rats were divided into 4 groups: sham group, which received a ileum transection (n = 6); sham + angiotensin-converting enzyme inhibitor (ACE-I) group, which received a ileum transection, and lavage with ACE-I (enalaprilat 2 mg · kg⁻¹ day⁻¹) (n = 6); short bowel syndrome (SBS) group, which received a 70% mid-intestinal resection (n = 6); and SBS + ACE-I group, which received a 70% mid-intestinal resection, and lavage with enalaprilat (2 mg · kg⁻¹ day⁻¹) (n = 6). Sampling was done 10 days after surgery. The expression of ANGII receptors Bax and Bcl-2 was detected with immunofluorescence, real-time-polymerase chain reaction, and Western blot methods. RESULTS: Massive small bowel resection led to a significant increase in epithelial cells apoptosis, and the addition of ACE-I to SBS rat significantly attenuated this increase in apoptosis. AT1R expression on intestinal mucosa surface decreased after small bowel resection. Pretreatment with the AT1R antagonist Losartan significantly attenuated the increase of epithelial cell apoptosis caused by ANGII administration. Moreover, the Bcl-2/Bax ratio was found to be increased in cells pretreated with Losartan, which indicates a proapoptotic role of AT1R in cultured HT-29 cell lines. CONCLUSIONS: These findings suggest that ANGII plays an important role in the regulation of apoptosis of the IECs. AT1R may be of crucial importance for the modulation of intestinal EC apoptosis.


Assuntos
Angiotensina II/metabolismo , Apoptose , Enterócitos/metabolismo , Receptor Tipo 1 de Angiotensina/agonistas , Transdução de Sinais , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Bloqueadores do Receptor Tipo 2 de Angiotensina II/farmacologia , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/metabolismo , Modelos Animais de Doenças , Enterócitos/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Células HT29 , Humanos , Masculino , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/agonistas , Receptor Tipo 2 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/metabolismo , Síndrome do Intestino Curto/tratamento farmacológico , Síndrome do Intestino Curto/metabolismo , Transdução de Sinais/efeitos dos fármacos
13.
Curr Pharm Des ; 19(17): 2981-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23176209

RESUMO

The renin-angiotensin system hormone angiotensin II Ang II plays a central role in the pathophysiology of vasoconstriction, cardiovascular hypertrophy and hyperplasia. Two distinct subtypes of Ang II receptor, type 1 AT1 and type 2 AT2, have been identified, and both have been shown to belong to the G protein-coupled receptors (GPCRs) superfamily. AT1 and AT2 receptors may have antagonistic action. While the crystal structures of GPCRs obtained from the rhodopsin, opsin, and ß1 and ß2- adrenergic receptors have recently been described in different conformational states, the crystal structures of Ang II receptors have not been elucidated. The conformation range and dynamics of the effects of ligands on GPCRs may differ from one receptor to another. This review focuses on the structure and function of Ang II receptors, such as the movement of transmembrane helices, functional selectivity for AT1 receptor activation, the possibility of constitutive activity of wild-type Ang II receptors and the homo- and hetero-dimerization of Ang II receptors.


Assuntos
Receptor Tipo 1 de Angiotensina/fisiologia , Receptor Tipo 2 de Angiotensina/fisiologia , Sequência de Aminoácidos , Animais , Humanos , Dados de Sequência Molecular , Conformação Proteica , Multimerização Proteica , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/química
14.
Curr Pharm Des ; 19(17): 2988-95, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23176210

RESUMO

The octapeptide angiotensin II (Ang II) plays a homeostatic role in the regulation of blood pressure and water and electrolyte balance, and also contributes to the progression of cardiovascular remodeling. Ang II activates Ang II type 1 (AT1) receptor and type 2 (AT2) receptor, both of which belong to the seven-transmembrane, G protein-coupled receptor family. Most of the actions of Ang II such as promotion of cellular prolifaration, hypertrophy, and fibrosis are mediated by AT1 receptor. However, in some pathological situations, AT2 receptor shows an increase in tissue expression and functions to antagonize the actions induced by AT1 receptor. Recent studies have advanced our understanding of the molecular mechanisms underlying receptor activation and signal transduction of AT1 and AT2 receptor in the cardiovascular system.


Assuntos
Receptor Tipo 1 de Angiotensina/fisiologia , Receptor Tipo 2 de Angiotensina/fisiologia , Transdução de Sinais/fisiologia , Animais , Cálcio/metabolismo , Humanos , Conformação Proteica , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/química , Estresse Mecânico
15.
PLoS One ; 7(10): e47016, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23056563

RESUMO

Despite heterologous expression of epitope-tagged GPCR is widely adopted for functional characterization, there is lacking of systematic analysis of the impact of expression host and epitope tag on GPCR expression. Angiotensin type II (AT2) receptor displays agonist-dependent and -independent activities, coupling to a spectrum of signaling molecules. However, consensus has not been reached on the subcellular distributions, signaling cascades and receptor-mediated actions. To examine the contributions of host cell and epitope tag on receptor expression and activity, epitope-tagged AT2 receptor variants were transiently or stably expressed in HEK293, CHO-K1 and PC12 cells. The epitope-tagged AT2 receptor variants were detected both on the cell membrane and in the perinuclear region. In transiently transfected HEK293 cells, Myc-AT2 existed predominantly as monomer. Additionally, a ladder of ubiquitinated AT2 receptor proteins was detected. By contrast, stably expressed epitope-tagged AT2 receptor variants existed as both monomer and high molecular weight complexes, and the latter was enriched in cell surface. Glycosylation promoted cell surface expression of Myc-AT2 but had no effect on AT2-GFP in HEK293 cells. In cells that stably expressed Myc-AT2, serum starvation induced apoptosis in CHO-K1 cells but not in HEK293 or PC12 cells. Instead, HEK293 and PC12 cells stably expressing Myc-AT2 exhibited partial cell cycle arrest with cells accumulating at G1 and S phases, respectively. Taken together, these results suggest that expression levels, subcellular distributions and ligand-independent constitutive activities of AT2 receptor were cell type-dependent while posttranslational processing of nascent AT2 receptor protein was modulated by epitope tag and mode of expression.


Assuntos
Epitopos/metabolismo , Receptor Tipo 2 de Angiotensina/genética , Receptor Tipo 2 de Angiotensina/metabolismo , Animais , Células CHO , Cricetinae , Cricetulus , Expressão Gênica , Células HEK293 , Humanos , Peso Molecular , Células PC12 , Multimerização Proteica , Estrutura Quaternária de Proteína , Ratos , Receptor Tipo 2 de Angiotensina/química , Transfecção , Ubiquitinação
16.
Cell Signal ; 24(3): 734-41, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22108089

RESUMO

AT(1)R has been reported to play an important role in the progression of HIV-associated nephropathy (HIVAN); however, the effect of AT(2)R has not been studied. Age and sex matched control (FVB/N) and Tg26 mice aged 4, 8, and 16weeks were studied for renal tissue expression of AT(1)R and AT(2)R (Protocol A). Renal tissue mRNA expression of AT(2)R was lower in Tg26 mice when compared with control mice. In Protocol B, Tg26 mice were treated with either saline, telmisartan (TEL, AT(1) blocker), PD123319 (PD, AT(2)R blocker), or TEL+PD for two weeks. TEL-receiving Tg26 (TRTg) displayed less advanced glomerular and tubular lesions when compared with saline-receiving Tg26 (SRTg). TRTgs displayed enhanced renal tissue AT(2)R expression when compared to SRTgs. Diminution of renal tissue AT(2)R expression was associated with advanced renal lesions in SRTgs; whereas, upregulation of AT(2)R expression in TRTgs was associated with attenuated renal lesions. PD-receiving Tg26 mice (PDRTg) did not show any alteration in the course of HIVAN; whereas, PD+TEL-receiving Tg26 (PD-TRTg) showed worsening of renal lesions when compared to TRTgs. Interestingly, plasma as well as renal tissues of Tg26 mice displayed several fold higher concentration of Ang III, a ligand of AT(2)R.


Assuntos
Nefropatia Associada a AIDS/patologia , Glomérulos Renais/patologia , Receptor Tipo 2 de Angiotensina/metabolismo , Nefropatia Associada a AIDS/metabolismo , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Bloqueadores do Receptor Tipo 2 de Angiotensina II/farmacologia , Animais , Benzimidazóis/farmacologia , Benzoatos/farmacologia , Humanos , Imidazóis/farmacologia , Glomérulos Renais/efeitos dos fármacos , Glomérulos Renais/metabolismo , Camundongos , Camundongos Transgênicos , Piridinas/farmacologia , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/química , Telmisartan
17.
Int J Mol Sci ; 12(7): 4206-13, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21845073

RESUMO

Hypertension is a risk factor for osteoporosis. Animal and epidemiological studies demonstrate that high blood pressure is associated with increased calcium loss, elevated parathyroid hormone, and increased calcium movement from bone. However, the mechanism responsible for hypertension-related osteoporosis remains elusive. Recent epidemiological studies indicate the benefits of Angiotensin II Receptors Blockade (ARB) on decreasing fracture risks. Since receptors for angiotensin II, the targets of ARB, are expressed in both osteoblasts and osteoclasts, we postulated that angiotensin II plays an important role in hypertension-related osteoporosis. Cbfa1 and RANKL, the important factors for maintaining bone homeostasis and key mediators in controlling osteoblast and osteoclast differentiation, are both regulated by cAMP-dependent signaling. Angiotensin II along with factors such as LDL, HDL, NO and homocysteine that are commonly altered both in hypertension and osteoporosis, can down-regulate the expression of Cbfa1 but up-regulate RANKL expression via the cAMP signaling pathway. We thus hypothesized that, by altering the ratio of Cbfa1/RANKL expression via the cAMP-dependent pathway, angiotensin II differently regulates osteoblast and osteoclast differentiation leading to enhanced bone resorption and reduced bone formation. Since ARB can antagonize the adverse effect of angiotensin II on bone by lowering cAMP levels and modifying other downstream targets, including LDL, HDL, NO and Cbfa1/RANKL, we propose the hypothesis that the antagonistic effects of ARB may also be exerted via cAMP signaling pathway.


Assuntos
Bloqueadores do Receptor Tipo 2 de Angiotensina II/farmacologia , Angiotensina II/farmacologia , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , AMP Cíclico/metabolismo , Ligante RANK/metabolismo , Transdução de Sinais/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana , Humanos , Hipertensão/complicações , Lipoproteínas HDL/sangue , Lipoproteínas LDL/sangue , Óxido Nítrico/sangue , Osteoporose/etiologia , Receptor Tipo 2 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/metabolismo
18.
Clin Sci (Lond) ; 121(7): 297-303, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21542804

RESUMO

AT1R (angiotensin type 1 receptor) and AT2R (angiotensin type 2 receptor) are well known to be involved in the complex cardiovascular actions of AngII (angiotensin II). However, shorter peptide fragments of AngII are thought to have biological activity in their own right and elicit effects that oppose those mediated by AngII. In the present study, we have used HEK (human embryonic kidney)-293 cells stably transfected with either AT1R or AT2R to perform a systematic analysis of binding affinities of all the major angiotensin peptides. Additionally, we tested the novel AT2R agonist Compound 21, as well as the MasR (Mas receptor) agonist and antagonist AVE0991 and A-779 respectively, for their ability to bind to AT1R or AT2R. Candesartan, CGP42214 and PD123319 were used as reference compounds. Binding studies using 125I-[Sar1Ile8]AngII on the AT1R-transfected HEK-293 cells revealed only AngII, AngIII [angiotensin III; angiotensin-(2-8)] and candesartan to have high affinity for AT1R. In the AT2R-transfected HEK-293 cells, competition for 125I-[Sar1Ile8]AngII binding was observed for all ligands except candesartan, AVE0991 and A-779, the latter two compounds having negligible affinity at either AT1R or AT2R. The rank order of affinity of ligands at AT2R was CGP42112>AngII≥AngIII>Compound 21≥PD123319≫AngIV [angiotensin IV; angiotensin-(3-8)]>Ang-(1-7) [angiotensin-(1-7)]. Of note, although AngIV and Ang-(1-7) exhibited only modest affinity at AT2R compared with AngII, these two angiotensin peptides, together with AngIII, had substantial AT2R selectivity over AT1R. Collectively, our results suggest that shorter angiotensin peptides can act as endogenous ligands at AT2R.


Assuntos
Angiotensinas/química , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/química , Desenho de Drogas , Avaliação Pré-Clínica de Medicamentos , Células HEK293 , Humanos , Imidazóis/farmacologia , Concentração Inibidora 50 , Ligantes , Peptídeos/química , Plasmídeos/metabolismo , Piridinas/farmacologia , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/metabolismo , Transfecção
19.
Nephrol Dial Transplant ; 26(3): 832-8, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20810455

RESUMO

BACKGROUND: The mechanisms of uraemia-induced atherosclerosis have not been fully delineated. The aims of this study were (i) to investigate the extent and the phenotype of atherosclerosis, including the activation of local renin-angiotensin system (RAS), in a mouse model of mild uraemia and (ii) to determine the effects of angiotensin II type1 (AT1) receptor blockade on the uraemic atherosclerosis, clarifying the mechanisms of its action. METHODS: Mild uraemia was induced by 5/6 nephrectomy in 8-week-old apo E-deficient mice (apoE-KO). After nephrectomy, the animals received either treatment with candesartan or no treatment for 12-weeks. Sham-operated apoE-KO mice were used as controls. RESULTS: Uraemia led to a two-fold increase in aortic plaque area. This was associated with a significant upregulation of aortic angiotensin-converting enzyme (ACE), AT1 receptor, connective tissue growth factor (CTGF), monocyte chemoattractant protein (MCP)-1 and vascular cell adhesion molecule (VCAM)-1. Candesartan significantly reduced aortic atherosclerosis, prevented the upregulation of the uraemia-induced genes and led to changes predicting greater stability of the plaques, without influencing blood pressure or serum lipids. CONCLUSIONS: This study indicates that uraemia leads to an acceleration of aortic atherosclerosis. The upregulation of aortic RAS and the reduced atherosclerosis following AT1 receptor blocker treatment highlights the pivotal role of the local RAS in the development and acceleration of atherosclerosis in uraemia.


Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/uso terapêutico , Apolipoproteínas E/fisiologia , Aterosclerose/prevenção & controle , Receptor Tipo 1 de Angiotensina/química , Insuficiência Renal/tratamento farmacológico , Insuficiência Renal/metabolismo , Animais , Aorta/efeitos dos fármacos , Aorta/patologia , Aterosclerose/metabolismo , Benzimidazóis/uso terapêutico , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Nefrectomia , Fenótipo , RNA Mensageiro/genética , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 1 de Angiotensina/metabolismo , Receptor Tipo 2 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/genética , Receptor Tipo 2 de Angiotensina/metabolismo , Insuficiência Renal/etiologia , Sistema Renina-Angiotensina/efeitos dos fármacos , Sistema Renina-Angiotensina/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Tetrazóis/uso terapêutico , Uremia/metabolismo , Uremia/prevenção & controle
20.
Nihon Rinsho ; 67(4): 687-94, 2009 Apr.
Artigo em Japonês | MEDLINE | ID: mdl-19348229

RESUMO

The octapeptide angiotensin II (AngII) plays a homeostatic role in the regulation of blood pressure and water and electrolyte balance, and contributes to the progression of cardiovascular remodeling. AngII activates AngII type 1 (AT1) receptor and type 2 (AT2) receptor, both of which belong to the seven-transmembrane, G protein-coupled receptor family. Most of the actions of AngII such as promotion of cellular proliferation, hypertrophy, and fibrosis are mediated by AT1 receptor. However, in some pathological situations, AT2 receptor showed an increase in expression level and functions to antagonize the actions by AT1 receptor stimulation. Recent studies have advanced our understanding of the molecular mechanisms underlying receptor activation and signal transduction, and elucidated the pathophysiological roles of AT1 and AT2 receptors in the cardiovascular system.


Assuntos
Receptor Tipo 1 de Angiotensina/fisiologia , Receptor Tipo 2 de Angiotensina/fisiologia , Animais , Receptor Tipo 1 de Angiotensina/química , Receptor Tipo 2 de Angiotensina/química , Transdução de Sinais/fisiologia
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