Upregulation of angiotensin II type 2 receptor expression in estrogen-induced pituitary hyperplasia

2004 ◽  
Vol 286 (5) ◽  
pp. E786-E794 ◽  
Author(s):  
Cecilia Suarez ◽  
Graciela Díaz-Torga ◽  
Arturo González-Iglesias ◽  
Carolina Cristina ◽  
Damasia Becu-Villalobos
Keyword(s):  
Angiotensin Ii ◽  
Receptor Expression ◽  
Receptor Subtype ◽  
At2 Receptor ◽  
Ang Ii ◽  
Pituitary Hyperplasia ◽  
Releasing Effect ◽  
At2 Receptors

Recent evidence shows that reexpression and upregulation of angiotensin II (ANG II) type 2 (AT2) receptor in adult tissues occur during pathological conditions such as tissue hyperplasia, inflammation, and remodeling. In particular, expression of functional AT2 receptors in the pituitary and their physiological significance and regulation have not been described. In this study, we demonstrate that chronic in vivo estrogen treatment, which induces pituitary hyperplasia, enhances local AT2 expression (measured by Western blot and RT-PCR) concomitantly with downregulation of ANG II type 1 (AT1) receptors. In vivo progesterone treatment of estrogen-induced pituitary hyperplasia did not modify either the ANG II receptor subtype expression pattern or octapeptide-induced and AT1-mediated calcium signaling. Nevertheless, an unexpected potentiation of the ANG II prolactin-releasing effect was observed in this group, and this response was sensitive to both AT1 and AT2 receptor antagonists. These data are the first to document that ANG II can act at the pituitary level through the AT2 receptor subtype and that estrogens display a differential regulation of AT1 and AT2 receptors at this level.

scholarly journals Angiotensin II type 2 receptors mediate inhibition of mitogen-activated protein kinase cascade and functional activation of SHP-1 tyrosine phosphatase

1997 ◽  
Vol 325 (2) ◽  
pp. 449-454 ◽  
Author(s):  
Katarina BEDECS ◽  
Nathalie ELBAZ ◽  
Malène SUTREN ◽  
Maryline MASSON ◽  
Christiane SUSINI ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Growth Factor ◽  
Protein Kinase ◽  
Map Kinases ◽  
Tyrosine Phosphatase ◽  
At2 Receptor ◽  
Ang Ii ◽  
Mitogen Activated Protein ◽  
At2 Receptors

Angiotensin II type 2 (AT2) receptors are involved in the inhibition of cell proliferation as well as in apoptosis and neuronal differentiation, through intracellular signalling pathways that remain poorly defined. The present study examines the effect of AT2-receptor stimulation on growth-factor-induced pathways leading to the activation of mitogen-activated protein (MAP) kinases. In N1E-115 neuroblastoma cells, AT2 receptors inhibit the activity of MAP kinases induced by serum as well as by epidermal growth factor. The inhibitory effect of angiotensin II (Ang II) is rapid and transient, and affects both ERK1 and ERK2 (extracellular signal-related protein kinase) isoforms of the enzyme. AT2-mediated MAP kinase inactivation is not sensitive to pertussis toxin or okadaic acid, but involves a vanadate-sensitive protein tyrosine phosphatase (PTP). Expression of MAP kinase phosphatase-1 (MKP-1) is not significantly modified upon AT2-receptor activation, and insensitivity to actinomycin D also rules out transcriptional induction of other MKPs as a possible mechanism for AT2-mediated inactivation of MAP kinases. In addition, we report here that both in N1E-115 cells and in Chinese hamster ovary cells expressing recombinant human AT2 receptors, Ang II rapidly stimulates the catalytic activity of SHP-1, a soluble PTP that has been implicated in termination of signalling by cytokine and growth-factor receptors. These findings thus demonstrate functional negative cross-talk between heptahelical AT2 receptors and receptor tyrosine kinases, and suggest that SHP-1 tyrosine phosphatase is an early transducer of the AT2 receptor signalling pathway.

Angiotensin II type 2 receptor-modulated changes in potassium currents in cultured neurons

1993 ◽  
Vol 265 (3) ◽  
pp. C607-C616 ◽  
Author(s):  
J. Kang ◽  
C. Sumners ◽  
P. Posner
Keyword(s):  
Angiotensin Ii ◽  
Ionic Current ◽  
Delayed Rectifier ◽  
Receptor Subtype ◽  
Cultured Neurons ◽  
Ang Ii ◽  
Maximal Conductance ◽  
K Current ◽  
At2 Receptors

We have previously shown that angiotensin II (ANG II) stimulates an increase in net outward ionic current (Ino) in neurons cocultured from neonate rat hypothalamus and brain stem, an effect mediated by ANG II type 2 (AT2) receptors. Ino consists mainly of K+ and Ca2+ currents, and in the present study we used whole cell voltage clamp procedures to define which of these currents are modulated by AT2 receptors. We determined that ANG II (50-100 nM) stimulated both transient K+ current (IA) and delayed-rectifier K+ current (IK) in cultured neurons. The effects were mediated by AT2 receptors (blocked by 1 microM PD-123177 but not by 1 microM losartan). For both IA and IK, ANG II elicited an increase in maximal conductance. By contrast, ANG II altered neither Ca(2+)-activated K+ current nor Ca2+ current. Our data demonstrate discrete AT2 receptor-mediated effects of ANG II on IA and IK in cultured neonate neurons. Importantly, these data provide an electrophysiological basis for behavioral or physiological effects (as yet undefined) mediated by this ANG II receptor subtype in the brain.

scholarly journals Angiotensin II AT2 receptors are functionally coupled to protein tyrosine dephosphorylation in N1E-115 neuroblastoma cells

1995 ◽  
Vol 306 (1) ◽  
pp. 87-92 ◽  
Author(s):  
C Nahmias ◽  
S M Cazaubon ◽  
M M Briend-Sutren ◽  
D Lazard ◽  
P Villageois ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Rank Order ◽  
Neuroblastoma Cells ◽  
Receptor Activation ◽  
Receptor Subtype ◽  
At2 Receptor ◽  
Ang Ii ◽  
Single Class ◽  
Protein Tyrosine ◽  
At2 Receptors

Murine N1E-115 neuroblastoma cells are shown to express a single class of angiotensin II (Ang II) receptors that display all the pharmacological properties defining the Ang II receptor subtype 2 (AT2): high affinity for 125I-labelled AT2-selective agonist CGP 42112 (Kd 91 +/- 19 pM); expected rank order of potency (CGP 42112 = (Sar1,Ile8)Ang II > or = Ang II > PD 123319 >> DUP 753) for several Ang II analogues; increased binding in the presence of the reducing reagent dithiothreitol (DTT); and insensitivity to analogues of GTP. Molecular cloning of cDNA encoding AT2 receptors from N1E-115 cells reveals nucleotide sequence identity with the AT2 subtype expressed in fetal tissue. Murine AT2 receptors transiently expressed in COS cells display the same pharmacological profile as endogenous Ang II receptors of N1E-115 cells. Taken together, these data reveal the exclusive presence of the AT2 receptor subtype in N1E-115 cells. Incubation of N1E-115 cells with Ang II leads to a marked decrease in the level of tyrosine phosphorylation of several proteins with apparent molecular masses of 80, 97, 120, 150 and 180 kDa respectively. Tyrosine dephosphorylation of the same set of proteins is observed after treatment with the AT2-specific agonist CGP 42112. The response to both effectors is rapid and transient, showing a maximum between 5 and 10 min, and returning to basal levels after 20-30 min. In both cases, tyrosine dephosphorylation can be prevented by co-incubation with an excess of the antagonist Sarile. These data thus establish that AT2 receptor activation leads to protein tyrosine dephosphorylation in N1E-115 cells, and support a possible role for AT2 receptors in the negative regulation of cell proliferation.

Expression of Angiotensin II Type 1 and Type 2 Receptor in Human Myocardium with Congestive Heart Failure

2000 ◽  
Vol 6 (S2) ◽  
pp. 618-619
Author(s):  
P. Y. Lau ◽  
M. G. Cardarelli ◽  
C. Wei
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Angiotensin Ii ◽  
Cardiac Tissue ◽  
Open Heart Surgery ◽  
Human Myocardium ◽  
Receptor Expression ◽  
At2 Receptors

Angiotensin II (AH) is a potent vasoconstrictor and mitogenic factor. AH receptors include type 1 (ATI) and type 2 (AT2) receptors. Recent studies demonstrated that both ATI and AT2 receptors expressed in human myocardium. Circulating and local tissue level of AH was increased in severe congestive heart failure (CHF). However, the expression of ATI and AT2 in cardiac tissue with CHF remains controversial. Therefore, the present study was designed to investigate the protein expression of ATI and AT2 receptors in normal human myocardium and in human cardiac tissue with mild and severe CHF.Human atrial tissues from normal subjects and CHF patients with ischemic cardiomyopathy and dilated cardiomyopathy were obtained from open-heart surgery and cardiac transplantation. ATI and AT2 receptor expression was investigated by immunohistochemical staining (IHCS). The results of IHCS was evaluated by IHCS staining density scores (0, no staining; 1, minimal staining; 2, mild staining; 3, moderate staining; and 4, strong staining).

scholarly journals Regulation of angiotensin II receptors and extracellular matrix turnover in human retinal pigment epithelium: role of angiotensin II

2008 ◽  
Vol 295 (6) ◽  
pp. C1633-C1646 ◽  
Author(s):  
Gary E. Striker ◽  
Francoiçe Praddaude ◽  
Oscar Alcazar ◽  
Scott W. Cousins ◽  
Maria E. Marin-Castaño
Keyword(s):  
Extracellular Matrix ◽  
Angiotensin Ii ◽  
Type Iv Collagen ◽  
Pigment Epithelium ◽  
Receptor Expression ◽  
Age Related Macular Degeneration ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Ang Ii ◽  
Type Iv

The early stage of age-related macular degeneration (AMD) is characterized by the formation of subretinal pigment epithelium (RPE) deposits as a result of the dysregulation in the turnover of extracellular matrix (ECM) molecules. However, the mechanism involved remains unclear. Hypertension (HTN) is an important risk factor for AMD, and angiotensin II (ANG II) is the most important hormone associated with HTN. However, the relevance of ANG II receptors and ANG II effects on RPE have not been investigated yet. Therefore, the expression and regulation of ANG II receptors as well as the ECM turnover were studied in human RPE. ANG II receptors were expressed and upregulated by ANG II in human RPE. This regulation resulted in functional receptor expression, since an increase in intracellular concentration of calcium was observed upon ANG II stimulation. ANG II also increased matrix metalloproteinase (MMP)-2 activity and MMP-14 at the mRNA and protein levels as well as type IV collagen degradation. These ANG II effects were abolished in the presence of the ANG II receptor subtype 1 (AT1) receptor antagonist candesartan. In contrast, ANG II decreased type IV collagen via both AT1 and AT2 receptors, suggesting a synergistic effect of the two receptor subtypes. In conclusion, we have confirmed the presence of ANG II receptors in human RPE and their regulation by ANG II as well as the regulation of ECM molecules via ANG II receptors. Our data support the hypothesis that ANG II may exert biological function in RPE through ANG II receptors and that ANG II may cause dysregulation of molecules that play a major role in the turnover of ECM in RPE basement membrane and Bruch's membrane, suggesting a pathogenic mechanism to explain the link between HTN and AMD.

Angiotensin II type 2 receptor (AT2R) in renal and cardiovascular disease

2016 ◽  
Vol 130 (15) ◽  
pp. 1307-1326 ◽  
Author(s):  
Bryna S.M. Chow ◽  
Terri J. Allen
Keyword(s):  
Angiotensin Ii ◽  
Renin Angiotensin System ◽  
Cellular Growth ◽  
Receptor Subtype ◽  
Electrolyte Balance ◽  
Ang Ii ◽  
Biological Responses

Angiotensin II (Ang II) is well-considered to be the principal effector of the renin–angiotensin system (RAS), which binds with strong affinity to the angiotensin II type 1 (AT1R) and type 2 (AT2R) receptor subtype. However, activation of both receptors is likely to stimulate different signalling mechanisms/pathways and produce distinct biological responses. The haemodynamic and non-haemodynamic effects of Ang II, including its ability to regulate blood pressure, maintain water–electrolyte balance and promote vasoconstriction and cellular growth are well-documented to be mediated primarily by the AT1R. However, its biological and functional effects mediated through the AT2R subtype are still poorly understood. Recent studies have emphasized that activation of the AT2R regulates tissue and organ development and provides in certain context a potential counter-regulatory mechanism against AT1R-mediated actions. Thus, this review will focus on providing insights into the biological role of the AT2R, in particular its actions within the renal and cardiovascular system.

scholarly journals COX-2 mediates angiotensin II-induced (pro)renin receptor expression in the rat renal medulla

2014 ◽  
Vol 307 (1) ◽  
pp. F25-F32 ◽  
Author(s):  
Fei Wang ◽  
Xiaohan Lu ◽  
Kexin Peng ◽  
Li Zhou ◽  
Chunling Li ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Expression ◽  
Renal Medulla ◽  
Receptor Expression ◽  
Ang Ii ◽  
Cox 2 ◽  
Renin Content

(Pro)renin receptor (PRR) is predominantly expressed in the distal nephron where it is activated by angiotensin II (ANG II), resulting in increased renin activity in the renal medulla thereby amplifying the de novo generation and action of local ANG II. The goal of the present study was to test the role of cycloxygenase-2 (COX-2) in meditating ANG II-induced PRR expression in the renal medulla in vitro and in vivo. Exposure of primary rat inner medullary collecting duct cells to ANG II induced sequential increases in COX-2 and PRR protein expression. When the cells were pretreated with a COX-2 inhibitor NS-398, ANG II-induced upregulation of PRR protein expression was almost completely abolished, in parallel with the changes in medium active renin content. The inhibitory effect of NS-398 on the PRR expression was reversed by adding exogenous PGE2. A 14-day ANG II infusion elevated renal medullary PRR expression and active and total renin content in parallel with increased urinary renin, all of which were remarkably suppressed by the COX-2 inhibitor celecoxib. In contrast, plasma and renal cortical active and total renin content were suppressed by ANG II treatment, an effect that was unaffected by COX-2 inhibition. Systolic blood pressure was elevated with ANG II infusion, which was attenuated by the COX-2 inhibition. Overall, the results obtained from in vitro and in vivo studies established a crucial role of COX-2 in mediating upregulation of renal medullary PRR expression and renin content during ANG II hypertension.

Differential blockade of central effects of angiotensin II by AT2-receptor antagonists

1993 ◽  
Vol 265 (1) ◽  
pp. H226-H231 ◽  
Author(s):  
R. E. Widdop ◽  
S. M. Gardiner ◽  
P. A. Kemp ◽  
T. Bennett
Keyword(s):  
Angiotensin Ii ◽  
Receptor Antagonist ◽  
Rapid Onset ◽  
At2 Receptor ◽  
Ang Ii ◽  
Central Administration ◽  
Inhibitory Effects ◽  
Binding Studies ◽  
Receptor Antagonists

In conscious, chronically instrumented, male Long-Evans rats, we showed previously that central administration (intracerebroventricular) of the AT1-receptor antagonist EXP-3174 (1 microgram) caused a rapid-onset marked, but transient, blockade of the regional hemodynamic responses to intracerebroventricular angiotensin II (ANG II). In contrast, the AT2-receptor antagonist PD-123319 (80 micrograms) caused a slow-onset, but marked and persistent, antagonism of the effects of intracerebroventricular ANG II. In the present study we attempted to mimic the actions of PD-123319 by giving a supramaximal dose of EXP-3174 (10 micrograms), and we also assessed the effects of PD-123177 (80 micrograms), an AT2-receptor antagonist that differs from PD-123319 only by a dimethyl group. The higher dose of EXP-3174 did not exert prolonged antagonistic effects against responses to intracerebroventricular ANG II, and PD-123177 was without inhibitory effects in this model. The results indicate important functional differences between putative AT2-receptor antagonists, when assessed in vivo, that are not apparent from binding studies.

scholarly journals Regulation of angiotensin II type 2 receptor gene expression in the adrenal medulla by acute and repeated immobilization stress

2012 ◽  
Vol 215 (2) ◽  
pp. 291-301 ◽  
Author(s):  
Regina Nostramo ◽  
Andrej Tillinger ◽  
Juan M Saavedra ◽  
Ashok Kumar ◽  
Varunkumar Pandey ◽  
...  
Keyword(s):  
Gene Expression ◽  
Angiotensin Ii ◽  
Receptor Gene ◽  
Receptor Expression ◽  
Mrna Levels ◽  
Ang Ii ◽  
Catecholamine Biosynthesis ◽  
Receptor Mrna ◽  
Receptor Gene Expression

While the renin–angiotensin system is important for adrenomedullary responses to stress, the involvement of specific angiotensin II (Ang II) receptor subtypes is unclear. We examined gene expression changes of angiotensin II type 1A (AT1A) and type 2 (AT2) receptors in rat adrenal medulla in response to immobilization stress (IMO). AT2 receptor mRNA levels decreased immediately after a single 2-h IMO. Repeated IMO also decreased AT2 receptor mRNA levels, but the decline was more transient. AT1A receptor mRNA levels were unaltered with either single or repeated IMO, although binding was increased following repeated IMO. These effects of stress on Ang II receptor expression may alter catecholamine biosynthesis, as tyrosine hydroxylase and dopamine β-hydroxylase mRNA levels in PC12 cells are decreased with Ang II treatment in the presence of ZD7155 (AT1 receptor antagonist) or with CGP42112 (AT2 receptor agonist) treatment. Involvement of stress-triggered activation of the hypothalamic–pituitary–adrenocortical or sympathoadrenal axis in AT2 receptor downregulation was examined. Cultured cells treated with the synthetic glucocorticoid dexamethasone displayed a transcriptionally mediated decrease in AT2 receptor mRNA levels. However, glucocorticoids are not required for the immediate stress-triggered decrease in AT2 receptor gene expression, as demonstrated in corticotropin-releasing hormone knockout (Crh KO) mice and hypophysectomized rats, although they can regulate basal gene expression. cAMP and pituitary adenylate cyclase-activating polypeptide also reduced AT2 receptor gene expression and may mediate this response. Overall, the effects of stress on adrenomedullary AT1A and AT2 receptor expression may contribute to allostatic changes, such as regulation of catecholamine biosynthesis.

Abstract 5535: In Vivo Activation Of Myocardial At2 Receptor Expression By Endogenous No And Pentaerythritol Tetranitrate

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Thao-Vi V Dao ◽  
Vera Balz ◽  
Marc Oppermann ◽  
Tatsiana Suvorava ◽  
Georg Kojda
Keyword(s):  
Blood Pressure ◽  
Left Ventricular ◽  
Receptor Expression ◽  
Left Ventricular Myocardium ◽  
Myocardial Tissue ◽  
At2 Receptor ◽  
Dependent Manner ◽  
Pentaerythritol Tetranitrate ◽  
At2 Receptors

There are many vascular signaling interactions between the vascular endothelial NO system and the renin-angiotensin-system. We hypothesized that endothelial NO might impact on the expression of angiotensin (AT) type 1 (AT1) and type 2 (AT2) receptors. We generated mice with an endothelial-specific overexpression of endothelial NO • -synthase (eNOS) using the Tie-2 promotor. Two of these lines were characterized by eNOS-Western blot analyses and blood pressure measurements in comparison to transgene negative controls. In addition, C57Bl/6 mice were fed with either 6 or 60 mg pentaerythritol tetranitrate (PETN) for 4 weeks and characterized as well. Analysis of line 1 of transgenic eNOS mice (1-eNOS) showed a 2.3±0.15 fold higher aortic expression of eNOS and a reduction of blood pressure to 109.6±2.0 mmHg (P<0.01, n=4–6). Line 2 of transgenic eNOS mice (2-eNOS) showed a 3.3±0.3 fold higher aortic expression of eNOS and a reduction of blood pressure to 105.0±3.0 mmHg (n=6, P<0.01). Treatment of 2-eNOS with the NOS-inhibitor L-nitroarginine (L-NAME) for 30 days inhibited the difference in blood pressure suggesting that this effect is due to increased bioavailability of endogenous nitric oxide (NO). In lungs and left ventricular myocardium of 2-eNOS the expression of AT1 receptors was similar to the controls (121.6±14.77%, and 100.1±12.43%, respectively, n=8, P>0.05). In striking contrast, the expression of AT2 receptors was increased by endothelial overexpression of eNOS in a gene-dose-dependent manner in the myocardium. In 1-eNOS the increase was 134.3±10.66% (P<0.05) and in 2-eNOS the increase was 177.7±20.93% (P<0.05). In lung tissue the increase of AT2 receptor expression in line 2 amounted to 139.3±13.73% (P<0.05) and to 131.8±.7 in line 1 of eNOS transgenic mice suggesting a vascular rather than a cardiomyocyte effect. Furthermore, preliminary experiments showed a significant increase of AT2 receptor expression in myocardial tissue of PETN-fed mice and a significant decrease in myocardial tissue of L-NAME-fed mice (respectively, n=4, P<0.05). These results show that NO can upregulate vascular AT2 receptor expression in the lung and in the myocardium in-vivo. This newly discovered regulation might contribute to vasoprotective effects of NO.

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