Synthesis and AT2 receptor-binding properties of angiotensin II analogues

A change from group housing to isolation in unfamiliar metabolic cages represents, for rodents, a significant emotional stress. We studied the effect of candesartan, a peripheral and central angiotensin II AT1-receptor antagonist, on the hormonal and sympathetic response to acute isolation. We pretreated rats with 1 mg/kg/day candesartan for 13 days via subcutaneously implanted osmotic minipumps, followed by 24-hour isolation in individual metabolic cages. We measured brain, pituitary and adrenal angiotensin II (Ang II) receptor binding by quantitative autoradiography and adrenal hormones and catecholamines by RIA and HPLC. Isolation increased adrenal catecholamines, aldosterone and corticosterone, AT1-receptor binding in the zona glomerulosa and AT2-receptor binding in the adrenal medulla. Candesartan pretreatment decreased adrenal catecholamines, aldosterone and corticosterone, AT1-receptor binding in adrenal zona glomerulosa and medulla, pituitary gland and the hypothalamic paraventricular nucleus, and AT2-receptor binding in adrenal medulla, but increased AT2-receptor binding in zona glomerulosa. We conclude that peripheral and central AT1-receptor blockade with candesartan decreases the sympatho-adrenal and hormonal response to acute stress. Our results indicate that Ang II is an important stress hormone and suggest that blockade of the physiologically active AT 1-receptors could influence stress-related disorders.

Download Full-text

Proceedings of the Symposium ‘Angiotensin AT1 Receptors: From Molecular Physiology to Therapeutics’: PRESENCE OF ANGIOTENSIN II AT2 RECEPTOR BINDING SITES IN THE ADVENTITIA OF HUMAN KIDNEY VASCULATURE

Clinical and Experimental Pharmacology and Physiology ◽

10.1111/j.1440-1681.1996.tb03077.x ◽

1996 ◽

Vol 23 (S3) ◽

pp. 147-154 ◽

Cited By ~ 35

Author(s):

Jialong Zhuo ◽

Rachael Dean ◽

Duncan MacGregor ◽

Daine Alcorn ◽

Frederick AO Mendelsohn

Keyword(s):

Angiotensin Ii ◽

Receptor Binding ◽

Binding Sites ◽

Human Kidney ◽

At2 Receptor ◽

Molecular Physiology ◽

At1 Receptors

Download Full-text

Angiotensin II AT1 and AT2 Receptors Contribute to Maintain Basal Adrenomedullary Norepinephrine Synthesis and Tyrosine Hydroxylase Transcription

Endocrinology ◽

10.1210/en.2002-0019 ◽

2003 ◽

Vol 144 (5) ◽

pp. 2092-2101 ◽

Cited By ~ 36

Author(s):

Miroslava Jezova ◽

Ines Armando ◽

Claudia Bregonzio ◽

Zu-Xi Yu ◽

Sujuan Qian ◽

...

Keyword(s):

Angiotensin Ii ◽

Receptor Binding ◽

At1 Receptor ◽

Receptor Protein ◽

At2 Receptor ◽

Receptor Blockade ◽

Ang Ii ◽

Th Mrna ◽

At2 Receptors

Angiotensin II (Ang II) AT1 receptors have been proposed to mediate the Ang II-dependent and the stress-stimulated adrenomedullary catecholamine synthesis and release. However, in this tissue, most of the Ang II receptors are of the AT2 type. We asked the question whether AT1 and AT2 receptors regulate basal catecholamine synthesis. Long-term AT1 receptor blockade decreased adrenomedullary AT1 receptor binding, AT2 receptor binding and AT2 receptor protein, rat tyrosine hydroxylase (TH) mRNA, norepinephrine (NE) content, Fos-related antigen 2 (Fra-2) protein, phosphorylated cAMP response element binding protein (pCREB), and ERK2. Long-term AT2 receptor blockade decreased AT2 receptor binding, TH mRNA, NE content and Fra-2 protein, although not affecting AT1 receptor binding or receptor protein, pCREB or ERK2. Angiotensin II colocalized with AT1 and AT2 receptors in ganglion cell bodies. AT2 receptors were clearly localized to many, but not all, chromaffin cells. Our data support the hypothesis of an AT1/AT2 receptor cross-talk in the adrenomedullary ganglion cells, and a role for both receptor types on the selective regulation of basal NE, but not epinephrine formation, and in the regulation of basal TH transcription. Whereas AT1 and AT2 receptors involve the Fos-related antigen Fra-2, AT1 receptor transcriptional effects include pCREB and ERK2, indicating common as well as different regulatory mechanisms for each receptor type.

Download Full-text

Regulation of angiotensin II AT1 and AT2 receptors in neonatal ureteral obstruction

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1997.273.2.r503 ◽

1997 ◽

Vol 273 (2) ◽

pp. R503-R509 ◽

Cited By ~ 10

Author(s):

K. H. Yoo ◽

V. F. Norwood ◽

S. S. el-Dahr ◽

I. Yosipiv ◽

R. L. Chevalier

Keyword(s):

Angiotensin Ii ◽

Receptor Binding ◽

Ureteral Obstruction ◽

Interstitial Fibrosis ◽

Renin Angiotensin System ◽

Sham Operation ◽

At2 Receptor ◽

Ang Ii ◽

Sprague Dawley ◽

Renal Vasoconstriction

Chronic unilateral ureteral obstruction (UUO) in early development activates the intrarenal renin-angiotensin system and leads to profound renal vasoconstriction, renal growth arrest, and interstitial fibrosis. To investigate the response of the AT1 and AT2 subtypes of the angiotensin II (ANG II) receptors to UUO, Sprague-Dawley rats underwent UUO or control sham operation in the first 48 h of life and were studied 1-28 days later. Renal mRNA for renin, AT1 and AT2 receptor, and receptor binding and distribution were determined. In contrast to controls, renin mRNA increased from 14 to 28 days in the obstructed kidney. After ipsilateral UUO, AT1 mRNA was suppressed at 1 day, but had increased compared with controls at 28 days. AT2 receptor mRNA fell rapidly in all kidneys from 1 to 3 days of age, after which it remained undetectable. Compared with the intact opposite kidney, AT2 mRNA was suppressed in the obstructed kidney 1 day after UUO. Compared with controls, AT1 and AT2 receptor binding was decreased by ipsilateral UUO at 1 day, whereas AT1 binding was increased at 28 days. Renal ANG II content was increased in the obstructed compared with the intact opposite kidney 28 days after UUO. In view of the increase in renal renin and angiotensin II production resulting from UUO, increased renal AT1 mRNA and receptor binding are likely to contribute to the vasoconstriction and interstitial fibrosis of the neonatal kidney after prolonged UUO.

Download Full-text

Analysis of the role of N-glycosylation in cell-surface expression and binding properties of angiotensin II type-2 receptor of rat pheochromocytoma cells

Biochemical Journal ◽

10.1042/bj3130297 ◽

1996 ◽

Vol 313 (1) ◽

pp. 297-304 ◽

Cited By ~ 31

Author(s):

Guy SERVANT ◽

David T. DUDLEY ◽

Emanuel ESCHER ◽

Gaétan GUILLEMETTE

Keyword(s):

Angiotensin Ii ◽

Cell Surface ◽

Surface Expression ◽

Cell Surface Expression ◽

Side Chains ◽

At2 Receptor ◽

Binding Properties ◽

Pheochromocytoma Cells ◽

Pc 12 Cells ◽

At2 Receptors

We previously demonstrated that the AT2 receptor is a glycoprotein containing N-linked oligosaccharide side chains and that the marked disparity between the sizes of AT2 receptors from different tissues was related to different degrees of N-glycosylation. In the present study, we used an inhibitor of N-glycosylation, tunicamycin, as well as an endoglycosidase, glycopeptidase-F, to examine the contribution of carbohydrate moieties to the ligand-binding properties, cell-surface expression and apparent molecular mass of AT2 receptors of rat pheochromocytoma cells (PC-12 cells). Photoaffinity labelling of cell-surface AT2 receptors revealed that PC-12 cells grown in the presence of tunicamycin expressed, in addition to the previously described 140 kDa receptor, lower-molecular-mass receptors of 63 kDa, 47 kDa and 32 kDa. Lectin affinity chromatography revealed that the 63 kDa and the 47 kDa receptors are partially glycosylated and that the 32 kDa receptor is completely deglycosylated. Competitive binding experiments were carried out on tunicamycin-treated cells that expressed predominantly the 63 kDa or the 47 kDa receptors. Both receptor forms exhibited a high affinity for angiotensin II, although a slight decrease (of about 2-fold) was consistently observed on tunicamycin-treated cells as compared with control cells. Endoglycosidase digestion of AT2 receptors of PC-12 cells also yielded smaller receptor forms of 47 kDa and 32 kDa. Similarly, angiotensin II showed a high but slightly decreased binding affinity (of about 2-fold) for deglycosylated membranes as compared with control membranes. In conclusion, the stepwise action of tunicamycin suggests the presence of at least three N-linked oligosaccharide side chains on the AT2 receptor of PC-12 cells. These oligosaccharide side chains have a minor contribution to the affinity of the receptor. Interestingly, glycosylation is not an essential requirement for the expression of AT2 receptor at the surface of PC-12 cells.

Download Full-text