scholarly journals Characterization of angiotensin II receptors (binding and mRNA) in the rat thyroid gland

1998 ◽  
Vol 20 (3) ◽  
pp. 299-304 ◽  
Author(s):  
M Montiel ◽  
E Jimenez
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Thyroid Gland ◽  
Binding Sites ◽  
Thyroid Tissue ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Ang Ii ◽  
Rat Thyroid ◽  
Rat Thyroid Gland

In this study we showed, for the first time, the existence of a moderate density of specific angiotensin II (Ang II) binding sites (Kd=3.9+/-1.7 nM and Bmax=467.2 130.0 fmol/mg protein) in plasma membrane preparations from rat thyroid gland. Reverse transcriptase/polymerase chain reactions, using primers based on the cloned AT1 and AT2 receptor subtypes, and pharmacological characterization, using the Ang II receptor subtype antagonists Losartan and PD 123319, revealed that these Ang II binding sites match with the AT1 receptor subtypes. To obtain more information on the molecular structure of this Ang II receptor, immunoblotting analyses were carried out using a polyclonal rabbit anti-AT1 antiserum. Western analysis of fresh plasma membrane preparations from thyroid tissue showed three prominent bands of approximately 60, 45 and 40 kDa which appear to be related to different degrees of glycosylation of the receptor molecule. The functional significance of the Ang II receptors in thyroid gland is currently not known. Nevertheless, since Ang II receptors play a pivotal role in the co-ordinated actions of the renin-angiotensin system (RAS), our findings support a reciprocal regulation of thyroid function by the RAS.

Thyrotrophin increases the α1b-adrenergic receptors in rat thyroid gland in vivo

1990 ◽  
Vol 126 (2) ◽  
pp. 317-322 ◽  
Author(s):  
H. Shimura ◽  
T. Endo ◽  
T. Onaya
Keyword(s):  
Thyroid Gland ◽  
Binding Sites ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Receptor Subtypes ◽  
Cent Increase ◽  
Rat Thyroid ◽  
And Control ◽  
Rat Thyroid Gland

ABSTRACT Using chlorethylclonidine (CEC), an αlb-adrenergic receptor-selective antagonist, we characterized α1-adrenoceptor subtypes in rat thyroid gland, and investigated the effect of methimazole (MMI)-induced high TSH levels on α1 receptor subtypes and noradrenaline-induced iodide organification. The density of thyroid α1-adrenergic receptors was increased about sixfold in rats treated with MMI for 3 weeks compared with controls. Pretreatment of thyroid membrane preparations with CEC (10 μmol/l) caused an 83% decrease in specific 2-[β-(hydroxy-3-[125I]iodophenyl) ethylaminomethyl]tetralone binding sites in MMI-treated rats, but only a 43% decrease in control rats. The density of CEC-insensitive α1 receptors (α1a) was similar in MMI-treated and control rats, so MMI was shown to increase CEC-sensitive α1 receptors (α1b). Noradrenaline-stimulated iodide organification was threefold greater in MMI-treated rats than in control rats when values were expressed as a per cent increase over basal levels. Pretreatment of thyroid lobes with 10 μmol CEC/1 for 30 min caused a 66% decrease in maximal noradrenaline-induced iodide organification in MMI-treated rats, but a significantly lower decrease (49%) in control rats. These results suggest that the rat thyroid gland contains both α1a and α1b receptors, both of which mediate noradrenaline-induced iodide organification, and also that TSH enhances noradrenaline-induced iodide organification by increasing α1b receptor density. Journal of Endocrinology (1990) 126, 317–322

Agonist-induced internalisation of the angiotensin II-binding sites from plasma membranes of isolated rat hepatocytes

1997 ◽  
Vol 152 (3) ◽  
pp. 407-412 ◽  
Author(s):  
M Montiel ◽  
M C Caro ◽  
E Jiménez
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Rat Hepatocytes ◽  
Receptor Complex ◽  
Ang Ii ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

Angiotensin II (Ang II) provokes rapid internalisation of its receptor from plasma membranes in isolated rat hepatocytes. After 10 min stimulation with Ang II, plasma membrane lost about 60% of its 125I-Ang II-binding capacity. Internalisation was blocked by phenylarsine oxide (PhAsO), whereas okadaic acid, which markedly reduced the sustained phase of calcium mobilization, did not have a preventive effect on Ang II–receptor complex sequestration. These data suggest that Ang II receptor internalisation is probably independent of a phosphorylation/dephosphorylation cycle of critical serine/threonine residues in the receptor molecule. To establish a relationship between sequestration of the Ang II receptor and the physical properties of the Ang II-binding sites, 125I-Ang II–receptor complex profiles were analysed by isoelectric focusing. In plasma membrane preparations two predominant Ang II-binding sites, migrating to pI 6·8 and 6·5 were found. After exposure to Ang II, cells lost 125I-Ang II-binding capacity to the Ang II–receptor complex migrating at pI 6·8 which was prevented in PhAsO-treated cells. Pretreatment of hepatocytes with okadaic acid did not modify Ang II–receptor complex profiles, indicating that the binding sites corresponding to pI 6·5 and pI 6·8 do not represent a phosphorylated and/or non-phosphorylated form of the Ang II receptor. The results show that the Ang II–receptor complex isoform at pI 6·8 represents a functional form of the type-1 Ang II receptor. Further studies are necessary to identify the Ang II-related nature of the binding sites corresponding to pI 6·5. Journal of Endocrinology (1997) 152, 407–412

scholarly journals Immunocytochemical localization of cathepsins B, H, L, and T4 in follicular cells of rat thyroid gland.

1989 ◽  
Vol 37 (5) ◽  
pp. 691-696 ◽  
Author(s):  
Y Uchiyama ◽  
T Watanabe ◽  
M Watanabe ◽  
Y Ishii ◽  
H Matsuba ◽  
...  
Keyword(s):  
Thyroid Gland ◽  
Thyroid Tissue ◽  
Double Immunostaining ◽  
Follicular Cells ◽  
Thin Sections ◽  
Dense Granules ◽  
Dense Bodies ◽  
Rat Thyroid ◽  
Monospecific Antibodies ◽  
Rat Thyroid Gland

To localize cathepsins B, H, and L in follicular cells of rat thyroid gland, we applied immunocytochemistry to the thyroid tissue using their respective monospecific antibodies. On serial semi-thin sections, cathepsins B, H, and L were localized in granules of various sizes located throughout the cytoplasm, whereas T4 was detected in larger granules located in the apical and supranuclear regions. By electron microscopy, cathepsins B, H, and L were localized in large less-dense granules (so-called colloid droplets) and in dense bodies of various sizes, whereas T4 was localized more intensely in large less-dense granules than in smaller dense bodies. By double immunostaining using an immunogold method, cathepsins H and B or L were co-localized in the same cytoplasmic granules. Moreover, immunoblotting demonstrated that proteins similar to cathepsins B, H, and L in the liver are present in the thyroid gland. These results suggest that cathepsins B, H, and L participate not only in degradation of thyroglobulin but in maturation of thyroid hormones, although it remains unknown whether all of them participate in the maturation process.

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 receptor subtypes in eel (Anguilla anguilla)

1994 ◽  
Vol 12 (1) ◽  
pp. 61-69 ◽  
Author(s):  
S Marsigliante ◽  
T Verri ◽  
S Barker ◽  
E Jimenez ◽  
G P Vinson ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Brush Border ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Anguilla Anguilla ◽  
Receptor Subtypes ◽  
European Eel ◽  
Ang Ii ◽  
Brush Border Membranes ◽  
Renal Brush Border Membrane

ABSTRACT Previous studies have shown the effects of angiotensin II (Ang II) in teleosts, and Ang II-binding sites have also been localized in tissues from rainbow trout. The purpose of this study was to extend these findings and to provide an analysis of Ang II receptor (Ang II-R) isoforms in three tissues obtained from European eel (Anguilla anguilla). Ang II-Rs were identified in eel liver, kidney and intestine membranes by the binding of either 0·5 nmol human 125I-labelled Tyr4-lle5-Ang II/l or increasing concentrations (1–120 nmol/l) of [3,5-3H]Tyr4-Ile5-Ang II. Using an isoelectric focusing technique, two Ang II-binding sites were identified in liver membranes. These migrated to isoelectric points (pI values) 6·5 and 6·7. Seventy per cent of binding to both sites was displaced by a 10 000-fold excess of unlabelled human Ang II. In both whole plasma membranes and brush border membranes from intestine, only one form of the Ang II-R was found, with pI 6·5 and high affinity (Kd=3·4 nmol/l) for the [3,5-3H]Tyr4-Ile5-Ang II. Similarly, only the isoform focusing at pI 6·5 was observed in renal tubular epithelial brush border membranes. Reduction of disulphide bridges with dithiothreitol significantly enhanced Ang II binding to the isoform at pI 6·5 in liver (P<0·05) and kidney (P<0·01), while in liver the binding to the isoform of pI 6·7 was significantly reduced (P<0·001). The data suggest the existence in eel liver of multiple forms of Ang II-R, which may have different functions, while one single form appeared to be present in enterocyte plasma membrane and in renal brush border membrane.

Glomerular angiotensin II receptor subtypes during development of rat kidney

1993 ◽  
Vol 265 (2) ◽  
pp. F264-F271 ◽  
Author(s):  
G. M. Ciuffo ◽  
M. Viswanathan ◽  
A. M. Seltzer ◽  
K. Tsutsumi ◽  
J. M. Saavedra
Keyword(s):  
Angiotensin Ii ◽  
Kidney Development ◽  
Developmental Stages ◽  
Rat Kidney ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Ang Ii ◽  
Kidney Medulla ◽  
At1 Receptors ◽  
Old Rats

We used quantitative autoradiography to investigate distribution of angiotensin II (ANG II) receptor subtypes during development of the kidney in the rat. In fetal, newborn, and 3-day-old rats, immature glomeruli in the form of comma and S-shaped bodies, located in the nephrogenic zone of the renal cortex, expressed only the angiotensin AT2 receptor subtype. Conversely, the juxtamedullary glomeruli, in more advanced developmental stages, expressed only the AT1 subtype. Similarly, maturing and fully developed glomeruli, present in 1-, 2-, and 8-wk-old rats, expressed only AT1 receptors. In the kidney medulla, there was a similar change in ANG II receptor subtype expression, with the AT2 subtype expressed earlier and the AT1 subtype later during development. Our results demonstrate a selective expression of ANG II receptor subtypes during kidney development. We have found glomerular and medullary AT1 receptors only at developmental stages when kidney function has matured. Conversely, AT2 receptors are expressed only in immature structures, suggesting that they may have a role during kidney organogenesis.

scholarly journals Localization of thyroid peroxidase and the site of iodination in rat thyroid gland

1976 ◽  
Vol 158 (2) ◽  
pp. 477-479 ◽  
Author(s):  
H H Edwards ◽  
M Morrison
Keyword(s):  
Endoplasmic Reticulum ◽  
Thyroid Gland ◽  
Thyroid Tissue ◽  
Follicular Cell ◽  
Thyroid Peroxidase ◽  
Tissue Slices ◽  
Rat Thyroid ◽  
Rat Thyroid Gland

The iodinated protein was localized in thyroid tissue slices by using radioautography. In unfixed tissue, the labelled protein was localized in the colloid, whereas, in tissue that was fixed before the 125I addition, the label was within the follicular cell. This localizes thyroid peroxidase largely on the endoplasmic reticulum of the cell.

Angiotensin II receptor isoforms in the rat adrenal gland: studies with the selective subtype antagonists DuP 753 and CGP42112A

1993 ◽  
Vol 11 (1) ◽  
pp. 69-75 ◽  
Author(s):  
M Montiel ◽  
S Barker ◽  
G P Vinson ◽  
E Jiménez
Keyword(s):  
Angiotensin Ii ◽  
Adrenal Gland ◽  
Binding Sites ◽  
Specific Binding ◽  
Zona Glomerulosa ◽  
Scatchard Analysis ◽  
Receptor Subtypes ◽  
Ang Ii ◽  
Angiotensin Ii Receptor ◽  
Receptor Isoforms

ABSTRACT The angiotensin II (Ang II)-binding sites in rat adrenal gland membranes were characterized using 125I-radiolabelled Ang II. While Scatchard analysis identified a single population of Ang II receptor sites, isoelectric focusing (IEF) on polyacrylamide gels revealed four peaks of specific Ang II binding which migrated to isoelectric points (pI values) 6·8, 6·7, 6·5 and 6·3. In binding assays in the presence of an excess of the Ang II receptor AT1 subtype antagonist DuP 753, a monophasic dose-dependent displacement of 125I-labelled Ang II binding by the Ang II receptor AT2 subtype antagonist CGP42112A was observed, and vice versa. In this system, reduction of disulphide bridges using 1 mmol dithiothreitol (DTT)/l markedly increased the number of binding sites in the adrenal zona glomerulosa without affecting receptor affinity. Using IEF, it was found that both DuP 753 and CGP42112A were able to reduce specific binding of each of the four peaks to some extent. However, the predominant effect of DuP 753 was to reduce the labelling of the isoform at pI 6·7 substantially, while CGP42112A significantly inhibited the specific 125I-labelled Ang II binding to the pI 6·3 isoform. When DuP 753 and CGP42112A were used together, specific binding of 125I-labelled Ang II to the isoforms of pI values 6·8, 6·7 and 6·3 was completely eliminated. These data suggest that the four peaks of specific binding found may be composed of different isoforms of both AT1 and AT2 receptor subtypes and that the Ang II receptor isoforms which migrated to pI 6·7 and pI 6·3 are predominantly composed of AT1 and AT2 receptor subtypes respectively. Interestingly, in the presence of both antagonists, 8·7 ± 0·9% of the specific binding migrating at pI 6·5 remained unaffected. This finding suggests the presence of an additional subtype, which is neither AT1 nor AT2, in the rat adrenal zona glomerulosa. In further studies, pretreatment with DTT was found to increase the specific 125I-labelled Ang II binding of all four isoforms. Moreover, DTT also produced a further specific binding component between pI 6·5 and pI 6·7 which exhibited AT2 subtype pharmacology in DTT-treated preparations. Since DTT has been reported to enhance only AT2 subtype binding this also suggests that the different isoforms may contain components related to both AT1 and AT2 receptor subtypes.

Characterization of α1-adrenergic receptor subtypes linked to iodide efflux in rat FRTL cells

1990 ◽  
Vol 124 (3) ◽  
pp. 433-441 ◽  
Author(s):  
H. Shimura ◽  
T. Endo ◽  
G. Tsujimoto ◽  
K. Watanabe ◽  
K. Hashimoto ◽  
...  
Keyword(s):  
Program Analysis ◽  
Binding Sites ◽  
Adrenergic Receptor ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Receptor Density ◽  
Maximal Increase ◽  
Thyroid Cells ◽  
Rat Thyroid

ABSTRACT We have characterized α1-adrenergic receptor subtypes in functional rat thyroid cells, FRTL, with relation to iodide efflux, and have also examined the effect of TSH on α1 receptor subtypes. FRTL cells grown in a medium containing 5 mU TSH/ml (6H cells) had five times the number of α1 receptors of those maintained in TSH-free medium (5H cells) (11·2 fmol/106 cells compared with 2·0 fmol/106 cells). Pretreatment with chlorethylclonidine (CEC; 10 μmol/l), which inactivates only α1b receptors, caused 98·8% and 97·0% decreases in the density of specific [3H]prazosin-binding sites in 5H and 6H cells respectively. LIGAND computer program analysis of the displacement curves for 2-(2,6-dimethoxyphenoxyethyl)-aminomethyl-1,4 benzodioxane (WB4101) showed that FRTL cells contained mostly low-affinity WB4101 sites. Using the phenoxybenzamine inactivation method, we found a linear relationship between α1 receptor density and the cytosolic free Ca2+ concentration response in FRTL cells. Pre-exposure of intact FRTL cells to CEC caused a 98·7% decrease in noradrenaline-stimulated maximal increase in cytosolic free Ca2+. Also, CEC and 3,4,5-trimethoxybenzoic acid 8-(diethylamino) octyl ester (TMB-8), but not nicardipine, inhibited noradrenaline-stimulated iodine efflux. The results suggest that FRTL cells contain mostly the α1b-adrenergic receptor subtype; that the α1b receptors mediate cytosolic free Ca2+ and iodide efflux responses, and that TSH enhances these responses by increasing the α1b receptor density without affecting the post-receptor mechanism. Journal of Endocrinology (1990) 124, 433–441

scholarly journals Expression of type 1 angiotensin II receptor subtypes and angiotensin II-induced calcium mobilization along the rat nephron.

1997 ◽  
Vol 8 (11) ◽  
pp. 1658-1667 ◽  
Author(s):  
N Bouby ◽  
A Hus-Citharel ◽  
J Marchetti ◽  
L Bankir ◽  
P Corvol ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Collecting Duct ◽  
At1 Receptor ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Thick Ascending Limb ◽  
Ang Ii ◽  
Angiotensin Ii Receptor ◽  
Nephron Segments

The localization of two type 1 angiotensin II receptor subtype mRNA, AT1A and AT1B, was determined by reverse transcription-PCR on microdissected glomeruli and nephron segments. The coupling sensitivity of these two receptor subtypes was evaluated by measuring variations in intracellular calcium ([Ca2+]i) elicited by angiotensin II (Ang II) in structures expressing either AT1A or AT1B mRNA, using Fura-2 fluorescence. The highest expression of AT1 mRNA was found in glomerulus, proximal tubule, and thick ascending limb. In glomerulus, AT1A and AT1B mRNA were similarly expressed, whereas in all nephron segments AT1A mRNA expression was dominant (approximately 84%). The increase in [Ca2+]i elicited by 10(-7) mol/L Ang II was highest in proximal segments (delta [Ca2+]i is approximately equivalent to 300 to 400 nmol/L) and thick ascending limb (delta [Ca2+]i is approximately equivalent to 200 nmol/L). In glomerulus and collecting duct, the response was lower (delta < 100 nmol/L). The median effective concentrations for Ang II were of the same order of magnitude in glomerulus (12.2 nmol/L), in which both AT1A and AT1B are expressed, and in cortical thick ascending limb (10.3 nmol/ L), in which AT1A is almost exclusively expressed. The Ang II-induced calcium responses were totally abolished by the AT1 receptor antagonist losartan (1 mumol/L) but not by the AT2 antagonist PD 123319 (1 mumol/L). In the absence of external Ca2+, the peak phase of the response induced by 10(-7) mol/L Ang II was reduced and shortened, suggesting that a part of the [Ca2+]i increase originated from the mobilization of the intracellular Ca2+ pool. In conclusion, these results demonstrate that in the rat kidney: (1) AT1A is the predominant AT1 receptor subtype expressed in the nephron segments, (2) glomerulus is the only structure with a relatively high AT1B mRNA content, and (3) AT1A and AT1B receptor subtypes do not differ in their efficiency for the activation of calcium second-messenger system.

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