Insulin and IGF I receptor-mediated Na+ transport in toad urinary bladders

1989 ◽  
Vol 257 (4) ◽  
pp. C612-C620 ◽  
Author(s):  
B. L. Blazer-Yost ◽  
M. Cox ◽  
R. Furlanetto
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
The Other ◽  
Na Transport ◽  
Renal Epithelium ◽  
Receptor Complexes ◽  
Factor I ◽  
Equilibrium Binding ◽  
Igf I ◽  
Specific Insulin ◽  
Toad Bufo

We compared the concentration dependence of insulin- and insulin-like growth factor I (IGF I)-stimulated Na+ transport with ligand-receptor affinities in the urinary bladder of the toad Bufo marinus. Threshold, half-maximal, and maximal natriferic concentrations of both peptides were approximately 0.1, 1, and 10 nM, respectively. Amiloride, but not ethyl isopropyl amiloride, (10(-5) M), abolished Na+ transport. Maximal responses to either peptide rendered the tissue insensitive to challenge with the other. Separate insulin and IGF I receptors were identified by equilibrium binding and polyacrylamide gel electrophoresis of cross-linked ligand-receptor complexes. For both peptides, half-maximal binding occurred at 3-10 nM; crossover binding to the other receptor occurred with 10- and 100-fold lower affinity. Thus, in this model "high-resistance" renal epithelium, 1) ligand binding to specific insulin and IGF I receptors stimulates transcellular Na+ flux, 2) the natriferic effects of insulin and IGF I apparently depend on activation of apical Na+ channels rather than Na+-H+ antiporters, and 3) the natriferic pathways activated by insulin and IGF I appear to converge subsequent to ligand-receptor binding but before the final transport ("effector") step(s).

Receptors for insulin-like growth factor-I in plasma membranes isolated from bovine mesenteric arteries

1988 ◽  
Vol 117 (4) ◽  
pp. 428-434 ◽  
Author(s):  
Karin E. Bornfeldt ◽  
Hans J. Arnqvist ◽  
Hans H. Dahlkvist ◽  
Anna Skottner ◽  
Jarl E. S. Wikberg
Keyword(s):  
Plasma Membranes ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mesenteric Arteries ◽  
Binding Characteristics ◽  
Factor I ◽  
Reducing Conditions ◽  
Ic50 Value ◽  
Igf I ◽  
High Concentrations

Abstract. Binding of IGF-I to plasma membranes from bovine mesenteric arteries was studied. The maximal specific binding of IGF-I was found to be 7.4 ± 1.7% of total 125I-IGF-I added to the incubation medium. Unlabelled IGF-I displaced 125I-IGF-I with an IC50 value of 0.5 nmol/l and a maximal displacement of 64.2 ± 2.8% of total binding. The potency of insulin to displace 125I-IGF-I was 100–1000-fold lower. Crosslinking of 125I-IGF-I to the receptor with disuccinimidyl suberate, followed by SDS-polyacrylamide gel electrophoresis under reducing conditions showed an IGF-I binding protein with a molecular weight of 146000 Dalton. In summary, we have shown the presence of receptors for IGF-I in plasma membranes isolated from macrovessels. The binding characteristics and the size of the binding unit were found to be similar to those of the IGF-1 receptor found in cultured vascular smooth muscle cells. Furthermore, insulin at high concentrations was found to interact with the IGF-I receptor.

Insulin and IGF-I receptors in trout adipose tissue are physiologically regulated by circulating hormone levels

2000 ◽  
Vol 203 (7) ◽  
pp. 1153-1159
Author(s):  
J.V. Planas ◽  
E. Mendez ◽  
N. Banos ◽  
E. Capilla ◽  
I. Navarro ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Salmo Trutta ◽  
Insulin Receptors ◽  
Direct Role ◽  
Factor I ◽  
Igf I ◽  
Brown Trout Salmo Trutta ◽  
First Time ◽  
Specific Insulin

In fish, insulin is believed to act on adipose tissue to promote lipid accumulation, but a direct role for insulin in fish adipose tissue lipogenesis has yet to be demonstrated. To investigate the role of insulin and insulin-like growth factor I (IGF-I) in fish adipose tissue function, we have investigated the presence and the regulation of insulin and IGF-I receptors in adipose tissue of brown trout (Salmo trutta). Receptors for insulin and IGF-I were detected in trout adipose tissue, with IGF-I receptors being more abundant (two- to tenfold) and having a higher affinity (twofold) than insulin receptors. In contrast to the situation in mammals, arginine treatment, which elevates the levels of insulin and IGF-I in plasma, increased the number of insulin receptors 1.7-fold and the number of IGF-I receptors 2.3-fold. When plasma levels of insulin and IGF-I were decreased by fasting, insulin receptor numbers fell 3.6-fold and IGF-I receptor numbers fell 2.2-fold. These results demonstrate for the first time the presence of specific insulin and IGF-I receptors in adipose tissue of ectothermic vertebrates and suggest that adipose tissue may be a target for the actions of insulin and IGF-I in fish.

Effects of growth hormone injections on ovulation rate in ewes

1990 ◽  
Vol 2 (2) ◽  
pp. 173 ◽  
Author(s):  
SR Davis ◽  
JF Smith ◽  
PD Gluckman
Keyword(s):  
Growth Hormone ◽  
Plasma Concentrations ◽  
Post Treatment ◽  
Ovulation Rate ◽  
The Other ◽  
Bovine Growth Hormone ◽  
Factor I ◽  
Igf I ◽  
Pre Treatment ◽  
Clover Pasture

Coopworth ewes were either treated with 5 mg recombinant-derived bovine growth hormone per day for each day of the oestrous cycle or were untreated. Ovulation rates at the pre-treatment, post-treatment and a subsequent oestrus were determined by endoscopy. These were 1.34, 1.51, 1.38 for the treated ewes and 1.32, 1.43, 1.39 for the control ewes. The ovulation rate post-treatment was significantly higher than for the other two cycles in the treated ewes but it was not significantly different from the post-treatment value of the control ewes. Plasma concentrations of insulin-like growth factor-I (IGF-I) were elevated during treatment (90-130 nmol L-1) compared with concentrations of 25-50 nmol L-1 in the control ewes. No relationship was found between plasma IGF-I concentration and ovulation rate. Injection of ewes grazing ryegrass/white clover pasture with bovine growth hormone did not result in increased ovulation rate.

scholarly journals PENAMBAHAN PROTEIN INSULIN LIKE GROWTH FACTOR-I COMPLEX DALAM PENGENCER PEMBEKUAN SEMEN TERHADAP KUALITAS SPERMATOZOA KAMBING PADA WAKTU EKUILIBRASI

2011 ◽  
Vol 5 (2) ◽  
Author(s):  
Suherni Susilowati ◽  
Tatik Hernawati
Keyword(s):  
Growth Factor ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Plasma Séminal ◽  
Igf I ◽  
Native Polyacrylamide Gel Electrophoresis ◽  
Growth Factor I

Penelitian ini bertujuan mengisolasi protein Insulin Like Growth Factor-I (IGF-I) complex untuk meningkatkan kualitas semen beku kambing pada waktu ekuilibrasi setelah penambahan protein IGF-I complex. Penelitian ini terdiri atas 2 tahap yaitu isolasi protein IGF-I complex dari plasma seminal kambing dan aplikasi terhadap prosesing pembekuan semen. Pada tahap pertama dilakukan identifikasi IGF-I complex dengan menggunakan gel native polyacrylamide gel electrophoresis dan isolasi IGF-I complex. Pada tahap kedua dilakukan aplikasi penambahan protein IGF-I complex pada prosesing semen beku. Semen dikoleksi dengan menggunakan vagina buatan dan kemudian disentrifus selama 5 menit dengan kecepatan 1800 rpm. Kemudian semen dibagi menjadi tiga kelompok. Pada kelompok I, II, dan III ditambahkan protein IGF-I complex masing-masing 0, 12, dan 618 ng/ 3X10 sperma. Selanjutnya dilakukan ekuilibrasi selama 1 jam dan dilanjutkan dengan evaluasi motilitas, viabilitas, dan membran sperma. Hasil penelitian menunjukkan perbedaaan motilitas, viabilitas, dan membran sperma yang signifikan (P<0,05) di antara tiga kelompok perlakuan. Dapat disimpulkan bahwa penambahan protein IGF-I complex dapat meningkatkan kualitas semen beku kambing pada fase ekuilibrasi.

scholarly journals Steroid-induced protein synthesis in giant-toad (Bufo marinus) urinary bladders. Correlation with natriferic activity

1984 ◽  
Vol 218 (1) ◽  
pp. 221-228 ◽  
Author(s):  
M Geheb ◽  
R Alvis ◽  
A Owen ◽  
E Hercker ◽  
M Cox
Keyword(s):  
Protein Synthesis ◽  
Epithelial Cell ◽  
Short Circuit ◽  
Polyacrylamide Gel Electrophoresis ◽  
Bufo Marinus ◽  
Cell Protein ◽  
Common Mechanism ◽  
Na Transport ◽  
Response Curves ◽  
Toad Bufo

We have identified a group of proteins (Mr approximately 70 000-80 000; pI approximately 5.5-6.0) in giant-toad (Bufo marinus) urinary bladders whose synthesis appears to be related to aldosterone-stimulated Na+ transport. Spironolactone, a specific mineralocorticoid antagonist in renal epithelia, inhibits the synthesis of these proteins as well as the natriferic effect of the hormone. Since a variety of other steroids (some of which are traditionally considered to be glucocorticoids) also stimulate Na+ transport in toad urinary bladders, we examined whether their natriferic activity was expressed in a fashion similar to that of aldosterone. Short-circuit current was used to measure Na+ transport, and epithelial-cell protein synthesis was detected with high-resolution two-dimensional polyacrylamide-gel electrophoresis and autoradiography. At a concentration of approximately 100 nM, dexamethasone, corticosterone and aldosterone were equinatriferic. Dexamethasone and aldosterone had identical dose-response curves, maximal and half-maximal activity being evident at concentrations of approximately 100 nM and 10 nM respectively. In contrast, at a concentration of approximately 10 nM, corticosterone had no effect on Na+ transport. The natriferic activities of these three steroids correlate with their known affinities for the putative mineralocorticoid receptor in toad urinary bladders. Natriferic concentrations of dexamethasone and corticosterone (140 nM) induced the synthesis of proteins with characteristics identical with those induced by aldosterone. Spironolactone, at an antagonist/agonist ratio of 2000:1, inhibited steroid-induced Na+ transport and the synthesis of these proteins. Thus it appears that all natriferic steroids share a common mechanism of action in toad urinary bladders. Natriferic activity can be correlated not only with relative steroid-receptor affinity but also with the induction of a specific group of epithelial-cell proteins.

Testosterone-induced increase of insulin-like growth factor I levels depends upon normal levels of growth hormone

1996 ◽  
Vol 135 (2) ◽  
pp. 211-215 ◽  
Author(s):  
Giuseppe Saggese ◽  
Graziano Cesaretti ◽  
Giulia Franchi ◽  
Luisa Startari
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Free Testosterone ◽  
The Other ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I ◽  
Nutritional Obesity ◽  
Hcg Test

Saggese G, Cesaretti G, Franchi G, Startari L. Testosterone-induced increase of insulin-like growth factor I levels depends upon normal levels of growth hormone. Eur J Endocrinol 1996;135:211–5. ISSN 0804–4643 Pubertal development is associated with a rise in plasma insulin-like growth factor I (IGF-I) levels that is related both to the increase in sex steroids and/or to the sex steroid-induced augmentation in endogenous growth hormone (GH) secretion. In order to investigate the relationship between IGF-I. GH and testosterone, we examined 42 male subjects with various clinical conditions (classical GH deficiency (CGHD, N = 5), non-classical GH deficiency (NCGHD, N = 7), short idiopathic stature (N = 6), nutritional obesity (N = 8), GH-treated CGHD (N = 4), GH-treated NCGHD (N = 5) and normal stature (N = 7)) in which, for evaluation of hypogonadism (i.e. the absence of one or both testes from the scrotal sac), human chorionic gonadotropin (hCG) tests were performed. We measured IGF-I, total and free testosterone and dehydroepiandrosterone sulfate (DHEAS) by radioimmunoassays before and 48 and 96 h after the start of the test. The values of IGF-I were lower (0.001 < p < 0.005) in CGHD and NCGHD than in the other groups. In comparison to basal levels, IGF-I values increased (0.005 < p < 0.05) both 48 and 96 h after the start of the hCG test in short idiopathic and normal stature children and in GH-treated subjects with NCGHD, but only 96 h in subjects with untreated NCGHD and GH-treated CGHD. No difference was demonstrated in basal values of total testosterone among any of the groups, while basal free testosterone levels were higher (0.001 < p < 0.05) in GH-treated subjects with NCGHD than in all the other groups except nutritional obesity; furthermore, free testosterone was higher (p < 0.05) in nutritional obesity than in CGHD. The values of total and free testosterone obtained both 48 and 96 h after the start of the hCG test were higher (0.001 < p < 0.05) than basal values in all groups. The DHEAS values did not show any significant change during the hCG test. Basal values were higher (0.01 <p < 0.05) in nutritional obesity than in the other groups. Considering all groups, chonological age, bone age and bone age/chronological age ratio were correlated with basal free testosterone, IGF-I and DHEAS levels (0.001 < p < 0.05), while basal free testosterone and IGF-I values were correlated with DHEAS levels (p < 0.005 and <0.01, respectively). In conclusion, our study during the hCG test in boys with various clinical conditions demonstrated an increase in IGF-I concentrations only in those boys with sufficient GH secretion or GH replacement therapy. These findings indicate that both sex steroids and GH are necessary to allow for the pubertal increase in IGF-I levels. Giuseppe Saggese, Endocrine Unit, Department of Pediatrics, University of Pisa, Via Rome 67, 56125 Pisa, Italy

Characterization of a specific insulin-like growth factor-I/somatomedin-C receptor on high density, primary monolayer cultures of bovine articular chondrocytes: regulation of receptor concentration by somatomedin, insulin and growth hormone

1985 ◽  
Vol 107 (2) ◽  
pp. 275-283 ◽  
Author(s):  
N. Watanabe ◽  
R. G. Rosenfeld ◽  
R. L. Hintz ◽  
L. A. Dollar ◽  
R. L. Smith
Keyword(s):  
Articular Chondrocytes ◽  
Porcine Insulin ◽  
Somatomedin C ◽  
Factor I ◽  
Monolayer Cultures ◽  
Igf I ◽  
Primary Monolayer ◽  
Bovine Articular Chondrocytes ◽  
Specific Insulin ◽  
Primary Monolayer Cultures

ABSTRACT In order to obtain a phenotypically stable cell population of chondrocytes, high density primary monolayer cultures of bovine articular chondrocytes were established. Using these cultures, a specific insulin-like growth factor-I/somatomedin-C (IGF-I/SM-C) receptor was demonstrated and characterized. At 15 °C steady-state binding was attained by 5 h, and averaged 25% per 2·2 × 106 cells. Fifty per cent displacement of 125I-labelled IGF-I/SM-C by unlabelled IGF-I/SM-C occurred at concentrations of only 2·3 ng/ml, whereas IGF-II and porcine insulin were approximately 15-and 1000-fold less potent respectively. Scatchard analysis gave a linear plot, with a calculated association constant of 2·26 × 109 l/mol and a receptor number of 15 400 sites per cell. Preincubation of chondrocyte monolayers with either IGF-I/SM-C or porcine insulin at 37 °C for 20 h resulted in reduction of 125I-labelled IGF-I/SM-C binding in a dose-dependent manner, although higher concentrations were required with insulin. More than 40% down-regulation of the receptor occurred with IGF-I/SM-C at concentrations of 10 nmol/l and nearly 70% reduction at 50 nmol/l. Interestingly, after preincubation with either human (h) or bovine (b)GH, 40% down-regulation of 125I-labelled IGF-I/SM-C binding was observed at concentrations of 10 μmol/l. Local production of IGF-I/SM-C by chondrocytes in response to GH stimulation may have occurred, but, because only 120 pmol IGF-I/SM-C and < 30 pmol IGF-I/SM-C per litre were recovered from serum-free conditioned media preincubated with bGH and hGH respectively, this was not established. These studies demonstrate that cultured bovine articular chondrocytes possess a highly specific IGF-I/SM-C receptor, and that this receptor population is regulated not only by IGF-I/SM-C and insulin but also by high concentrations of either hGH or bGH. These results are consistent with the growth-promoting action of IGF-I/SM-C on skeletal tissues, and suggest the possibility that GH itself may play its own role to modulate IGF-I/SM-C receptors on chondrocytes. J. Endocr. (1985) 107, 275–283

scholarly journals Immunological relationships between receptors for insulin and insulin-like growth factor I. Evidence for structural heterogeneity of insulin-like growth factor I receptors involving hybrids with insulin receptors

1989 ◽  
Vol 263 (2) ◽  
pp. 553-563 ◽  
Author(s):  
M A Soos ◽  
K Siddle
Keyword(s):  
Growth Factor ◽  
Insulin Receptor ◽  
Insulin Receptors ◽  
Insulin Like Growth Factor ◽  
Intact Cells ◽  
Receptor Complexes ◽  
Factor I ◽  
Igf I ◽  
Alpha Beta ◽  
Growth Factor I

The receptors for insulin and insulin-like growth factor-I (IGF-I) are closely related in primary sequence and overall structure. We have examined the immunological relationships between these receptors by testing the reactivity of anti-(insulin receptor) monoclonal antibodies with IGF-I receptors in various tissues and cell lines. Antibodies for six distinct epitopes reacted with a subfraction of IGF-I receptors, as shown by inhibition of 125I-IGF-I binding, precipitation of 125I-IGF-I-receptor complexes or immunodepletion of receptor from tissue extracts before binding assays. Both immunoreactive and non-immunoreactive subfractions displayed the expected properties of ‘classical’ IGF-I receptors, in terms of relative affinities for IGF-I and insulin. The proportion of total IGF-I receptors which was immunoreactive varied in different cell types, being approx. 40% in Hep G2 cells, 35-40% in placental membranes and 75-85% in IM-9 cells. The immunoreactive fraction was somewhat higher in solubilized receptors than in the corresponding intact cells or membranes. A previously described monoclonal antibody, alpha-IR-3, specific for IGF-I receptors, inhibited IGF-I binding by more than 80% in all preparations. When solubilized placental receptors were pretreated with dithiothreitol (DTT) under conditions reported to reduce intramolecular (class I) disulphide bonds, the immunoreactivity of IGF-I receptors was abolished although total IGF-I binding was little affected. Under the same conditions insulin receptors remained fully immunoreactive. When solubilized receptor preparations were fractionated by gel filtration, both IGF-I and insulin receptors ran as symmetrical peaks of identical mobility. After DTT treatment, the IGF-I receptor was partially converted to a lower molecular mass form which was not immunoreactive. The insulin receptor peak showed a much less pronounced skewing and remained fully immunoreactive in all fractions. It is concluded that the anti- (insulin receptor) antibodies do not react directly with IGF-I receptor polypeptide, and that the apparent immunoreactivity of a subfraction of IGF-I receptors reflects their physical association with insulin receptors, both in cell extracts and in intact cells. The most likely basis for this association appears to be a ‘hybrid’ receptor containing one half (alpha beta) of insulin receptor polypeptide and the other (alpha‘beta’) of IGF-I receptor polypeptide within the native (alpha beta beta‘alpha’) heterotetrameric structure.

scholarly journals Expression profiles of growth hormone receptor and insulin-like growth factor I in cattle and yak tissues revealed by quantitative real-time PCR

2013 ◽  
Vol 56 (1) ◽  
pp. 700-708
Author(s):  
J. . Pei ◽  
X. Lang ◽  
P. Bao ◽  
C. Liang ◽  
M. Chu ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Mammary Gland ◽  
Growth Factor ◽  
Growth Hormone Receptor ◽  
Expression Profiles ◽  
The Other ◽  
Mrna Levels ◽  
Transcript Levels ◽  
Factor I ◽  
Igf I

Abstract. The goals of this study were to compare the mRNA expression profiles of growth hormone recep tor (GHR) and insulin-like growth factor I (IGF-I) in various tissues of cattle and the semi-wild yak (Datong yak) and to find out whether the mRNA levels of the two genes are correlated. The mRNA levels of GHR and IGF-I in heart, lung, liver, spleen, pancreas, kidney, muscle, mammary gland and ovary of cattle and yak were investigated by using quantitative real-time po ly mer ase chain reaction (PCR). The experiments showed that the transcript levels of the two genes were signif icantly higher in liver (P<0.05) than in the other tissues for both species and that IGF-I levels varied more among tissues (P<0.01) than did GHR levels. The GHR tran script level in pancreas was higher in yak (P<0.05) than in cattle. There was no statistically sig nif i cant difference in IGF-I tran script levels among all the tissues of both bovine groups. Growth hormone receptor and IGF-I transcript levels were positively correlated in mammary gland (P<0.01), lung (P<0.05) and muscle (P<0.05) in yak, negatively correlated in cattle heart (P<0.05) and not correlated in the other tissues. The results indicate that the two genes are reg u lated differently in various tissues under normal physiological conditions in these two bovine species.

scholarly journals Mineralocorticoid-specificity of aldosterone-induced protein synthesis in giant-toad (Bufo marinus) urinary bladders

1983 ◽  
Vol 214 (1) ◽  
pp. 29-35 ◽  
Author(s):  
M Geheb ◽  
R Alvis ◽  
E Hercker ◽  
M Cox
Keyword(s):  
Protein Synthesis ◽  
Short Circuit ◽  
Polyacrylamide Gel Electrophoresis ◽  
Short Circuit Current ◽  
Bufo Marinus ◽  
Molar Ratio ◽  
Cell Protein ◽  
Na Transport ◽  
Mineralocorticoid Antagonist ◽  
Toad Bufo

We have identified a group of proteins (Mr approximately 70000-80000; pI approximately 5.8-6.4) in giant-toad (Bufo marinus) urinary-bladder epithelial cells whose synthesis appears to be related to aldosterone-stimulated Na+ transport. To define this relationship further, we examined whether submaximal natriferic concentrations of aldosterone induced these proteins and whether spironolactone (a specific mineralocorticoid antagonist in renal epithelia) inhibited their synthesis. Short-circuit current was used to measure Na+ transport and epithelial-cell protein synthesis was detected with high-resolution two-dimensional polyacrylamide-gel electrophoresis and autoradiography. Submaximal natriferic concentrations of aldosterone (1.4 X 10(-8) M) induced the same proteins as maximal concentrations of the hormone (1.4 X 10(-7) M). In contrast, in previous experiments, similar proteins were not induced by subnatriferic concentrations (5.0 X 10(-8) M) of cortisol, a glucocorticoid. A spironolactone/aldosterone molar ratio of 2000:1 was required to inhibit aldosterone-stimulated Na+ transport completely; ratios of 200:1 and 500:1 produced partial inhibition. Concentrations of spironolactone that abolished aldosterone-stimulated Na+ transport also inhibited aldosterone-induced protein synthesis. We conclude that the synthesis of the proteins we have identified is specifically related to activation of the mineralocorticoid pathway.

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