Effects and fate of human IGF-binding protein-5 in rat osteoblast cultures

1996 ◽  
Vol 271 (6) ◽  
pp. E1029-E1035 ◽  
Author(s):  
C. Schmid ◽  
I. Schlapfer ◽  
M. A. Gosteli-Peter ◽  
E. R. Froesch ◽  
J. Zapf
Keyword(s):  
Cell Layer ◽  
Physiological Role ◽  
Igf Binding Proteins ◽  
Igf Binding ◽  
Rat Osteoblast ◽  
Igf Binding Protein ◽  
Rat Osteoblasts ◽  
Igfbp 3 ◽  
Insulin Like Growth Factors

Osteoblasts prepared from calvaria of newborn rats produce insulin-like growth factors (IGF) and IGF-binding proteins (IGFBP), IGFBP-5 was discovered in bone extracts. However, we could not detect IGFBP-5 in the medium of newborn rat osteoblasts, although we found mRNA expression. To find an explanation for this discrepancy and to learn more about the physiological role of IGFBP-5 in these cells, we studied the biological activity and the fate of recombinant human (rh) IGFBP-5 in comparison to rhIGFBP-3. IGFBP-5 but not IGFBP-3 stimulated thymidine incorporation into DNA both in the absence and presence of IGF-I. However, IGFBP-5 did not enhance uridine incorporation into RNA and glucose incorporation into glycogen. 125I-rhIGFBP-5 but not 125I-rhIGFBP-3 rapidly disappeared from the culture medium consistent with the observation that endogenous (rat) IGFBP-3 but not IGFBP-5 accumulated in the medium. However, intact 125I-labeled or unlabeled rhIGFBP-5 was associated with the cell-layer matrix, whereas IGFBP-5 fragments appeared in the medium. Trapping of IGFBP-5 in the cell layer matrix may enhance local availability of IGF.

scholarly journals Isolation of complexes formed between insulin-like growth factor-binding protein-3 and transferrin from the human serum

2012 ◽  
Vol 77 (5) ◽  
pp. 607-617 ◽  
Author(s):  
Goran Miljus ◽  
Miomir Petrovic ◽  
Olgica Nedic
Keyword(s):  
Growth Factors ◽  
Binding Protein ◽  
Biologically Active ◽  
Molecular Forms ◽  
Igf Binding Proteins ◽  
Igf Binding ◽  
The Relationship ◽  
Igfbp 3 ◽  
Insulin Like Growth Factors

Insulin-like growth factors (IGFs) play an important role in the regulation of cell growth, differentiation and metabolism. The amount of free, biologically active IGFs is regulated by the IGF-binding proteins (IGFBPs). IGFBP-3 is the most abundant binding protein and it is known to interact with other circulating proteins, including transferrin (Tf). In order to elucidate the possible role of IGF/IGFBP-3 in the iron metabolism, it is necessary to isolate IGFBP-3/Tf complexes. Several affinity-based techniques were employed. Results have shown that only double immunoprecipitation method with anti-Tf and anti-IGFBP-3 antibodies selectively separated complexes from other molecular forms, such as monomers, oligomers or fragments of IGFBP-3 and Tf. Isolated complexes can now be used to investigate the relationship between IGF/IGFBP-3 and iron, both in structural and metabolic t?rms.

scholarly journals Steroid Receptor Coactivator 3 Maintains Circulating Insulin-Like Growth Factor I (IGF-I) by Controlling IGF-Binding Protein 3 Expression

2008 ◽  
Vol 28 (7) ◽  
pp. 2460-2469 ◽  
Author(s):  
Lan Liao ◽  
Xian Chen ◽  
Shu Wang ◽  
Albert F. Parlow ◽  
Jianming Xu
Keyword(s):  
Vitamin D ◽  
Growth Factor ◽  
Insulin Like Growth Factor ◽  
Steroid Receptor Coactivator ◽  
Factor I ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

ABSTRACT Steroid receptor coactivator 3 (SRC-3/AIB1/ACTR/NCoA-3) is a transcriptional coactivator for nuclear receptors including vitamin D receptor (VDR). Growth hormone (GH) regulates insulin-like growth factor I (IGF-I) expression, and IGF-I forms complexes with acid-labile subunit (ALS) and IGF-binding protein 3 (IGFBP-3) to maintain its circulating concentration and endocrine function. This study demonstrated that the circulating IGF-I was significantly reduced in SRC-3−/− mice with the C57BL/6J background. However, SRC-3 deficiency affected neither GH nor ALS expression. The low IGF-I level in SRC-3−/− mice was not due to the failure of IGF-I mRNA and protein synthesis but was a consequence of rapid degradation. The rapid IGF-I degradation was associated with drastically reduced IGFBP-3 levels. Because IGF-I and IGFBP-3 stabilize each other, SRC-3−/− mice were crossbred with the liver-specific transthyretin (TTR)-IGF-I transgenic mice to assess the relationship between reduced IGF-I and IGFBP-3. In SRC-3−/−/TTR-IGF-I mice, the IGF-I level was significantly increased over that in SRC-3−/− mice, but the IGFBP-3 level failed to increase proportionally, indicating that the low IGFBP-3 level is a responsible factor that limits the IGF-I level in SRC-3−/− mice. Furthermore, IGFBP-3 mRNA was reduced in SRC-3−/− mice. The IGFBP-3 promoter activity induced by vitamin D, through VDR, was diminished in SRC-3−/− cells, suggesting an important role of SRC-3 in VDR-mediated transactivation of the IGFBP-3 gene. In agreement with the role of SRC-3 in VDR function, the expression of several VDR target genes was also reduced in SRC-3−/− mice. Therefore, SRC-3 maintains IGF-I in the circulation through enhancing VDR-regulated IGFBP-3 expression.

Growth hormone (GH), insulin-like growth factors (IGFs), and IGF-binding protein-3 (IGFBP-3) in a child with Proteus syndrome

1994 ◽  
Vol 50 (2) ◽  
pp. 204-210 ◽  
Author(s):  
Günter Rudolph ◽  
Werner F. Blum ◽  
Enno W. Jenne ◽  
Martin Schöning ◽  
Herbert Enders ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factors ◽  
Binding Protein ◽  
Proteus Syndrome ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3 ◽  
Insulin Like Growth Factors

scholarly journals The Role of IGF-Binding Proteins in Mediating the Effects of Recombinant Human IGF-I on Insulin Requirements in Type 1 Diabetes Mellitus

2001 ◽  
Vol 86 (8) ◽  
pp. 3686-3691 ◽  
Author(s):  
E. C. Crowne ◽  
J. S. Samra ◽  
T. Cheetham ◽  
C. L. Acerini ◽  
A. Watts ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Binding Protein ◽  
Igf Binding Proteins ◽  
Insulin Requirements ◽  
Free Insulin ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

To determine the role of IGF-binding proteins in mediating the direct effects of recombinant human IGF-I on insulin requirements in type 1(insulin-dependent) diabetes mellitus, overnight changes in IGF-I, IGF-II, and IGF-binding protein-1, -2, and -3, collected under euglycemic conditions, were compared in nine subjects after double blind, randomized, sc administration of recombinant human IGF-I (40μ g/kg) or placebo at 1800 h. On both nights a somatostatin analog infusion (300 ng/kg·h) suppressed endogenous GH production, and three timed discrete GH pulses (total, 0.029 IU/kg·night) ensured identical GH levels. After recombinant human IGF-I administration, IGF-I levels and the IGF-I/IGF-binding protein-3 ratio increased [mean ± sem:IGF-I, 401 ± 22 ng/ml; placebo, 256 ± 20 ng/ml (P = 0.0002); IGF-I, 0.108 ± 0.006; placebo, 0.074 ± 0.004 (P = 0.0003), respectively], and insulin requirements decreased (IGF-I, 0.12 ± 0.03; placebo, 0.23 ± 0.03 U/kg·min; P = 0.008). The normal within-individual inverse relationships between insulin and IGF-binding protein-1 levels were observed (lag time 2 h: r =− 0.34; P < 0.01). Yet despite reduced free insulin levels (8.5 ± 1.5; placebo, 12.2 ± 1.2 mU/liter; P = 0.03), IGF-binding protein-1 levels were reduced after recombinant human IGF-I administration (53.7 ± 6.8; placebo, 82.2 ± 11.8 ng/ml; P = 0.008). The largest reductions in free insulin levels after recombinant human IGF-I and thus putative improvement in insulin sensitivity occurred in subjects with the smallest increase in the plasma IGF-I/IGF-binding protein-3 ratio (r = 0.7; P = 0.03). Taken together, these data are consistent with the hypothesis that transcapillary movement of IGF-I (perhaps mediated by IGF-binding protein-1), out of the circulation facilitates altered insulin sensitivity. These data have important implications for risk-benefit assessment of recombinant human IGF-I therapy in type 1 diabetes mellitus.

scholarly journals 40 YEARS OF IGF1: Role of IGF-binding proteins in regulating IGF responses to changes in metabolism

2018 ◽  
Vol 61 (1) ◽  
pp. T139-T169 ◽  
Author(s):  
David R Clemmons
Keyword(s):  
Binding Protein ◽  
Surface Proteins ◽  
Type I ◽  
Cellular Functions ◽  
Igf Binding Proteins ◽  
Distinct Cell ◽  
Type I Igf Receptor ◽  
Igf Binding ◽  
Igf Binding Protein

The IGF-binding protein family contains six members that share significant structural homology. Their principal function is to regulate the actions of IGF1 and IGF2. These proteins are present in plasma and extracellular fluids and regulate access of both IGF1 and II to the type I IGF receptor. Additionally, they have functions that are independent of their ability to bind IGFs. Each protein is regulated independently of IGF1 and IGF2, and this provides an important mechanism by which other hormones and physiologic variables can regulate IGF actions indirectly. Several members of the family are sensitive to changes in intermediary metabolism. Specifically the presence of obesity/insulin resistance can significantly alter the expression of these proteins. Similarly changes in nutrition or catabolism can alter their synthesis and degradation. Multiple hormones such as glucocorticoids, androgens, estrogen and insulin regulate IGFBP synthesis and bioavailability. In addition to their ability to regulate IGF access to receptors these proteins can bind to distinct cell surface proteins or proteins in extracellular matrix and several cellular functions are influenced by these interactions. IGFBPs can be transported intracellularly and interact with nuclear proteins to alter cellular physiology. In pathophysiologic states, there is significant dysregulation between the changes in IGFBP synthesis and bioavailability and changes in IGF1 and IGF2. These discordant changes can lead to marked alterations in IGF action. Although binding protein physiology and pathophysiology are complex, experimental results have provided an important avenue for understanding how IGF actions are regulated in a variety of physiologic and pathophysiologic conditions.

scholarly journals Association between hepatic steatosis and serum IGF1 and IGFBP-3 levels in a population-based sample

2009 ◽  
Vol 161 (5) ◽  
pp. 705-713 ◽  
Author(s):  
Henry Völzke ◽  
Matthias Nauck ◽  
Rainer Rettig ◽  
Marcus Dörr ◽  
Claire Higham ◽  
...  
Keyword(s):  
Alcohol Consumption ◽  
Hepatic Steatosis ◽  
Population Based ◽  
The Metabolic Syndrome ◽  
Igf Binding ◽  
History Of ◽  
Igf Binding Protein ◽  
Low Serum ◽  
Igfbp 3

ContextIt is assumed that hepatic steatosis plays a role in the development and progression of the metabolic syndrome and its cardiovascular sequelae. Low serum IGF1 levels might mediate these associations.ObjectivesThe aims of this study were i) to investigate the associations of hepatic steatosis with serum IGF1 and IGF binding protein-3 (IGFBP-3) levels using ultrasound and serum alanine aminotransaminase (ALT) data to define hepatic steatosis, and ii) to analyze the specific role of alcohol consumption in this context.DesignWe analyzed data from the population-based Study of Health in Pomerania.MethodsWe used data from 3863 subjects (1971 women) aged 20–79 years who had no history of viral hepatitis, liver cirrhosis, or malignant diseases. Liver hyperechogenicity was diagnosed using ultrasound. Serum IGF1 and IGFBP-3 levels were determined by automated two-site chemiluminescence immunoassays.ResultsHyperechogenic liver pattern was associated with low serum IGF1 levels and low serum IGF1/IGFBP-3 ratios. The lowest serum IGF1 and IGF1/IGFBP-3 values and highest IGFBP-3 levels were present in subjects who had a hyperechogenic liver pattern and increased serum ALT levels. All of these associations were independent of alcohol consumption.ConclusionsOur data show that hepatic steatosis is associated with low serum IGF1 levels. This association is independent of alcohol consumption.

scholarly journals The role of IGF binding protein-3 as a parameter of activity in acromegalic patients

1999 ◽  
pp. 145-148 ◽  
Author(s):  
I Halperin ◽  
R Casamitjana ◽  
L Flores ◽  
M Fernandez-Balsells ◽  
E Vilardell
Keyword(s):  
Binding Protein ◽  
Serum Levels ◽  
Glucose Load ◽  
Gh Secretion ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Normal Standard ◽  
Igfbp 3

OBJECTIVE: The production of insulin-like growth factor binding protein-3 (IGFBP-3), the main IGF-I binding protein, is regulated by GH, and its serum levels are increased in acromegaly. We investigated its potential value as a parameter of acromegaly activity or remission in comparison with IGF-I, taking GH suppression below 2 microg/l after glucose load as the normal standard. METHODS: Data from 40 acromegalic patients (12 males and 28 females, aged 28 to 79 years) were obtained retrospectively from stored samples. From these, 145 pairs of IGF-I/IGFBP-3 values were collected; in 67 of them, simultaneous measurement of GH after glucose loading allowed their classification as active or inactive acromegaly. Relationships between IGF-I, IGFBP-3 and GH after glucose load were assessed, as well as differences between IGF-I and IGFBP-3 levels in active and inactive acromegaly. RESULTS: Significant positive correlation between IGF-I and IGFBP-3 in 145 samples was observed (r=0.49, P<0. 0001). As for the 67 samples in which activity or remission could be defined in terms of GH after glucose load, 50 were active and 17 inactive. Both IGF-I and IGFBP-3 significantly correlated with minimum GH (r=0.53, P<0.0001 and r=0.41, P<0.001 respectively). For both parameters, significant differences of means between active and inactive cases were observed (623+/-296 vs 300+/-108 ng/ml, P<0.0001 for IGF-I, and 4.1+/-1.3 vs 3.2+/-0.9 microg/ml, P<0.006 for IGFBP-3). Yet, when comparing in individual cases their classification as active or inactive with the finding of normal or increased IGF-I and IGFBP-3, among active cases 16% appeared as normal according to IGF-I, and 50% appeared as normal in terms of IGFBP-3. Among inactive cases, 23.5% appeared as active according to IGF-I, while 17.5% appeared as active in terms of IGFBP-3. CONCLUSION: Even though IGFBP-3 reflects GH secretion, it offers no advantage over IGF-I in the assessment of acromegaly, and it may underestimate disease activity in acromegalic patients.

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