Role of IGF-I and IGFBPs in the changes of mass and phenotype induced in rat soleus muscle by clenbuterol

2002 ◽  
Vol 282 (1) ◽  
pp. E31-E37 ◽  
Author(s):  
Bonaventure L. Awede ◽  
Jean-Paul Thissen ◽  
Jean Lebacq
Keyword(s):  
Soleus Muscle ◽  
Muscle Hypertrophy ◽  
Mrna Levels ◽  
Fivefold Increase ◽  
Igf I ◽  
Female Wistar Rats ◽  
Igf Binding ◽  
Rat Soleus Muscle ◽  
Igf Binding Protein

Clenbuterol induces hypertrophy and a slow-to-fast phenotype change in skeletal muscle, but the signaling mechanisms remain unclear. We hypothesized that clenbuterol could act via local expression of insulin-like growth factor I (IGF-I). Administration of clenbuterol to 3-mo-old female Wistar rats resulted in a 10 and 13% increase of soleus muscle mass after 3 and 9 days, respectively, reaching 16% after 4 wk. When associated with triiodothyronine, clenbuterol induced a dramatic slow-to-fast phenotype change. In parallel, clenbuterol administration induced in soleus muscle a fivefold increase in IGF-I mRNA levels associated with an eightfold increase in IGF-binding protein (IGFBP)-4 and a fivefold increase of IGFBP-5 mRNA levels on day 3. This increased IGF-I gene expression was associated with an increase in muscle IGF-I content, already detected on day 1 and persisting until day 5 without increase in serum IGF-I concentrations. These data show that muscle hypertrophy induced by clenbuterol is associated with a local increase in muscle IGF-I content. They suggest that clenbuterol-induced muscle hypertrophy could be mediated by local production of IGF-I.

Role of IGF system of mitogens in the induction of fibroblast proliferation by keloid-derived keratinocytes in vitro

2003 ◽  
Vol 284 (4) ◽  
pp. C860-C869 ◽  
Author(s):  
Toan-Thang Phan ◽  
Ivor Jiun Lim ◽  
Boon Huat Bay ◽  
Robert Qi ◽  
Michael Thornton Longaker ◽  
...  
Keyword(s):  
Mrna Levels ◽  
Igf System ◽  
Normal Keratinocytes ◽  
Wound Healing Response ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

Keloids are proliferative dermal growths representing a pathological wound-healing response. We report high proliferation rates in normal (NF) and keloid-derived fibroblasts (KF) cocultured with keloid-derived keratinocytes (KK). IGF binding protein (IGFBP)-3 mRNA and secreted IGFBP-3 in conditioned media were increased in NF cocultured with KK compared with NF but markedly reduced in KF cocultured with KK or normal keratinocytes (NK). IGFBP-2 and IGFBP-4 mRNA levels were elevated, whereas IGFBP-5 mRNA was decreased in KF cocultured with KK or NK. Significant increases in IGFBP-2 and -4 mRNA in KF cocultured with KK did not correlate with protein secretion. Downstream IGF signaling cascade components, phospho-Raf, phospho-MEK1/2, phospho-MAPK, PI-3 kinase, phospho-Akt, and phospho-Elk-1, were elevated in KF cocultured with KK. Addition of recombinant human IGFBP-3 or antibodies against IGF-I or IGF-IR significantly inhibited proliferation of KF. The bioavailability of IGF-I may be related to the levels of IGFBP-3 produced, which in turn influences KF proliferation, suggesting that modulation of IGF-I, IGF-IR, and IGFBP-3, individually or in combination, may represent novel approaches to the treatment of keloids.

scholarly journals Formoterol treatment prevents the effects of endotoxin on muscle TNF/NF-kB, Akt/mTOR, and proteolytic pathways in a rat model. Role of IGF-I and miRNA 29b

2018 ◽  
Vol 315 (4) ◽  
pp. E705-E714 ◽  
Author(s):  
Ana Isabel Martín ◽  
Ana Belén Gómez-SanMiguel ◽  
Teresa Priego ◽  
Asunción López-Calderón
Keyword(s):  
Inflammatory Diseases ◽  
Mammalian Target Of Rapamycin ◽  
Ring Finger ◽  
Mrna Levels ◽  
Igf I ◽  
Male Wistar Rats ◽  
Igf Binding ◽  
Β2 Adrenergic Receptor ◽  
Igf Binding Protein

Inflammatory diseases are associated with muscle wasting as a result of an increase in proteolysis. The purpose of this study was to elucidate whether administration of a β2 adrenergic agonist, formoterol, was able to prevent the acute effects of sepsis induced by liposaccharide (LPS) injection on rat gastrocnemius muscle and to evaluate the possible roles of corticosterone, IGF-I, miR-23a, and miR-29b. For this purpose, male Wistar rats were injected with LPS and/or formoterol. Formoterol treatment decreased LPS-induced increase in serum corticosterone, TNFα upregulation, and NF-κB(p65) and Forkhead box protein O1 activation in the gastrocnemius. Atrogin-1, muscle RING-finger protein-1, microtubule-associated protein-1 light chain 3b (LC3b), and the lipidation of LC3b-I to LC3b-II were increased by LPS, and formoterol blocked these effects. Serum IGF-I and its mRNA levels in the gastrocnemius were decreased, whereas mecano growth factor and IGF binding protein 3 mRNA levels were increased in the rats injected with LPS but not in the rats that received LPS and formoterol. Similarly, LPS decreased Akt and mammalian target of rapamycin phosphorylation, and formoterol blocked these decreases. Finally, miR-29b expression in the gastrocnemius was upregulated by endotoxin injection, whereas miR-23a was not significantly different. Formoterol treatment did not significantly modify LPS-induced increase in muscle miR-29b. Furthermore, in control rats formoterol increased the expression of this miRNA. We conclude that formoterol decreases endotoxin-induced inflammation and proteolysis in rat skeletal muscle. Those responses can be a direct effect of β2 adrenergic receptor stimulation or/and of blocking the effects of LPS on corticosterone and IGF-I. Muscle miR-23a and -29b do not seem to play an important role in those responses.

scholarly journals Dexamethasone administration attenuates the inhibitory effect of lipopolysaccharide on IGF-I and IGF-binding protein-3 in adult rats

2005 ◽  
Vol 185 (3) ◽  
pp. 467-476 ◽  
Author(s):  
Teresa Priego ◽  
Miriam Granado ◽  
Ana Isabel Martín ◽  
Asunción López-Calderón ◽  
María Angeles Villanúa
Keyword(s):  
Gene Expression ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Serum Concentrations ◽  
Gh Receptor ◽  
Its Gene ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

The aim of this study was to investigate whether glucocorticoid administration had a beneficial effect on serum concentrations of insulin-like growth factor I (IGF-I) and on IGF-binding protein 3 (IGFBP-3) in rats injected with lipopolysaccharide (LPS). Adult male rats were injected with LPS or saline and pretreated with dexamethasone or saline. Dexamethasone administration decreased growth hormone (GH) receptor and IGF-I mRNA levels in the liver of control rats. LPS decreased GH receptor and IGF-I gene expression in the liver of saline-treated rats but not in the liver of dexamethasone-pretreated rats. In the kidney, GH receptor mRNA levels were not modified by dexamethasone or LPS treatment. However, LPS decreased renal IGF-I gene expression and dexamethasone pretreatment prevented this decrease. Serum concentrations of IGF-I were decreased by LPS, and dexamethasone pretreatment attenuated this effect. The gene expression of IGFBP-3 in the liver and kidney and its circulating levels were decreased by LPS. In control rats dexamethasone increased circulating IGFBP-3 and its gene expression in the liver, and decreased the proteolysis of this protein. Dexamethasone pretreatment attenuated the LPS-induced decrease in IGFBP-3 gene expression in the liver and prevented the LPS-induced decrease in IGFBP-3 gene expression in the kidney. Moreover, dexamethasone pretreatment attenuated the LPS-induced decrease in serum concentrations of IGFBP-3 and decreased the LPS-induced IGFBP-3 proteolysis in serum. In conclusion, dexamethasone pretreatment partially attenuates the inhibitory effect of LPS on serum IGF-I by blocking the decrease of its gene expression in the kidney as well as by attenuating the decrease in serum concentrations of IGFBP-3.

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.

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.

Changes in IGF-I and -II expression and secretion during the proliferation and differentiation of normal rat osteoblasts

1995 ◽  
Vol 144 (2) ◽  
pp. 251-259 ◽  
Author(s):  
R S Birnbaum ◽  
R R Bowsher ◽  
K M Wiren
Keyword(s):  
Extracellular Matrix ◽  
Physiological Role ◽  
Mrna Levels ◽  
Proliferation And Differentiation ◽  
Igf I ◽  
Igf Binding ◽  
Normal Rat ◽  
Osteoblast Development ◽  
Igf Binding Protein

Abstract IGF-I and -II have potent effects on proliferation and differentiation of osteoblasts in vitro. These cells secrete both IGFs and expression of these peptides is regulated by several of the hormones and growth factors that promote bone resorption and/or formation. However, the physiological role(s) of IGFs in the remodelling process of adult bone is still unclear. Some confusion may arise from results influenced, in part, by differences in the state of osteoblast development of in vitro cultures. Several laboratories have demonstrated that murine osteoblast cultures progress from proliferating preosteoblasts, to mature differentiated osteoblasts that form an extracellular matrix, to cultures that form a mineralized matrix. We have recently documented changes in IGF-binding protein expression and secretion in these cultures. To complement and extend this work, we have examined IGF-I expression and secretion and IGF-II expression during in vitro osteoblast development. Steady-state mRNA levels of both IGF-I and -II increased from the earliest time examined, day 5 in culture, to a maximum at day 11 and, thereafter, declined. IGF-I secreted into the medium also changed in a biphasic manner, but IGF-II could not be quantitated due to the sensitivity of our assay. Secretion of IGF-I was lowest between days 8 and 14. IGF-I secretion on day 5 was significantly greater than day 8. Similarly, IGF-I secretion from day 17 to 26 was also greater than observed for days 8 to 14. If differentiation of the cells was inhibited, this late rise in IGF-I secretion was abolished. We conclude that IGF-I is an autocrine mitogen of the proliferating preosteoblasts. Further, we also suggest that the rise in IGF-I secretion, late in osteoblast development, may lead to sequestration of this mitogen in the extracellular matrix for release during a subsequent remodelling cycle. Journal of Endocrinology (1995) 144, 251–259

Differential role of glucocorticoids in mediating endotoxin-induced changes in IGF-I and IGFBP-1

1997 ◽  
Vol 272 (6) ◽  
pp. R1990-R1997 ◽  
Author(s):  
Y. H. Li ◽  
J. Fan ◽  
C. H. Lang
Keyword(s):  
Plasma Corticosterone ◽  
Mrna Abundance ◽  
Male Rats ◽  
Ru 486 ◽  
Igf I ◽  
Igf Binding ◽  
Induced Changes ◽  
Igf Binding Protein

The purpose of the present study was to determine whether endogenous elevations in glucocorticoids mediate the changes in insulin-like growth factor (IGF) 1 and IGF binding protein (IGFBP) 1 levels in plasma and tissues observed after in vivo administration of lipopolysaccharide (LPS). In overnight-fasted male rats LPS injected via the tail vein decreased the IGF-I concentration in plasma, liver, and skeletal muscle (30-45%) and increased IGF-I content in kidney (approximately 3-fold). LPS also decreased IGF-I mRNA abundance in liver and muscle and increased gene expression in kidney. Concomitantly, IGFBP-1 levels in plasma, liver, and muscle were markedly elevated by LPS. All these changes were associated with a greater than fourfold elevation in plasma corticosterone. Pretreatment of rats with the glucocorticoid receptor antagonist RU-486 completely prevented or blunted the LPS-induced changes in IGF-I content in plasma, liver, muscle, and kidney. In liver and muscle RU-486 significantly attenuated the reduction in IGF-I mRNA abundance produced by LPS, but in kidney the LPS-induced increase in IGF-I mRNA was still evident. In contrast, pretreatment with RU-486 did not prevent or attenuate the LPS-induced increase in IGFBP-1 levels in plasma, liver, or muscle. These data suggest that glucocorticoids play a major role in regulating IGF-I mRNA and peptide content in tissues in response to LPS, but the increased IGFBP-1 in blood and tissues induced by LPS appears largely glucocorticoid independent.

scholarly journals Insulin-Like Growth Factor (IGF)-Binding Protein-1 Is Highly Induced during Acute Carbon Tetrachloride Liver Injury and Potentiates the IGF-I-Stimulated Activation of Rat Hepatic Stellate Cells

Endocrinology ◽  
2004 ◽  
Vol 145 (7) ◽  
pp. 3463-3472 ◽  
Author(s):  
Jens-Gerd Scharf ◽  
Frank Dombrowski ◽  
Ruslan Novosyadlyy ◽  
Christoph Eisenbach ◽  
Ilaria Demori ◽  
...  
Keyword(s):  
Carbon Tetrachloride ◽  
Liver Injury ◽  
Hepatic Stellate Cells ◽  
Binding Protein ◽  
Stellate Cells ◽  
Hepatic Tissue ◽  
Mrna Levels ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

Abstract Hepatic stellate cells (HSC) play a pivotal role in hepatic tissue repair and fibrogenesis. IGF-I has been considered a mitogenic signal for activation and proliferation of HSC in vitro. In the present study IGF-I and IGF-binding protein (IGFBP) gene expression was studied in a model of acute liver injury induced by a single intragastric dose of carbon tetrachloride (CCl4) in adult rats. Northern blot analysis revealed a marked increase in IGFBP-1 mRNA levels, with a maximum between 3 and 9 h after CCl4 application, whereas steady state mRNA levels of IGF-I were only moderately altered. In situ hybridization experiments demonstrated that this increase in IGFBP-1 mRNA was due to a strong expression of IGFBP-1 in the perivenous region 6–12 h after CCl4 application, extending to the midzonal region of the acinus within 24–48 h. Consequently, a prominent immunostaining for IGFBP-1 was observed in perivenous areas, with a maximum 24–48 h after intoxication. Preincubation of early cultured HSC with a nonphosphorylated IGFBP-1 from human amniotic fluid resulted in a 3.4-fold increase in IGF-I-induced DNA synthesis. The mitogenic effect of IGF-I was also potentiated when HSC were cocultivated with IGFBP-1-overexpressing BHK-21 cells compared with nontransfected cells. These data suggest that IGFBP-1 released during the early steps of liver tissue damage and repair may interact with HSC and potentiate the sensitivity of IGF-I to mitogenic signals.

scholarly journals Metabolic hormones regulate insulin-like growth factor binding protein-1 mRNA levels in primary cultured salmon hepatocytes; lack of inhibition by insulin

2006 ◽  
Vol 191 (2) ◽  
pp. 379-386 ◽  
Author(s):  
A L Pierce ◽  
M Shimizu ◽  
L Felli ◽  
P Swanson ◽  
W W Dickhoff
Keyword(s):  
Gene Expression ◽  
Growth Factor ◽  
Hormonal Regulation ◽  
Growth And Development ◽  
Mrna Levels ◽  
Igf Binding Proteins ◽  
Metabolic Hormones ◽  
Igf I ◽  
Igf Binding

IGF-binding proteins (IGFBPs) modulate the effects of the IGFs, major stimulators of vertebrate growth and development. In mammals, IGFBP-1 inhibits the actions of IGF-I. Rapid increases in circulating IGFBP-1 occur during catabolic states. Insulin and glucocorticoids are the primary regulators of circulating IGFBP-1 in mammals. Insulin inhibits and glucocorticoids stimulate hepatocyte IGFBP-1 gene expression and production. A 22 kDa IGFBP in salmon blood also increases during catabolic states and has recently been identified as an IGFBP-1 homolog. We examined the hormonal regulation of salmon IGFBP-1 mRNA levels and protein secretion in primary cultured salmon hepatocytes. The glucocorticoid agonist dexamethasone progressively increased hepatocyte IGFBP-1 mRNA levels (eightfold) and medium IGFBP-1 immunoreactivity over concentrations comparable with stressed circulating cortisol levels (10−9–10−6 M). GH progressively reduced IGFBP-1 mRNA levels (0.3-fold) and medium IGFBP-1 immunoreactivity over physiological concentrations (5 × 10−11–5 × 10−9 M). Unexpectedly, insulin slightly increased hepatocyte IGFBP-1 mRNA (1.4-fold) and did not change medium IGFBP-1 immunoreactivity over physiological concentrations and above (10−9–10−6 M). Triiodothyronine had no effect on hepatocyte IGFBP-1 mRNA, whereas glucagon increased IGFBP-1 mRNA (2.2-fold) at supraphysiological concentrations (10−6 M). This study suggests that the major inhibitory role of insulin in the regulation of liver IGFBP-1 production in mammals is not found in salmon. However, regulation of salmon liver IGFBP-1 production by other metabolic hormones is similar to what is found in mammals.

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