Regulation of IGF-binding protein-6 by dexamethasone and IGFs in PC12 rat phaeochromocytoma cells

1997 ◽  
Vol 155 (2) ◽  
pp. 225-232 ◽  
Author(s):  
LA Bach ◽  
KS Leeding ◽  
SL Leng
Keyword(s):  
Pc12 Cells ◽  
Binding Protein ◽  
Mrna Level ◽  
Cell Number ◽  
Mrna Levels ◽  
Protein Levels ◽  
Igf Receptors ◽  
Igf Binding ◽  
A Cell ◽  
Igf Binding Protein

PC12 rat phaeochromocytoma cells are widely used as a model of neuronal differentiation. They express IGF receptors and are responsive to IGFs. The main IGF-binding protein synthesized by these cells is IGFBP-6. Glucocorticoids induce differentiation of PC12 cells towards a chromaffin phenotype. The effect of dexamethasone on IGFBP-6 levels was therefore studied. Dexamethasone (500 nM) decreased IGFBP-6 protein in conditioned media and mRNA levels to 61 +/- 5% (P < 0.0001) and 34 +/- 14% (P = 0.03) of control levels respectively. Incubation of PC12 cells with IGF-II (100 ng/ml) for 72 h increased IGFBP-6 protein levels in media to 217 +/- 19% of control (P < 0.0001). IGFBP-6 mRNA levels, however, were unchanged. IGF-I had similar effects on IGFBP-6 protein and mRNA levels. IGFs increased cell number by 50-60%, but this was insufficient to explain the increases in protein levels. IGFBP-6 was not released from a cell-associated reservoir or protected from proteolysis by IGFs, excluding these post-translational mechanisms as explanations for the IGF effects on IGFBP-6 levels. The effects of IGF-II and dexamethasone on IGFBP-6 levels were independent. These results indicated that (1) dexamethasone decrease IGFBP-6 at the mRNA level, and (2) IGFs stimulate IGFBP-6 levels by a post-transcriptional mechanism.

Developmentally regulated expression of insulin-like growth factors by differentiated murine teratocarcinomas and extraembryonic mesoderm

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 193-212
Author(s):  
John K. Heath ◽  
Wai-Kang Shi
Keyword(s):  
Plasma Membrane ◽  
Binding Protein ◽  
Membrane Receptors ◽  
Developmentally Regulated ◽  
Igf Receptors ◽  
Igf Binding ◽  
Plasma Membrane Receptors ◽  
Igf Binding Protein ◽  
Culture Supernatants ◽  
Insulin Like Growth Factors

The expression of plasma membrane receptors for insulin-like growth factors (IGFs) by PC13 embryonal carcinoma (EC) cells, and their immediate differentiated progeny PC13END was examined by binding radiolabelled IGF-I to cell monolayers. Both cell types express high-affinity IGF receptors, but the apparent number of unoccupied receptor sites falls by about 60% upon differentiation. Crosslinking studies reveal that both type 1 and type 2 IGF receptors are expressed by PC13EC cells. PC13END-cell-conditioned medium contains developmentally regulated, separable activities, one of which reacts directly with IGF-II, and the other with IGF for plasma membrane receptors. The former activity represents a soluble secreted IGF-binding protein. The latter activity is structurally and functionally similar to rat IGF-II. Polyclonal antibodies raised against purified rat IGF-II specifically recognize multiple forms of IGF in radiolabelled culture supernatants and material which closely resembles the soluble IGF-binding protein. Immunoprecipitation of radiolabelled culture supernatants with anti-rat IGF-II reveals that the differentiation of PC13EC cells is accompanied by the coexpression of IGF-like molecules and the soluble binding protein, and that IGF-like molecules are expressed by extraembryonic tissues of mesodermal origin in the early postimplantation mouse embryo. These findings show that IGF-like molecules are expressed in early mammalian development and may act in an autocrine fashion in vivo.

IGF-I and IGF-binding protein gene expressions in spontaneous dwarf rat

1994 ◽  
Vol 267 (3) ◽  
pp. E396-E401 ◽  
Author(s):  
H. Nogami ◽  
T. Watanabe ◽  
S. Kobayashi
Keyword(s):  
Binding Protein ◽  
Mrna Level ◽  
Pituitary Hormones ◽  
Acute Administration ◽  
Gene Expressions ◽  
Igf I ◽  
Igf Binding ◽  
Normal Rat ◽  
Igf Binding Protein ◽  
Serum Gh

Effects of growth hormone (GH) and fasting on hepatic expressions of insulin-like growth factor I (IGF-I) and IGF-I-binding protein (IGFBP)-1, -2, -3, and -4 were examined in spontaneous dwarf rats (SDR), which completely and specifically lack GH among pituitary hormones. The hepatic expressions of mRNA encoding IGF-I and IGFBP-3 were reduced and IGFBP-1 mRNA was elevated in the SDR. Both chronic and acute administration of GH restored these changes, indicating the association of GH but not other pituitary hormones with hepatic expressions of these genes. In addition, the present examination revealed that mRNA level of IGFBP-2 was elevated in SDR, which could not be attenuated by exogenous GH, and that GH may not be directly relevant to the regulation of hepatic IGFBP-4 expression. Fasting for 2 days reduced IGF-I mRNA level and increased IGFBP-2 mRNA level in the SDR, as well as in the normal rat, suggesting the presence of factors other than reduced serum GH responsible for fasting-induced alteration in the expression of these mRNAs. On the other hand, fasting resulted in little change or even a reduction of IGFBP-1 mRNA level in the SDR.

Purification from Transformed Mouse Fibroblast of a Cell Growth Inhibitor which is an IGF-Binding Protein

1992 ◽  
Vol 6 (1) ◽  
pp. 65-75 ◽  
Author(s):  
C. Blat ◽  
J. Villaudy ◽  
J. Delbe ◽  
F. Troalen ◽  
A. Golde ◽  
...  
Keyword(s):  
Cell Growth ◽  
Binding Protein ◽  
Growth Inhibitor ◽  
Mouse Fibroblast ◽  
Igf Binding ◽  
A Cell ◽  
Igf Binding Protein

scholarly journals Low Dose Administration of Glutamate Triggers a Non-Apoptotic, Autophagic Response in PC12 Cells

2015 ◽  
Vol 37 (5) ◽  
pp. 1750-1758 ◽  
Author(s):  
Eleni Stamoula ◽  
Theofanis Vavilis ◽  
Eleni Aggelidou ◽  
Aikaterini Kaidoglou ◽  
Angeliki Cheva ◽  
...  
Keyword(s):  
Pc12 Cells ◽  
Cell Fate ◽  
Low Dose ◽  
Mrna Level ◽  
Neuronal Cell ◽  
Cellular Level ◽  
Mrna Levels ◽  
Protein Levels ◽  
Low Concentrations ◽  
Discrete Effect

Background/Aims: Increasing amounts of the neurotransmitter glutamate are associated with excitotoxicity, a phenomenon related both to homeostatic processes and neurodegenerative diseases such as multiple sclerosis. Methods: PC12 cells (rat pheochromocytoma) were treated with various concentrations of the non-essential amino acid glutamate for 0.5-24 hours. The effect of glutamate on cell morphology was monitored with electron microscopy and haematoxylin-eosin staining. Cell survival was calculated with the MTT assay. Expression analysis of chaperones associated with the observed phenotype was performed using either Western Blotting at the protein level or qRT-PCR at the mRNA level. Results: Administration of glutamate in PC12 cells in doses as low as 10 μM causes an up-regulation of GRP78, GRP94 and HSC70 protein levels, while their mRNA levels show the opposite kinetics. At the same time, GAPDH and GRP75 show reduced protein levels, irrespective of their transcriptional rate. On a cellular level, low concentrations of glutamate induce an autophagy-mediated pro-survival phenotype, which is further supported by induction of the autophagic marker LC3. Conclusion: The findings in the present study underline a discrete effect of glutamate on neuronal cell fate depending on its concentration. It was also shown that a low dose of glutamate orchestrates a unique expression signature of various chaperones and induces cell autophagy, which acts in a neuroprotective fashion.

Insulin-like growth factors sustain insulin-like growth factor-binding protein-5 expression in osteoblasts

1998 ◽  
Vol 275 (2) ◽  
pp. E222-E228
Author(s):  
Bari Gabbitas ◽  
Ernesto Canalis
Keyword(s):  
Growth Factors ◽  
Cell Function ◽  
Binding Protein ◽  
Bone Cell ◽  
Mrna Levels ◽  
Protein Levels ◽  
Basal Expression ◽  
Fetal Rat ◽  
Igf Binding ◽  
Insulin Like Growth Factors

Insulin-like growth factors (IGFs) I and II are considered to be autocrine regulators of bone cell function. Recently, we demonstrated that IGF-I induces IGF-binding protein-5 (IGFBP-5) expression in cultures of osteoblast-enriched cells from 22-day fetal rat calvariae (Ob cells). In the present study, we postulated that IGFs play an autocrine role in the maintenance of IGFBP-5 basal expression in Ob cells. IGFBP-2 and -3, at concentrations that bind endogenous IGFs, decreased IGFBP-5 mRNA levels, as determined by Northern blot analysis, and protein levels, as determined by Western immunoblots of extracellular matrix extracts of Ob cells. IGFBP-2 and -3 in excess inhibited IGFBP-5 heterogeneous nuclear RNA levels, as determined by RT-PCR, and did not alter the half-life of IGFBP-5 mRNA in transcriptionally arrested Ob cells. In conclusion, blocking endogenous IGFs in Ob cells represses IGFBP-5 expression, suggesting that IGFs are autocrine inducers of IGFBP-5 synthesis in osteoblasts.

An acid-stable insulin-like growth factor (IGF)-binding protein from pig serum inhibits binding of IGF-I and IGF-II to vascular endothelial cells

1989 ◽  
Vol 120 (2) ◽  
pp. 231-236 ◽  
Author(s):  
R. Gopinath ◽  
P. E. Walton ◽  
T. D. Etherton
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Binding Protein ◽  
Type I ◽  
Insulin Like Growth Factor ◽  
Igf Receptors ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Acid Stable

ABSTRACT The effects of a porcine insulin-like growth factor (IGF)-binding protein on binding of IGF-I and IGF-II to porcine aortic endothelial cells (PAEC) were determined. Binding of 125I-labelled IGF-I and -II to IGF receptors was inhibited by IGF-binding protein. IGF-binding protein inhibited binding of IGF-I and -II in a dose-dependent manner with half-maximal inhibition occurring at 5·43 and 108 μg/l respectively. A125I-labelled IGF-I–IGF-binding protein complex, formed by incubating 125I-labelled IGF-I with IGF-binding protein overnight at 4 °C, did not effectively bind to endothelial IGF receptors. Addition of IGF-binding protein to PAEC previously incubated with IGF-I caused a marked dissociation of bound IGF-I (47% dissociation within 12 h). These results indicate that the acid-stable IGF-binding protein which appears to be a part of the 150 kDa GH-dependent binding protein, blocks binding of IGF-I and -II by the IGF receptors and appears to exhibit a higher affinity for IGF-I than the endothelial type-I IGF receptor. The ramifications of this latter point with respect to transfer of circulating IGFs (bound to their IGF-binding proteins) across the vascular endothelium are not clear. Journal of Endocrinology (1989) 120, 231–236

scholarly journals Modulation of insulin-like growth factor (IGF) and IGF binding protein biosynthesis by hypoxia in cultured vascular endothelial cells

1998 ◽  
Vol 157 (1) ◽  
pp. 13-24 ◽  
Author(s):  
M Tucci ◽  
K Nygard ◽  
BV Tanswell ◽  
HW Farber ◽  
DJ Hill ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Binding Protein ◽  
Protein Biosynthesis ◽  
Cell Types ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

Endothelial cells (EC) are hypoxia-tolerant and their capacity to proliferate in low oxygen tension is essential to maintain vascular endothelium integrity. The present study addresses whether hypoxia alters the expression of insulin-like growth factor (IGF) and IGF binding protein (IGFBP) genes in bovine aortic EC (BAEC) and bovine pulmonary artery EC (BPAEC). EC were cultured in normoxic (21%) conditions and exposed to 0% oxygen for 24, 48, or 72 h; some cells were reoxygenated by exposure to 21% oxygen for 24 or 48 h following hypoxia. IGF-I peptide and mRNA levels were very low in both cell types, and decreased further with exposure to hypoxia. Ligand blotting showed that both cell types synthesized 24 kDa (IGFBP-4), 30 kDa (IGFBP-5 and/or IGFBP-6), 43 kDa and 48 kDa IGFBPs (IGFBP-3 glycosylation variants). IGFBP-4 was the predominant IGFBP expressed by both cell types and did not change with exposure to hypoxia. Hypoxia caused a significant increase in IGFBP-3 secretion in BPAEC but not in BAEC. IGFBP-3 stable mRNA levels in BPAEC were increased correspondingly. IGFBP-5 was expressed only in BAEC and decreased with exposure to hypoxia. IGFBP-6 mRNA expression was low and increased in both cell types with exposure to hypoxia. These results demonstrate that EC IGFBP baseline expression as well as its expression in hypoxia vary in different vascular beds and suggest that the IGFBPs may be the dominant paracrine regulators of proliferation of EC as well as maintenance of endothelium integrity during hypoxia.

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.

Effect of high-protein feed supplements on concentrations of growth hormone (GH), insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in plasma and on the amounts of GH and messenger RNA for GH in the pituitary glands of adult rams

1993 ◽  
Vol 138 (3) ◽  
pp. 421-427 ◽  
Author(s):  
I. J. Clarke ◽  
T. P. Fletcher ◽  
C. C. Pomares ◽  
J. H. G. Holmes ◽  
F. Dunshea ◽  
...  
Keyword(s):  
Binding Protein ◽  
Plasma Concentrations ◽  
High Protein ◽  
Mrna Levels ◽  
Igf I ◽  
Pituitary Glands ◽  
Igf Binding ◽  
Plasma Gh ◽  
Igf Binding Protein ◽  
Igfbp 3

ABSTRACT Three groups of mature rams were maintained on diets of hay, hay+2% lupin or hay+2% cowpea for 11 weeks. Serial blood samples were taken at 15-min intervals for 12 h for the determination of GH and IGF-I content by radioimmunoassay and for IGF-binding protein-3 (IGFBP-3) levels by Western blotting. The rams were killed after 77 days of supplementary feeding and their pituitary glands analysed for content of GH and GH mRNA. Mean plasma GH and baseline GH levels were significantly (P<0·01) decreased in the rams fed lupin and cowpea compared with controls fed hay and GH pulse amplitude was significantly (P<0·001) decreased in the group fed the cowpea diet. The frequency of GH pulses was not significantly altered by either treatment. Plasma concentrations of IGF-I were elevated in rams fed lupin (P<0·001) or cowpea (P<0·05). IGFBP-3 levels were not significantly (P>0·05) altered by either treatment. There were no significant differences in pituitary content of GH mRNA but pituitary content of GH was increased in rams fed lupin (P<0·05) and cowpea (P=0·07). In conclusion, a high-protein diet decreases plasma GH levels and increases IGF-I without changing plasma IGFBP-3 levels in rams. Thus ongoing synthesis of GH, as indicated by the mRNA levels, may cause a build up of GH stores in the pituitary gland. Journal of Endocrinology (1993) 138, 421–427

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