Transcriptional and post-translational regulation of insulin-like growth factor-binding protein-5 in rat articular chondrocytes

1996 ◽  
Vol 148 (2) ◽  
pp. 355-369 ◽  
Author(s):  
T Matsumoto ◽  
S E Gargosky ◽  
Y Oh ◽  
R G Rosenfeld
Keyword(s):  
Growth Factor ◽  
Articular Chondrocytes ◽  
Primary Cultures ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Igf I ◽  
Igf Receptor ◽  
Dose Dependent

Abstract The aim of this study was to assess the regulation of insulin-like growth factor-binding proteins (IGFBPs) by IGFs in primary cultures of rat articular chondrocytes (RAC). Employing Western ligand blotting, immunoprecipitation and Northern blot analysis, RAC were found to secrete IGFBP-5 (29 kDa) and IGFBP-4 (24 kDa) as the predominant IGFBPs, as well as IGFBP-2 (32–30 kDa) and IGFBP-3 (43–39 kDa) as the minor species. Treatment of cells with IGF-I and IGF-II resulted in a dose-dependent increase of IGFBP-5 and a small increase in IGFBP-4 in conditioned media (CM). Des(1–3) IGF-I and [Gln6, Ala7,Tyr18, Leu19] IGF-II ([QAYL] IGF-II), which bind to the type 1 IGF receptor but not to IGFBPs, also induced IGFBP-5 peptide, although the increase was less than with IGF-I or IGF-II treatment of RAC. [Leu27] IGF-II, which does not bind to the type 1 IGF receptor but binds to IGFBPs, resulted in little induction of IGFBP-5, while [QAYL-Leu27] IGF-II, which has reduced affinity for both the type 1 IGF receptor and IGFBPs, did not increase IGFBP-5. These data suggest that the increase in IGFBP-5 in CM is modulated by both the type 1 IGF receptor and the interaction between IGFs and IGFBPs. Northern blotting analysis showed that IGF-I, IGF-II and des(1–3) IGF-I treatment of RAC increased steady state levels of IGFBP-5 mRNA, suggesting that the IGF-mediated increase in IGFBP-5 is transcriptionally modulated. Interestingly, the increase in IGFBP-5 peptide levels and mRNA were not parallel, suggesting the possibility of post-translational modifications of IGFBP-5, such as those seen with IGFBP-5 protease. IGFBP-5 protease activity was detectable in untreated CM, whereas treatment with IGF-I and IGF-II partially protected IGFBP-5 from proteolysis. In summary, treatment of RAC with IGF-I and IGF-II results in dose-dependent increases in both IGFBP-5 peptide in the CM and mRNA levels. These changes are mediated by interactions via the type 1 IGF receptor as well as IGFBPs, both transcriptionally and post-translationally. Journal of Endocrinology (1996) 148, 355–369

scholarly journals The C Region of Human Insulin-like Growth Factor (IGF) I Is Required for High Affinity Binding to the Type 1 IGF Receptor

1989 ◽  
Vol 264 (19) ◽  
pp. 11004-11008 ◽  
Author(s):  
M L Bayne ◽  
J Applebaum ◽  
D Underwood ◽  
G G Chicchi ◽  
B G Green ◽  
...  
Keyword(s):  
Growth Factor ◽  
Human Insulin ◽  
Affinity Binding ◽  
Insulin Like Growth Factor ◽  
High Affinity Binding ◽  
High Affinity ◽  
Igf I ◽  
Igf Receptor

scholarly journals Insulin-like growth factor (IGF) receptor, IGF-I, interleukin-1 beta (IL-1 beta), and IL-6 mRNA expression in osteoarthritic and normal human cartilage.

1996 ◽  
Vol 44 (2) ◽  
pp. 133-141 ◽  
Author(s):  
J Middleton ◽  
A Manthey ◽  
J Tyler
Keyword(s):  
Extracellular Matrix ◽  
Growth Factor ◽  
Interleukin 1 ◽  
Insulin Like Growth Factor ◽  
Interleukin 1 Beta ◽  
Normal Cartilage ◽  
Igf I ◽  
Cartilage Cells ◽  
Igf Receptor

Insulin-like growth factor-I (IGF-I) stimulates the production of extracellular matrix by cartilage cells and this action is mediated through the Type 1 IGF receptor. Expression of the genes for the IGF receptor and for IGF-I was examined in normal and osteoarthritic (OA) human articular cartilage by in situ hybridization. RNA transcripts for Type 1 receptor were detected in all 73 tissue samples and in 80-100% of chondrocytes per section. Signal for the receptor was present in normal and OA cells, and the highest message levels were in the tissues exhibiting advanced pathology. Strong message signals in the cells of the more advanced lesions were also noted for IGF-I, whereas little or no IGF-I mRNA was detected in normal samples. Interleukin-1 beta (IL-1 beta) induces degradation of extracellular matrix by cartilage cells, and expression of this gene was examined with digoxygenin-labeled oligonucleotide probes. mRNA transcripts were detected in only one in five of the cartilage samples taken from OA joints. Unlike IGF-I, expression did not correlate with the degree of OA pathology and positive cells were demonstrated also in samples from young normal cartilage. IL-6 mRNA was present both in surface and deep cells of fibrillated OA cartilage, but no signal was evident in histologically normal cartilage from OA tissue or in normal young joints.

Characteristics of binding of insulin-like growth factor (IGF)-I and IGF-II analogues to the type 1 IGF receptor determined by BIAcore analysis

2002 ◽  
Vol 269 (3) ◽  
pp. 961-968 ◽  
Author(s):  
Briony E. Forbes ◽  
Perry J. Hartfield ◽  
Kerrie A. McNeil ◽  
Kathy H. Surinya ◽  
Steven J. Milner ◽  
...  
Keyword(s):  
Growth Factor ◽  
Insulin Like Growth Factor ◽  
Igf I ◽  
Igf Receptor

Insulin-like growth factor (IGF)-I A- and B-domain analogues with altered type 1 IGF and insulin receptor binding specificities

1996 ◽  
Vol 17 (3) ◽  
pp. 237-246 ◽  
Author(s):  
G K Shooter ◽  
B Magee ◽  
M A Soos ◽  
G L Francis ◽  
K Siddle ◽  
...  
Keyword(s):  
Growth Factor ◽  
Insulin Receptor ◽  
Receptor Binding ◽  
Insulin Like Growth Factor ◽  
Receptor Isoforms ◽  
Insulin Receptor Isoforms ◽  
Igf I ◽  
Igf Receptor ◽  
Specificity Of Binding

ABSTRACT Insulin-like growth factor-I (IGF-I) analogues were produced with the aim of identifying IGF-I residues that contribute to the specificity of binding to the type 1 IGF receptor as opposed to the insulin receptor. Receptor binding properties of a series of A- and B-domain analogues were compared using rat L6 myoblasts, soluble human IGF type 1 receptors and soluble human insulin receptor isoforms HIR-A (−Ex11) and HIR-B (+Ex11). IGF-I analogues, [Leu8] IGF-I and [Phe59] IGF-I, were shown to exhibit respectively, a 28- and 17-fold decrease in affinity for the HIR-A with only a 6- and 5-fold decrease in affinity for the human IGF type 1 receptor. In contrast, the analogue [His4] IGF-I was equipotent to IGF-I in binding to the soluble type 1 IGF receptor while showing 7-fold and 4-fold increases in HIR-A and HIR-B binding respectively. Furthermore, [Leu62] IGF-I was 8-fold less potent than IGF-I in soluble IGF type 1 receptor binding but only showed a 2-fold decrease in HIR-A and HIR-B binding. Our study supports the conclusion that the co-evolution of the IGF-I and insulin receptor/ligand systems has resulted in subtle structural differences in the A- and B-regions of each ligand important for defining receptor binding specificity.

Differential regulation by TGF-beta 1 and insulin of insulin-like growth factor binding protein-2 in IEC-6 cells

1995 ◽  
Vol 268 (6) ◽  
pp. E1199-E1204
Author(s):  
Y. S. Guo ◽  
C. M. Townsend ◽  
G. F. Jin ◽  
R. D. Beauchamp ◽  
J. C. Thompson
Keyword(s):  
Growth Factor ◽  
Inhibitory Action ◽  
Binding Protein ◽  
High Dose ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Tgf Beta ◽  
Factor Binding ◽  
Growth Inhibitory ◽  
Igf I

The purposes of this study were to determine the regulation of insulin-like growth factor binding protein-2 (IGFBP-2) in IEC-6 cells by transforming growth factor-beta 1 (TGF-beta 1) and insulin and to determine whether IGFBP-2 mediated the growth-inhibitory action on the cells. Utilizing Western ligand blot analysis, we found that TGF-beta 1 at concentrations of 0.5, 1.0, and 2 ng/ml significantly increased levels of 32-kDa IGFBP in the conditioned medium (CM) of IEC-6 cells in a dose-dependent fashion and that low doses of insulin (1.0 and 5.0 microgram/ml) also increased IGFBP levels in the CM of IEC-6 cells, but a high dose of insulin (10 micrograms/ml) depressed IGFBP release in the CM. Immunoblotting has shown that the IGFBP of 32 kDa was IGFBP-2 and further confirmed the above results. IGFBP-2 mRNA levels were stimulated by TGF-beta 1 (2.0 ng/ml) and suppressed by insulin (5.0 micrograms/ml). In addition, des (1–3) IGF-I (50 ng/ml) and insulin stimulated the proliferation of IEC-6 cells. Anti-IGFBP-2 antibodies partially blocked the inhibitory role in IEC-6 cell growth evoked by des (1–3) IGF-I. These findings suggest that the upregulation of IGFBP-2 by TGF-beta 1 occurs, at least in part, at the level of mRNA, whereas the regulation by insulin appears to be at a posttranslational level, and that the TGF-beta 1-stimulated production of IGFBP may contribute to the growth-inhibitory action in intestinal epithelial cells.x

Growth hormone (GH) modulates insulin-like growth factor I (IGF-I) and type I IGF receptor mRNA levels in the ovary of prepubertal GH-deficient rats

1995 ◽  
Vol 132 (4) ◽  
pp. 497-501 ◽  
Author(s):  
Saul Malozowski ◽  
Toni G Parmer ◽  
Sabina Trojan ◽  
George R Merriam ◽  
Geula Gibori ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Type I ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Receptor Mrna ◽  
Type I Igf Receptor ◽  
Igf I ◽  
Igf Receptor

Malozowski S, Parmer TG, Trojan S, Merriam GR, Gibori G, Roberts Jr CT, LeRoith D, Werner H, Zilberstein M. Growth hormone (GH) modulates insulin-like growth factor I (IGF-I) and type I IGF receptor mRNA levels in the ovary of prepubertal GH-deficient rats. Eur J Endocrinol 1995;132:497–501. ISSN 0804–4643 In order to explore the potential role of growth hormone (GH) in modulating insulin-like growth factor I (IGF-I) gene expression in the prepubertal rat ovary, female rats were rendered GH deficient by neonatal administration of monosodium glutamate (MSG). One group of rats received vehicle and served as the control. At 21 days of age, MSG-treated rats received either GH or vehicle for 2 weeks. On days 21, 24, 28 and 31 animals were weighed and subsets were sacrificed for liver RNA extraction. The remaining animals were sacrificed at day 35 when livers and ovaries were collected, and serum was obtained for GH determinations. The IGF-I mRNA levels were estimated by Northern blots and corroborated further by slot-blot analysis. The MSG-treated rats had lower body weights (p < 0.01) and GH levels (p < 0.05) than controls. Growth hormone replacement significantly accelerated the weight gain of MSG-treated rats. At day 24 and thereafter, three RNA IGF-I species (7.5, 1.8 and 0.8–1.2 kB) were seen in the liver. In the ovary, at age 35 days, two major IGF-I mRNA species (7.5 and 0.8–1.2kb) were seen. The MSG treatment consistently reduced the levels of both IGF-I mRNA species in the ovary. Growth hormone administration partially restored their expression, both in the liver and in the ovary. In addition, ovarian type I IGF receptor mRNA levels were increased in the MSG-treated rats when compared to controls. This trend was reversed by GH replacement. In summary, we have found that in prepubertal female rats rendered GH deficient with MSG, ovarian IGF-I gene expression is reduced while type I IGF receptor mRNA levels are increased. These findings are reversed with GH replacement. These results suggest a physiological role for GH in modulating IGF-I and type I IGF receptor genes in the ovary. Saul Malozowski, FDA, HFD-510, Rockville, MD 20897, USA

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