scholarly journals Insulin receptor is phosphorylated in response to treatment of HepG2 cells with insulin-like growth factor I

1990 ◽  
Vol 270 (1) ◽  
pp. 27-32 ◽  
Author(s):  
V Duronio
Keyword(s):  
Growth Factor ◽  
Insulin Receptor ◽  
Hepg2 Cells ◽  
Insulin Binding ◽  
Response To Treatment ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I ◽  
In Cells

1. Binding of insulin and insulin-like growth factor I (IGF-I) to HepG2 cells was analysed with regard to competition by both insulin and IGF-I. At concentrations of insulin that caused maximal phosphorylation of the insulin receptor, virtually no displacement of IGF-I binding was observed. Similarly, at concentrations of IGF-I that caused maximal phosphorylation of the IGF-I receptor, no displacement of insulin binding was observed. 2. When the phosphorylation of both receptors was examined individually by using specific monoclonal antibodies to immunoprecipitate the receptors, phosphorylation of the insulin receptor was found to increase on both serine and tyrosine residues in cells treated with 100 ng of IGF-I/ml. In contrast, no increased phosphorylation of IGF-I receptor was observed in cells treated with 100 ng of insulin/ml. 3. The increase in phosphorylation of insulin receptor in response to IGF-I correlated with the dose-response of IGF-I-stimulated phosphorylation of the IGF-I receptor. 4. The IGF-I-stimulated phosphorylation of the insulin receptor could be blocked by preincubation with a monoclonal antibody that blocks IGF-I binding to the IGF-I receptor.

Insulin-Like Growth Factor I (IGF-I) and Insulin Binding to Erythrocytes of Normal Prepubertal Children and Adults

1991 ◽  
Vol 23 (11) ◽  
pp. 545-552 ◽  
Author(s):  
C. Dooghe ◽  
G. Grizard ◽  
A. Labbe ◽  
D. Dardevet ◽  
M. Meyer ◽  
...  
Keyword(s):  
Growth Factor ◽  
Insulin Binding ◽  
Insulin Like Growth Factor ◽  
Prepubertal Children ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

Negative cooperativity in the insulin-like growth factor-I receptor and a chimeric IGF-I/insulin receptor.

Endocrinology ◽  
1994 ◽  
Vol 135 (1) ◽  
pp. 472-475 ◽  
Author(s):  
C T Christoffersen ◽  
K E Bornfeldt ◽  
C M Rotella ◽  
N Gonzales ◽  
H Vissing ◽  
...  
Keyword(s):  
Growth Factor ◽  
Insulin Receptor ◽  
Negative Cooperativity ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

scholarly journals Dephosphorylation of human insulin-like growth factor I (IGF-I) receptors by membrane-associated tyrosine phosphatases

1992 ◽  
Vol 285 (1) ◽  
pp. 71-78 ◽  
Author(s):  
P Peraldi ◽  
S Hauguel-de Mouzon ◽  
F Alengrin ◽  
E Van Obberghen
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Insulin Receptor ◽  
Dependent Manner ◽  
Insulin Like Growth Factor ◽  
Tyrosine Phosphatases ◽  
Insulin Receptor Tyrosine Kinase ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

The insulin-like growth factor-I (IGF-I) receptor exhibits structural and functional similarities to the insulin receptor. Although the regulation of the insulin-receptor tyrosine kinase has been extensively investigated, the mechanisms involved in phosphorylation/dephosphorylation of the IGF-I receptor have received only little attention. To obtain a better understanding of the mode of IGF-I action, we have investigated the effects of protein phosphotyrosine phosphatases (PTPases) on the phosphorylation status of the IGF-I receptor. The dephosphorylation of the human IGF-I receptor by membrane-associated tyrosine phosphatases was studied by an immuno-enzymic assay based on the recognition of phosphotyrosine residues by anti-phosphotyrosine antibodies. Using intact IGF-I receptors as substrates, we show that they could be completely dephosphorylated by different cellular PTPases. Three pieces of evidence indicate that receptor dephosphorylation takes place on phosphotyrosine, i.e. the inhibition profile of phosphatase activity by zinc and vanadate, its absolute requirement for thiol compounds and the diminution of [32P]phosphotyrosine labelling of the beta subunit assessed by SDS/PAGE and phosphoamino acid analysis. Tyrosine kinase activity and autophosphorylation of the IGF-I receptor were decreased in a dose-dependent manner by PTPases, indicating that partial dephosphorylation of the receptor was associated with a decrease in its intrinsic activity. The sensitivity of the activated human IGF-I receptor to dephosphorylation on tyrosine leads to the speculation that IGF-I receptor activity might be regulated by mechanisms such as those described for the insulin receptor. Further investigation of the pathways of IGF-I receptor dephosphorylation will contribute to define the role(s) of PTPases in the overall mechanism of IGF-I signalling.

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.

Severe resistance to insulin and insulin-like growth factor-I in cells from a patient with leprechaunism as a result of two mutations in the tyrosine kinase domain of the insulin receptor

Metabolism ◽  
1996 ◽  
Vol 45 (12) ◽  
pp. 1493-1500 ◽  
Author(s):  
Christèle Desbois-Mouthon ◽  
Claude Danan ◽  
Serge Amselem ◽  
Marie-José Blivet-Van Eggelpoel ◽  
Caroline Sert-Langeron ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Insulin Receptor ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Resistance To Insulin ◽  
Growth Factor I ◽  
In Cells

scholarly journals Insulin-like growth factor-I-induced DNA synthesis in insulin-secreting cell line RINm5F is associated with phosphorylation of the insulin-like growth factor-I receptor and the insulin receptor substrate-2

1998 ◽  
Vol 156 (3) ◽  
pp. 573-581 ◽  
Author(s):  
Q Zhang ◽  
PO Berggren ◽  
A Hansson ◽  
M Tally
Keyword(s):  
Growth Factor ◽  
Dna Synthesis ◽  
Insulin Receptor ◽  
Cell Line ◽  
Insulin Receptor Substrate ◽  
Insulin Like Growth Factor ◽  
Rinm5f Cells ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

A proliferative effect of insulin-like growth factor-I (IGF-I) was previously shown in pancreatic islets. However, the mechanism under which IGF-I actions are exerted in insulin-secreting cells is not clear. The rat insulinoma cell line, RINm5F, was shown to have both IGF-I receptors and IGF-Il/mannose-6-phosphate receptors. IGF-I binding to cell surface receptors stimulated phosphorylation of 97 kDa and 93 kDa subunits of the IGF-I receptor and incorporation of [3H]thymidine into RINm5F cells. Both the IGF-I-induced protein phosphorylation and [3H]thymidine incorporation were abolished in the presence of the tyrosine kinase inhibitor, genistein. Under basal conditions, IGF-I did not induce insulin release or changes in cytosolic free Ca2+ concentration. Immunoprecipitation of proteins from RINm5F cells, using phosphotyrosine antibodies, followed by western blotting using antibody against IRS-1 revealed no distinct band of phosphorylated insulin receptor substrate (IRS)-1. Instead, tyrosine-phosphorylated IRS-2 was detected and stimulated by IGF-I when western blotting was performed using antibody against IRS-2. These results indicate that IRS-1 is not likely to be involved in IGF-I signalling in RINm5F cells. Hence, IGF-I stimulated DNA synthesis in RINm5F cells was associated with phosphorylation of IGF-I receptors and IRS-2.

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