scholarly journals The juxtamembrane but not the carboxyl-terminal domain of the insulin receptor mediates insulin's metabolic functions in primary adipocytes and cultured hepatoma cells

2000 ◽  
Vol 24 (3) ◽  
pp. 419-432 ◽  
Author(s):  
K Paz ◽  
S Boura-Halfon ◽  
LS Wyatt ◽  
D LeRoith ◽  
Y Zick
Keyword(s):  
Insulin Receptor ◽  
Alternative Pathway ◽  
Insulin Binding ◽  
Hepatoma Cells ◽  
Metabolic Effects ◽  
Quantitative Expression ◽  
Metabolic Functions ◽  
Downstream Effectors ◽  
Carboxyl Terminal

Insulin-stimulated signaling pathways are activated upon interactions between the intracellular domains of the receptor and its downstream effectors. Insulin receptor substrate proteins (IRS-1, -2, -3 and -4) are the best-studied substrates for the insulin receptor kinase (IRK). We have previously shown that IRS-1 and IRS-2 interact with the juxtamembrane (JM) but not with the carboxyl-terminal (CT) region of the insulin receptor (IR) in vitro. However, the precise role of these IR regions in mediating insulin's bioeffects is still unresolved. In the present work we made use of vaccinia virus as a vector for quantitative expression of the JM and CT domains within the cytoplasm of physiologically insulin-responsive primary rat adipocytes and rat hepatoma Fao cells. We could demonstrate that overexpression of either the JM or the CT domains did not inhibit either insulin binding or insulin-stimulated receptor autophosphorylation. In contrast, metabolic effects such as insulin-induced glucose utilization in adipocytes, and insulin-induced amino acid utilization in Fao hepatoma cells were inhibited (70-80%) in cells overexpressing the JM but not the CT domains of IR. The inhibitory effects of the overexpressed JM domain were accompanied by inhibition of insulin-stimulated IRS-1 phosphorylation, decreased IRS-1-associated PI3K activity, and decreased phosphorylation of the downstream effectors of PI3K, PKB and p70 S6K. Insulin-stimulated thymidine incorporation in Fao cells was also inhibited (40%) upon overexpression of the JM but not the CT region of IR. Our findings suggest that interactions between the JM region of IR and its downstream effectors are obligatory for insulin-stimulated metabolic functions in physiologically relevant insulin responsive cells. They also rule out the possibility that interaction of proteins, including PI3K, with the CT domain can provide an alternative pathway.

scholarly journals Estradiol Binds to Insulin and Insulin Receptor Decreasing Insulin Binding in vitro

2014 ◽  
Vol 5 ◽  
Author(s):  
Robert Root-Bernstein ◽  
Abigail Podufaly ◽  
Patrick F. Dillon
Keyword(s):  
Insulin Receptor ◽  
Insulin Binding

scholarly journals Lipid-induced insulin resistance in cultured hepatoma cells is associated with a decreased insulin receptor tyrosine kinase activity.

1991 ◽  
Vol 2 (1) ◽  
pp. 65-72 ◽  
Author(s):  
P Hubert ◽  
C Bruneau-Wack ◽  
G Cremel ◽  
Y Le Marchand-Brustel ◽  
C Staedel
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Kinase Activity ◽  
Insulin Binding ◽  
Hepatoma Cells ◽  
Receptor Kinase ◽  
Insulin Receptor Tyrosine Kinase ◽  
Normal Medium ◽  
Insulin Receptor Kinase ◽  
Insulin Receptor Kinase Activity

We have shown previously that experimental modifications of the cellular lipid composition of an insulin-sensitive rat hepatoma cell line (Zajdela Hepatoma Culture, ZHC) affect both binding and biological actions of insulin. Discrepancies between insulin binding and actions implied a postbinding defect, responsible for the observed insulin resistance in lipid-treated cells. To elucidate the mechanism for this defect, we have studied insulin binding and insulin receptor kinase activity in partially purified receptor preparations from ZHC cells grown either in normal medium or in medium supplemented with linoleic acid or 25-hydroxycholesterol. Insulin binding to the lectin-purified insulin receptor showed only a small alteration in receptor affinity for the preparations from lipid-treated cells. Insulin-stimulated autophosphorylation of the beta-subunit of the insulin receptor, as well as insulin-induced phosphorylation of the artificial substrate poly(Glu,Tyr)4:1, was significantly decreased in the preparations from lipid-modified cells. Although differences in basal levels were observed, the magnitude of the insulin-stimulated kinase activity was significantly decreased in receptor preparations from lipid-treated cells. These findings indicate that experimental modification of the lipids of cultured hepatoma cells can produce in insulin receptor kinase activity changes that are proportional to the reduced insulin action observed in these cells.

In vitro regulation of human monocyte insulin receptors by insulin and 1-methyl-3-isobutylxanthine

1983 ◽  
Vol 245 (5) ◽  
pp. E494-E501
Author(s):  
R. H. Whitson ◽  
S. A. Kaplan
Keyword(s):  
Insulin Receptor ◽  
Cultured Cells ◽  
Phosphodiesterase Inhibitor ◽  
Insulin Receptors ◽  
Human Monocyte ◽  
Insulin Binding ◽  
Receptor Downregulation ◽  
Independent Process ◽  
Dose Dependent

Monocytes separated from human blood by Ficoll-Hypaque and adherence to polystyrene flasks were maintained successfully in culture for 7 days. The cultured cells showed normal morphology and good viability. The insulin binding properties of the cultured monocytes were also identical to those of fresh monocytes. In vitro pretreatment of the monocytes with insulin decreased both the number and affinity of insulin receptors, resulting in a 72% reduction in the binding of tracer quantities of 125I-insulin. Insulin-induced receptor down regulation was dose-dependent and specific to the insulin receptor. Monocytes pretreated with insulin in the presence of the cyclic nucleotide phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine (MIX) lost significantly fewer insulin receptors than monocytes treated with insulin alone. Tracer binding to these cells was 62% of control levels. MIX had no effect on basal insulin binding. The cAMP analogues N6,O2'-dibutyryl cAMP and 8-bromo-cAMP did not counteract insulin-induced receptor downregulation by themselves and did not significantly enhance the effects of MIX. These results indicate that MIX may counteract insulin receptor downregulation by a cAMP-independent process.

The Metabolic Effects of Nonvolatile Anesthetics on Mammalian Hepatoma Cells in Vitro

1971 ◽  
Vol 34 (5) ◽  
pp. 409-414 ◽  
Author(s):  
Stephen H. Jackson ◽  
Ralph A. Epstein
Keyword(s):  
Hepatoma Cells ◽  
Metabolic Effects

scholarly journals An Mr 180000 protein is an endogenous substrate for the insulin-receptor-associated tyrosine kinase in human placenta

1987 ◽  
Vol 243 (3) ◽  
pp. 797-801 ◽  
Author(s):  
F Machicao ◽  
H Häring ◽  
M F White ◽  
J M Carrascosa ◽  
B Obermaier ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Human Placenta ◽  
Insulin Binding ◽  
Specific Protein ◽  
Beta Subunit ◽  
Phosphorylated Proteins ◽  
Endogenous Substrate ◽  
32P Incorporation ◽  
Insulin Receptor Kinase

The beta-subunit of the insulin receptor contains a tyrosine-specific protein kinase. Insulin binding activates this kinase and causes phosphorylation of the beta-subunit of the insulin receptor. It is believed that phosphorylation of other proteins might transmit the insulin signal from the receptor to the cell. In the present study we used a polyclonal anti-phosphotyrosine antibody to detect other proteins that become tyrosine phosphorylated upon insulin stimulation. Glycoproteins from human placenta membranes were enriched by wheat germ agglutinin chromatography and phosphorylation was studied with [gamma-32P]ATP and insulin in vitro. Phosphorylated proteins were immunoprecipitated by antibodies against the insulin receptor and by serum containing the anti-phosphotyrosine antibody. Beside the insulin-stimulated phosphorylation of the 95 kDa beta-subunit of the insulin receptor, an insulin-stimulated phosphorylation of a 180 kDa protein was found. The phosphorylation of both proteins occurred only on tyrosine residues. Insulin increased 32P incorporation into the 180 kDa band 2.7-fold (S.E.M. +/- 0.3, n = 5). The 180 kDa protein was not precipitated by antibodies against the insulin receptor. H.p.l.c. chromatograms of tryptic fragments of the phosphorylated 180 kDa protein and of the beta-subunit of the insulin receptor revealed different patterns for both proteins. Insulin-stimulated phosphorylation of the 180 kDa protein was also detectable in unfractionated detergent-solubilized membranes. The phosphorylation of the 180 kDa protein was stimulated by insulin with the same dose-response curve as the phosphorylation of the beta-subunit, suggesting that this protein might be another endogenous substrate of the insulin receptor kinase.

scholarly journals Stepwise autophosphorylation regulates biased agonism of the insulin receptor

2019 ◽  
Author(s):  
Na-Oh Yunn ◽  
Mangeun Park ◽  
Jungeun Noh ◽  
Sung Ho Ryu
Keyword(s):  
Insulin Receptor ◽  
Mapk Pathway ◽  
Insulin Binding ◽  
Kinase Domain ◽  
Mitogen Activated Protein Kinase ◽  
Metabolic Effects ◽  
Intermediate Step ◽  
Peripheral Tissues ◽  
Biased Agonism ◽  
Mitogen Activated Protein

SummaryInsulin is a key regulator of energy metabolism in peripheral tissues but also functions as a growth factor. Insulin binding to the insulin receptor (IR) leads to autophosphorylation of intracellular tyrosine residues, which simultaneously initiates a multitude of signals and functions. In contrast, some artificial (non-insulin) ligands for the IR result in biased agonism, selectively activating the PI3K/AKT pathway and metabolic effects without activating mitogen-activated protein kinase (MAPK) pathway and mitogenic effects. However, the precise mechanism of biased agonism at the receptor level remains unclear. The biased agonist IR-A48 aptamer selectively induces mono-phosphorylation of Tyr1150 residue (m-pY1150) in the kinase domain of IR. Hence, we hypothesized that IR autophosphorylation is a stepwise process in which formation of m-pY1150 represents an intermediate step. To explore this idea, we used hybrid receptors in which insulin can bind only one of the two binding sites of the dimeric receptor. Asymmetric insulin binding selectively induced symmetric m-pY1150 in both kinase domains. Moreover, the juxtamembrane domain, which interacts with the kinase domain, restricted the full activation of IR, and symmetric m-pY1150 played a crucial role in the rearrangement of intracellular domains to release this restriction. Our findings demonstrate that the symmetry of insulin binding to a dimeric receptor determines the stepwise autophosphorylation of IR. Furthermore, considering that the degree of ligand symmetry on a receptor depends mainly on ligand concentration, our results suggest that IR may play metabolic-biased roles in peripheral tissues dependent on local insulin concentrations.

Metformin ameliorates extreme insulin resistance in a patient with anti-insulin receptor antibodies: description of insulin receptor and postreceptor effects in vivo and in vitro

1992 ◽  
Vol 126 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Salvatore Di Paolo
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Glucose Transport ◽  
Insulin Binding ◽  
Severe Insulin Resistance ◽  
Binding Data ◽  
Extreme Insulin Resistance ◽  
Receptor Antibodies

The effect of metformin on insulin binding and insulin action in the presence of anti-insulin receptor antibodies was investigated in a case of type B extreme insulin resistance. Oral administration of metformin (1 500 mg/d) for 10 days significantly decreased plasma blood glucose and insulin levels and enhanced the hypoglycemic response to exogenous insulin. In vitro preincubation of normal erythrocytes with insulin receptor antibody from the patient plus 4× 10−5 mol/l metformin markedly enhanced insulin binding to receptors, compared to cells incubated with antibody alone. This effect was apparent after 2 h, was maximal after 4 h and did not change up to 24 h. Closely similar results were found when human adipocytes were studied. Analysis of binding data confirmed the increase in both receptor number and affinity. One hour exposure of control adipocytes to metformin enhanced basal lipogenesis by more than 30%. Acute exposure of fat cells to the patient's receptor antibodies resulted in a stimulation of glucose transport and a state of severe insulin resistance. The addition of metformin to antibody in preincubation buffer strongly enhanced basal glucose incorporation into lipids, but did not prevent insulin unresponsiveness. It is suggested that metformin increases, possibly through a change in the spatial conformation of insulin receptor within the plasma membrane, the availability of preexisting receptors to insulin binding and/or decreases the availability of specific epitopes to antibody anchoring. Further, in the model of insulin resistance described here, metformin enhanced the basal rate of glucose transport through a direct insulin-mimicking activity and/or a potentiation of the sensitivity of glucose transport to the antibody.

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