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

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Insulin resistance in uremia: insulin receptor kinase activity in liver and muscle from chronic uremic rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1988.254.4.e394 ◽

1988 ◽

Vol 254 (4) ◽

pp. E394-E401 ◽

Cited By ~ 10

Author(s):

F. Cecchin ◽

O. Ittoop ◽

M. K. Sinha ◽

J. F. Caro

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Receptor ◽

Kinase Activity ◽

Insulin Binding ◽

Beta Subunit ◽

Receptor Kinase ◽

Ad Libitum ◽

Insulin Receptor Kinase ◽

Insulin Receptor Kinase Activity

We have studied the structure and function of the partially purified insulin receptors from liver and skeletal muscle in a rat model of severe chronic uremia. 125I-insulin binding was higher in the liver from uremic rats when compared with ad libitum- and pair-fed controls. Furthermore, the ability of insulin to stimulate the autophosphorylation of the beta-subunit and insulin receptor kinase activity using Glu80, Tyr20 as exogenous phosphoacceptor was increased in the liver of the uremic animals. The structural characteristic of the receptors, as determined by electrophoretic mobilities of affinity labeled alpha-subunit and the phosphorylated beta-subunit, were normal in uremia. 125I-insulin binding and insulin receptor kinase activity were similar in the skeletal muscle from uremic and pair- and ad libitum-fed animals. Thus our data are supportive of the hypothesis that in liver and muscle of chronic uremic rats, insulin resistance is due to a defect(s) distal to the insulin receptor kinase.

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Effect of a high-fat-sucrose diet on in vivo insulin receptor kinase activation

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.259.1.e111 ◽

1990 ◽

Vol 259 (1) ◽

pp. E111-E116 ◽

Cited By ~ 1

Author(s):

J. J. Boyd ◽

I. Contreras ◽

M. Kern ◽

E. B. Tapscott ◽

D. L. Downes ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Glucose Uptake ◽

Kinase Activity ◽

Insulin Binding ◽

Receptor Kinase ◽

High Fat ◽

Glucose Injection ◽

Insulin Receptor Kinase

Insulin-stimulated glucose uptake into muscle is depressed by high-fat-sucrose (HFS) feeding of rats. To investigate the mechanism of this insulin resistance, the in vivo activation of the insulin receptor kinase in liver and muscle of control and HFS-fed rats was determined. Rats were injected with glucose and insulin and killed 0, 5, 15, and 30 min after injection. Insulin binding was not changed in partially purified receptors from muscle of HFS rats. In control rats insulin receptor kinase activity was maximally stimulated threefold in liver at 5 min and fourfold in muscle at 15 min after insulin-glucose injection. The insulin-stimulated tyrosine kinase activity of receptors isolated from the liver of rats fed the HFS diet was decreased by 30% in comparison with the controls. In contrast, receptors isolated from muscle did not show any difference in basal or insulin-stimulated kinase activity between HFS-fed and control rats. Decreased in vivo activation of the insulin receptor kinase may be at least partially responsible for insulin resistance in liver. Because insulin binding and insulin stimulation of receptor kinase were normal in muscle of HFS-fed animals, it is concluded that the insulin resistance of glucose uptake into muscle is caused by a defect distal to the insulin receptor.

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The inhibition of insulin action and glucose metabolism by porcine growth hormone in porcine adipocytes is not the result of any decrease in insulin binding or insulin receptor kinase activity

Biochemical Journal ◽

10.1042/bj2660107 ◽

1990 ◽

Vol 266 (1) ◽

pp. 107-113 ◽

Cited By ~ 51

Author(s):

K A Magri ◽

M Adamo ◽

D Leroith ◽

T D Etherton

Keyword(s):

Insulin Receptor ◽

Glucose Transport ◽

Kinase Activity ◽

Insulin Binding ◽

Transport Rate ◽

Receptor Kinase ◽

Insulin Responsiveness ◽

Porcine Adipocytes ◽

Insulin Receptor Kinase ◽

Insulin Receptor Kinase Activity

The present study was undertaken to determine the effects of porcine growth hormone (pGH) on glucose transport, to establish which lipogenic enzymes were affected by pGH, and to determine if changes in insulin binding or insulin receptor kinase activity contributed to the diminished insulin responsiveness of adipocytes from pigs treated with pGH. Pigs were treated with pGH daily (70 micrograms/kg body wt.) for 7 days. pGH treatment reduced the basal (non-insulin-stimulated) glucose transport rate by 62% and the insulin-stimulated transport rate by 47%. The decline in glucose transport rate was paralleled by a 64% decrease in fatty acid synthesis. The reduction in the lipogenic rate was associated with a marked decline in the activity of several lipogenic enzymes: glucose-6-phosphate dehydrogenase (50% decrease), 6-phosphogluconate dehydrogenase (11% decrease), malic enzyme (62% decrease) and fatty acid synthase (activity not detectable after pGH treatment). The pGH-dependent decline in insulin responsiveness was not associated with any change in the binding of insulin to intact adipocytes or to plasma membrane preparations. The insulin-stimulated tyrosine kinase activity of the wheat-germ agglutinin-purified receptors from pGH-treated adipocytes was not different from that in control adipocytes, except when high concentrations of insulin were employed. These findings establish that pGH elicits a number of metabolic effects in porcine adipocytes which collectively diminish the rate of lipid synthesis, and thereby contribute to the decrease in lipid deposition observed in pGH-treated pigs. Furthermore, the pGH-dependent impairment in insulin action appears to be mediated at some location distal to the receptor kinase step or in other signal pathway(s) which mediate the biological effects of insulin that are not dependent on activation of insulin receptor tyrosine kinase activity.

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Insulin receptor kinase activity in muscles and white adipose tissue during course of VMH obesity

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1992.262.2.e161 ◽

1992 ◽

Vol 262 (2) ◽

pp. E161-E166 ◽

Cited By ~ 1

Author(s):

A. Pujol ◽

B. Cousin ◽

A. F. Burnol ◽

M. Loizeau ◽

L. Picon ◽

...

Keyword(s):

Adipose Tissue ◽

Insulin Receptor ◽

White Adipose Tissue ◽

Kinase Activity ◽

Insulin Receptors ◽

Ventromedial Hypothalamus ◽

Receptor Kinase ◽

Insulin Receptor Tyrosine Kinase ◽

Insulin Receptor Kinase ◽

Insulin Receptor Kinase Activity

Early after lesion of the ventromedial hypothalamus nuclei (VMH), insulin-induced glucose utilization is increased in white adipose tissue (WAT), whereas oxidative and glycolytic muscles are, respectively, normoresponsive or resistant to insulin. Five weeks later, all of the muscles are resistant, whereas WAT returns to normal responsiveness. The aim of this study was to characterize the insulin receptor kinase activity in WAT and muscles 1 and 6 wk after lesion. The number and affinity of insulin receptors were not modified in any of the tissues studied. Autophosphorylation and phosphorylation of an exogenous substrate were similar in oxidative and glycolytic muscles of VMH and control rats both 1 and 6 wk after the lesion. Insulin receptors from WAT of 1-wk VMH rats exhibited a 2.5-fold increase in insulin-stimulated autophosphorylation and phosphorylation. Six weeks after the lesion, both autophosphorylation and phosphorylation returned to normal values. This suggests that insulin receptor tyrosine kinase activity does not play a significant role in the insulin resistance of skeletal muscles but has a crucial role in mediating the variations of insulin action on WAT observed during the development of VMH obesity.

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