Regulation of insulin receptors in erythroid cells

Ginsberg, Barry H.; Brown, Thomas J.

doi:10.1016/0026-0495(82)90205-0

Cited by 15 publications

(8 citation statements)

References 21 publications

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“…Our data are in agreement with those of Ginsberg and Brown [3], These authors dem onstrated the inhability of mature RBC, but not of immature crythroid cells, to reduce the 1R number after a 16-hour incubation with insulin (10~8 mol/1). Our data are in agreement with the idea that down-regulation requires active protein synthesis [1,2], The changes that occur in plasma membranes and intracel lular organelles [18,19] during red cell matu ration can then explain the mature RBC inha bility to down-regulate insulin receptors.…”

Section: Discussionsupporting

confidence: 83%

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Insulin Receptor Regulation in Human Mature Red Cells in vitro

Gherzi¹,

Andraghetti²,

Adezati³

et al. 1985

Horm Res

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We have studied the ability of mature red cells to regulate the number and affinity of their insulin receptors, in vitro. Our data show that mature red cells are not able to change either the number and the affinity of their insulin receptors, after preincubation with high concentrations of insulin alone or insulin and glucose. We conclude that mature red cells possess an insulin receptor system not completely similar to that of major target cells such as hepatocytes and adipocytes, and therefore we suggest some criticism in evaluating these cells in clinical studies, regarding the insulin receptor status.

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Section: Discussionsupporting

confidence: 83%

“…This datum is in agreement with the findings of Ginsberg and Brown [3] that were unable to show any down regula tion in human RBC, as in all other cells unable to synthetize protein like avian eryth rocytes [3]. On the other hand, recently, Pe terson el al.…”

Section: Introductionsupporting

confidence: 80%

Insulin Receptor Regulation in Human Mature Red Cells in vitro

Gherzi¹,

Andraghetti²,

Adezati³

et al. 1985

Horm Res

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“…Insulin binding has been shown to be high in imma ture red cells [36,37], Therefore, we took particular care to minimize the presence of reticulocytes in our red cell suspensions.…”

Section: Discussionmentioning

confidence: 99%

Insulin Binding and Glycolytic Activity in Erythrocytes from Dialyzed and Nondialyzed Uremic Patients

Weisinger¹,

Contreras²,

Cajias³

et al. 1988

Nephron

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Insulin resistance in uremia has been attributed to impaired hormone-receptor binding or to postbinding defects. Oral glucose tolerance tests, insulin binding, and in vitro glycolytic activity were studied in purified red blood cells from normal control subjects (C) and from uremic patients belonging to three groups: nondialyzed (U), on chronic hemodialysis (HD), and on continuous ambulatory peritoneal dialysis (CAPD). Glucose intolerance and hyperinsulinemia were demonstrated in all groups of patients. Maximal specific binding of ¹²⁵I-insulin to erythrocytes, kinetically derived receptor numbers per cell, and affinity constants for insulin binding did not differ between control and patient groups. No correlation was found between the degree of glucose intolerance and insulin binding parameters. Basal lactate production by erythrocytes incubated invitro was significantly higher in U and HD patients than in Cwhereas CAPD patients did not differ from C in this respect. Addition of 1 mI dibutiryl-cAMP and 0.5 mM isobutyl-methyl-xanthine during incubation of erythrocytes caused an increase in the rate of lactate production that was similar in magnitude in the U, HD and C groups, whereas cells from CAPD subjects showed a significantly larger absolute response to these compounds after 1 h of incubation. There was no evidence of impairment of glycolytic capacity in red blood cells from uremic patients. In addition, no correlation was found between the degree of glucose intolerance and basal or stimulated lactate production by erythrocytes. Our results obtained in human erythrocytes suggest that the insulin resistance observed in uremia does not involve a defect in hormone binding or in the intracellular capacity to utilize glucose through glycolysis.

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“…They are capable of limited protein synthesis due to performed mRNA, although they cannot synthesize mRNA [10]. Thus, Bihr et al should not have seen insulin internalization in reticulocytes.…”

Section: Insulin Internalization In Human Erythrocytesmentioning

confidence: 99%

Insulin internalization in human erythrocytes

Nerurkar¹,

Gambhir

1984

Diabetologia

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Insulin internalization in human erythrocytesDear Sir, In a recent Letter to the Editor, Bihr et al.[1] concluded from their studies that "(1) insulin binding is not necessarily followed by internalization of insulin; (2) only cells with nuclei internalize insulin; (3) insulin may well exert different effects on intracellular metabolism depending upon nuclei content; and (4) reticulocytes that can internalize insulin might be of importance concerning the rate of insulin degradation in circulating blood."In contrast with these suggestions, we take the following view. Bihr et al. used electron microscopy to show insulin internalization in blood cells [1]. Prior to this technique, biochemical methods involving receptor down-regulation in vitro pioneered studies of insulin internalization [2]. Unlike electron microscopy, the biochemical methods can evaluate various physiological actions involved in insulin receptor down-regulation and insulin internalization [3]. These biochemical studies are equally important and should be considered simultaneously before arriving at any conclusion from electron microscopic studies of insulin internalization.The first conclusion by Bihr et al was apparently based upon electron microscopic observations of insulin bound to human erythrocytes. They did not specify the temperature and incubation time for insulin binding prior to the observation.However, binding is similar at 0 ~ and 4 ~ for both nucleated cells [4] and human erythrocytes. We have shown that 91% 98% of bound insulin at 4 ~ is extractable and the extractable insulin is intact [5]. At 15 ~ after 3.5 h of binding, 80% of bound insulin is extractable and 60% of the extractable insulin is intact, while at 37 ~ with increasing time of incubation, the extractability of cell-bound insulin and the proportion of intact, undegraded, extractable insulin decreases. Since the degradation of insulin in these erythrocytes can only be by cytosolic enzyme [7], degradation is a measure of internalization. Thus, these findings clearly show that insulin internalization is time-and temperature-dependent in human erythrocytes.In contrast with the second conclusion of Bihr et al.[1], our published data [5][6][7][8] provided the following evidence of insulin internalization by human erythrocytes at 37~ (a) human erythrocyte cell membranes lack an insulin degrading enzyme [6]; (b) there is a very specific and potent insulin degrading enzyme in cell cytosol (7.8); (c) there is a time-dependent continuous increase in insulin association with the cells at 37 ~ [6]; and (d) about 56% of the cell-associated insulin is degraded at the end of 5 h of incubation at 37 ~ [6]. Moreover, according to biochemical studies performed to evaluate insulin receptor down-regulation (and thereby assess insulin internalization) in 1M-9 lymphocytes (nucleated cells), contradictory results were obtained by Baldwin et al. [9], that is, insulin internalization was not observed.Reticulocytes are known not to have nuclei. They are capable of limited protein synthesis due t...

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Regulation of insulin receptors in erythroid cells

Cited by 15 publications

References 21 publications

Insulin Receptor Regulation in Human Mature Red Cells in vitro

Insulin Receptor Regulation in Human Mature Red Cells in vitro

Insulin Binding and Glycolytic Activity in Erythrocytes from Dialyzed and Nondialyzed Uremic Patients

Insulin internalization in human erythrocytes

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