Mechanism of insulin receptor kinase inhibition in non-insulin-dependent diabetes mellitus patients. Phosphorylation of serine 1327 or threonine 1348 is unaltered.

Kellerer, Monika; Coghlan, Mathew; Capp, Edison; Mühlhöfer, A; Kroder, G; Mosthaf, Luitgard; Galante, P.; Siddle, Kenneth; Häring, Hans Ulrich

doi:10.1172/jci118073

Cited by 22 publications

(10 citation statements)

References 35 publications

(32 reference statements)

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“…Phosphorylation of serine/threonine residues on the insulin receptor has been suggested as one cause of decreased insulin-stimulated IRTK activity in diabetes (27,38,39); however, this mechanism has not been demonstrated in humans with the disease (40). In the present study, we did not measure serine/threonine phosphorylation of the insulin receptors directly.…”

Section: Fig 2 Pc-1 Protein Content In the Skeletal Muscle Of Nonprmentioning

confidence: 75%

Decreased insulin receptor tyrosine kinase activity and plasma cell membrane glycoprotein-1 overexpression in skeletal muscle from obese women with gestational diabetes mellitus (GDM): evidence for increased serine/threonine phosphorylation in pregnancy and GDM.

et al. 2000

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The cellular mechanisms for the insulin resistance of pregnancy and gestational diabetes mellitus (GDM) are unknown. The membrane protein plasma cell membrane glycoprotein-1 (PC-1) has been identified as an inhibitor of insulin receptor tyrosine kinase (IRT K ) a c t i v i t y. We investigated insulin receptor function and PC-1 levels in muscle from three groups of obese subjects: women with GDM, pregnant women with normal glucose tolerance, and nonpregnant control subjects. Subjects (n = 6 for each group) were similar in age and degree of obesity (body fat >30%). IRTK activity, insulin receptor tyrosine phosphorylation, and protein levels of membrane glycoprotein PC-1 were determined in rectus abdominus muscle biopsies obtained at the time of either elective cesarean section or gynecological surgery. No significant differences were evident in basal insulin receptor tyrosine phosphorylation or I RTK activity in the three groups. After maximal insulin (10 -7 mol/l) stimulation, IRTK activity measured with the artificial substrate poly(Glu,Ty r ) increased in all subjects but was lower in women with GDM by 25% (P < 0.05) and 39% (P < 0.001) compared with pregnant and nonpregnant control subjects, r e s p e c t i v e l y. Similarly, insulin receptor tyrosine phosphorylation was significantly decreased in subjects with GDM (P < 0.05) compared with pregnant and nonpregnant control subjects. Treatment of the insulin receptors with alkaline phosphatase to dephosphorylate serine/threonine residues increased insulin-stimulated IRTK activity significantly in pregnant control and GDM subjects (P < 0.05), but these rates were still lower compared with nonpregnant control subjects (P < 0.05). PC-1 content in muscle from GDM subjects was increased by 63% compared with pregnant control subjects (P < 0.05) and by 206% compared with nonpregnant control subjects (P < 0.001). PC-1 content was negatively correlated with insulin receptor phosphorylation (r = -0.55, P < 0.05) and IRTK activity (r = -0.66, P < 0.05). These results indicate that pregnant control and GDM subjects had increased PC-1 content and suggest excessive phosphorylation of serine/threonine residues in muscle insulin receptors and that both may contribute to decreased IRTK activity. These changes worsen in women with GDM when controlling for obesity. These postreceptor defects in insulin signaling may contribute to the pathogenesis of GDM and the increased risk for type 2 diabetes later in life. Diabetes 4 9 :6 0 3-610, 2000 D uring pregnancy, one of the most signific a n t maternal metabolic adaptations is a decrease in insulin sensitivity. Studies with the hyperinsulinemic-euglycemic clamp technique indicate that insulin-mediated glucose disposal decreases as much as 40-60% from early to late pregnancy (1,2). This adaptation provides adequate glucose and other nutrients for the development of the fetus. However, in 3-5% of pregnant women, glucose intolerance develops. Gestational diabetes mellitus (GDM) is characterized by further decrements in insulin sensitivi...

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Section: Fig 2 Pc-1 Protein Content In the Skeletal Muscle Of Nonprmentioning

confidence: 75%

Decreased insulin receptor tyrosine kinase activity and plasma cell membrane glycoprotein-1 overexpression in skeletal muscle from obese women with gestational diabetes mellitus (GDM): evidence for increased serine/threonine phosphorylation in pregnancy and GDM.

et al. 2000

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“…The role of the insulin-stimulated phosphorylation of the IR at Thr 1336 is not clear. Previous in vitro studies demonstrated that this residue of the IR does not participate in the activation or regulation of the IRK (Anderson & Olefsky 1991, Tavare et al 1991, Coghlan et al1994, Kellerer et al 1995. Possibly, this site could have a regulatory role in the interaction between the IR and intracellular substrates.…”

Section: Discussionmentioning

confidence: 95%

“…In addition, Thr 1336 of the IR was identified as a major target for phosphorylation by PKC (Lewis et al 1990b). However, no relationship between the level of phosphorylation of these sites and the activation state of the IRK has been established (Anderson & Olefsky 1991, Tavare et al 1991, Coghlan et al 1994, Kellerer et al 1995, Strack et al 1997.…”

Section: Introductionmentioning

confidence: 99%

Increased in vivo phosphorylation of insulin receptor at serine 994 in the liver of obese insulin-resistant Zucker rats

Muñoz¹,

Dominici²,

Toblli³

et al. 2004

Journal of Endocrinology

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Serine phosphorylation of the insulin receptor (IR) has been proposed to exert an inhibitory influence on its tyrosine kinase activity. Previous works using site-directed mutagenesis suggested that serine 994 of the IR (IR Ser 994) might be part of an inhibitory domain of the receptor. In this study we examined whether this residue is subjected to phosphorylation in vivo. We used a sitephosphospecific antibody to determine the extent of phosphorylation of IR Ser 994 in insulin target tissues from two animal models of insulin resistance with different IR kinase (IRK) activity: obese (fa/fa) Zucker rats and transgenic mice overexpressing bovine growth hormone (PEPCK-bGH mice).Phosphorylation at IR Ser 994 was markedly increased in liver of obese rats. This alteration appeared to be tissue-selective since no phosphorylation on Ser 994 was detected in IRs isolated from skeletal muscle of these animals. On the other hand, the phosphorylation level of IR Ser 994 was very low in liver of PEPCK-bGH mice and did not differ from that of the control group. We have also demonstrated that protein kinase (PK) C isoforms , I and are able to promote the in vitro phosphorylation of the IR on Ser 994. Differential findings in these two models of insulin resistance might thus reflect increased PKC activity resulting from increased lipid availability in obese Zucker rats. Our results suggest that Ser 994 is a novel in vivo IR phosphorylation site that might be involved in the regulation of the IRK in some states of insulin resistance.

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“…Although this has not been a consistent observation (Coghlan & Siddle 1993, Kellerer et al 1995, no correlation was found between the level of tyrosine kinase activity and the extent of Ser/Thr phosphorylation at specific sites of the InsR (Kellerer et al 1995). …”

Section: Figurementioning

confidence: 86%

Role of hyperinsulinemia on hepatic insulin receptor concentration and autophosphorylation in the presence of high growth hormone levels in transgenic mice overexpressing growth hormone gene

Dominici

Balbis²,

Bartke³

et al. 1998

Journal of Endocrinology

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Overexpression of bovine growth hormone (bGH) in transgenic (PEPCK-bGH) mice induces resistance to insulin, which is compensated by a major increase in insulin levels. In these animals, hepatic insulin receptors (InsRs) are downregulated while tyrosine kinase activity of wheat germ agglutinin (WGA)-purified InsRs towards exogenous substrates is unexpectedly increased. By normalizing insulinemia, we attempted to determine whether the alterations detected in the early steps of insulin signal transduction are due to exposure to chronically high GH levels or are secondary to hyperinsulinemia. Transgenic PEPCK-bGH animals were treated with a single intraperitoneal administration of streptozotocin (STZ) or were deprived of food for 48 h, to normalize insulin levels. Both fasting and STZ treatment were effective in reducing insulin blood levels to control values or below, while GH levels remained unchanged (STZ treatment) or increased (fasted animals). In the liver of untreated transgenic mice, the number of InsRs as determined by 125 I-insulin binding was significantly diminished (65 5% and 60 6% of normal values in microsomes and solubilized membranes respectively; P<0·01 vs control mice). In treated transgenic mice, the number of InsRs increased to values similar to or slightly higher than those found in normal control mice (STZ-treated: 139 26% and 126 8%; fasted: 128 5% (P<0·05) and 102 1·5%, for microsomes and solubilized membranes respectively). Neither treatment altered InsR affinity. InsR concentration in liver as determined by immunoblotting using an antibody against the -subunit of the insulin receptor was found to be reduced in transgenic mice (69 3% of normal values, P<0·001) and was normalized after both STZ treatment (105 4%) and fasting (109 4%). Insulin-stimulated autophosphorylation activity of InsRs in transgenic mice was increased (154 13%, P<0·01 compared with the control group), essentially normalized by STZ treatment (96 14%), and reduced by fasting, to below the values measured in normal control mice (56 15%, P<0·05).The potential influence of basal serine/threonine (Ser/ Thr) phosphorylation of the InsR -subunit on the regulation of the InsRs from transgenic mice was also investigated. The autophosphorylation activity of WGApurified InsRs from all groups of mice studied was essentially unchanged after dephosphorylation with alkaline phosphatase or mild trypsinization. Consequently, our results suggest that the observed changes in InsR number and autophosphorylation activity in the liver of bGH transgenic mice are directly related to changes in insulin blood levels, and that Ser/Thr phosphorylation is apparently not involved in the regulation of the InsR autophosphorylation activity in this model of insulin resistance.

show abstract

Mechanism of insulin receptor kinase inhibition in non-insulin-dependent diabetes mellitus patients. Phosphorylation of serine 1327 or threonine 1348 is unaltered.

Cited by 22 publications

References 35 publications

Decreased insulin receptor tyrosine kinase activity and plasma cell membrane glycoprotein-1 overexpression in skeletal muscle from obese women with gestational diabetes mellitus (GDM): evidence for increased serine/threonine phosphorylation in pregnancy and GDM.

Decreased insulin receptor tyrosine kinase activity and plasma cell membrane glycoprotein-1 overexpression in skeletal muscle from obese women with gestational diabetes mellitus (GDM): evidence for increased serine/threonine phosphorylation in pregnancy and GDM.

Increased in vivo phosphorylation of insulin receptor at serine 994 in the liver of obese insulin-resistant Zucker rats

Role of hyperinsulinemia on hepatic insulin receptor concentration and autophosphorylation in the presence of high growth hormone levels in transgenic mice overexpressing growth hormone gene

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