Insulin stimulates glucose uptake and activates protein kinase B in contracting muscles without increasing IRS-1/2 associated PI 3-kinase activity

2000 ◽  
Vol 50 ◽  
pp. 164
Author(s):  
J Jensen ◽  
M.A Soos ◽  
R Aslesen ◽  
S O'Rahilly ◽  
J.P Whitehead
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Kinase Activity ◽  
Protein Kinase B

scholarly journals Contraction inhibits insulin-stimulated insulin receptor substrate-1/2-associated phosphoinositide 3-kinase activity, but not protein kinase B activation or glucose uptake, in rat muscle

2000 ◽  
Vol 349 (3) ◽  
pp. 775-781 ◽  
Author(s):  
Jonathan P. WHITEHEAD ◽  
Maria A. SOOS ◽  
Rune ASLESEN ◽  
Stephen O'RAHILLY ◽  
Jørgen JENSEN
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Kinase Activity ◽  
Insulin Signalling ◽  
Protein Kinase B ◽  
Fold Increase ◽  
Simultaneous Treatment ◽  
Phosphoinositide 3 Kinase

The initial stages of insulin-stimulated glucose uptake are thought to involve tyrosine phosphorylation of insulin receptor substrates (IRSs), which recruit and activate phosphoinositide 3-kinase (PI 3-kinase), leading to the activation of protein kinase B (PKB) and other downstream effectors. In contrast, contraction stimulates glucose uptake via a PI 3-kinase-independent mechanism. The combined effects of insulin and contraction on glucose uptake are additive. However, it has been reported that contraction causes a decrease in insulin-stimulated IRS-1-associated PI 3-kinase activity. To investigate this paradox, we have examined the effects of contraction on insulin-stimulated glucose uptake and proximal insulin-signalling events in isolated rat epitrochlearis muscle. Stimulation by insulin or contraction produced a 3-fold increase in glucose uptake, with the effects of simultaneous treatment by insulin and contraction being additive. Wortmannin completely blocked the additive effect of insulin in contracting skeletal muscle, indicating that this is a PI 3-kinase-dependent effect. Insulin-stimulated recruitment of PI 3-kinase to IRS-1 was unaffected by contraction; however, insulin produced no discernible increase in PI 3-kinase activity in IRS-1 or IRS-2 immunocomplexes in contracting skeletal muscle. Consistent with this, contraction inhibited insulin-stimulated p70S6K activation. In contrast, insulin-stimulated activation of PKB was unaffected by contraction. Thus, in contracting skeletal muscle, insulin stimulates glucose uptake and activates PKB, but not p70S6K, by a PI 3-kinase-dependent mechanism that is independent of changes in IRS-1- and IRS-2-associated PI 3-kinase activity.

scholarly journals A Novel Protein Kinase B (PKB)/AKT-binding Protein Enhances PKB Kinase Activity and Regulates DNA Synthesis

2005 ◽  
Vol 280 (18) ◽  
pp. 18525-18535 ◽  
Author(s):  
Motonobu Anai ◽  
Nobuhiro Shojima ◽  
Hideki Katagiri ◽  
Takehide Ogihara ◽  
Hideyuki Sakoda ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Dna Synthesis ◽  
Kinase Activity ◽  
Protein Kinase B ◽  
Binding Protein ◽  
Novel Protein

scholarly journals Muscle Adaptation to Short-Term Fasting in Healthy Lean Humans

2008 ◽  
Vol 93 (7) ◽  
pp. 2900-2903 ◽  
Author(s):  
Maarten R. Soeters ◽  
Hans P. Sauerwein ◽  
Peter F. Dubbelhuis ◽  
Johanna E. Groener ◽  
Mariëtte T. Ackermans ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Protein Kinase B ◽  
Muscle Adaptation ◽  
Short Term ◽  
Akt Phosphorylation ◽  
Induce Insulin Resistance ◽  
Before And After ◽  
Muscle Biopsies

Abstract Context: It has been demonstrated repeatedly that short-term fasting induces insulin resistance, although the exact mechanism in humans is unknown to date. Intramyocellular sphingolipids (i.e. ceramide) have been suggested to induce insulin resistance by interfering with the insulin signaling cascade in obesity. Objective: Our objective was to study peripheral insulin sensitivity together with muscle ceramide concentrations and protein kinase B/AKT phosphorylation after short-term fasting. Main Outcome Measures and Design: After 14- and 62-h fasting, glucose fluxes were measured before and after a hyperinsulinemic euglycemic clamp. Muscle biopsies were performed in the basal state and during the clamp to assess muscle ceramide and protein kinase B/AKT. Results: Insulin-mediated peripheral glucose uptake was significantly lower after 62-h fasting compared with 14-h fasting. Intramuscular ceramide concentrations tended to increase during fasting. During the clamp the phosphorylation of protein kinase B/AKT at serine473 in proportion to the total amount of protein kinase B/AKT was significantly lower. Muscle ceramide did not correlate with plasma free fatty acids. Conclusions: Fasting for 62 h decreases insulin-mediated peripheral glucose uptake with lower phosphorylation of AKT at serine473. AKT may play a regulatory role in fasting-induced insulin resistance. Whether the decrease in AKT can be attributed to the trend to higher muscle ceramide remains unanswered.

scholarly journals A Cell Number Counting Factor Regulates Akt/Protein Kinase B To Regulate Dictyostelium discoideum Group Size

2004 ◽  
Vol 3 (5) ◽  
pp. 1176-1184 ◽  
Author(s):  
Tong Gao ◽  
David Knecht ◽  
Lei Tang ◽  
R. Diane Hatton ◽  
Richard H. Gomer
Keyword(s):  
Protein Kinase ◽  
Dictyostelium Discoideum ◽  
Group Size ◽  
Kinase Activity ◽  
Fluorescent Protein ◽  
Protein Kinase B ◽  
Cell Number ◽  
Pleckstrin Homology Domain ◽  
Wild Type ◽  
High Concentration

ABSTRACT Little is known about how individual cells can organize themselves to form structures of a given size. During development, Dictyostelium discoideum aggregates in dendritic streams and forms groups of ∼20,000 cells. D. discoideum regulates group size by secreting and simultaneously sensing a multiprotein complex called counting factor (CF). If there are too many cells in a stream, the associated high concentration of CF will decrease cell-cell adhesion and increase cell motility, causing aggregation streams to break up. The pulses of cyclic AMP (cAMP) that mediate aggregation cause a transient translocation of Akt/protein kinase B (Akt/PKB) to the leading edge of the plasma membrane and a concomitant activation of the kinase activity, which in turn stimulates motility. We found that countin− cells (which lack bioactive CF) and wild-type cells starved in the presence of anticountin antibodies (which block CF activity) showed a decreased level of cAMP-stimulated Akt/PKB membrane translocation and kinase activity compared to parental wild-type cells. Recombinant countin has the bioactivity of CF, and a 1-min treatment of cells with recombinant countin potentiated Akt/PKB translocation to membranes and Akt/PKB activity. Western blotting of total cell lysates indicated that countin does not affect the total level of Akt/PKB. Fluorescence microscopy of cells expressing an Akt/PKB pleckstrin homology domain-green fluorescent protein (PH-GFP) fusion protein indicated that recombinant countin and anti-countin antibodies do not obviously alter the distribution of Akt/PKB PH-GFP when it translocates to the membrane. Our data indicate that CF increases motility by potentiating the cAMP-stimulated activation and translocation of Akt/PKB.

scholarly journals Interleukin-1β-Induced Insulin Resistance in Adipocytes through Down-Regulation of Insulin Receptor Substrate-1 Expression

Endocrinology ◽  
2007 ◽  
Vol 148 (1) ◽  
pp. 241-251 ◽  
Author(s):  
Jennifer Jager ◽  
Thierry Grémeaux ◽  
Mireille Cormont ◽  
Yannick Le Marchand-Brustel ◽  
Jean-François Tanti
Keyword(s):  
Insulin Resistance ◽  
Protein Kinase ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Insulin Signaling ◽  
Protein Kinase B ◽  
Transcriptional Level ◽  
Insulin Receptor Substrate ◽  
Down Regulation ◽  
Glut 4

Inflammation is associated with obesity and insulin resistance. Proinflammatory cytokines produced by adipose tissue in obesity could alter insulin signaling and action. Recent studies have shown a relationship between IL-1β level and metabolic syndrome or type 2 diabetes. However, the ability of IL-1β to alter insulin signaling and action remains to be explored. We demonstrated that IL-1β slightly increased Glut 1 translocation and basal glucose uptake in 3T3-L1 adipocytes. Importantly, we found that prolonged IL-1β treatment reduced the insulin-induced glucose uptake, whereas an acute treatment had no effect. Chronic treatment with IL-1β slightly decreased the expression of Glut 4 and markedly inhibited its translocation to the plasma membrane in response to insulin. This inhibitory effect was due to a decrease in the amount of insulin receptor substrate (IRS)-1 but not IRS-2 expression in both 3T3-L1 and human adipocytes. The decrease in IRS-1 amount resulted in a reduction in its tyrosine phosphorylation and the alteration of insulin-induced protein kinase B activation and AS160 phosphorylation. Pharmacological inhibition of ERK totally inhibited IL-1β-induced down-regulation of IRS-1 mRNA. Moreover, IRS-1 protein expression and insulin-induced protein kinase B activation, AS160 phosphorylation, and Glut 4 translocation were partially recovered after treatment with the ERK inhibitor. These results demonstrate that IL-1β reduces IRS-1 expression at a transcriptional level through a mechanism that is ERK dependent and at a posttranscriptional level independently of ERK activation. By targeting IRS-1, IL-1β is capable of impairing insulin signaling and action, and could thus participate in concert with other cytokines, in the development of insulin resistance in adipocytes.

scholarly journals Occludin regulates glucose uptake and ATP production in pericytes by influencing AMP-activated protein kinase activity

2017 ◽  
Vol 38 (2) ◽  
pp. 317-332 ◽  
Author(s):  
Victor Castro ◽  
Marta Skowronska ◽  
Jorge Lombardi ◽  
Jane He ◽  
Neil Seth ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Blood Brain Barrier ◽  
Kinase Activity ◽  
Brain Barrier ◽  
Protein Kinase Activity ◽  
Atp Production ◽  
Blood Brain ◽  
Amp Activated Protein Kinase ◽  
The Impact

Energetic regulation at the blood-brain barrier is critical for maintaining its integrity, transport capabilities, and brain demands for glucose. However, the underlying mechanisms that regulate these processes are still poorly explored. We recently characterized the protein occludin as a NADH oxidase and demonstrated its influence on the expression and activation of the histone deacetylase SIRT-1. Because SIRT-1 works in concert with AMP-activated protein kinase (AMPK) (AMPK), we investigated the impact of occludin on this metabolic switch. Here we show that in blood-brain barrier pericytes, occludin promotes AMPK expression and activation, influencing the expression of glucose transporters GLUT-1 and GLUT-4, glucose uptake, and ATP content. Furthermore, occludin expression, AMP-dependent protein kinase activity, and glucose uptake were altered under inflammatory (TNFα) and infectious (HIV) conditions. We also show that pericytes share glucose and mitochondria with astrocytes, and that occludin levels modify the ability of pericytes to share those energetic resources. In addition, we demonstrate that murine mitochondria can be transferred from live brain microvessels to energetically impaired human astrocytes, promoting their survival. Our findings demonstrate that occludin plays an important role in blood-brain barrier pericyte metabolism by influencing AMPK protein kinase activity, glucose uptake, ATP production, and by regulating the ability of pericytes to interact metabolically with astrocytes.

scholarly journals Dexamethasone impairs insulin signalling and glucose transport by depletion of insulin receptor substrate-1, phosphatidylinositol 3-kinase and protein kinase B in primary cultured rat adipocytes

2002 ◽  
pp. 419-429 ◽  
Author(s):  
J Buren ◽  
HX Liu ◽  
J Jensen ◽  
JW Eriksson
Keyword(s):  
Insulin Resistance ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Insulin Signalling ◽  
Protein Kinase B ◽  
Insulin Binding ◽  
Insulin Receptor Substrate ◽  
Phosphatidylinositol 3 Kinase ◽  
Rat Adipocytes

OBJECTIVE: Glucocorticoid excess leads to insulin resistance. This study explores the effects of glucocorticoids on the glucose transport system and insulin signalling in rat adipocytes. The interaction between glucocorticoids and high levels of insulin and glucose is also addressed. DESIGN AND METHODS: Isolated rat adipocytes were cultured for 24 h at different glucose concentrations (5 and 15 mmol/l) with or without the glucocorticoid analogue dexamethasone (0.3 micromol/l) and insulin (10(4) microU/ml). After the culture period, the cells were washed and then basal and insulin-stimulated glucose uptake, insulin binding and lipolysis as well as cellular content of insulin signalling proteins (insulin receptor substrate-1 (IRS-1), IRS-2, phosphatidylinositol 3-kinase (PI3-K) and protein kinase B (PKB)) and glucose transporter isoform GLUT4 were measured. RESULTS: Dexamethasone in the medium markedly decreased both basal and insulin-stimulated glucose uptake at both 5 and 15 mmol/l glucose (by approximately 40-50%, P<0.001 and P<0.05 respectively). Combined long-term treatment with insulin and dexamethasone exerted additive effects in decreasing basal, and to a lesser extent insulin-stimulated, glucose uptake capacity (P<0.05) compared with dexamethasone alone, but this was seen only at high glucose (15 mmol/l). Insulin binding was decreased (by approximately 40%, P<0.05) in dexamethasone-treated cells independently of surrounding glucose concentration. Following dexamethasone treatment a approximately 75% decrease (P<0.001) in IRS-1 expression and an increase in IRS-2 (by approximately 150%, P<0.001) was shown. Dexamethasone also induced a subtle decrease in PI3-K (by approximately 20%, P<0.01) and a substantial decrease in PKB content (by approximately 45%, P<0.001). Insulin-stimulated PKB phosphorylation was decreased (by approximately 40%, P<0.01) in dexamethasone-treated cells. Dexamethasone did not alter the amount of total cellular membrane-associated GLUT4 protein. The effects of dexamethasone per se on glucose transport and insulin signalling proteins were mainly unaffected by the surrounding glucose and insulin levels. Dexamethasone increased the basal lipolytic rate (approximately 4-fold, P<0.05), but did not alter the antilipolytic effect of insulin. CONCLUSIONS: These results suggest that glucocorticoids, independently of the surrounding glucose and insulin concentration, impair glucose transport capacity in fat cells. This is not due to alterations in GLUT4 abundance. Instead dexamethasone-induced insulin resistance may be mediated via reduced cellular content of IRS-1 and PKB accompanied by a parallel reduction in insulin-stimulated activation of PKB.

scholarly journals Participation of phosphatidyl inositol 3-kinase/protein kinase B and ERK1/2 pathways in interleukin-1β stimulation of lactate production in Sertoli cells

Reproduction ◽  
2007 ◽  
Vol 133 (4) ◽  
pp. 763-773 ◽  
Author(s):  
María Fernanda Riera ◽  
María Noel Galardo ◽  
Eliana Herminia Pellizzari ◽  
Silvina Beatriz Meroni ◽  
Selva Beatriz Cigorraga
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Sertoli Cell ◽  
Sertoli Cells ◽  
Protein Kinase B ◽  
Lactate Production ◽  
Phosphatidyl Inositol ◽  
Interleukin 1Β ◽  
Mrna Levels ◽  
Stimulation Of

Interleukin-1β (IL1β ) belongs to a set of intratesticular regulators that provide the fine-tuning of cellular processes implicated in the maintenance of spermatogenesis. The aim of the present study was to analyze the signaling pathways that may participate in IL1β regulation of Sertoli cell function. Sertoli cell cultures from 20-day-old rat were used. Stimulation of the cultures with IL1β showed increments in phosphorylated protein kinase B (PKB), P70S6K, and ERK1/2 levels. A phosphatidyl inositol 3-kinase (PI3K) inhibitor (wortmannin (W)), a mammalian target of rapamycin inhibitor (rapamycin (R)), and a MEK inhibitor (PD98059 (PD)) were utilized to evaluate the participation of PI3K/PKB, P70S6K, and ERK1/2 pathways in the regulation of lactate production by IL1β . PD and W, but not R, decreased IL1β-stimulated lactate production. The participation of these pathways in the regulation of glucose uptake and lactate dehydrogenase (LDH) A mRNA levels by IL1β was also analyzed. It was observed that W decreased IL1β-stimulated glucose uptake, whereas PD and R did not modify it. On the other hand, PD decreased the stimulation of LDH A mRNA levels by IL1β , whereas W and R did not modify it. In summary, results presented herein demonstrate that IL1β stimulates PI3K/PKB-, P70S6K-, and ERK1/2-dependent pathways in rat Sertoli cells. Moreover, these results show that while IL1β utilizes the PI3K/PKB pathway to regulate glucose transport, it utilizes the ERK1/2 pathway to regulate LDH A mRNA levels. This study reveals that IL1β utilizes different signal transduction pathways to modify the biochemical steps that are important to regulate lactate production in rat Sertoli cells.

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