7-O-Methylaromadendrin Stimulates Glucose Uptake and Improves Insulin Resistance in Vitro

Obesity-related insulin resistance is linked to a chronic state of systemic and adipose tissue-derived inflammation. Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone also acting on adipocytes. We investigated whether GIP affects inflammation, lipolysis, and insulin resistance in human adipocytes. Human subcutaneous preadipocyte-derived adipocytes, differentiated in vitro, were treated with human GIP to analyze mRNA expression and protein secretion of cytokines, glycerol, and free fatty acid release and insulin-induced glucose uptake. GIP induced mRNA expression of IL-6, IL-1β, and the IL-1 receptor antagonist IL-1Ra, whereas TNFα, IL-8, and monocyte chemotactic protein (MCP)-1 remained unchanged. Cytokine induction involved PKA and the NF-κB pathway as well as an autocrine IL-1 effect. Furthermore, GIP potentiated IL-6 and IL-1Ra secretion in the presence of LPS, IL-1β, and TNFα. GIP induced lipolysis via activation of hormone-sensitive lipase and was linked to NF-κB activation. Finally, chronic GIP treatment impaired insulin-induced glucose uptake possibly due to the observed impaired translocation of glucose transporter GLUT4. In conclusion, GIP induces an inflammatory and prolipolytic response via the PKA -NF-κB-IL-1 pathway and impairs insulin sensitivity of glucose uptake in human adipocytes.

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Metformin protects against insulin resistance induced by high uric acid in cardiomyocytes via AMPK signaling pathways in vitro and in vivo

10.21203/rs.3.rs-300030/v1 ◽

2021 ◽

Author(s):

Zhenyu Jiao ◽

Yingqun Chen ◽

Yang Xie ◽

Yanbing Li ◽

Zhi Li

Keyword(s):

Insulin Resistance ◽

Uric Acid ◽

Glucose Metabolism ◽

Glucose Tolerance ◽

Mouse Model ◽

Glucose Uptake ◽

Glucose Transporter ◽

Abnormal Glucose Metabolism ◽

Insulin Tolerance

Abstract BackgroundHigh uric acid (HUA) is associated with insulin resistance and abnormal glucose metabolism in cardiomyocytes. Metformin is a recognized agonist of AMP-activated protein kinase (AMPK) and an antidiabetic drug widely used for type 2 diabetes. It can play a cardioprotective role in many pathways. We investigated whether metformin protects against HUA-induced insulin resistance and abnormal glucose metabolism in cardiomyocytes.MethodsWe exposed primary cardiomyocytes to HUA, and cellular glucose uptake was quantified by measuring the uptake of 2-NBDG, a fluorescent glucose analog, after insulin excitation.ResultsTreatment with metformin (10 µmol/L) protected against HUA-inhibited glucose uptake induced by insulin in primary cardiomyocytes, as shown by fluorescence microscopy and flow cytometry analysis. HUA directly inhibited the phosphorylation of Akt and the translocation of glucose transporter type 4 (GLUT4) induced by insulin, which was blocked by metformin. Metformin promoted phosphorylation of AMPK, renewed HUA-inhibited glucose uptake induced by insulin and protected against insulin resistance in cardiomyocytes. As a result of these effects, in a mouse model of acute hyperuricemia, metformin improved insulin tolerance and glucose tolerance, accompanied by increased AMPK phosphorylation, Akt phosphorylation and translocation of GLUT4 in myocardial tissues. As expected, AICAR, another AMPK activator, had equivalent effects to metformin, demonstrating the important role of AMPK activation in protecting against insulin resistance induced by HUA in cardiomyocytes. Metformin protects against insulin resistance induced by HUA in cardiomyocytes and improves insulin tolerance and glucose tolerance in an acute hyperuricemic mouse model, along with the activation of AMPK.ConclusionsConsequently, metformin may be an important potential new treatment strategy for hyperuricemia-related cardiovascular disease.

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Characterization of the Active Components of the Multimerized sTNFRII-Adiponectin Fusion Protein Showing Both TNFα-Antagonizing and Glucose Uptake-Promoting Activities

Endocrine Metabolic & Immune Disorders - Drug Targets ◽

10.2174/1871530320666200121100449 ◽

2020 ◽

Vol 20 (7) ◽

pp. 1081-1089

Author(s):

Yao Wang ◽

Hui Lian ◽

Xitong Wang ◽

Tianyu Zheng ◽

Xiaoxiao Yu ◽

...

Keyword(s):

Insulin Resistance ◽

Fusion Protein ◽

Glucose Uptake ◽

Cell Model ◽

Glucose Consumption ◽

Antagonistic Activity ◽

H9c2 Cells ◽

Active Components ◽

Exclusion Chromatography

Background: The sTNFRII-adiponectin fusion protein previously showed strong TNFα antagonistic activity. However, the fusion protein exists as mixture of different multimers. The aim of the present study was to characterize its active components. Methods: In this study, the fusion protein was isolated and purified by Ni-NTA affinity and gel exclusion chromatography, and further identified by Coomassie staining and western blotting. The TNFα antagonistic and glucose uptake-promoting activities were determined in vitro. The glucose detection kit and 2- NBDG (2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose) were used to measure their effects on glucose metabolism (including glucose consumption and glucose uptake in HepG2 and H9C2 cells). The effect of the fusion protein on glucose uptake was also examined in free fatty acid (FFA)- induced insulin resistance cell model. Results: The sTNFRII-adiponectin fusion protein was found to exist in three forms: 250 kDa (hexamer), 130 kDa (trimer), and 60 kDa (monomer), with the final purity of 90.2%, 60.1%, and 81.6%, respectively. The fusion protein could effectively antagonize the killing effect of TNFα in L929 cells, and the multimer was found to be superior to the monomer. In addition, the fusion protein could increase glucose consumption without impacting the number of cells (HepG2, H9C2 cells) in a dosedependent manner. Mechanistically, glucose uptake was found to be enhanced by the translocation of GLUT4. However, it could not improve glucose uptake in the cell model of insulin resistance. Conclusion: In summary, the active components of the fusion protein are hexamers and trimers. The hexamer and trimer of sTNFRII-adiponectin fusion protein had both TNFα-antagonizing and glucose uptake-promoting activities, although neither of them could improve glucose uptake in the cell model of insulin resistance.

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Synthesis, Characterization, and Preclinical Evaluation of New Thiazolidin-4-ones Substituted with p-Chlorophenoxy Acetic Acid and Clofibric Acid against Insulin Resistance and Metabolic Disorder

BioMed Research International ◽

10.1155/2014/620434 ◽

2014 ◽

Vol 2014 ◽

pp. 1-14 ◽

Cited By ~ 2

Author(s):

Vasantharaju S. Gowdra ◽

Jayesh Mudgal ◽

Punit Bansal ◽

Pawan G. Nayak ◽

Seethappa A. Manohara Reddy ◽

...

Keyword(s):

Insulin Resistance ◽

Glucose Uptake ◽

Metabolic Disorders ◽

Insulin Resistant ◽

Insulin Sensitizers ◽

Uptake Assay ◽

Glucose Uptake Assay ◽

Plasma Leptin

We synthesized twenty thiazolidin-4-one derivatives, which were then characterized by standard chromatographic and spectroscopic methods. From thein vitroglucose uptake assay, two compounds behaved as insulin sensitizers, where they enhanced glucose uptake in isolated rat diaphragm. In high-carbohydrate diet-induced insulin resistant mice, these two thiazolidin-4-ones attenuated hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hypercholesterolemia, and glucose intolerance. They raised the plasma leptin but did not reverse the diabetes-induced hypoadiponectinemia. Additionally, compound3areduced adiposity. The test compounds were also able to reverse the disturbed liver antioxidant milieu. To conclude, these two novel thiazolidin-4-ones modulated multiple mechanisms involved in metabolic disorders, reversing insulin resistance and thus preventing the development of type-2 diabetes.

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Angiotensin II Enhances Insulin Sensitivity in Vitro and in Vivo

Endocrinology ◽

10.1210/en.2004-1136 ◽

2005 ◽

Vol 146 (5) ◽

pp. 2246-2254 ◽

Cited By ~ 35

Author(s):

Chi-Chang Juan ◽

Yueh Chien ◽

Liang-Yi Wu ◽

Wei-Ming Yang ◽

Chih-Ling Chang ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Sensitivity ◽

Angiotensin Ii ◽

Glucose Uptake ◽

Intracellular Signaling ◽

Binding Capacity ◽

Critical Role ◽

At1 Antagonist

Abstract The renin-angiotensin system plays a critical role in the pathogenesis of obesity, obesity-associated hypertension, and insulin resistance. However, the biological actions of angiotensin II (AII) on insulin sensitivity remain controversial. Because angiotensinogen and AII receptors are expressed on adipose tissue, we investigated the effect of AII on the insulin sensitivity of isolated rat adipocytes. The results of a receptor binding assay showed the maximal AII binding capacity of adipocytes to be 8.3 ± 0.9 fmol/7 × 106 cells and the dissociation constant to be 2.72 ± 0.11 nm. Substantial expression of both type 1 and 2 AII (AT1 and AT2) receptors was detected by RT-PCR. AII had no effect on basal glucose uptake, but significantly potentiated insulin-stimulated glucose uptake; this effect was abolished by the AT1 antagonist, losartan. In addition, AII did not alter the insulin binding capacity of adipocytes, but increased insulin-stimulated tyrosine phosphorylation of the insulin receptor β-subunit, Akt phosphorylation, and translocation of glucose transporter 4 to the plasma membrane. AII potentiated insulin-stimulated glucose uptake through the AT1 receptor and by alteration of the intracellular signaling of insulin. Intraperitoneal injection of Sprague Dawley rats with AII increased insulin sensitivity in vivo. In conclusion, we have shown that AII enhances insulin sensitivity both in vitro and in vivo, suggesting that dysregula-tion of the insulin-sensitizing effect of AII may be involved in the development of insulin resistance.

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In vitro contraction protects against palmitate-induced insulin resistance in C2C12 myotubes

AJP Cell Physiology ◽

10.1152/ajpcell.00123.2017 ◽

2017 ◽

Vol 313 (5) ◽

pp. C575-C583 ◽

Cited By ~ 16

Author(s):

Stephan Nieuwoudt ◽

Anny Mulya ◽

Ciarán E. Fealy ◽

Elizabeth Martelli ◽

Srinivasan Dasarathy ◽

...

Keyword(s):

Insulin Resistance ◽

Glucose Uptake ◽

Insulin Signaling ◽

Protective Role ◽

Electrode System ◽

C2c12 Myotubes ◽

Noise Mapping ◽

Whole Cell ◽

Akt Phosphorylation

We are interested in understanding mechanisms that govern the protective role of exercise against lipid-induced insulin resistance, a key driver of type 2 diabetes. In this context, cell culture models provide a level of abstraction that aid in our understanding of cellular physiology. Here we describe the development of an in vitro myotube contraction system that provides this protective effect, and which we have harnessed to investigate lipid-induced insulin resistance. C2C12 myocytes were differentiated into contractile myotubes. A custom manufactured platinum electrode system and pulse stimulator, with polarity switching, provided an electrical pulse stimulus (EPS) (1 Hz, 6-ms pulse width, 1.5 V/mm, 16 h). Contractility was assessed by optical flow flied spot noise mapping and inhibited by application of ammonium acetate. Following EPS, myotubes were challenged with 0.5 mM palmitate for 4 h. Cells were then treated with or without insulin for glucose uptake (30 min), secondary insulin signaling activation (10 min), and phosphoinositide 3-kinase-α (PI3Kα) activity (5 min). Prolonged EPS increased non-insulin-stimulated glucose uptake (83%, P = 0.002), Akt (Thr308) phosphorylation ( P = 0.005), and insulin receptor substrate-1 (IRS-1)-associated PI3Kα activity ( P = 0.048). Palmitate reduced insulin-specific action on glucose uptake (−49%, P < 0.001) and inhibited insulin-stimulated Akt phosphorylation ( P = 0.049) and whole cell PI3Kα activity ( P = 0.009). The inhibitory effects of palmitate were completely absent with EPS pretreatment at the levels of glucose uptake, insulin responsiveness, Akt phosphorylation, and whole cell PI3Kα activity. This model suggests that muscle contraction alone is a sufficient stimulus to protect against lipid-induced insulin resistance as evidenced by changes in the proximal canonical insulin-signaling pathway.

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Effect of Eriodictyol on Glucose Uptake and Insulin Resistance in Vitro

Journal of Agricultural and Food Chemistry ◽

10.1021/jf300601z ◽

2012 ◽

Vol 60 (31) ◽

pp. 7652-7658 ◽

Cited By ~ 53

Author(s):

Wei-Yun Zhang ◽

Jung-Jin Lee ◽

Yohan Kim ◽

In-Su Kim ◽

Joo-Hui Han ◽

...

Keyword(s):

Insulin Resistance ◽

Glucose Uptake

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Attenuation of Free Fatty Acid (FFA)-Induced Skeletal Muscle Cell Insulin Resistance by Resveratrol is Linked to Activation of AMPK and Inhibition of mTOR and p70 S6K

International Journal of Molecular Sciences ◽

10.3390/ijms21144900 ◽

2020 ◽

Vol 21 (14) ◽

pp. 4900

Author(s):

Danja J. Den Hartogh ◽

Filip Vlavcheski ◽

Adria Giacca ◽

Evangelia Tsiani

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Glucose Uptake ◽

Glucose Transporter ◽

Muscle Insulin Resistance ◽

Skeletal Muscle Insulin Resistance ◽

Specific Proteins ◽

P70 S6k

Insulin resistance, a main characteristic of type 2 diabetes mellitus (T2DM), is linked to obesity and excessive levels of plasma free fatty acids (FFA). Studies indicated that significantly elevated levels of FFAs lead to skeletal muscle insulin resistance, by dysregulating the steps in the insulin signaling cascade. The polyphenol resveratrol (RSV) was shown to have antidiabetic properties but the exact mechanism(s) involved are not clearly understood. In the present study, we examined the effect of RSV on FFA-induced insulin resistance in skeletal muscle cells in vitro and investigated the mechanisms involved. Parental and GLUT4myc-overexpressing L6 rat skeletal myotubes were used. [3H]2-deoxyglucose (2DG) uptake was measured, and total and phosphorylated levels of specific proteins were examined by immunoblotting. Exposure of L6 cells to FFA palmitate decreased the insulin-stimulated glucose uptake, indicating insulin resistance. Palmitate increased ser307 (131% ± 1.84% of control, p < 0.001) and ser636/639 (148% ± 10.1% of control, p < 0.01) phosphorylation of IRS-1, and increased the phosphorylation levels of mTOR (174% ± 15.4% of control, p < 0.01) and p70 S6K (162% ± 20.2% of control, p < 0.05). Treatment with RSV completely abolished these palmitate-induced responses. In addition, RSV increased the activation of AMPK and restored the insulin-mediated increase in (a) plasma membrane GLUT4 glucose transporter levels and (b) glucose uptake. These data suggest that RSV has the potential to counteract the FFA-induced muscle insulin resistance.

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Peripheral insulin resistance in ILK-depleted mice by reduction of GLUT4 expression

Journal of Endocrinology ◽

10.1530/joe-16-0662 ◽

2017 ◽

Vol 234 (2) ◽

pp. 115-128 ◽

Cited By ~ 8

Author(s):

Marco Hatem-Vaquero ◽

Mercedes Griera ◽

Andrea García-Jerez ◽

Alicia Luengo ◽

Julia Álvarez ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Sensitivity ◽

Glucose Uptake ◽

Glucose Transporter ◽

Chow Diet ◽

Peripheral Tissues ◽

Akt Phosphorylation ◽

Glut4 Expression

The development of insulin resistance is characterized by the impairment of glucose uptake mediated by glucose transporter 4 (GLUT4). Extracellular matrix changes are induced when the metabolic dysregulation is sustained. The present work was devoted to analyze the possible link between the extracellular-to-intracellular mediator integrin-linked kinase (ILK) and the peripheral tissue modification that leads to glucose homeostasis impairment. Mice with general depletion of ILK in adulthood (cKD-ILK) maintained in a chow diet exhibited increased glycemia and insulinemia concurrently with a reduction of the expression and membrane presence of GLUT4 in the insulin-sensitive peripheral tissues compared with their wild-type littermates (WT). Tolerance tests and insulin sensitivity indexes confirmed the insulin resistance in cKD-ILK, suggesting a similar stage to prediabetes in humans. Under randomly fed conditions, no differences between cKD-ILK and WT were observed in the expression of insulin receptor (IR-B) and its substrate IRS-1 expressions. The IR-B isoform phosphorylated at tyrosines 1150/1151 was increased, but the AKT phosphorylation in serine 473 was reduced in cKD-ILK tissues. Similarly, ILK-blocked myotubes reduced their GLUT4 promoter activity and GLUT4 expression levels. On the other hand, the glucose uptake capacity in response to exogenous insulin was impaired when ILK was blocked in vivo and in vitro, although IR/IRS/AKT phosphorylation states were increased but not different between groups. We conclude that ILK depletion modifies the transcription of GLUT4, which results in reduced peripheral insulin sensitivity and glucose uptake, suggesting ILK as a molecular target and a prognostic biomarker of insulin resistance.

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