scholarly journals Triterpenoid Saponins from Stauntonia chinensis Ameliorate Insulin Resistance via the AMP-Activated Protein Kinase and IR/IRS-1/PI3K/Akt Pathways in Insulin-Resistant HepG2 Cells

2014 ◽  
Vol 15 (6) ◽  
pp. 10446-10458 ◽  
Author(s):  
Xin Hu ◽  
Sha Wang ◽  
Jing Xu ◽  
De-Bing Wang ◽  
Yu Chen ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Protein Kinase ◽  
Hepg2 Cells ◽  
Triterpenoid Saponins ◽  
Insulin Resistant ◽  
Amp Activated Protein Kinase ◽  
Ameliorate Insulin Resistance

scholarly journals The Heme Oxygenase System Abates Hyperglycemia in Zucker Diabetic Fatty Rats by Potentiating Insulin-Sensitizing Pathways

Endocrinology ◽  
2008 ◽  
Vol 150 (5) ◽  
pp. 2098-2108 ◽  
Author(s):  
Joseph Fomusi Ndisang ◽  
Nina lane ◽  
Ashok Jadhav
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Protein Kinase ◽  
Insulin Signaling ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Antidiabetic Effect ◽  
Insulin Resistant ◽  
Aldolase B ◽  
Amp Activated Protein Kinase

Emerging evidence indicates that aldosterone causes oxidative stress by stimulating proinflammatory/oxidative mediators, including nuclear factor-κB, activating protein (AP-1), and c-Jun N-terminal kinase. Thus, in insulin-resistant type 2 diabetes (T2D), oxidative stress generated by hyperglycemia and aldosterone would potentiate the oxidative destruction of tissue and important regulators of glucose metabolism like adiponectin and insulin. Although heme oxygenase (HO)-1 is cytoprotective, its effects on T2D have not been fully characterized. Here we report an enduring antidiabetic effect of the HO inducer, hemin, on Zucker diabetic-fatty rat (ZDF), a model of insulin-resistant T2D. Chronically applied hemin to ZDF reduced and maintained significantly low fasting and postprandial hyperglycemia for 4 months after therapy. The antidiabetic effect was accompanied by enhanced HO activity, catalase, cyclic GMP, bilirubin, ferritin, total antioxidant capacity, and insulin. In contrast, reduced aldosterone alongside markers/mediators of oxidative stress, including 8-isoprostane, c-Jun N-terminal kinase, nuclear factor-κB, AP-1, and AP-2 were observed. Interestingly, in hemin-treated ZDF, inhibitory proteins of insulin-signaling, such as glycogen synthase kinase-3 and protein-tyrosine phosphastase-1B were reduced, whereas agents that promote insulin signaling including adiponectin, cAMP, AMP-activated protein kinase, aldolase-B, and glucose transporter-4 (GLUT4), were robustly increased. Correspondingly, hemin improved ip glucose tolerance, reduced insulin intolerance, and lowered insulin resistance (homeostasis model assessment of insulin resistance), and the inability of insulin to enhance GLUT4 was overturned. These results suggest that the suppression of hyperglycemia and aldosterone-induced oxidative stress alongside the potentiation of insulin-sensitizing pathways may account for the 4-month enduring antidiabetic effect. The synergistic interaction between the HO system, aldolase-B, adiponectin, AMP-activated protein kinase, and GLUT4 may be explored for novel strategies against postprandial/fasting hyperglycemia and insulin-resistant T2D.

scholarly journals AMP-activated Protein Kinase Is Required for the Lipid-lowering Effect of Metformin in Insulin-resistant Human HepG2 Cells

2004 ◽  
Vol 279 (46) ◽  
pp. 47898-47905 ◽  
Author(s):  
Mengwei Zang ◽  
Adriana Zuccollo ◽  
Xiuyun Hou ◽  
Daisuke Nagata ◽  
Kenneth Walsh ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Hepg2 Cells ◽  
Lipid Lowering ◽  
Insulin Resistant ◽  
Lowering Effect ◽  
Amp Activated Protein Kinase ◽  
Lipid Lowering Effect

scholarly journals Polysaccharide Derived from Nelumbo nucifera Lotus Plumule Shows Potential Prebiotic Activity and Ameliorates Insulin Resistance in HepG2 Cells

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1780
Author(s):  
Bao Le ◽  
Pham-Thi-Ngoc Anh ◽  
Seung-Hwan Yang
Keyword(s):  
Insulin Resistance ◽  
Hepg2 Cells ◽  
Structural Characteristics ◽  
Physicochemical Characterization ◽  
Deae Cellulose ◽  
Hot Water ◽  
Nelumbo Nucifera ◽  
Molar Ratio ◽  
Prebiotic Activity ◽  
Insulin Resistant

Polysaccharides are key bioactive compounds in lotus plumule tea, but their anti-diabetes activities remain unclear. The purpose of this study was to investigate the prebiotic activities of a novel polysaccharide fraction from the Nelumbo nucifera lotus plumule, and to examine its regulation of glucose metabolism in insulin-resistant HepG2 cells. The N. nucifera polysaccharide (NNP) was purified after discoloration, hot water extraction, ethanol precipitation, and DEAE-cellulose chromatography to obtain purified polysaccharide fractions (NNP-2). Fourier transform infrared spectroscopy was used to analyze the main structural characteristics and functional group of NNP-2. Physicochemical characterization indicated that NNP-2 had a molecular weight of 110.47 kDa and consisted of xylose, glucose, fructose, galactose, and fucose in a molar ratio of 33.4:25.7:22.0:10.5:8.1. The prebiotic activity of NNP-2 was demonstrated in vitro using Lactobacillus and Bifidobacterium. Furthermore, NNP-2 showed bioactivity against α-glucosidase (IC50 = 97.32 µg/mL). High glucose-induced insulin-resistant HepG2 cells were used to study the effect of NNP-2 on glucose consumption, and the molecular mechanism of the insulin transduction pathway was studied using RT-qPCR. NNP-2 could improve insulin resistance by modulating the IRS1/PI3K/Akt pathway in insulin-resistant HepG2 cells. Our data demonstrated that the Nelumbo nucifera polysaccharides are potential sources for nutraceuticals, and we propose functional food developments from the bioactive polysaccharides of N. nucifera for the management of diabetes.

scholarly journals Attenuation of Free Fatty Acid-Induced Muscle Insulin Resistance by Rosemary Extract

Nutrients ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1623 ◽  
Author(s):  
Filip Vlavcheski ◽  
Evangelia Tsiani
Keyword(s):  
Insulin Resistance ◽  
Glucose Uptake ◽  
Muscle Cell ◽  
Serine Phosphorylation ◽  
Rosemary Extract ◽  
Muscle Insulin Resistance ◽  
Insulin Resistant ◽  
L6 Myotubes ◽  
P70 S6k ◽  
Amp Activated Protein Kinase

Elevated blood free fatty acids (FFAs), as seen in obesity, impair muscle insulin action leading to insulin resistance and Type 2 diabetes mellitus. Serine phosphorylation of the insulin receptor substrate (IRS) is linked to insulin resistance and a number of serine/threonine kinases including JNK, mTOR and p70 S6K have been implicated in this process. Activation of the energy sensor AMP-activated protein kinase (AMPK) increases muscle glucose uptake, and in recent years AMPK has been viewed as an important target to counteract insulin resistance. We reported recently that rosemary extract (RE) increased muscle cell glucose uptake and activated AMPK. However, the effect of RE on FFA-induced muscle insulin resistance has never been examined. In the current study, we investigated the effect of RE in palmitate-induced insulin resistant L6 myotubes. Exposure of myotubes to palmitate reduced the insulin-stimulated glucose uptake, increased serine phosphorylation of IRS-1, and decreased the insulin-stimulated phosphorylation of Akt. Importantly, exposure to RE abolished these effects and the insulin-stimulated glucose uptake was restored. Treatment with palmitate increased the phosphorylation/activation of JNK, mTOR and p70 S6K whereas RE completely abolished these effects. RE increased the phosphorylation of AMPK even in the presence of palmitate. Our data indicate that rosemary extract has the potential to counteract the palmitate-induced muscle cell insulin resistance and further studies are required to explore its antidiabetic properties.

scholarly journals Glycyrrhetinic Acid Improves Insulin-Response Pathway by Regulating the Balance between the Ras/MAPK and PI3K/Akt Pathways

Nutrients ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 604 ◽  
Author(s):  
Yuan Zhang ◽  
Shengnan Yang ◽  
Man Zhang ◽  
Zhihua Wang ◽  
Xin He ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Protein Kinase ◽  
Insulin Signaling ◽  
Hepg2 Cells ◽  
Mapk Pathway ◽  
Insulin Response ◽  
Glycyrrhetinic Acid ◽  
Intracellular Enzyme ◽  
Target Proteins ◽  
Iκb Kinase

Glycyrrhetinic acid (GA), a bioactive component in the human diet, has been reported to improve hyperglycemia, dyslipidemia, insulin resistance and obesity in rats with metabolic syndrome. However, GA-specific target proteins and the mechanisms involved in the downstream signaling and cross-talk to improve insulin sensitivity have not been fully elucidated. In this study, the potential targets of GA were identified by chemical proteomics strategies using serial GA probes for target fishing and cell molecular imaging. Intracellular enzyme activity evaluation and insulin resistance models were used for validating the function of the target proteins on the downstream insulin signaling pathways. Collectively, our data demonstrate that GA improved the insulin-responsive pathway and glucose consumption levels via multiple diabetogenic factors that activated the insulin signaling pathway in HepG2 cells. GA improved Glucose transporter 4(GLUT4) expression by targeting the Ras protein to regulate the mitogen-activated protein kinase (MAPK) pathway. GA exhibited a strong inhibitory effect on IRS1ser307 phosphorylation in cells treated with the Protein kinase C (PKC) activator Phorbol 12-myristate 13-acetate (PMA.) Consistently, IRS1ser307 phosphorylation was also inhibited by GA in Free fatty acid (FFA)-treated HepG2 cells. GA also inhibited the PMA-induced phosphorylation of IκB kinase α/β (IKKα/β), c-Jun N-terminal kinase (JNK) and p38 proteins (P38), suggesting that IKKα/β, JNK and P38 activation is dependent on PKC activity.

Fish oil supplementation inhibits endoplasmic reticulum stress and improves insulin resistance: involvement of AMP-activated protein kinase

2017 ◽  
Vol 8 (4) ◽  
pp. 1481-1493 ◽  
Author(s):  
Wenqi Yang ◽  
Xu Chen ◽  
Ming Chen ◽  
Yanping Li ◽  
Qing Li ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Endoplasmic Reticulum Stress ◽  
Fish Oil ◽  
Er Stress ◽  
Protective Effects ◽  
Ampk Activation ◽  
Amp Activated Protein Kinase ◽  
Fish Oil Supplementation

ER stress inhibition through AMPK activation may explain the protective effects of fish oil against HFD-induced insulin resistance.

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