Carpachromene Ameliorates Insulin Resistance in HepG2 Cells via Modulating IR/IRS1/PI3k/Akt/GSK3/FoxO1 Pathway

Insulin resistance contributes to several disorders including type 2 diabetes and cardiovascular diseases. Carpachromene is a natural active compound that inhibits α-glucosidase enzyme. The aim of the present study is to investigate the potential activity of carpachromene on glucose consumption, metabolism and insulin signalling in a HepG2 cells insulin resistant model. A HepG2 insulin resistant cell model (HepG2/IRM) was established. Cell viability assay of HepG2/IRM cells was performed after carpachromene/metformin treatment. Glucose concentration and glycogen content were determined. Western blot analysis of insulin receptor, IRS1, IRS2, PI3k, Akt, GSK3, FoxO1 proteins after carpachromene treatment was performed. Phosphoenolpyruvate carboxykinase (PEPCK) and hexokinase (HK) enzymes activity was also estimated. Viability of HepG2/IRM cells was over 90% after carpachromene treatment at concentrations 6.3, 10, and 20 µg/mL. Treatment of HepG2/IRM cells with carpachromene decreased glucose concentration in a concentration- and time-dependant manner. In addition, carpachromene increased glycogen content of HepG2/IRM cells. Moreover, carpachromene treatment of HepG2/IRM cells significantly increased the expression of phosphorylated/total ratios of IR, IRS1, PI3K, Akt, GSK3, and FoxO1 proteins. Furthermore, PEPCK enzyme activity was significantly decreased, and HK enzyme activity was significantly increased after carpachromene treatment. The present study examined, for the first time, the potential antidiabetic activity of carpachromene on a biochemical and molecular basis. It increased the expression ratio of insulin receptor and IRS1 which further phosphorylated/activated PI3K/Akt pathway and phosphorylated/inhibited GSK3 and FoxO1 proteins. Our findings revealed that carpachromene showed central molecular regulation of glucose metabolism and insulin signalling via IR/IRS1/ PI3K/Akt/GSK3/FoxO1 pathway.

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Global proteomic analysis of insulin receptor interactors in glomerular podocytes

Wellcome Open Research ◽

10.12688/wellcomeopenres.16072.1 ◽

2020 ◽

Vol 5 ◽

pp. 202

Author(s):

Salman B. Hosawi ◽

Jonathan D. Humphries ◽

Richard J. Coward ◽

David Knight ◽

Martin J. Humphries ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Time Course ◽

Insulin Signalling ◽

Label Free ◽

Insulin Resistant ◽

Filtration Barrier ◽

Proteomic Approach ◽

Insulin Signalling Pathway ◽

Organ Systems

Background: Insulin signalling contributes to diverse cellular activities including protein synthesis, proliferation and cell survival. Insulin resistance describes the inability of cells to activate the insulin signalling pathway effectively; leading to pathological effects in multiple organ systems including the kidney. In diabetic kidney disease, there is progressive glomerular dysfunction and recent studies have demonstrated that the kidney podocyte is a direct target for insulin action. In this study we defined the literature-based insulin receptor (INSR) interactome and utilised an unbiased proteomic approach to examine INSR interactors in podocytes. Methods: Human podocytes expressing the INSR were characterised under basal and insulin resistant conditions. The INSR was isolated by whole cell immunoprecipitation following a time course stimulation of 2, 7, and 15 minutes with of 100nM insulin. The resulting INSR complexes were analysed by label-free mass spectrometry (MS) to detect protein interactors. Results: We identified 27 known, direct INSR interactors in addition to novel interactors including doublecortin domain-containing protein 2 (DCDC2). The interaction of DCDC2 with the INSR was confirmed by immunoprecipitation and immunofluorescence, and under insulin resistant conditions, DCDC2 had increased association with the INSR. siRNA knockdown of DCDC2 in podocytes resulted in cell morphological change and altered INSR localisation. Conclusion: This study provides insight into the complexity of INSR interactors in podocytes and highlights DCDC2 as a novel INSR binding protein. Involvement of this novel interactor in insulin signalling and podocyte biology may explain how insulin resistance alters morphology and integrity of the glomerular filtration barrier.

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Aspalathin-Enriched Green Rooibos Extract Reduces Hepatic Insulin Resistance by Modulating PI3K/AKT and AMPK Pathways

International Journal of Molecular Sciences ◽

10.3390/ijms20030633 ◽

2019 ◽

Vol 20 (3) ◽

pp. 633 ◽

Cited By ~ 23

Author(s):

Sithandiwe Mazibuko-Mbeje ◽

Phiwayinkosi Dludla ◽

Candice Roux ◽

Rabia Johnson ◽

Samira Ghoor ◽

...

Keyword(s):

Insulin Resistance ◽

Lipid Metabolism ◽

Insulin Sensitivity ◽

Protein Kinase ◽

Insulin Receptor ◽

Glucose Transporter ◽

Insulin Signalling ◽

Hepatic Insulin Resistance ◽

Insulin Resistant ◽

Glucose Transporter 2

We previously demonstrated that an aspalathin-enriched green rooibos extract (GRE) reversed palmitate-induced insulin resistance in C2C12 skeletal muscle and 3T3-L1 fat cells by modulating key effectors of insulin signalling such as phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B (PI3K/AKT) and AMP-activated protein kinase (AMPK). However, the effect of GRE on hepatic insulin resistance is unknown. The effects of GRE on lipid-induced hepatic insulin resistance using palmitate-exposed C3A liver cells and obese insulin resistant (OBIR) rats were explored. GRE attenuated the palmitate-induced impairment of glucose and lipid metabolism in treated C3A cells and improved insulin sensitivity in OBIR rats. Mechanistically, GRE treatment significantly increased PI3K/AKT and AMPK phosphorylation while concurrently enhancing glucose transporter 2 expression. These findings were further supported by marked stimulation of genes involved in glucose metabolism, such as insulin receptor (Insr) and insulin receptor substrate 1 and 2 (Irs1 and Irs2), as well as those involved in lipid metabolism, including Forkhead box protein O1 (FOXO1) and carnitine palmitoyl transferase 1 (CPT1) following GRE treatment. GRE showed a strong potential to ameliorate hepatic insulin resistance by improving insulin sensitivity through the regulation of PI3K/AKT, FOXO1 and AMPK-mediated pathways.

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

Polymers ◽

10.3390/polym13111780 ◽

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.

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Novel Grb14-Mediated Cross Talk between Insulin and p62/Nrf2 Pathways Regulates Liver Lipogenesis and Selective Insulin Resistance

Molecular and Cellular Biology ◽

10.1128/mcb.00170-16 ◽

2016 ◽

Vol 36 (16) ◽

pp. 2168-2181 ◽

Cited By ~ 11

Author(s):

Lucie Popineau ◽

Lucille Morzyglod ◽

Nadège Carré ◽

Michèle Caüzac ◽

Pascale Bossard ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Metabolic Diseases ◽

De Novo ◽

Liver Steatosis ◽

Growth Factor Receptor ◽

Glucose Production ◽

Acid Synthesis ◽

Related Factor ◽

Insulin Resistant

A long-standing paradox in the pathophysiology of metabolic diseases is the selective insulin resistance of the liver. It is characterized by a blunted action of insulin to reduce glucose production, contributing to hyperglycemia, whilede novolipogenesis remains insulin sensitive, participating in turn to hepatic steatosis onset. The underlying molecular bases of this conundrum are not yet fully understood. Here, we established a model of selective insulin resistance in mice by silencing an inhibitor of insulin receptor catalytic activity, the growth factor receptor binding protein 14 (Grb14) in liver. Indeed, Grb14 knockdown enhanced hepatic insulin signaling but also dramatically inhibitedde novofatty acid synthesis. In the liver of obese and insulin-resistant mice, downregulation of Grb14 markedly decreased blood glucose and improved liver steatosis. Mechanistic analyses showed that upon Grb14 knockdown, the release of p62/sqstm1, a partner of Grb14, activated the transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2), which in turn repressed the lipogenic nuclear liver X receptor (LXR). Our study reveals that Grb14 acts as a new signaling node that regulates lipogenesis and modulates insulin sensitivity in the liver by acting at a crossroad between the insulin receptor and the p62-Nrf2-LXR signaling pathways.

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Selective in vitro reversal of the insulin resistance of glucose transport in denervated rat skeletal muscle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1989.257.3.e418 ◽

1989 ◽

Vol 257 (3) ◽

pp. E418-E425 ◽

Cited By ~ 1

Author(s):

M. O. Sowell ◽

S. L. Dutton ◽

M. G. Buse

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Receptor ◽

Glucose Transport ◽

Glycogen Synthesis ◽

Insulin Response ◽

Medium Composition ◽

Insulin Resistant ◽

Denervated Muscles

Denervation (24 h) of skeletal muscle causes severe postreceptor insulin resistance of glucose transport and glycogen synthesis that is demonstrable in isolated muscles after short (30 min) preincubations. After longer preincubations (2-4 h), the insulin response of glucose transport increased to normal, whereas glycogen synthesis remained insulin resistant. Basal and insulin-stimulated amino acid transport were significantly lower in denervated muscles than in controls after short or long incubations, although the percentage stimulation of transport by insulin was not significantly different. The development of glucose transport insulin resistance after denervation was not attributable to increased sensitivity to glucocorticoids or adenosine. The selective in vitro reversal of glucose transport insulin resistance was not dependent on medium composition, did not require protein or prostaglandin synthesis, and could not be attributed to release of a positive regulator into the medium. The data suggest 1) the insulin receptor in muscle stimulates glucose transport by a signaling pathway that is not shared by other insulin-sensitive effector systems, and 2) denervation may affect insulin receptor signal transduction at more than one site.

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Insulin receptor autophosphorylation in cultured myoblasts correlates to glucose disposal in Pima Indians

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1999.276.5.e990 ◽

1999 ◽

Vol 276 (5) ◽

pp. E990-E994 ◽

Cited By ~ 2

Author(s):

Jack F. Youngren ◽

Ira D. Goldfine ◽

Richard E. Pratley

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Glucose Disposal ◽

Pima Indians ◽

Insulin Resistant ◽

Highly Sensitive ◽

Fasting Plasma Insulin ◽

The Relationship ◽

Muscle Biopsies

In a previous study [Youngren, J. F., I. D. Goldfire, and R. E. Pratley. Am. J. Physiol. 273 ( Endocrinol. Metab. 36): E276–E283, 1997] of skeletal muscle biopsies from insulin-resistant, nondiabetic Pima Indians, we demonstrated that diminished insulin receptor (IR) autophosphorylation correlated with in vivo insulin resistance. In the present study, to determine whether decreased IR function is a primary trait of muscle, and not secondary to an altered in vivo environment, we cultured myoblasts from 17 nondiabetic Pima Indians in whom insulin-stimulated glucose disposal (M) was measured during hyperinsulinemic-euglycemic glucose clamps. Myoblast IR autophosphorylation was determined by a highly sensitive ELISA. IR autophosphorylation directly correlated with M ( r = 0.56, P = 0.02) and inversely correlated with the fasting plasma insulin ( r = −0.58, P < 0.05). The relationship between M and IR autophosphorylation remained significant after M was adjusted for the effects of percent body fat (partial r = 0.53, P < 0.04). The relationship between insulin resistance and the capacity for myoblast IR autophosphorylation in nondiabetic Pima Indians suggests that variations in IR-signaling capacity may be intrinsic characteristics of muscle that contribute to the genetic component determining insulin action in this population.

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Role of O-GlcNAcylation and endoplasmic reticulum stress on obesity and insulin resistance

Turkish Journal of Biochemistry ◽

10.1515/tjb-2018-0303 ◽

2019 ◽

Vol 44 (5) ◽

pp. 599-610 ◽

Cited By ~ 1

Author(s):

Benan Pelin Sermikli ◽

Gulizar Aydogdu ◽

Afsar Abbasi Taghidizaj ◽

Erkan Yilmaz

Keyword(s):

Insulin Resistance ◽

Endoplasmic Reticulum ◽

Western Blot ◽

Er Stress ◽

Insulin Receptor ◽

Serine Phosphorylation ◽

Wild Type ◽

Adipose Tissues ◽

Insulin Resistant

Abstract Background Obesity is a global public health problem. Obesity closely associated with various metabolic diseases such as; insulin resistance, hypertension, dyslipidemia and cardiovascular diseases. Endoplasmic reticulum (ER) stress is a critical factor for insulin resistance. O-linked N-acetyl-glucosamine (O-GlcNAc); is the post-translational modification which is has a vital role in biological processes; including cell signaling, in response to nutrients, stress and other extracellular stimuli. Materials and methods In this study, we aimed to investigate the role of O-GlcNAc modification in the context of obesity and obesity-associated insulin resistance in adipose tissue. For this purpose, first, the visceral and epididymal adipose tissues of obese and insulin resistant C57BL/6 Lepob/Lepob and wild-type mice were used to determine the O-GlcNAc modification pattern by western blot. Secondly, the external stimulation of O-GlcNAc modification in wild-type mice achieved by intraperitoneal 5 mg/kg/day glucosamine injection every 24 h for 5 days. The effect of increased O-GlcNAc modification on insulin resistance and ER stress investigated in adipose tissues of glucosamine challenged wild-type mice through regulation of the insulin signaling pathway and unfolded protein response (UPR) elements by western blot. In addition to that, the O-GlcNAc status of the insulin receptor substrate-1 (IRS1) investigated in epididymal and visceral adipose tissues of ob/ob, wild-type and glucosamine challenged mice by immunoprecipitation. Results We found that reduced O-GlcNAc levels in visceral and epididymal adipose tissues of obese and insulin-resistant ob/ob mice, although interestingly we observed that increased O-GlcNAc modification in glucosamine challenged wild-type mice resulted in insulin resistance and ER stress. Furthermore, we demonstrated that the IRS1 was modified with O-GlcNAc in visceral and epididymal adipose tissues in both ob/ob mice and glucosamine-injected mice, and was compatible with the serine phosphorylation of this modification. Conclusion Our results suggest that O-GlcNAcylation of proteins is a crucial factor for intracellular trafficking regulates insulin receptor signaling and UPR depending on the cellular state of insulin resistance.

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Wu-Mei-Wan Reduces Insulin Resistance via Inhibition of NLRP3 Inflammasome Activation in HepG2 Cells

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2017/7283241 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Xueping Yang ◽

Lingli Li ◽

Ke Fang ◽

Ruolan Dong ◽

Jingbin Li ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Insulin Signaling ◽

Nlrp3 Inflammasome ◽

Hepg2 Cells ◽

Glucose Transporter ◽

Interleukin 1 ◽

Serine Phosphorylation ◽

Inflammasome Activation ◽

Glucose Consumption Rate

Wu-Mei-Wan (WMW) is a Chinese herbal formula used to treat type 2 diabetes. In this study, we aimed to explore the effects and mechanisms of WMW on insulin resistance in HepG2 cells. HepG2 cells were pretreated with palmitate (0.25 mM) to impair the insulin signaling pathway. Then, they were treated with different doses of WMW-containing medicated serum and stimulated with 100 nM insulin. Results showed that palmitate could reduce the glucose consumption rate in HepG2 cells and impair insulin signaling related to phosphorylation of insulin receptor (IR) and insulin receptor substrate-1 (IRS-1), thereby regulating the downstream signaling pathways. However, medicated serum of WMW restored impaired insulin signaling, upregulated the expression of phospho-IR (pIR), phosphatidylinositol 3-kinase p85 subunit, phosphoprotein kinase B, and glucose transporter 4, and decreased IRS serine phosphorylation. In addition, it decreased the expression of interleukin-1β and tumor necrosis factor-α, which are the key proinflammatory cytokines involved in insulin resistance; besides, it reduced the expression of NLRP3 inflammasome. These results suggested that WMW could alleviate palmitate-induced insulin resistance in HepG2 cells via inhibition of NLRP3 inflammasome and reduction of proinflammatory cytokine production.

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Cardiac Development and Transcription Factors: Insulin Signalling, Insulin Resistance, and Intrauterine Nutritional Programming of Cardiovascular Disease

Journal of Nutrition and Metabolism ◽

10.1155/2018/8547976 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 7

Author(s):

Annelene Govindsamy ◽

Strinivasen Naidoo ◽

Marlon E. Cerf

Keyword(s):

Insulin Resistance ◽

Cardiovascular Disease ◽

Transcription Factors ◽

Cardiac Development ◽

Insulin Signalling ◽

Life Stages ◽

Sequential Process ◽

Insulin Resistant ◽

Sensitive Organ ◽

And Function

Programming with an insult or stimulus during critical developmental life stages shapes metabolic disease through divergent mechanisms. Cardiovascular disease increasingly contributes to global morbidity and mortality, and the heart as an insulin-sensitive organ may become insulin resistant, which manifests as micro- and/or macrovascular complications due to diabetic complications. Cardiogenesis is a sequential process during which the heart develops into a mature organ and is regulated by several cardiac-specific transcription factors. Disrupted cardiac insulin signalling contributes to cardiac insulin resistance. Intrauterine under- or overnutrition alters offspring cardiac structure and function, notably cardiac hypertrophy, systolic and diastolic dysfunction, and hypertension that precede the onset of cardiovascular disease. Optimal intrauterine nutrition and oxygen saturation are required for normal cardiac development in offspring and the maintenance of their cardiovascular physiology.

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Tyrosine kinase activity of liver insulin receptor is inhibited in rats at term gestation

Biochemical Journal ◽

10.1042/bj2630267 ◽

1989 ◽

Vol 263 (1) ◽

pp. 267-272 ◽

Cited By ~ 9

Author(s):

C Martínez ◽

P Ruiz ◽

A Andrés ◽

J Satrústegui ◽

J M Carrascosa

Keyword(s):

Insulin Receptor ◽

Kinase Activity ◽

Insulin Signalling ◽

Insulin Receptors ◽

Insulin Binding ◽

Late Gestation ◽

Receptor Kinase ◽

Pregnant Rats ◽

Insulin Resistant ◽

32P Incorporation

Late gestation is associated with insulin resistance in rats and humans. It has been reported that rats at term gestation show active hepatic gluconeogenesis and glycogenolysis, and diminished lipogenesis, despite normal or mildly elevated plasma insulin concentrations, indicating a state of resistance to the hormone action. Since autophosphorylation of the insulin receptor has been reported to play a key role in the hormone signal transduction, we have partially purified plasma-membrane liver insulin receptors from virgin and 22-day-pregnant rats and studied their binding and kinase activities. (1) Insulin binding to partially purified receptors does not appear to be influenced by gestation, as indicated by the observed KD and Bmax. values. (2) The rate of autophosphorylation and the maximal 32P incorporation into the receptor beta-subunit from pregnant rats at saturating concentrations of insulin are markedly decreased with respect to the corresponding values for virgin rats. (3) The diminished autophosphorylation rate was due to a decreased responsiveness of the kinase activity to the action of insulin. (4) Phosphorylation of the exogenous substrates casein and poly(Glu80Tyr20) by insulin-receptor kinase was also less when receptors from pregnant rats were used. These results show the existence of an impairment at the receptor kinase level of the insulin signalling mechanism that might be related to the insulin-resistant state characteristic of term gestation in rats.

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