Palmitic Acid Induces MicroRNA-221 Expression to Decrease Glucose Uptake in HepG2 Cells via the PI3K/AKT/GLUT4 Pathway

Obesity-related insulin resistance and high fatty acid concentrations occur during the development of type 2 diabetes mellitus. The role of high concentrations of plasma-free fatty acids is not fully understood. In this study, palmitic acid (PA, 0.8 mM for 24 h) induced the expression of miR-221 that bound to phosphoinositide 3-kinases (PI3K) mRNA to inhibit glucose uptake by HepG2 cells. Compared with controls, PA significantly decreased glucose uptake, increased insulin receptor substrate-2 (IRS-2) and miR-221 expression, and decreased phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and glucose transporter type 4 (GLUT4) mRNA expression. Luciferase reporter assay revealed that miR-221 binding inhibited PI3K expression. Transfection of HepG2 cells with an miR-221 mimic induced miR-221 expression and inhibited the PI3K/AKT pathway. PA decreased glucose uptake in HepG2 cells by inducing the expression of miR-221, which bound to PI3K mRNA and suppressed PI3K/AKT signaling. miR-221 may be a novel target for preventing and treating obesity-induced insulin resistance.

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Theaflavins Improve Insulin Sensitivity through Regulating Mitochondrial Biosynthesis in Palmitic Acid-Induced HepG2 Cells

Molecules ◽

10.3390/molecules23123382 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3382 ◽

Cited By ~ 6

Author(s):

Tuantuan Tong ◽

Ning Ren ◽

Park Soomi ◽

Jiafan Wu ◽

Na Guo ◽

...

Keyword(s):

Insulin Resistance ◽

Palmitic Acid ◽

Glucose Uptake ◽

Hepg2 Cells ◽

Molecular Mechanisms ◽

Glucose Transporter ◽

Mrna Level ◽

Food Ingredients ◽

Insulin Resistant ◽

Mitochondrial Dna Copy Number

Theaflavins, the characteristic and bioactive polyphenols in black tea, possess the potential improving effects on insulin resistance-associated metabolic abnormalities, including obesity and type 2 diabetes mellitus. However, the related molecular mechanisms are still unclear. In this research, we investigated the protective effects of theaflavins against insulin resistance in HepG2 cells induced by palmitic acid. Theaflavins significantly increased glucose uptake of insulin-resistant cells at noncytotoxic doses. This activity was mediated by upregulating the total and membrane bound glucose transporter 4 protein expressions, increasing the phosphor-Akt (Ser473) level, and decreasing the phosphorylation of IRS-1 at Ser307. Moreover, theaflavins were found to enhance the mitochondrial DNA copy number, down-regulate the PGC-1β mRNA level and increase the PRC mRNA expression. Mdivi-1, a selective mitochondrial division inhibitor, could attenuate TFs-induced promotion of glucose uptake in insulin-resistant HepG2 cells. Taken together, these results suggested that theaflavins could improve hepatocellular insulin resistance induced by free fatty acids, at least partly through promoting mitochondrial biogenesis. Theaflavins are promising functional food ingredients and medicines for improving insulin resistance-related disorders.

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Theaflavins Improve Insulin Sensitivity through Regulating Mitochondrial Biosynthesis in Palmitic Acid-Induced HepG2 Cells

10.20944/preprints201811.0321.v1 ◽

2018 ◽

Author(s):

Tuantuan Tong ◽

Ning Ren ◽

Jiafan Wu ◽

Na Guo ◽

Xiaobo Liu ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Sensitivity ◽

Palmitic Acid ◽

Hepg2 Cells ◽

Molecular Mechanisms ◽

Glucose Transporter ◽

Hepatic Insulin Resistance ◽

Insulin Resistant ◽

Mitochondrial Dna Copy Number ◽

Increase Glucose Uptake

Theaflavins, the characteristic and bioactive polyphenols in black tea, possess the potential improvement effects on insulin resistance-associated metabolic abnormalities including obesity and type 2 diebetes. However, the molecular mechanisms of theaflavins improving insulin sensitivity are still not clear. In this study, we investigated the protective effects and mechanisms of theaflavins on palmitic acid-induced insulin resistance in HepG2 cells. Theaflavins could significantly increase glucose uptake of insulin-resistant cells at noncytotoxic doses. This activity was mediated by upregulating the glucose transporter 4 protein expression, increasing the phosphorylation of IRS-1 at Ser307, and reduced the phosphor-Akt (Ser473) level. Moreover, theaflavins were found to enhance mitochondrial DNA copy number through down-regulate the PGC-1β mRNA level and up-regulate PRC mRNA expression in insulin-resistant HepG2 cells. These results indicated that theaflavins could improve free fatty acid-induced hepatic insulin resistance by promoting mitochondrial biogenesis, and were promising functional food and medicines for insulin resistance-related disorders.

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Palmitic Acid Regulates miRNA-3148 via Insulin Receptor Substrate-1 and is Involved in Insulin Resistance

Journal of Biomaterials and Tissue Engineering ◽

10.1166/jbt.2021.2576 ◽

2021 ◽

Vol 11 (4) ◽

pp. 767-771

Author(s):

Xiaoxi Xiang ◽

Changwei Zhang ◽

Daying Long

Keyword(s):

Insulin Resistance ◽

Palmitic Acid ◽

Insulin Receptor ◽

Hepg2 Cells ◽

Luciferase Reporter ◽

Insulin Receptor Substrate ◽

Insulin Receptor Substrate 1 ◽

Over Expression ◽

Reporter Assays ◽

The Impact

Previous studies reported that saturated fatty acid palmitic acid (PA) is closely related to insulin resistance. miR-3148 regulates insulin receptor substrate-1 (IRS1) predicted by MiRDB analysis. However, whether PA regulates IRS1 via miR-3148 remains to be elucidated. Therefore, in this work, we assessed whether PA regulates miRNA-3148 via IRS1 in insulin resistance. We cultured HepG2 cells in vitro and classified them into control group (NC group), miR-3148 Mimics group, and miR-3148 Mimics+ pFBD-IRS1 group. We used qRT-PCR to detect miR-3148 and IRS1 mRNA; used Dual-Luciferase Reporter Assays to detect miR-3148 with 3′-UTR region of IRS1 mRNA; and utilized Western blot (WB) to detect IRS1, p-AKT, AKT and Tubulin. Our results showed that PA could increase miR-3148 and decrease IRS1 which is a target protein of miR-3148, as shown by Dual-Luciferase Reporter assays. miR-3148 significantly inhibited the impact of insulin on p-AKT level (P < 0.01) and over-expression of IRS1 by pFBD-IRS1 can partially alleviate the inhibitory effect of miR-3148 mimics on p-AKT. In HepG2 cells, PA regulates miR-3148. Via targeting IRS1 mRNA, miR-3148 impairs insulin signaling pathway, leading to insulin resistance. Over-expression of IRS1 by pFBD-IRS1 alleviates miR-3148-induced insulin resistance.

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microRNA-4458 Regulates Insulin Resistance in Hepatic Cells by Targeting the Insulin-Like Growth Factor 1 Receptor

Journal of Biomaterials and Tissue Engineering ◽

10.1166/jbt.2021.2597 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1812-1817

Author(s):

Jingjing Zhou ◽

Wenjuan Zhu ◽

Zheng Mao ◽

Zhen Li ◽

Xiaoqin Li ◽

...

Keyword(s):

Insulin Resistance ◽

Mrna Expression ◽

Glucose Uptake ◽

Hepg2 Cell ◽

Molecular Mechanisms ◽

Cell Model ◽

Serum Insulin ◽

Luciferase Reporter ◽

Control Group ◽

Hepatic Cells

Background: The objective of the research was to investigate the roles of miR-4458 in the regulation of insulin resistance in hepatic cells and to explore the underlying molecular mechanisms. Methods: The blood samples were collected from the T2D patients and the health controls, and the liver tissues were collected from the DM and control rats. The relationship between IGF1R and miR-4458 was predicted by TargetScan and verified by the dual luciferase reporter gene system. qRT-PCR was used to measure the mRNA expression of miR-4458, IGF1R, G6Pase and PEPCK. The protein expression of IGF1R, p-AKT and AKT were measured by Western blot analysis. The rat insulin ELISA Kit and glucose Uptake Colorimteric Assay Kit were used to determine the level of serum insulin and the glucose uptake. Results: miR-4458 was high expressed in T2D patients. We predicted and verified that IGF1R was a direct target of miR-4458, and the mRNA expression of IGF1R was reduced in type 2 diabetes patients. We established the diabetes model (DM) and IR HepG2 cell model, and found that the blood glucose and serum insulin levels were significantly elevated in the DM group. miR-4458 expression was up-regulated, while the expression of IGF1R and p-AKT, and p-AKT/AKT ratio were reduced in the DM group and IR HepG2 cell model. miR-4458 inhibitor and IGF1R-siRNA significantly decreased the expression of miR-4458 and IGF1R respectively. In comparison with IR+inhibitor control group, miR-4458 inhibitor increased 2-DG6P content, IGF1R expression, p-AKT expression and p-AKT/AKT ratio, reduced the expression of G6Pase and PEPCK, and all the effects were reversed by down-regulating IGF1R. Conclusion: miR-4458 regulated the insulin resistance in hepatic cells by regulating the IGF1R/PI3K/AKT signal pathway, which will be a potential target for the treatment of diabetes.

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Hypoglycemic Effect of Vitexin in C57BL/6J Mice and HepG2 Models

Journal of Food Quality ◽

10.1155/2021/5535476 ◽

2021 ◽

Vol 2021 ◽

pp. 1-7

Author(s):

Weidong Xu ◽

Jiayao Li ◽

Weipeng Qi ◽

Ye Peng

Keyword(s):

Insulin Resistance ◽

Body Weight ◽

Weight Gain ◽

Blood Glucose ◽

Glucose Uptake ◽

Lipid Content ◽

Hepg2 Cells ◽

Body Weight Gain ◽

Tnf Α ◽

Hepatic Lipid Content

Apigenin-8-C-glucoside (vitexin), a natural phytochemical contained in hawthorn, has been reported to have versatile beneficial bioactivities, such as antioxidation, anticancer property, and adipogenesis inhibition. The present research aimed to determine the influence of vitexin on insulin resistance elicited by HFD in mice and HepG2 cells. Vitexin markedly alleviated body weight gain and improved glucose and insulin intolerance induced by HFD. Vitexin partially normalized blood glucose, cholesterol, TNF-α, and hepatic lipid content. Moreover, vitexin recovered the reduced glucose uptake induced by glucosamine. The present results indicate that vitexin prevents HFD-induced insulin resistance.

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Alleviative Effect of Ruellia tuberosa L. on Insulin Resistance and Abnormal Lipid Accumulation in TNF-α-Treated FL83B Mouse Hepatocytes

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2021/9967910 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Hong-Jie Chen ◽

Chih-Yuan Ko ◽

Jian-Hua Xu ◽

Yu-Chu Huang ◽

James Swi-Bea Wu ◽

...

Keyword(s):

Insulin Resistance ◽

Ethyl Acetate ◽

Glucose Uptake ◽

Insulin Signaling ◽

Lipid Accumulation ◽

Glucose Transporter ◽

Peroxisome Proliferator ◽

Glucose Transporter 2 ◽

Tnf Α ◽

Mouse Hepatocytes

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease, and most patients with T2DM develop nonalcoholic fatty liver disease (NAFLD). Both diseases are closely linked to insulin resistance (IR). Our previous studies demonstrated that Ruellia tuberosa L. (RTL) extract significantly enhanced glucose uptake in the skeletal muscles and ameliorated hyperglycemia and IR in T2DM rats. We proposed that RTL might be via enhancing hepatic antioxidant capacity. However, the potent RTL bioactivity remains unidentified. In this study, we investigated the effects of RTL on glucose uptake, IR, and lipid accumulation in vitro to mimic the T2DM accompanied by the NAFLD paradigm. FL83B mouse hepatocytes were treated with tumor necrosis factor-α (TNF-α) to induce IR, coincubated with oleic acid (OA) to induce lipid accumulation, and then, treated with RTL fractions, fractionated with n-hexane or ethyl acetate (EA), from column chromatography, and analyzed by thin-layer chromatography. Our results showed that the ethyl acetate fraction (EAf2) from RTL significantly increased glucose uptake and suppressed lipid accumulation in TNF-α plus OA-treated FL83B cells. Western blot analysis showed that EAf2 from RTL ameliorated IR by upregulating the expression of insulin-signaling-related proteins, including protein kinase B, glucose transporter-2, and peroxisome proliferator-activated receptor alpha in TNF-α plus OA-treated FL83B cells. The results of this study suggest that EAf2 from RTL may improve hepatic glucose uptake and alleviate lipid accumulation by ameliorating and suppressing the hepatic insulin signaling and lipogenesis pathways, respectively, in hepatocytes.

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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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Overfeeding during Lactation in Rats is Associated with Cardiovascular Insulin Resistance in the Short-Term

Nutrients ◽

10.3390/nu12020549 ◽

2020 ◽

Vol 12 (2) ◽

pp. 549 ◽

Cited By ~ 2

Author(s):

Daniel González-Hedström ◽

Lucía Guerra-Menéndez ◽

Antonio Tejera-Muñoz ◽

Sara Amor ◽

María de la Fuente-Fernández ◽

...

Keyword(s):

Insulin Resistance ◽

Glucose Transporter ◽

Mitogen Activated Protein Kinase ◽

Lactation Period ◽

Cardiovascular Comorbidities ◽

Rat Pups ◽

Mitogen Activated Protein ◽

Phosphoinositide 3 Kinase ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Childhood obesity is associated with metabolic and cardiovascular comorbidities. The development of these alterations may have its origin in early life stages such as the lactation period through metabolic programming. Insulin resistance is a common complication in obese patients and may be responsible for the cardiovascular alterations associated with this condition. This study analyzed the development of cardiovascular insulin resistance in a rat model of childhood overweight induced by overfeeding during the lactation period. On birth day, litters were divided into twelve (L12) or three pups per mother (L3). Overfed rats showed a lower increase in myocardial contractility in response to insulin perfusion and a reduced insulin-induced vasodilation, suggesting a state of cardiovascular insulin resistance. Vascular insulin resistance was due to decreased activation of phosphoinositide 3-kinase (PI3K)/Akt pathway, whereas cardiac insulin resistance was associated with mitogen-activated protein kinase (MAPK) hyperactivity. Early overfeeding was also associated with a proinflammatory and pro-oxidant state; endothelial dysfunction; decreased release of nitrites and nitrates; and decreased gene expression of insulin receptor (IR), glucose transporter-4 (GLUT-4), and endothelial nitric oxide synthase (eNOS) in response to insulin. In conclusion, overweight induced by lactational overnutrition in rat pups is associated with cardiovascular insulin resistance that could be related to the cardiovascular alterations associated with this condition.

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