scholarly journals Astragaloside IV facilitates glucose transport in C2C12 myotubes through the IRS1/AKT pathway and suppresses the palmitate-induced activation of the IKK/IκBα pathway

2016 ◽  
Vol 37 (6) ◽  
pp. 1697-1705 ◽  
Author(s):  
RONGFENG ZHU ◽  
JIANJUN ZHENG ◽  
LIZHEN CHEN ◽  
BIN GU ◽  
SHENGLI HUANG
2008 ◽  
Vol 198 (3) ◽  
pp. 561-569 ◽  
Author(s):  
Wenbin Shang ◽  
Ying Yang ◽  
Libin Zhou ◽  
Boren Jiang ◽  
Hua Jin ◽  
...  

A series of clinical trials and animal experiments have demonstrated that ginseng and its major active constituent, ginsenosides, possess glucose-lowering action. In our previous study, ginsenoside Rb1 has been shown to regulate peroxisome proliferator-activated receptor γ activity to facilitate adipogenesis of 3T3-L1 cells. However, the effect of Rb1 on glucose transport in insulin-sensitive cells and its molecular mechanism need further elucidation. In this study, Rb1 significantly stimulated basal and insulin-mediated glucose uptake in a time- and dose-dependent manner in 3T3-L1 adipocytes and C2C12 myotubes; the maximal effect was achieved at a concentration of 1 μM and a time of 3 h. In adipocytes, Rb1 promoted GLUT1 and GLUT4 translocations to the cell surface, which was examined by analyzing their distribution in subcellular membrane fractions, and enhanced translocation of GLUT4 was confirmed using the transfection of GLUT4-green fluorescence protein in Chinese Hamster Ovary cells. Meanwhile, Rb1 increased the phosphorylation of insulin receptor substrate-1 and protein kinase B (PKB), and stimulated phosphatidylinositol 3-kinase (PI3K) activity in the absence of the activation of the insulin receptor. Rb1-induced glucose uptake as well as GLUT1 and GLUT4 translocations was inhibited by the PI3K inhibitor. These results suggest that ginsenoside Rb1 stimulates glucose transport in insulin-sensitive cells by promoting translocations of GLUT1 and GLUT4 by partially activating the insulin signaling pathway. These findings are useful in understanding the hypoglycemic and anti-diabetic properties of ginseng and ginsenosides.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Benedetta Rizzo ◽  
Laura Zambonin ◽  
Cristina Angeloni ◽  
Emanuela Leoncini ◽  
Francesco Vieceli Dalla Sega ◽  
...  

Extracts fromStevia rebaudianaBertoni, a plant native to Central and South America, have been used as a sweetener since ancient times. Currently,Steviaextracts are largely used as a noncaloric high-potency biosweetener alternative to sugar, due to the growing incidence of type 2 diabetes mellitus, obesity, and metabolic disorders worldwide. Despite the large number of studies onSteviaand steviol glycosidesin vivo, little is reported concerning the cellular and molecular mechanisms underpinning the beneficial effects on human health. The effect of four commercialSteviaextracts on glucose transport activity was evaluated in HL-60 human leukaemia and in SH-SY5Y human neuroblastoma cells. The extracts were able to enhance glucose uptake in both cellular lines, as efficiently as insulin. Our data suggest that steviol glycosides could act by modulating GLUT translocation through the PI3K/Akt pathway since treatments with both insulin andSteviaextracts increased the phosphorylation of PI3K and Akt. Furthermore,Steviaextracts were able to revert the effect of the reduction of glucose uptake caused by methylglyoxal, an inhibitor of the insulin receptor/PI3K/Akt pathway. These results corroborate the hypothesis thatSteviaextracts could mimic insulin effects modulating PI3K/Akt pathway.


2022 ◽  
Vol 2022 ◽  
pp. 1-8
Author(s):  
Zhenhuan Jiang ◽  
Gang Wang ◽  
Lingling Meng ◽  
Yunzhao Tang ◽  
Min Yang ◽  
...  

Background. Elevated uric acid (UA) has been found to damage pancreatic β-cell, promote oxidative stress, and cause insulin resistance in type 2 diabetes (T2D). Astragaloside IV (AS-IV), a major active monomer extracted from Astragalus membranaceus (Fisch.) Bunge. which belongs to TRIB. Galegeae (Br.) Torrey et Gray, Papilionaceae, exhibits various activities in a pathophysiological environment and has been widely employed to treat diseases. However, the effects of AS-IV on UA-induced pancreatic β-cell damage need to be investigated and the associating mechanism needs to be elucidated. This study was designed to determine the protective effects and underlying mechanism of AS-IV on UA-induced pancreatic β-cell dysfunction in T2D. Methods. UA-treated Min6 cells were exposed to AS-IV or wortmannin. Thereafter, the 3-(45)-dimethylthiahiazo(-z-y1)-35-di-phenytetrazoliumromide (MTT) assay and flow cytometry were employed to determine the effect of AS-IV on cell proliferation and apoptosis, respectively. Insulin secretion was evaluated using the glucose-stimulated insulin secretion (GSIS) assay. Finally, western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to determine the effect of AS-IV on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway in UA-treated cells. Results. AS-IV had no cytotoxic effects on Min6 cells. UA significantly suppressed Min6 cell growth, promoted cell apoptosis, and enhanced caspase-3 activity; however, AS-IV abolished these effects in a dose-dependent manner. Further, decreased insulin secretion was found in UA-treated Min6 cells compared to control cells, and the production of insulin was enhanced by AS-IV in a dose-dependent manner. AS-IV significantly increased phosphorylated (p)-AKT expression and the ratio of p-AKT/AKT in Min6 cells exposed to UA. No evident change in AKT mRNA level was found in the different groups. However, the effects of AS-IV on UA-stimulated Min6 cells were reversed by 100 nM wortmannin. Conclusion. Collectively, our data suggest that AS-IV protected pancreatic β-cells from UA-treated dysfunction by activating the PI3K/AKT pathway. Such findings suggest that AS-IV may be an efficient natural agent against T2D.


2020 ◽  
Vol 318 (6) ◽  
pp. C1214-C1225
Author(s):  
Amanda M. Eccardt ◽  
Ross J. Pelzel ◽  
Lyn Mattathil ◽  
Yerin A. Moon ◽  
Mark H. Mannino ◽  
...  

Reactive oxygen species such as hydrogen peroxide have been implicated in causing metabolic dysfunction such as insulin resistance. Heme groups, either by themselves or when incorporated into proteins, have been shown to scavenge peroxide and demonstrate protective effects in various cell types. Thus, we hypothesized that a metalloporphyrin similar in structure to heme, Fe(III)tetrakis(4-benzoic acid)porphyrin (FeTBAP), would be a peroxidase mimetic that could defend cells against oxidative stress. After demonstrating that FeTBAP has peroxidase activity with reduced nicotinamide adenine dinucleotide phosphate (NADPH) and NADH as reducing substrates, we determined that FeTBAP partially rescued C2C12 myotubes from peroxide-induced insulin resistance as measured by phosphorylation of AKT (S473) and insulin receptor substrate 1 (IRS-1, Y612). Furthermore, we found that FeTBAP stimulates insulin signaling in myotubes and mouse soleus skeletal muscle to about the same level as insulin for phosphorylation of AKT, IRS-1, and glycogen synthase kinase 3β (S9). We found that FeTBAP lowers intracellular peroxide levels and protects against carbonyl formation in myotubes exposed to peroxide. Additionally, we found that FeTBAP stimulates glucose transport in myotubes and skeletal muscle to about the same level as insulin. We conclude that a peroxidase mimetic can blunt peroxide-induced insulin resistance and also stimulate insulin signaling and glucose transport, suggesting a possible role of peroxidase activity in regulation of insulin signaling.


2021 ◽  
Vol 62 (1) ◽  
Author(s):  
Lie-Fen Shyur ◽  
Viola Varga ◽  
Chiao-Ming Chen ◽  
Shu-Chi Mu ◽  
Yu-Chih Chang ◽  
...  

Abstract Background White sweet potato (WSP; Ipomoea batatas L. Simon No. 1) has many potential beneficial effects on metabolic control and diabetes-related insulin resistance. The improvement of insulin resistance by WSP tuber extracts on glucose uptake were not investigated in C2C12 myoblast cells. Results WSP tuberous ethanol extract (WSP-E) was partitioned with ethyl-acetate and water to obtain ethyl-acetate layer (WSP-EA) and water layer (WSP-EW). The WSP-EA shows the highest total phenolic contents and highest antioxidant activity by Folin-Ciocalteu and (2,2-diphenyl-1-picryl-hydrazyl-hydrate, DPPH) assay, respectively. After low concentration horse serum on differentiation inducement of C2C12 myoblasts into mature myotubes, the cells were treated with TNF-α to induce insulin resistance. WSP-EA and WSP-EW extracts increased the uptake of fluorescence glucose analogue (2-[N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino]-2-deoxy-d-glucose, 2-NBDG) in a dose-dependent manner as examined by flow cytometry. The WSP-EA enhanced glucose uptake by activation of phosphorylation of IR (pIR), IRS-1 (pIRS-1) and Akt (pAkt) involved in PI3K (phosphatidylinositol 3-kinase)/protein kinase B (Akt) pathway, also upregulated glucose transporter 4 (GLUT4) expression in myotubes. Conclusions WSP-EA enhanced the glucose uptake in C2C12 myotubes through upregulating the PI3K/Akt pathway. The in vitro data reveal that WSP tuber extracts has potential applications to improve insulin resistance in diabetes.


2021 ◽  
Vol 281 ◽  
pp. 114558
Author(s):  
Pin Gong ◽  
Xuyang Xiao ◽  
Shuang Wang ◽  
Fuxiong Shi ◽  
Ni Liu ◽  
...  

2004 ◽  
Vol 279 (19) ◽  
pp. 19721-19731 ◽  
Author(s):  
Qi Shen ◽  
Gary W. Cline ◽  
Gerald I. Shulman ◽  
Mark D. Leibowitz ◽  
Peter J. A. Davies

Rexinoids and thiazolidinediones (TZDs) are two classes of nuclear receptor ligands that induce insulin sensitization in diabetic rodents. TZDs are peroxisome proliferator-activated receptor γ (PPARγ) activators, whereas rexinoids are selective ligands for the retinoid X receptors (RXRs). Activation of both the insulin receptor substrates (IRSs)/Akt and the c-Cbl-associated protein (CAP)/c-Cbl pathways are important in regulating insulin-stimulated glucose transport. We have compared the effects of a rexinoid (LG268) and a TZD (rosiglitazone) on these two signal pathways in skeletal muscle of diabetic (db/db) mice. The results we have obtained show that treatment ofdb/dbmice with either LG268 or rosiglitazone for 2 weeks results in a significant increase in insulin-stimulated glucose transport activity in skeletal muscle. Treatment with LG268 increases insulin-stimulated IRS-1 tyrosine phosphorylation and Akt phosphorylation in skeletal muscle without affecting the activity of the CAP/c-Cbl pathway. In contrast, rosiglitazone increases the levels of CAP expression and insulin-stimulated c-Cbl phosphorylation without affecting the IRS-1/Akt pathway. The effects of LG268 on the IRS-1/Akt pathway were associated with a decrease in the level of IRS-1 Ser307phosphorylation. Taken together, these data suggest that rexinoids improve insulin sensitivity via changes in skeletal muscle metabolism that are distinct from those induced by TZDs. Rexinoids represent a novel class of insulin sensitizers with potential applications in the treatment of insulin resistance.


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