scholarly journals Isoorientin Reverts TNF-α-Induced Insulin Resistance in Adipocytes Activating the Insulin Signaling Pathway

Endocrinology ◽  
2012 ◽  
Vol 153 (11) ◽  
pp. 5222-5230 ◽  
Author(s):  
Angel Josabad Alonso-Castro ◽  
Rocio Zapata-Bustos ◽  
Guadalupe Gómez-Espinoza ◽  
Luis A. Salazar-Olivo
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Insulin Signaling Pathway ◽  
Insulin Resistant ◽  
Expression Of Genes ◽  
Tnf Α ◽  
Genes Encoding ◽  
Insight Into ◽  
Antidiabetic Effects

Abstract Isoorientin (ISO) is a plant C-glycosylflavonoid with purported antidiabetic effects but unexplored mechanisms of action. To gain insight into its antidiabetic mechanisms, we assayed nontoxic ISO concentrations on the 2-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino)-2-deoxy-d-glucose (2-NBDG) uptake by murine 3T3-F442A and human sc adipocytes. In insulin-sensitive adipocytes, ISO stimulated the 2-NBDG uptake by 210% (murine) and 67% (human), compared with insulin treatment. Notably, ISO also induced 2-NBDG uptake in murine (139%) and human (60%) adipocytes made resistant to insulin by treatment with TNF-α, compared with the incorporation induced in these cells by rosiglitazone. ISO induction of glucose uptake in adipocytes was abolished by inhibitors of the insulin signaling pathway. These inhibitors also blocked the proper phosphorylation of insulin signaling pathway components induced by ISO in both insulin-sensitive and insulin-resistant adipocytes. Additionally, ISO stimulated the transcription of genes encoding components of insulin signaling pathway in murine insulin-sensitive and insulin-resistant adipocytes. In summary, we show here that ISO exerts its antidiabetic effects by activating the insulin signaling pathway in adipocytes, reverts the insulin resistance caused in these cells by TNF-α by stimulating the proper phosphorylation of proteins in this signaling pathway, and induces the expression of genes encoding these proteins.

The key role of Akt protein kinase in metabolic-inflammatory pathways cross-talk: TNF-α down-regulation and improving of insulin resistance in HepG2 cell line

2020 ◽  
Vol 20 ◽  
Author(s):  
Iraj Alipourfard ◽  
Salar Bakhtiyari ◽  
Ali Gheysarzadeh ◽  
Laura Di Renzo ◽  
Antonio De Lorenzo ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Hepg2 Cells ◽  
Insulin Signaling Pathway ◽  
Target Cells ◽  
Down Regulation ◽  
Akt Phosphorylation ◽  
Insulin Resistant ◽  
Tnf Α

Background: Elevation of plasma free fatty acids as a principal aspect of type 2 diabetes maintains etiologically insulin insensitivity in target cells. TNF-α inhibitory effects on key insulin signaling pathway elements remain to be verified in insulin-resistant hepatic cells. Thus, TNF-α knockdown effects on the key elements of insulin signaling were investigated in the palmitate-induced insulin-resistant hepatocytes. The Akt serine kinase, a key protein of the insulin signaling pathway, phosphorylation was monitored to understand the TNF-α effect on probable enhancing of insulin resistance. Methods: Insulin-resistant HepG2 cells were produced using 0.5 mM palmitate treatment and shRNA-mediated TNF-α gene knockdown and its down-regulation confirmed using ELISA technique. Western blotting analysis used to assess the Akt protein phosphorylation status. Results: Palmitate-induced insulin resistance caused TNF-α protein overexpression 1.2-, 2.78, and 2.25- fold as compared to the control cells at post-treatment times of 8 h, 16 h, and 24 h, respectively. In the presence of palmitate, TNF-α expression showed around 30% reduction in TNF-α knockdown cells as compared to normal cells. In the TNF-α down-regulated cell, Akt phosphorylation was approximately 62% more than control cells after treatment with 100 nM insulin in conjugation with 0.5 mM palmitate. Conclusions: The obtained data demonstrated that TNF-α protein expression reduction improved insulin-stimulated Akt phosphorylation in the HepG2 cells and decreased lipid-induced insulin resistance of the diabetic hepatocytes.

scholarly journals TNF-α Downregulation Modifies Insulin Receptor Substrate 1 (IRS-1) in Metabolic Signaling of Diabetic Insulin-Resistant Hepatocytes

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Iraj Alipourfard ◽  
Nelly Datukishvili ◽  
Davit Mikeladze
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Insulin Response ◽  
Insulin Signaling Pathway ◽  
Target Tissue ◽  
Normal Cells ◽  
Insulin Resistant ◽  
Diabetic Model ◽  
Tnf Α

One of the major mechanisms of hyperglycemia in type 2 diabetes is insulin resistance (IR) which can induce free fatty acids like palmitate. In hepatic cell, as an insulin target tissue, insulin resistance can be stimulated by inflammatory cytokine TNF-α. The interaction of intracellular TNF-α signal with the insulin signaling pathway is not well identified. Hence, we aimed to investigate the effect of TNF-α elimination on the diabetic model of palmitate-induced insulin-resistant hepatocytes (HepG2). The changes of phosphorylation rate in IRS-1 protein are determined to know the effect of TNF-α on this key protein of the insulin signaling pathway. HepG2 cells were treated with 0.5 Mm palmitate, and TNF-α gene knockdown was performed by shRNA-mediated technique. Western blot analysis was used to evaluate the phosphorylated activity of the insulin signaling pathway. Palmitate-induced IR could increase TNF-α protein expression 1.2-, 2.78-, and 2.25-fold compared to the control cells at times of 8 h, 16 h, and 24 h, respectively. TNF-α expression in downregulated cells transfected with shRNA-TNF-α is approximately 47.0% of normal cells and 49.0% in the case of scrambled cells. IRS-1 phosphorylation in TNF-α-downregulated and stimulated cells with 100 nM insulin, after treatment and in the absence of palmitate, was 45% and 29% higher than the normal cells. These data support the evidence that TNF-α downregulation strategy contributes to the improvement of IRS-1 phosphorylation after insulin stimulation and insulin response in HepG2 liver cells.

Duodenal-jejunal exclusion improves insulin resistance in type 2 diabetic rats by upregulating the hepatic insulin signaling pathway

Nutrition ◽  
2015 ◽  
Vol 31 (5) ◽  
pp. 733-739 ◽  
Author(s):  
Ze-Qiang Ren ◽  
Peng-Bo Zhang ◽  
Xiu-Zhong Zhang ◽  
Shou-Kun Chen ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Diabetic Rats ◽  
Insulin Signaling Pathway ◽  
Hepatic Insulin Signaling ◽  
Type 2 Diabetic

A novel PTP1B inhibitor extracted fromGanoderma lucidumameliorates insulin resistance by regulating IRS1-GLUT4 cascades in the insulin signaling pathway

2018 ◽  
Vol 9 (1) ◽  
pp. 397-406 ◽  
Author(s):  
Zhou Yang ◽  
Fan Wu ◽  
Yanming He ◽  
Qiang Zhang ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Insulin Signaling Pathway ◽  
Schematic Diagram ◽  
L6 Cells

A schematic diagram showing the IRS1-GLUT4 insulin signaling pathway influenced by PTP1B and FYGL in L6 cells.

scholarly journals 1197Identification of insulin signaling pathway-related circulating circRNAs as novel biomarkers of type 2 diabetes

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Yu-xiang Yan ◽  
Ya-Ke Lu ◽  
Xi Chu ◽  
Yue Sun ◽  
Jing Dong
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Akt Signaling ◽  
Insulin Signaling Pathway ◽  
Luciferase Reporter ◽  
Mirna Targets ◽  
Novel Biomarkers

Abstract Background The underlying molecular mechanism of type 2 diabetes (T2D) and insulin resistance is that abnormalities occur in the complex insulin signaling pathway. Circular RNAs (circRNAs) are involved in the development of diseases by regulating gene expression and become promising novel biomarkers for diseases. This study screened and validated the insulin signaling pathway-related circulating circRNAs, which are associated with T2D. Methods Based on circRNA microarray, candidate circRNAs involved in the insulin PI3K/Akt signaling pathway were selected and validated by RT-qPCR. The association between circRNAs and T2D and their clinical significance were further assessed by logistic regression model, correlation analysis and ROC curve in a large cohort. The miRNA targets of validated circRNAs was verified by dual-luciferase reporter assay. Results A total of 370 upregulated circRNAs and 180 downregulated circRNAs were differentially expressed between new T2D cases and controls. hsa_circ_0063425, hsa_circ_0056891 and hsa_circ_0104123 were selected as candidate circRNAs for validation. Low expressed circ_0063425 and hsa_circ_0056891 were independent predictors of T2D, impaired fasting glucose (IFG) and insulin resistance. The two-circRNA panel had a high diagnostic accuracy for discriminating T2D and IFG from healthy controls. miR-19a-3p and miR-1-3p were identified as the miRNA targets of hsa_circ_0063425 and hsa_circ_0056891, respectively. Significantly positive correlations were found between the expression levels of AKT and hsa_circ_0063425, PI3K and hsa_circ_0056891, in the total sample and subgroups stratified by glucose levels. Conclusion hsa_circ_0063425 and hsa_circ_0056891 are valuable circulating biomarkers for early detection of T2D, which may be involved in regulation of PI3K/AKT signaling. Key messages Insulin signaling pathway-related circulating circRNAs was identification as novel biomarkers of type 2 diabetes. Keywords circRNA; type 2 diabetes; insulin signaling; biomarker.

scholarly journals Intracellular pH Regulation of Skeletal Muscle in the Milieu of Insulin Signaling

Nutrients ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2910
Author(s):  
Dheeraj Kumar Posa ◽  
Shahid P. Baba
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Metabolic Syndrome ◽  
Signaling Pathway ◽  
Intracellular Ph ◽  
Cross Talk ◽  
Insulin Signaling ◽  
Insulin Signaling Pathway ◽  
Glycolytic Pathway ◽  
Insulin Responses

Type 2 diabetes (T2D), along with obesity, is one of the leading health problems in the world which causes other systemic diseases, such as cardiovascular diseases and kidney failure. Impairments in glycemic control and insulin resistance plays a pivotal role in the development of diabetes and its complications. Since skeletal muscle constitutes a significant tissue mass of the body, insulin resistance within the muscle is considered to initiate the onset of diet-induced metabolic syndrome. Insulin resistance is associated with impaired glucose uptake, resulting from defective post-receptor insulin responses, decreased glucose transport, impaired glucose phosphorylation, oxidation and glycogen synthesis in the muscle. Although defects in the insulin signaling pathway have been widely studied, the effects of cellular mechanisms activated during metabolic syndrome that cross-talk with insulin responses are not fully elucidated. Numerous reports suggest that pathways such as inflammation, lipid peroxidation products, acidosis and autophagy could cross-talk with insulin-signaling pathway and contribute to diminished insulin responses. Here, we review and discuss the literature about the defects in glycolytic pathway, shift in glucose utilization toward anaerobic glycolysis and change in intracellular pH [pH]i within the skeletal muscle and their contribution towards insulin resistance. We will discuss whether the derangements in pathways, which maintain [pH]i within the skeletal muscle, such as transporters (monocarboxylate transporters 1 and 4) and depletion of intracellular buffers, such as histidyl dipeptides, could lead to decrease in [pH]i and the onset of insulin resistance. Further we will discuss, whether the changes in [pH]i within the skeletal muscle of patients with T2D, could enhance the formation of protein aggregates and activate autophagy. Understanding the mechanisms by which changes in the glycolytic pathway and [pH]i within the muscle, contribute to insulin resistance might help explain the onset of obesity-linked metabolic syndrome. Finally, we will conclude whether correcting the pathways which maintain [pH]i within the skeletal muscle could, in turn, be effective to maintain or restore insulin responses during metabolic syndrome.

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