scholarly journals The Influence of Coumestrol on Sphingolipid Signaling Pathway and Insulin Resistance Development in Primary Rat Hepatocytes

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 268
Author(s):  
Hubert Zywno ◽  
Wiktor Bzdega ◽  
Adrian Kolakowski ◽  
Piotr Kurzyna ◽  
Ewa Harasim-Symbor ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
De Novo ◽  
Rat Hepatocytes ◽  
Nutritional Therapy ◽  
Hepatic Insulin Resistance ◽  
Fatty Acid Transport ◽  
Resistance Development ◽  
Primary Rat Hepatocytes ◽  
Insulin Resistant

Coumestrol is a phytoestrogen widely known for its anti-diabetic, anti-oxidant, and anti-inflammatory properties. Thus, it gets a lot of attention as a potential agent in the nutritional therapy of diseases such as obesity and type 2 diabetes. In our study, we evaluated whether coumestrol affects insulin resistance development via the sphingolipid signaling pathway in primary rat hepatocytes. The cells were isolated from the male Wistar rat’s liver with the use of collagenase perfusion. Next, we incubated the cells with the presence or absence of palmitic acid and/or coumestrol. Additionally, some groups were incubated with insulin. The sphingolipid concentrations were assessed by HPLC whereas the expression of all the proteins was evaluated by Western blot. Coumestrol markedly reduced the accumulation of sphingolipids, namely, ceramide and sphinganine through noticeable inhibition of the ceramide de novo synthesis pathway in insulin-resistant hepatocytes. Moreover, coumestrol augmented the expression of fatty acid transport proteins, especially FATP5 and FAT/CD36, which also were responsible for excessive sphingolipid accumulation. Furthermore, coumestrol altered the sphingolipid salvage pathway, which was observed as the excessive deposition of the sphingosine-1-phosphate and sphingosine. Our study clearly showed that coumestrol ameliorated hepatic insulin resistance in primary rat hepatocytes. Thus, we believe that our study may contribute to the discovery of novel preventive and therapeutic methods for metabolic disorders.

scholarly journals Fas-Associated Factor 1 Promotes Hepatic Insulin Resistance via JNK Signaling Pathway

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bao Sun ◽  
Jiecan Zhou ◽  
Yongchao Gao ◽  
Fazhong He ◽  
Heng Xu ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Signaling Pathway ◽  
Metabolic Disorder ◽  
Immunofluorescence Assay ◽  
Hepatic Insulin Resistance ◽  
Ros Production ◽  
Loss Of Function ◽  
Associated Factor ◽  
Insulin Resistant ◽  
Signaling Complex

Fas-associated factor 1 (FAF1), a member of the Fas death-inducing signaling complex, is reported to interact potentially with diverse proteins and function in diverse cellular possesses. It remains unclear, however, whether FAF1 is involved in hepatic metabolic disorder and insulin resistance. This study aims to elucidate the role and the molecular mechanism of FAF1 in hepatic insulin resistance. Rats treated with high-fat diets are used as hepatic insulin resistance animal models. Quantitative real-time PCR, immunohistochemistry, and immunofluorescence assay are utilized to detect the FAF1 expression. The expression of relevant proteins is detected by Western blotting. We determine ROS production, lipid accumulation, and glucose uptake by using flow cytometry. Immunoprecipitation is employed to investigate protein-protein interaction. We find that increased expression of FAF1 occurred in the livers of insulin-resistant rats. Using gain-of-function and loss-of-function approaches, we observe dramatic exacerbation of insulin resistance, upregulated gluconeogenesis genes, downregulated glucose transport genes, and enhanced ROS production by FAF1 overexpression, whereas downregulation of FAF1 leads to a completely opposite phenotype. Mechanistically, FAF1 interacts directly with c-Jun N-terminal kinase (JNK) and activates its phosphorylation, thereby blocking the downstream insulin signaling pathway and leading to insulin resistance. Our data indicate that FAF1 is a potent regulator in hepatic metabolic disorder and insulin resistance.

scholarly journals Sulforaphane Prevents Hepatic Insulin Resistance by Blocking Serine Palmitoyltransferase 3-Mediated Ceramide Biosynthesis

Nutrients ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1185 ◽  
Author(s):  
Wendi Teng ◽  
Yuan Li ◽  
Min Du ◽  
Xingen Lei ◽  
Siyu Xie ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Signaling Pathway ◽  
Glucose Homeostasis ◽  
Hepg2 Cells ◽  
Hepatic Insulin Resistance ◽  
Serine Palmitoyltransferase ◽  
Insulin Resistant ◽  
Ceramide Production

Sulforaphane (SFA), a naturally active isothiocyanate compound from cruciferous vegetables used in clinical trials for cancer treatment, was found to possess potency to alleviate insulin resistance. But its underlying molecular mechanisms are still incompletely understood. In this study, we assessed whether SFA could improve insulin sensitivity and glucose homeostasis both in vitro and in vivo by regulating ceramide production. The effects of SFA on glucose metabolism and expression levels of key proteins in the hepatic insulin signaling pathway were evaluated in insulin-resistant human hepatic carcinoma HepG2 cells. The results showed that SFA dose-dependently increased glucose uptake and intracellular glycogen content by regulating the insulin receptor substrate 1 (IRS-1)/protein kinase B (Akt) signaling pathway in insulin-resistant HepG2 cells. SFA also reduced ceramide contents and downregulated transcription of ceramide-related genes. In addition, knockdown of serine palmitoyltransferase 3 (SPTLC3) in HepG2 cells prevented ceramide accumulation and alleviated insulin resistance. Moreover, SFA treatment improved glucose tolerance and insulin sensitivity, inhibited SPTLC3 expression and hepatic ceramide production and reduced hepatic triglyceride content in vivo. We conclude that SFA recovers glucose homeostasis and improves insulin sensitivity by blocking ceramide biosynthesis through modulating SPTLC3, indicating that SFA may be a potential candidate for prevention and amelioration of hepatic insulin resistance via a ceramide-dependent mechanism.

scholarly journals Hepatic Insulin Resistance Is Not Pathway Selective in Humans With Nonalcoholic Fatty Liver Disease

2020 ◽  
Author(s):  
Kasper W. ter Horst ◽  
Daniel F. Vatner ◽  
Dongyan Zhang ◽  
Gary W. Cline ◽  
Mariette T. Ackermans ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Bariatric Surgery ◽  
Liver Disease ◽  
Fatty Liver ◽  
Insulin Signaling ◽  
Fatty Liver Disease ◽  
De Novo ◽  
Glucose Production ◽  
Hepatic Insulin Resistance ◽  
Alcoholic Fatty Liver

<b>Objective</b>: Both glucose and triglyceride production are increased in Type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). For decades, the leading hypothesis to explain these paradoxical observations has been selective hepatic insulin resistance, wherein insulin drives <i>de novo</i> lipogenesis (DNL), while failing to suppress glucose production. Here, we aimed to test this hypothesis in humans. <p><b>Research Design and Methods</b>: We recruited obese subjects who met criteria for bariatric surgery with (n=16) or without (n=15) NAFLD and assessed: i) insulin-mediated regulation of hepatic and peripheral glucose metabolism using hyperinsulinemic-euglycemic clamps with [6,6-<sup>2</sup>H<sub>2</sub>]glucose, ii) fasting and carbohydrate-driven hepatic DNL using deuterated water (<sup>2</sup>H<sub>2</sub>O), and iii) hepatocellular insulin signaling in liver biopsies collected during bariatric surgery.</p> <p><b>Results</b>: As compared with subjects without NAFLD, subjects with NAFLD demonstrated impaired insulin-mediated suppression of glucose production and attenuated -not increased- glucose-stimulated/high-insulin lipogenesis. Fructose-stimulated/low-insulin lipogenesis was intact. Hepatocellular insulin signaling, assessed for the first time in humans, exhibited a proximal block in insulin-resistant subjects: signaling was attenuated from the level of the insulin receptor through both glucose <i>and</i> lipogenesis pathways. The carbohydrate-regulated lipogenic transcription factor <i>ChREBP</i> was increased in subjects with NAFLD. </p> <b>Conclusions</b>: Acute increases in lipogenesis in humans with NAFLD are not explained by altered molecular regulation of lipogenesis through a paradoxical increase in lipogenic insulin action; rather, increases in lipogenic substrate availability may be the key. <a></a>

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

2016 ◽  
Vol 36 (16) ◽  
pp. 2168-2181 ◽  
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.

scholarly journals Hepatic saturated fatty acid fraction is associated with de novo lipogenesis and hepatic insulin resistance

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Kay H. M. Roumans ◽  
Lucas Lindeboom ◽  
Pandichelvam Veeraiah ◽  
Carlijn M. E. Remie ◽  
Esther Phielix ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Saturated Fatty Acid ◽  
De Novo ◽  
Fatty Acid Fraction ◽  
De Novo Lipogenesis ◽  
Hepatic Insulin Resistance ◽  
Acid Fraction

scholarly journals Suppression of the mTORC1/STAT3/Notch1 pathway by activated AMPK prevents hepatic insulin resistance induced by excess amino acids

2014 ◽  
Vol 306 (2) ◽  
pp. E197-E209 ◽  
Author(s):  
Hongliang Li ◽  
Jiyeon Lee ◽  
Chaoyong He ◽  
Ming-Hui Zou ◽  
Zhonglin Xie
Keyword(s):  
Insulin Resistance ◽  
Amino Acids ◽  
Amino Acid ◽  
Signaling Pathway ◽  
High Protein Diet ◽  
Chronic Administration ◽  
Hepatic Insulin Resistance ◽  
Notch1 Signaling ◽  
Mtorc1 Signaling ◽  
Notch1 Signaling Pathway

Nutrient overload is associated with the development of obesity, insulin resistance, and type 2 diabetes. However, the underlying mechanisms for developing insulin resistance in the presence of excess nutrients are incompletely understood. We investigated whether activation of AMP-activated protein kinase (AMPK) prevents the hepatic insulin resistance that is induced by the consumption of a high-protein diet (HPD) and the presence of excess amino acids. Exposure of HepG2 cells to excess amino acids reduced AMPK phosphorylation, upregulated Notch1 expression, and impaired the insulin-stimulated phosphorylation of Akt Ser473 and insulin receptor substrate-1 (IRS-1) Tyr612. Inhibition of Notch1 prevented amino acid-induced insulin resistance, which was accompanied by reduced expression of Rbp-Jk, hairy and enhancer of split-1, and forkhead box O1. Mechanistically, mTORC1 signaling was activated by excess amino acids, which then positively regulated Notch1 expression through the activation of the signal transducer and activator of transcription 3 (STAT3). Activation of AMPK by metformin inhibited mTORC1-STAT3 signaling, thereby preventing excess amino acid-impaired insulin signaling. Finally, HPD feeding suppressed AMPK activity, activated mTORC1/STAT3/Notch1 signaling, and induced insulin resistance. Chronic administration of either metformin or rapamycin inhibited the HPD-activated mTORC1/STAT3/Notch1 signaling pathway and prevented hepatic insulin resistance. We conclude that the upregulation of Notch1 expression by hyperactive mTORC1 signaling is an essential event in the development of hepatic insulin resistance in the presence of excess amino acids. Activation of AMPK prevents amino acid-induced insulin resistance through the suppression of the mTORC1/STAT3/Notch1 signaling pathway.

scholarly journals RNA-sequencing analysis reveals the potential contribution of lncRNAs in palmitic acid-induced insulin resistance of skeletal muscle cells

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Mei Han ◽  
Lianghui You ◽  
Yanting Wu ◽  
Nan Gu ◽  
Yan Wang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Palmitic Acid ◽  
Signaling Pathway ◽  
Rna Sequencing ◽  
Metabolic Diseases ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
C2c12 Myotubes ◽  
Insulin Resistant

Abstract Insulin resistance (IR) has been considered as the common pathological basis and developmental driving force for most metabolic diseases. Long noncoding RNAs (lncRNAs) have emerged as pivotal regulators in modulation of glucose and lipid metabolism. However, the comprehensive profile of lncRNAs in skeletal muscle cells under the insulin resistant status and the possible biological effects of them were not fully studied. In this research, using C2C12 myotubes as cell models in vitro, deep RNA-sequencing was performed to profile lncRNAs and mRNAs between palmitic acid-induced IR C2C12 myotubes and control ones. The results revealed that a total of 144 lncRNAs including 70 up-regulated and 74 down-regulated (|fold change| &gt; 2, q &lt; 0.05) were significantly differentially expressed in palmitic acid-induced insulin resistant cells. In addition, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases revealed that the target genes of the differentially expressed lncRNAs were significantly enriched in fatty acid oxidation, lipid oxidation, PPAR signaling pathway, and insulin signaling pathway. Moreover, Via qPCR, most of selected lncRNAs in myotubes and db/db mice skeletal muscle showed the consistent expression trends with RNA-sequencing. Co-expression analysis also explicated the key lncRNA–mRNA interactions and pointed out a potential regulatory network of candidate lncRNA ENSMUST00000160839. In conclusion, the present study extended the skeletal muscle lncRNA database and provided novel potential regulators for future genetic and molecular studies on insulin resistance, which is helpful for prevention and treatment of the related metabolic diseases.

scholarly journals ADP Induces Blood Glucose Through Direct and Indirect Mechanisms in Promotion of Hepatic Gluconeogenesis by Elevation of NADH

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinyu Cao ◽  
Xiaotong Ye ◽  
Shuang Zhang ◽  
Li Wang ◽  
Yanhong Xu ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Blood Glucose ◽  
Signaling Pathway ◽  
Liver Tissue ◽  
Hepatic Insulin Resistance ◽  
Indirect Pathway ◽  
Hepatic Gluconeogenesis ◽  
Insulin Tolerance ◽  
Elevated Expression

Extracellular ADP, a derivative of ATP, interacts with the purinergic receptors in the cell membrane to regulate cellular activities. This signaling pathway remains unknown in the regulation of blood glucose in vivo. We investigated the acute activity of ADP in mice through a peritoneal injection. In the lean mice, in response to the ADP treatment, the blood glucose was elevated, and pyruvate tolerance was impaired. Hepatic gluconeogenesis was enhanced with elevated expression of glucogenic genes (G6pase and Pck1) in the liver. An elevation was observed in NADH, cAMP, AMP, GMP and citrate in the liver tissue in the targeted metabolomics assay. In the primary hepatocytes, ADP activated the cAMP/PKA/CREB signaling pathway, which was blocked by the antagonist (2211) of the ADP receptor P2Y13. In the circulation, gluconeogenic hormones including glucagon and corticosterone were elevated by ADP. Insulin and thyroid hormones (T3 and T4) were not altered in the blood. In the diet-induced obese (DIO) mice, NADH was elevated in the liver tissue to match the hepatic insulin resistance. Insulin resistance was intensified by ADP for further impairment in insulin tolerance. These data suggest that ADP induced the blood glucose through direct and indirect actions in liver. One of the potential pathways involves activation of the P2Y13/cAMP/PKA/CREB signaling pathway in hepatocytes and the indirect pathway may involve induction of the gluconeogenic hormones. NADH is a signal for gluconeogenesis in the liver of both DIO mice and lean mice.

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