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

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
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.

scholarly journals Serine Phosphorylation Proximal to Its Phosphotyrosine Binding Domain Inhibits Insulin Receptor Substrate 1 Function and Promotes Insulin Resistance

2004 ◽  
Vol 24 (21) ◽  
pp. 9668-9681 ◽  
Author(s):  
Yan-Fang Liu ◽  
Avia Herschkovitz ◽  
Sigalit Boura-Halfon ◽  
Denise Ronen ◽  
Keren Paz ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
Insulin Treatment ◽  
Binding Domain ◽  
Serine Phosphorylation ◽  
Insulin Receptor Substrate ◽  
Control Mechanisms ◽  
Insulin Receptor Substrate 1 ◽  
Phosphotyrosine Binding Domain

ABSTRACT Ser/Thr phosphorylation of insulin receptor substrate (IRS) proteins negatively modulates insulin signaling. Therefore, the identification of serine sites whose phosphorylation inhibit IRS protein functions is of physiological importance. Here we mutated seven Ser sites located proximal to the phosphotyrosine binding domain of insulin receptor substrate 1 (IRS-1) (S265, S302, S325, S336, S358, S407, and S408) into Ala. When overexpressed in rat hepatoma Fao or CHO cells, the mutated IRS-1 protein in which the seven Ser sites were mutated to Ala (IRS-17A), unlike wild-type IRS-1 (IRS-1WT), maintained its Tyr-phosphorylated active conformation after prolonged insulin treatment or when the cells were challenged with inducers of insulin resistance prior to acute insulin treatment. This was due to the ability of IRS-17A to remain complexed with the insulin receptor (IR), unlike IRS-1WT, which underwent Ser phosphorylation, resulting in its dissociation from IR. Studies of truncated forms of IRS-1 revealed that the region between amino acids 365 to 430 is a main insulin-stimulated Ser phosphorylation domain. Indeed, IRS-1 mutated only at S408, which undergoes phosphorylation in vivo, partially maintained the properties of IRS-17A and conferred protection against selected inducers of insulin resistance. These findings suggest that S408 and additional Ser sites among the seven mutated Ser sites are targets for IRS-1 kinases that play a key negative regulatory role in IRS-1 function and insulin action. These sites presumably serve as points of convergence, where physiological feedback control mechanisms, which are triggered by insulin-stimulated IRS kinases, overlap with IRS kinases triggered by inducers of insulin resistance to terminate insulin signaling.

scholarly journals Central Insulin Signaling Is Attenuated by Long-Term Insulin Exposure via Insulin Receptor Substrate-1 Serine Phosphorylation, Proteasomal Degradation, and Lysosomal Insulin Receptor Degradation

Endocrinology ◽  
2010 ◽  
Vol 151 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Christopher M. Mayer ◽  
Denise D. Belsham
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
Time Course ◽  
Proteasomal Degradation ◽  
Serine Phosphorylation ◽  
Neuronal Function ◽  
Protein Levels ◽  
Phosphorylated Akt

Abstract Central insulin signaling is critical for the prevention of insulin resistance. Hyperinsulinemia contributes to insulin resistance, but it is not yet clear whether neurons are subject to cellular insulin resistance. We used an immortalized, hypothalamic, clonal cell line, mHypoE-46, which exemplifies neuronal function and expresses the components of the insulin signaling pathway, to determine how hyperinsulinemia modifies neuronal function. Western blot analysis indicated that prolonged insulin treatment of mHypoE-46 cells attenuated insulin signaling through phospho-Akt. To understand the mechanisms involved, time-course analysis was performed. Insulin exposure for 4 and 8 h phosphorylated Akt and p70-S6 kinase (S6K1), whereas 8 and 24 h treatment decreased insulin receptor (IR) and IR substrate 1 (IRS-1) protein levels. Insulin phosphorylation of S6K1 correlated with IRS-1 ser1101 phosphorylation and the mTOR-S6K1 pathway inhibitor rapamycin prevented IRS-1 serine phosphorylation. The proteasomal inhibitor epoxomicin and the lysosomal pathway inhibitor 3-methyladenine prevented the degradation of IRS-1 and IR by insulin, respectively, and pretreatment with rapamycin, epoxomicin, or 3-methyladenine prevented attenuation of insulin signaling by long-term insulin exposure. Thus, a sustained elevation of insulin levels diminishes neuronal insulin signaling through mTOR-S6K1-mediated IRS-1 serine phosphorylation, proteasomal degradation of IRS-1 and lysosomal degradation of the IR.

Oxidative stress impairs insulin signal in skeletal muscle and causes insulin resistance in postinfarct heart failure

2011 ◽  
Vol 300 (5) ◽  
pp. H1637-H1644 ◽  
Author(s):  
Yukihiro Ohta ◽  
Shintaro Kinugawa ◽  
Shouji Matsushima ◽  
Taisuke Ono ◽  
Mochamad A. Sobirin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Signaling ◽  
Glucose Transporter ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Serine Phosphorylation ◽  
Glucose Transporter 4

Insulin resistance has been shown to occur as a consequence of heart failure. However, its exact mechanisms in this setting remain unknown. We have previously reported that oxidative stress is enhanced in the skeletal muscle from mice with heart failure after myocardial infarction (MI) ( 30 ). This study is aimed to investigate whether insulin resistance in postinfarct heart failure is due to the impairment of insulin signaling in the skeletal muscle caused by oxidative stress. Mice were divided into four groups: sham operated (sham); sham treated with apocynin, an inhibitor of NAD(P)H oxidase activation (10 mmol/l in drinking water); MI; and MI treated with apocynin. After 4 wk, intraperitoneal insulin tolerance tests were performed, and skeletal muscle samples were obtained for insulin signaling measurements. MI mice showed left ventricular dilation and dysfunction by echocardiography and increased left ventricular end-diastolic pressure and lung weight. The decrease in glucose level after insulin load significantly attenuated in MI compared with sham. Insulin-stimulated serine phosphorylation of Akt and glucose transporter-4 translocation were decreased in MI mice by 61 and 23%, respectively. Apocynin ameliorated the increase in oxidative stress and NAD(P)H oxidase activities measured by the lucigenin assay in the skeletal muscle after MI. It also improved insulin resistance and inhibited the decrease of Akt phosphorylation and glucose transporter-4 translocation. Insulin resistance was induced by the direct impairment of insulin signaling in the skeletal muscle from postinfarct heart failure, which was associated with the enhanced oxidative stress via NAD(P)H oxidase.

(Pro)renin receptor in skeletal muscle is involved in the development of insulin resistance associated with postinfarct heart failure in mice

2014 ◽  
Vol 307 (6) ◽  
pp. E503-E514 ◽  
Author(s):  
Arata Fukushima ◽  
Shintaro Kinugawa ◽  
Shingo Takada ◽  
Shouji Matsushima ◽  
Mochamad Ali Sobirin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Signaling ◽  
Glucose Transporter ◽  
Renin Angiotensin System ◽  
Left Ventricular ◽  
Serine Phosphorylation ◽  
Superoxide Production

We previously reported that insulin resistance was induced by the impairment of insulin signaling in the skeletal muscle from heart failure (HF) via NAD(P)H oxidase-dependent oxidative stress. (Pro)renin receptor [(P)RR] is involved in the activation of local renin-angiotensin system and subsequent oxidative stress. We thus examined whether (P)RR inhibitor, handle region peptide (HRP), could ameliorate insulin resistance in HF after myocardial infarction (MI) by improving oxidative stress and insulin signaling in the skeletal muscle. C57BL6J mice were divided into four groups: sham operated (Sham, n = 10), Sham treated with HRP (Sham+HRP, 0.1 mg·kg−1·day−1, n = 10), MI operated (MI, n = 10), and MI treated with HRP (MI+HRP, 0.1 mg/kg/day, n = 10). After 4 wk, MI mice showed left ventricular dysfunction, which was not affected by HRP. (P)RR was upregulated in the skeletal muscle after MI (149% of sham, P < 0.05). The decrease in plasma glucose after insulin load was smaller in MI than in Sham (21 ± 2 vs. 44 ± 3%, P < 0.05), and was greater in MI+HRP (38 ± 2%, P < 0.05) than in MI. Insulin-stimulated serine phosphorylation of Akt and glucose transporter 4 translocation were decreased in the skeletal muscle from MI by 48 and 49% of Sham, both of which were ameliorated in MI+HRP. Superoxide production and NAD(P)H oxidase activities were increased in MI, which was inhibited in MI+HRP. HRP ameliorated insulin resistance associated with HF by improving insulin signaling via the inhibition of NAD(P)H oxidase-induced superoxide production in the skeletal muscle. The (P)RR pathway is involved in the development of insulin resistance, at least in part, via the impairment of insulin signaling in the skeletal muscle from HF.

scholarly journals Inhibitory effect of hyperglycemia on insulin-induced Akt/protein kinase B activation in skeletal muscle

2001 ◽  
Vol 280 (5) ◽  
pp. E816-E824 ◽  
Author(s):  
Akira Oku ◽  
Masao Nawano ◽  
Kiichiro Ueta ◽  
Takuya Fujita ◽  
Itsuro Umebayashi ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Protein Kinase ◽  
Insulin Receptor ◽  
Soleus Muscle ◽  
Insulin Signaling ◽  
Skeletal Muscles ◽  
Glucose Transporter ◽  
Protein Kinase B ◽  
Diabetic Rats

To determine the molecular mechanism underlying hyperglycemia-induced insulin resistance in skeletal muscles, postreceptor insulin-signaling events were assessed in skeletal muscles of neonatally streptozotocin-treated diabetic rats. In isolated soleus muscle of the diabetic rats, insulin-stimulated 2-deoxyglucose uptake, glucose oxidation, and lactate release were all significantly decreased compared with normal rats. Similarly, insulin-induced phosphorylation and activation of Akt/protein kinase B (PKB) and GLUT-4 translocation were severely impaired. However, the upstream signal, including phosphorylation of the insulin receptor (IR) and insulin receptor substrate (IRS)-1 and -2 and activity of phosphatidylinositol (PI) 3-kinase associated with IRS-1/2, was enhanced. The amelioration of hyperglycemia by T-1095, a Na+-glucose transporter inhibitor, normalized the reduced insulin sensitivity in the soleus muscle and the impaired insulin-stimulated Akt/PKB phosphorylation and activity. In addition, the enhanced PI 3-kinase activation and phosphorylation of IR and IRS-1 and -2 were reduced to normal levels. These results suggest that sustained hyperglycemia impairs the insulin-signaling steps between PI 3-kinase and Akt/PKB, and that impaired Akt/PKB activity underlies hyperglycemia-induced insulin resistance in skeletal muscle.

scholarly journals Tissue-Specific Difference in the Molecular Mechanisms for the Development of Acute Insulin Resistance after Injury

Endocrinology ◽  
2008 ◽  
Vol 150 (1) ◽  
pp. 24-32 ◽  
Author(s):  
Li Li ◽  
LaWanda H. Thompson ◽  
Ling Zhao ◽  
Joseph L. Messina
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
Molecular Mechanisms ◽  
Rapid Development ◽  
Serine Phosphorylation ◽  
Synthesis Inhibitor ◽  
Adult Rats ◽  
Counterregulatory Hormones

Acute insulin resistance occurs after injury, hemorrhage, infection, and critical illness. However, little is known about the development of this acute insulin-resistant state. In the current study, we found that insulin resistance develops rapidly in skeletal muscle, with the earliest insulin signaling defects at 60 min. However, defects in insulin signaling were measurable even earlier in liver, by as soon as 15 min after hemorrhage. To begin to understand the mechanisms for the development of acute insulin resistance, serine phosphorylation of insulin receptor substrate (IRS)-1 and c-Jun N-terminal kinase phosphorylation/activation was investigated. These markers (and possible contributors) of insulin resistance were increased in the liver after hemorrhage but not measurable in skeletal muscle. Because glucocorticoids are important counterregulatory hormones responsible for glucose homeostasis, a glucocorticoid synthesis inhibitor, metyrapone, and a glucocorticoid receptor antagonist, RU486, were administered to adult rats prior to hemorrhage. In the liver, the defects of insulin signaling after hemorrhage, including reduced tyrosine phosphorylation of the insulin receptor and IRS-1, association between IRS-1 and phosphatidylinositol 3-kinase and serine phosphorylation of Akt in response to insulin were not altered by pretreatment of rats with metyrapone or RU486. In contrast, hemorrhage-induced defects in insulin signaling were dramatically reversed in skeletal muscle, indicating a prevention of insulin resistance in muscle. These results suggest that distinct mechanisms for hemorrhage-induced acute insulin resistance are present in these two tissues and that glucocorticoids are involved in the rapid development of insulin resistance in skeletal muscle, but not in the liver, after hemorrhage. Glucocorticoids play a major role in the development of acute insulin resistance following hemorrhage in skeletal muscle, but not in the liver.

Vascular insulin resistance related to endoplasmic reticulum stress in aortas from a rat model of chronic kidney disease

2012 ◽  
Vol 303 (9) ◽  
pp. H1154-H1165 ◽  
Author(s):  
Qiu Gen Zhou ◽  
Xiao Jing Fu ◽  
Guo Yu Xu ◽  
Wei Cao ◽  
Hong Fa Liu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Insulin Resistance ◽  
Chronic Kidney Disease ◽  
Endothelial Cells ◽  
Endoplasmic Reticulum ◽  
Kidney Disease ◽  
Er Stress ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
Serine Phosphorylation

Metabolic insulin resistance has been demonstrated in patients with nondiabetic chronic kidney disease (CKD), yet their vascular insulin signaling remains poorly understood. Here we tested the hypothesis that vascular insulin signaling was impaired and related with endoplasmic reticulum (ER) stress in aortas from the reduced renal mass (RRM) model of CKD. The activity of insulin signaling and markers of ER were determined in aortas from rats with RRM and cultured human umbilical vein endothelial cells. Tyrosine phosphorylation of insulin receptor-β and insulin receptor substrate (IRS)-1 and phosphorylation of protein kinase B and endothelial nitric oxide synthase were all decreased in aorta from RRM rats, whereas serine phosphorylation of IRS-1, a marker of insulin resistance, was increased. In addition, nitric oxide generation and insulin-mediated vasorelaxation were decreased in aortas from RRM rats. Insulin signaling in cultured vascular endothelial cells was impaired by induction of ER stress and was restored in aortas of RRM rats by inhibition of ER stress. Taken together, rats with RRM had vascular insulin resistance that was linked to ER stress. This identified vascular insulin resistance and ER stress as a potential therapeutic target for cardiovascular complications in patients with CKD.

scholarly journals Insulin Resistance in Human Preeclamptic Placenta Is Mediated by Serine Phosphorylation of Insulin Receptor Substrate-1 and -2

2006 ◽  
Vol 91 (2) ◽  
pp. 709-717 ◽  
Author(s):  
Marco Scioscia ◽  
Khalid Gumaa ◽  
Sirilaksana Kunjara ◽  
Malcolm A. Paine ◽  
Luigi E. Selvaggi ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
Serine Phosphorylation ◽  
Regulatory Subunit ◽  
Insulin Receptor Substrate ◽  
Insulin Receptor Substrate 1 ◽  
Cross Sectional ◽  
Maternal Risk ◽  
Therapeutic Implications

Context: Preeclampsia is a severe complication of human pregnancy often associated with maternal risk factors. Insulin resistance represents a major risk for developing preeclampsia during pregnancy. Objective: A putative second messenger of insulin, inositol phosphoglycan P type (P-IPG), was previously shown to be highly increased during active preeclampsia. Its association with insulin resistance was investigated. Design and Setting: A cross-sectional study was carried out in a referral center. Patients: Nine preeclamptic (PE) and 18 healthy women were recruited and matched for maternal age, body mass index, parity, and ethnicity in a 1:2 ratio. Placental specimens were collected immediately after delivery. Intervention: Placental tissue was incubated with insulin and P-IPG production assessed. Insulin signaling proteins were subsequently studied by immunoblotting. Results: P-IPG extracted from human term placentas upon incubation with insulin was found to be far lower in those with preeclampsia than controls (P &lt; 0.001). Immunoblotting studies revealed serine phosphorylation of insulin receptor substrate-1 and -2 in PE placentas (P &lt; 0.001) with downstream impairment of insulin signaling. The activation of the p85 regulatory subunit of phosphatidylinositol 3- kinase was markedly decreased in PE samples (P &lt; 0.001). Conclusions: These findings highlight the importance of P-IPG in active preeclampsia and demonstrate a substantially different response to the insulin stimulus of human PE placentas. Acquired alterations in activation of proteins involved in insulin signaling may play a role in the complex pathogenesis of preeclampsia, probably as a consequence of the immunological dysfunction that occurs in this syndrome. These results seem to confirm an insulin-resistant state in PE placenta and shed a different light on its role in the pathogenesis of this disease with potential therapeutic implications.

scholarly journals Interleukin-1α Inhibits Insulin Signaling with Phosphorylating Insulin Receptor Substrate-1 on Serine Residues in 3T3-L1 Adipocytes

2006 ◽  
Vol 20 (1) ◽  
pp. 114-124 ◽  
Author(s):  
Jianying He ◽  
Isao Usui ◽  
Ken Ishizuka ◽  
Yukiko Kanatani ◽  
Kazuyuki Hiratani ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Tyrosine Phosphorylation ◽  
Proinflammatory Cytokines ◽  
Insulin Signaling ◽  
Serine Phosphorylation ◽  
Insulin Receptor Substrate ◽  
Akt Phosphorylation ◽  
Iκb Kinase ◽  
Serine Kinases

Abstract Proinflammatory cytokines are recently reported to inhibit insulin signaling causing insulin resistance. IL-1α is also one of the proinflammatory cytokines; however, it has not been clarified whether IL-1α may also cause insulin resistance. Here, we investigated the effects of IL-1α treatment on insulin signaling in 3T3-L1 adipocytes. IL-1α treatment up to 4 h did not alter insulin-stimulated insulin receptor tyrosine phosphorylation, whereas tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and the association with phosphatidylinositol 3-kinase were partially inhibited with the maximal inhibition in around 15 min. IRS-1 was transiently phosphorylated on some serine residues around 15 min after IL-1α stimulation, when several serine kinases, IκB kinase, c-Jun-N-terminal kinase, ERK, and p70S6K were activated. Chemical inhibitors for these kinases inhibited IL-1α-induced serine phosphorylation of IRS-1. Tyrosine phosphorylation of IRS-1 was recovered only by the IKK inhibitor or JNK inhibitor, suggesting specific involvement of these two kinases. Insulin-stimulated Akt phosphorylation and 2-deoxyglucose uptake were not inhibited only by IL-1α. Interestingly, Akt phosphorylation was synergistically inhibited by IL-1α in the presence of IL-6. Taken together, short-term IL-1α treatment transiently causes insulin resistance at IRS-1 level with its serine phosphorylation. IL-1α may suppress insulin signaling downstream of IRS-1 in the presence of other cytokines, such as IL-6.

Timosaponin B-II Ameliorates Palmitate-Induced Insulin Resistance and Inflammation via IRS-1/PI3K/Akt and IKK/NF-κB Pathways

2016 ◽  
Vol 44 (04) ◽  
pp. 755-769 ◽  
Author(s):  
Yong-Liang Yuan ◽  
Bao-Qin Lin ◽  
Chun-Feng Zhang ◽  
Ling-Ling Cui ◽  
Shi-Xia Ruan ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Hepg2 Cells ◽  
Serine Phosphorylation ◽  
Insulin Receptor Substrate ◽  
Phosphatidylinositol 3 Kinase ◽  
Insulin Receptor Substrate 1 ◽  
Akt Activation ◽  
Related Proteins ◽  
Anemarrhena Asphodeloides

This study aimed to investigate the effect of timosaponin B-II (TB-II) on palmitate (PA)-induced insulin resistance and inflammation in HepG2 cells, and probe the potential mechanisms. TB-II, a main ingredient of the traditional Chinese medicine Anemarrhena asphodeloides Bunge, notably ameliorated PA-induced insulin resistance and inflammation, and significantly improved cell viability, decreased PA-induced production of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text]) and interleukin-6 (IL-6) levels. Further, TB-II treatment notably decreased malondialdehyde (MDA) and lactate dehydrogenase (LDH) levels, and improved superoxide dismutase (SOD) and nitric oxide (NO). TB-II also reduced HepG2 cells apoptosis. Insulin receptor substrate-1 (IRS1)/phosphatidylinositol 3-kinase (PI3K)/Akt and inhibitor of nuclear factor [Formula: see text]-B kinase (IKK)/NF-[Formula: see text]B pathways-related proteins, and IKK[Formula: see text], p65 phosphorylation, serine phosphorylation of insulin receptor substrate-1 (IRS-1) at S307, tyrosine phosphorylation of IRS-1, and Akt activation were determined by Western blot. Compared to model group, TB-II significantly downregulated the expression of p-NF-[Formula: see text]Bp65, p-IKK[Formula: see text], p-IRS-1, p-PI3K and p-Akt. TB-II is a promising potential agent for the management of palmitate-induced insulin resistance and inflammation, which might be via IR/IRS-1/PI3K/Akt and IKK/NF-[Formula: see text]B pathways.

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