Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0948265 (metabolic syndrome)
 24,271 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin resistance has been described in several diseases that increase cardiovascular risk and mortality, such as diabetes, obesity, hypertension, metabolic syndrome, and heart failure. Abnormalities of insulin signaling account for insulin resistance. Insulin mediates its action on target organs through phosphorylation of a transmembrane-spanning tyrosine kinase receptor, the insulin receptor (IR). Several mechanisms have been described as responsible for the inhibition of insulin-stimulated tyrosine phosphorylation of IR and the IR substrate (IRS) proteins, including proteasome-mediated degradation, phosphatase-mediated dephosphorylation, and kinase-mediated serine/threonine phosphorylation. In particular, phosphorylation of IRS-1 on serine Ser612 causes dissociation of the p85 subunit of phosphatidylinositol 3-kinase, inhibiting further signaling. On the other hand, phosphorylation of IRS-1 on Ser307 results in its dissociation from the IR and triggers proteasome-dependent degradation. Dysregulation of sympathetic nervous and renin-angiotensin systems resulting in enhanced stimulation of both adrenergic and angiotensin II receptors is a typical feature of several cardiovascular diseases and, at the same time, is involved in the pathogenesis of insulin resistance. The characterization of molecular mechanisms involved in the pathogenesis of insulin resistance may help to design efficacious pharmacologic molecules to treat endothelial and metabolic dysfunction associated with insulin resistance states to reduce the cardiovascular risk and to ameliorate the prognosis of patients with cardiovascular diseases.
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PMID:Insulin resistance and cardiovascular risk: New insights from molecular and cellular biology. 1683 60

Insulin resistance is a feature of a number of clinical disorders, including type 2 diabetes/glucose intolerance, obesity, dyslipidaemia and hypertension clustering in the so-called metabolic syndrome. Insulin resistance in skeletal muscle manifests itself primarily as a reduction in insulin-stimulated glycogen synthesis due to reduced glucose transport. Ectopic lipid accumulation plays an important role in inducing insulin resistance. Multiple defects in insulin signalling are responsible for impaired glucose metabolism in target tissues of subjects with features of insulin resistance. Inflammatory molecules and lipid metabolites inhibit insulin signalling by stimulating a number of different serine kinases which are responsible for serine phosphorylation of Insulin Receptor Substrate-1 (IRS-1).
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PMID:Pathophysiology of insulin resistance. 1716 38

Insulin resistance is a pathophysiological link of obesity to type 2 diabetes. The initial cause of insulin resistance is critical for prevention and treatment of type 2 diabetes. Lipotoxicity is a well-known concept in the explanation of initiation of insulin resistance. Although there are several prevailing hypotheses about the cellular/molecular mechanisms of lipotoxicity, such as inflammation, oxidative stress, hyperinsulinemia, and ER stress, the relative importance of these hypothesized events remains to be determined. The role of hyperinsulinemia is relatively under documented in the literature for the initiation of insulin resistance. In this review, an interaction of fatty acid and beta-cells, and a synergy between free fatty acids (FFAs) and insulin are emphasized for the role of hyperinsulinemia. This article presents the evidence about FFA-induced insulin secretion in vitro and in vivo, recent advances in the molecular mechanism of FFA action in beta-cells, a role of GPR40 in the development of insulin resistance, and the negative feedback loop of the insulin receptor signal pathway. The negative feedback loop is discussed in detail with a focus on IRS-1 serine kinases. This article provides a substantial support for the role of insulin in the early stages of FFA-associated insulin resistance. The hypothesis of insulin's role in lipotoxicity is referred to as the "insulin hypothesis" in this review. According to this hypothesis, prevention of increased beta-cell response to glucose may be a potential approach for early intervention of metabolic syndrome.
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PMID:Role of insulin in the pathogenesis of free fatty acid-induced insulin resistance in skeletal muscle. 1734 4

Essential hypertension is an insulin resistant state. Early insulin signaling steps are impaired in essential hypertension and a large body of data suggests that there is a crosstalk at multiple levels between the signal transduction pathways that mediate insulin and angiotensin II actions. At the extracellular level the angiotensin converting enzyme (ACE) regulates the synthesis of angiotensin II and bradykinin that is a powerful vasodilator. At early intracellular level angiotensin II acts on JAK-2/IRS1-IRS2/PI3-kinase, JNK and ERK to phosphorylate serine residues of key elements of insulin signaling pathway therefore inhibiting signaling by the insulin receptor. On another level angiotensin II inhibits the insulin signaling inducing the regulatory protein SOCS 3. Angiotensin II acting through the AT1 receptor can inhibit insulin-induced nitric oxide (NO) production by activating ERK 1/2 and JNK and enhances the activity of NADPH oxidase that leads to an increased reactive oxygen species generation. From the clinical standpoint, the inhibition of the renin angiotensin system improves insulin sensitivity and decreases the incidence of Type 2 Diabetes Mellitus (T2DM). This might represent an alternative approach to prevent type 2 diabetes in patients with hypertension and metabolic syndrome, (i.e. insulin resistant patients). This review will discuss: a) the molecular mechanisms of the crosstalk between the insulin and angiotensin II signaling systems b) the results of clinical studies employing drugs targeting the renin-angiotensin II-aldosterone systems and their role in glucose metabolism and diabetes prevention.
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PMID:The crosstalk between insulin and renin-angiotensin-aldosterone signaling systems and its effect on glucose metabolism and diabetes prevention. 1885 18

Oxidized LDL (oxLDL) increase in patients affected by type-2 diabetes, obesity, and metabolic syndrome. Likewise, insulin resistance, an impaired responsiveness of target tissues to insulin, is associated with those pathological conditions. To investigate a possible causal relationship between oxLDL and the onset of insulin resistance, we evaluated the response to insulin of 3T3-L1 adipocytes treated with oxLDL. We observed that oxLDL inhibited glucose uptake (-40%) through reduced glucose transporter 4 (GLUT4) recruitment to the plasma membrane (-70%), without affecting GLUT4 gene expression. These findings were associated to the impairment of insulin signaling. Specifically, in oxLDL-treated cells insulin receptor (IR) substrate-1 (IRS-1) was highly degraded likely because of the enhanced Ser(307)phosphorylation. This process was largely mediated by the activation of the inhibitor of kappaB-kinase beta (IKKbeta) and the c-Jun NH(2)-terminal kinase (JNK). Moreover, the activation of IKKbeta positively regulated the nuclear content of nuclear factor kappaB (NF-kappaB), by inactivating the inhibitor of NF-kappaB (IkappaBalpha). The activated NF-kappaB further impaired per se GLUT4 functionality. Specific inhibitors of IKKbeta, JNK, and NF-kappaB restored insulin sensitivity in adipocytes treated with oxLDL. These data provide the first evidence that oxLDL, by activating serine/threonine kinases, impaired adipocyte response to insulin affecting pathways involved in the recruitment of GLUT4 to plasma membranes (PM). This suggests that oxLDL might participate in the development of insulin resistance.
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PMID:Oxidized LDL impair adipocyte response to insulin by activating serine/threonine kinases. 1913 67

Insulin resistance is commonly found in a large number of adults-in particular, those with android obesity, the metabolic syndrome or type 2 diabetes. Strong adverse relationships between adipose tissue, liver and muscles in these patients result in lipotoxicity, with deposition of triglycerides (TG) within the liver and muscles together with insulin resistance. Such a situation is also seen in lipodystrophic patients with fat loss. Insulin signals in the liver through its tyrosine-kinase receptors to negatively control hepatic glucose production (HGP), replenish glycogen stores and synthesize fatty acids (FA), leading to TG exported as VLDL. In liver insulin resistance, HGP is increased mainly by activation of the gluconeogenic pathway, resulting in increased fasting glycemia. Lipogenesis is also increased possibly due to direct activation of the SREBP-1 transcription factor and together with increased FA availability results in an increased production of VLDL-TG. An imbalance between the pathways of TG synthesis and oxidation or export results in 'metabolic' steatosis. Increased cellular FA derivatives activate stress kinases, leading to phosphorylation of serine in insulin receptor substrate (IRS) proteins and, hence, insulin resistance. A number of studies in normal subjects and patients have revealed a strong association between insulin resistance and metabolic steatosis. Moreover, when insulin resistance is decreased by weight loss in obese subjects or by treatment with insulin sensitizers such as thiazolidinediones, the levels of liver fat and insulin resistance vary accordingly. An important question that remains unanswered concerns the relationship between steatosis and non-alcoholic steatohepatitis (NASH), and the potential roles of insulin resistance together with inflammation and oxidative stress in such a setting.
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PMID:Insulin resistance and steatosis in humans. 1919 26

Angiotensin II suppresses the insulin sensitivity via enhancement of serine phosphorylation of insulin receptor and suppression of tyrosine phosphorylation of IRS-1. Adiponectin increases insulin sensitivity, and TNF-alpha decreases insulin sensitivity. From our studies, the suppressed adiponectin and increased TNF-alpha may play an important role of the insulin resistance mechanisms. Angiotensin II suppresses the differentiation of adipocyte. Large sized adipocytes increase TNF-alpha and decrease adiponectin. Angiotensin II also has the direct stimulating action on TNF-alpha synthesis. ARB increases adiponectin a nddecreases TNF-alpha. Improvements of these adipocytokines dysfunction by ARB may concern tothe improvement of insulin resistance. The significance of various adipocytokines in insulin resistance and metabolic syndrome is also introduced.
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PMID:[Metabolic syndrome]. 1934 41

The hepatitis C virus (HCV) induces lipid accumulation in vitro and in vivo. The pathogenesis of steatosis is due to both viral and host factors. Viral steatosis is mostly reported in patients with genotype 3a, whereas metabolic steatosis is often associated with genotype 1 and metabolic syndrome. Several molecular mechanisms responsible for steatosis have been associated with the HCV core protein, which is able to induce gene expression and activity of sterol regulatory element binding protein 1 (SREBP1) and peroxisome proliferator-activated receptor gamma (PPARgamma), increasing the transcription of genes involved in hepatic fatty acid synthesis. Steatosis has been also implicated in viral replication. In infected cells, HCV core protein is targeted to lipid droplets which serve as intracellular storage organelles. These studies have shown that lipid droplets are essential for virus assembly. Thus, HCV promotes steatosis as an efficient mechanism for stable viral replication. Chronic HCV infection can also induce insulin resistance. In patients with HCV, insulin resistance is more strongly associated with viral load than visceral obesity. HCV seems to lead to insulin resistance through interference of intracellular insulin signalling by HCV proteins, mainly, the serine phosphorylation of insulin receptor-1 (IRS-1) and impairment of the downstream Akt signalling pathway. The HCV core protein interferes with in vitro insulin signalling by genotype-specific mechanisms, where the role of suppressor of cytokine signal 7 (SOCS-7) in genotype 3a and mammalian target of rapamycin (mTOR) in genotype 1 in IRS-1 downregulation play key roles. Steatosis and insulin resistance have been associated with fibrosis progression and a reduced rate of sustained response to peginterferon plus ribavirin.
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PMID:Steatosis and insulin resistance in hepatitis C: a way out for the virus? 1985 93

A breakthrough using "reverse pharmacology" identified and characterized acyl ghrelin from the stomach as the endogenous cognate ligand for the growth hormone (GH) secretagogue receptor (GHS-R) 1a. The unique post-translational modification of O-n-octanoylation at serine 3 is the first in peptide discovery history and is essential for GH-releasing ability. Des-acyl ghrelin, lacking O-n-octanoylation at serine 3, is also produced in the stomach and remains the major molecular form secreted into the circulation. The third ghrelin gene product, obestatin, a novel 23-amino acid peptide identified from rat stomach, was found by comparative genomic analysis. Three ghrelin gene products actively participate in modulating appetite, adipogenesis, gut motility, glucose metabolism, cell proliferation, immune, sleep, memory, anxiety, cognition, and stress. Knockdown or knockout of acyl ghrelin and/or GHS-R1a, and overexpression of des-acyl ghrelin show benefits in the therapy of obesity and metabolic syndrome. By contrast, agonism of acyl ghrelin and/or GHS-R1a could combat human anorexia-cachexia, including anorexia nervosa, chronic heart failure, chronic obstructive pulmonary disease, liver cirrhosis, chronic kidney disease, burn, and postsurgery recovery, as well as restore gut dysmotility, such as diabetic or neurogenic gastroparesis, and postoperative ileus. The ghrelin acyl-modifying enzyme, ghrelin O-Acyltransferase (GOAT), which attaches octanoate to serine-3 of ghrelin, has been identified and characterized also from the stomach. To date, ghrelin is the only protein to be octanylated, and inhibition of GOAT may have effects only on the stomach and is unlikely to affect the synthesis of other proteins. GOAT may provide a critical molecular target in developing novel therapeutics for obesity and type 2 diabetes.
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PMID:Ghrelin gene products and the regulation of food intake and gut motility. 2003 70

Consumption of a diet high in barley beta-glucan (BG) has been shown to prevent insulin resistance. To investigate the mechanism for the effects of barley BG, three groups of male 7-wk-old C57BL/6J mice were fed high-fat diets containing 0, 2, or 4% of barley BG for 12 wk. The 2% BG and 4% BG groups had significantly lower body weights compared with the 0% BG group. The 4% BG group demonstrated improved glucose tolerance and lower levels of insulin-resistance index and glucose-dependent insulinotropic polypeptide. Consumption of the BG diet decreased hepatic lipid content. Mice on the BG diet also demonstrated decreased fatty acid synthase and increased cholesterol 7alpha-hydroxylase gene expression levels. The BG diet promoted hepatic insulin signaling by decreasing serine phosphorylation of insulin receptor substrate 1 and activating Akt, and it decreased mRNA levels of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase. In summary, consumption of BG reduced weight gain, decreased hepatic lipid accumulation, and improved insulin sensitivity in mice fed a high-fat diet. Insulin signaling enhanced due to the expression changes of glucose and lipid metabolism genes by BG consumption. Consumption of barley BG could be an effective strategy for preventing obesity, insulin resistance, and the metabolic syndrome.
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PMID:Consumption of barley beta-glucan ameliorates fatty liver and insulin resistance in mice fed a high-fat diet. 2011 96


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