Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.31 (AMP-activated protein kinase)
 13,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although simple steatosis was originally thought to be a pathologically inert histological change, fat accumulation in the liver may play a critical role not only in disease initiation, but also in the progression to nonalcoholic steatohepatitis and cirrhosis. Therefore, prevention of fat accumulation in the liver may be an effective therapy for multiple stages of nonalcoholic fatty liver disease (NAFLD). Promising beneficial effects of betaine supplementation on human NAFLD have been reported in some pilot clinical studies; however, data related to betaine therapy in NAFLD are limited. In this study, we examined the effects of betaine on fat accumulation in the liver induced by high-sucrose diet and evaluated mechanisms by which betaine could attenuate or prevent hepatic steatosis in this model. Male C57BL/6 mice weighing 20 +/- 0.5 g (means +/- SE) were divided into four groups (8 mice per group) and started on one of four treatments: standard diet (SD), SD+betaine, high-sucrose diet (HS), and HS + betaine. Betaine was supplemented in the drinking water at a concentration of 1% (wt/vol) (anhydrous). Long-term feeding of high-sucrose diet to mice caused significant hepatic steatosis accompanied by markedly increased lipogenic activity. Betaine significantly attenuated hepatic steatosis in this animal model, and this change was associated with increased activation of hepatic AMP-activated protein kinase (AMPK) and attenuated lipogenic capability (enzyme activities and gene expression) in the liver. Our findings are the first to suggest that betaine might serve as a therapeutic tool to attenuate hepatic steatosis by targeting the hepatic AMPK system.
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PMID:Involvement of AMP-activated protein kinase in beneficial effects of betaine on high-sucrose diet-induced hepatic steatosis. 1770 54

This study evaluates the protective effect of Juniperus chinensis hot water extract (JCE) against high-fat-diet (HFD)-induced obesity and its molecular mechanisms in the visceral adipose tissue of rats. JCE supplementation significantly lowered body weight gain, visceral fat-pad weights, blood lipid levels, and blood insulin and leptin levels of rats rendered obese by an HFD. Feeding with JCE significantly reversed the HFD-induced down-regulation of the epididymal adipose tissue genes implicated in adipogenesis, such as the peroxisome proliferator-activated receptors gamma2 (PPARgamma2), adipocyte protein 2 (aP2), sterol regulatory element binding protein 1c (SREBP1c), fatty acid synthase (FAS), and HMG-CoA reductase (HMGR), as well as those involved in uncoupled respiration, such as the uncoupling protein 2 (UCP2) and uncoupling protein 3 (UCP3). Dietary supplementation with JCE also reversed the HFD-induced decreases in the AMP-activated protein kinase (AMPK) and the acetyl-CoA carboxylase 2 (ACC2) expressions at both the mRNA and protein levels and restored the HFD-induced inhibitions in the AMPK and ACC2 phosphorylation, which are related to fatty acid beta-oxidation, in the epididymal adipose tissue. This study reports, for the first time, that the JCE can have an anti-obesity effect in a rodent model with HFD-induced obesity through an enhanced gene transcription of the uncoupling protein as well as an elevated AMPK protein expression and phosphorylation in the visceral adipose tissue.
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PMID:Anti-obesity effects of Juniperus chinensis extract are associated with increased AMP-activated protein kinase expression and phosphorylation in the visceral adipose tissue of rats. 1859 85

Expression of all of the isoforms of the subunits of AMP-activated protein kinase (AMPK) and AMPK activity is increased in skeletal muscle of hyperthyroid rats. Activity of AMPK in skeletal muscle is regulated principally by the upstream kinase, LKB1. This experiment was designed to determine whether the increase in AMPK activity is accompanied by increased expression of the LKB1, along with binding partner proteins. LKB1, MO25, and downstream targets were determined in muscle extracts in control rats, in rats given 3 mg of thyroxine and 1 mg of triiodothyronine per kilogram chow for 4 wk, and in rats given 0.01% propylthiouracil (PTU; an inhibitor of thyroid hormone synthesis) in drinking water for 4 wk (hypothyroid group). LKB1 and MO25 increased in the soleus of thyroid hormone-treated rats vs. the controls. In other muscle types, LKB1 responses were variable, but MO25 increased in all. In soleus, MO25 mRNA increased with thyroid hormone treatment, and STRAD mRNA increased with PTU treatment. Phospho-AMPK and phospho-ACC were elevated in soleus and gastrocnemius of hyperthyroid rats. Thyroid hormone treatment also increased the amount of phospho-cAMP response element binding protein (CREB) in the soleus, heart, and red quadriceps. Four proteins having CREB response elements (CRE) in promoter regions of their genes (peroxisome proliferator-activated receptor-gamma coactivator-1alpha, uncoupling protein 3, cytochrome c, and hexokinase II) were all increased in soleus in response to thyroid hormones. These data provide evidence that thyroid hormones increase soleus muscle LKB1 and MO25 content with subsequent activation of AMPK, phosphorylation of CREB, and expression of mitochondrial protein genes having CRE in their promoters.
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PMID:Thyroid hormone effects on LKB1, MO25, phospho-AMPK, phospho-CREB, and PGC-1alpha in rat muscle. 1866 38

Ischemic tolerance decreases with aging, and the cardioprotective effect of ischemic preconditioning (IPC) is impaired in middle-aged animals. We have demonstrated that short-term caloric restriction (CR) improves myocardial ischemic tolerance in young and old animals via the activation of adiponectin-AMP-activated protein kinase (AMPK)-mediated signaling. However, it is unknown whether prolonged CR confers cardioprotection in a similar manner. Furthermore, little is known regarding the myocardial expression of silent information regulator 1 (Sirt1; which reportedly mediates various aspects of the CR response) with prolonged CR. Thus, 6-mo-old male Fischer-344 rats were randomly divided into ad libitum (AL) and CR groups. Six months later, isolated perfused hearts were subjected to 25 min of global ischemia followed by 120 min of reperfusion with or without IPC. CR improved the recovery of left ventricular function and reduced infarct size after ischemia-reperfusion and restored the IPC effect. Serum adiponectin levels increased, but myocardial levels of total and phosphorylated AMPK did not change with prolonged CR. Total levels of Sirt1 did not change with CR; however, in the nuclear fraction, CR significantly increased Sirt1 and decreased acetyl-histone H3. Eleven rats from each group were given N-nitro-l-arginine methyl ester in their drinking water for 4 wk before death. In these hearts, chronic inhibition of nitric oxide synthase prevented the increase in nuclear Sirt1 content by CR and abrogated CR-induced cardioprotection. These results demonstrate that 1) prolonged CR improves myocardial ischemic tolerance and restores the IPC effect in middle-aged rats and 2) CR-induced cardioprotection is associated with a nitric oxide-dependent increase in nuclear Sirt1 content.
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PMID:Impact of 6-mo caloric restriction on myocardial ischemic tolerance: possible involvement of nitric oxide-dependent increase in nuclear Sirt1. 1893 Oct 29

The vectorial transport of ions and water across epithelial cells depends to a large extent on the coordination of the apical and basolateral ion fluxes with energy supply. In this work we provide the first evidence for a regulation by the 5'-AMP-activated protein kinase (AMPK) of the calcium-activated potassium channel KCa3.1 expressed at the basolateral membrane of a large variety of epithelial cells. Inside-out patch-clamp experiments performed on human embryonic kidney (HEK) cells stably transfected with KCa3.1 first revealed a decrease in KCa3.1 activity following the internal addition of AMP at a fixed ATP concentration. This effect was dose dependent with half inhibition at 140 muM AMP in 1 mM ATP. Evidence for an interaction between the COOH-terminal region of KCa3.1 and the gamma1-subunit of AMPK was next obtained by two-hybrid screening and pull-down experiments. Our two-hybrid analysis confirmed in addition that the amino acids extending from Asp(380) to Ala(400) in COOH-terminal were essential for the interaction AMPK-gamma1/KCa3.1. Inside-out experiments on cells coexpressing KCa3.1 with the dominant negative AMPK-gamma1-R299G mutant showed a reduced sensitivity of KCa3.1 to AMP, arguing for a functional link between KCa3.1 and the gamma1-subunit of AMPK. More importantly, coimmunoprecipitation experiments carried out on bronchial epithelial NuLi cells provided direct evidence for the formation of a KCa3.1/AMPK-gamma1 complex at endogenous AMPK and KCa3.1 expression levels. Finally, treating NuLi monolayers with the membrane permeant AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) caused a significant decrease of the KCa3.1-mediated short-circuit currents, an effect reversible by coincubation with the AMPK inhibitor Compound C. These observations argue for a regulation of KCa3.1 by AMPK in a functional epithelium through protein/protein interactions involving the gamma1-subunit of AMPK.
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PMID:Inhibition of the KCa3.1 channels by AMP-activated protein kinase in human airway epithelial cells. 1905 60

Recently, deep sea water (DSW) has started to receive much attention for therapeutic intervention in some lifestyle diseases. In this study, the anti-obesity and antidiabetic effects of DSW in ob/ob mice were investigated. The animals were randomly divided into two groups with six animals: control group received tap water; the experimental group was treated with DSW of hardness 1000 for 84 days. The body weight gain after 84 days in DSW-fed group was decreased by 7% compared to the control group. The plasma glucose levels in the DSW-fed mice were substantially reduced by 35.4%, as compared to control mice. The results of oral glucose tolerance test revealed that DSW-fed groups significantly increased the glucose disposal after 84 days. DSW increased plasma protein levels of adiponectin and decreased plasma protein levels of resistin, RBP4, and fatty acid binding protein. Moreover, GLUT4 and AMP-activated protein kinase levels in skeletal muscle tissue were increased while peroxisome proliferator-activated receptor gamma and adiponectin were decreased in adipose tissue of DSW-fed mice. These results suggest that the antidiabetic and anti-obesity activities of DSW were mediated by modulating the expression of diabetes- and obesity-specific molecules. Taken together, these results provide a possibility that continuous intake of DSW can ameliorate obesity and diabetes.
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PMID:Anti-obesity and antidiabetic effects of deep sea water on ob/ob mice. 1908 59

Dietary L-arginine (Arg) supplementation reduces white-fat gain in diet-induced obese rats but the underlying mechanisms are unknown. This study tested the hypothesis that Arg treatment affects expression of genes related to lipid metabolism in adipose tissue. Four-week-old male Sprague-Dawley rats were fed a low-fat (LF) or high-fat (HF) diet for 15 weeks. Thereafter, lean or obese rats continued to be fed their same respective diets and received drinking water containing 1.51% Arg-HCl or 2.55% L: -alanine (isonitrogenous control). After 12 weeks of Arg supplementation, rats were euthanized to obtain retroperitoneal adipose tissue for analyzing global changes in gene expression by microarray. The results were confirmed by RT-PCR analysis. HF feeding decreased mRNA levels for lipogenic enzymes, AMP-activated protein kinase, glucose transporters, heme oxygenase 3, glutathione synthetase, superoxide dismutase 3, peroxiredoxin 5, glutathione peroxidase 3, and stress-induced protein, while increasing expression of carboxypeptidase-A, peroxisome proliferator activated receptor (PPAR)-alpha, caspase 2, caveolin 3, and diacylglycerol kinase. In contrast, Arg supplementation reduced mRNA levels for fatty acid binding protein 1, glycogenin, protein phosphates 1B, caspases 1 and 2, and hepatic lipase, but increased expression of PPARgamma, heme oxygenase 3, glutathione synthetase, insulin-like growth factor II, sphingosine-1-phosphate receptor, and stress-induced protein. Biochemical analysis revealed oxidative stress in white adipose tissue of HF-fed rats, which was prevented by Arg supplementation. Collectively, these results indicate that HF diet and Arg supplementation differentially regulate gene expression to affect energy-substrate oxidation, redox state, fat accretion, and adipocyte differentiation in adipose tissue. Our findings provide a molecular mechanism to explain a beneficial effect of Arg on ameliorating diet-induced obesity in mammals.
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PMID:High fat feeding and dietary L-arginine supplementation differentially regulate gene expression in rat white adipose tissue. 1921 6

In the present study, we successively extracted the pu-erh raw tea with methanol (PR-1), chloroform (PR-2), ethyl acetate (PR-3), n-butanol (PR-4), and water (PR-5). Among these extracts, PR-3 extract contained ingredients with the most effective hypolipidemic potential and was further purified by column chromatography. Moreover, chronic administration of PR-3 provoked a significant reduction in levels of serum triglyceride and low-density lipoprotein (LDL) in rats. Our study demonstrated that fraction 5 from the PR-3 extract (PR-3-5s) showed a hypolipidemic effect in human hepatoma HepG2 cells. PR-3-5s decreased the expression of fatty acid synthase (FASN) and inhibited the activity of acetyl-coenzyme A carboxylase (ACC) by stimulating AMP-activated protein kinase (AMPK) through the LKB1 pathway. Moreover, PR-3-5s blocked the progression of the cell cycle at the G1 phase by inducing p53 expression and in turn upregulating p21 expression.
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PMID:Pu-erh tea attenuates hyperlipogenesis and induces hepatoma cells growth arrest through activating AMP-activated protein kinase (AMPK) in human HepG2 cells. 1945 11

We investigated the effect of acetic acid (AcOH) on the prevention of obesity in high-fat-fed mice. The mice were intragastrically administrated with water or 0.3 or 1.5% AcOH for 6 weeks. AcOH administration inhibited the accumulation of body fat and hepatic lipids without changing food consumption or skeletal muscle weight. Significant increases were observed in the expressions of genes for peroxisome-proliferator-activated receptor alpha (PPARalpha) and for fatty-acid-oxidation- and thermogenesis-related proteins: acetyl-CoA oxidase (ACO), carnitine palmitoyl transferase-1 (CPT-1), and uncoupling protein-2 (UCP-2), in the liver of the AcOH-treatment groups. PPARalpha, ACO, CPT-1, and UCP-2 gene expressions were increased in vitro by acetate addition to HepG2 cells. However, the effects were not observed in cells depleted of alpha2 5'-AMP-activated protein kinase (AMPK) by siRNA. In conclusion, AcOH suppresses accumulation of body fat and liver lipids by upregulation of genes for PPARalpha and fatty-acid-oxidation-related proteins by alpha2 AMPK mediation in the liver.
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PMID:Acetic acid upregulates the expression of genes for fatty acid oxidation enzymes in liver to suppress body fat accumulation. 1946 36

The adipocyte-derived hormone adiponectin plays an important role in modulating energy homeostasis through peripheral tissues and the central nervous system. Several studies have reported that adiponectin exists in cerebrospinal fluid and that adiponectin receptors are expressed in the hypothalamus, including the paraventricular nucleus (PVN), which plays a key role in controlling pituitary hormone secretion. Furthermore, it has been reported that magnocellular arginine vasopressin (AVP) neurones within the PVN express adiponectin receptors. These findings suggest a central role of adiponectin in the modulation of neuroendocrinological functions. In the present study, we investigated the effect of centrally-administered adiponectin on AVP release in conscious rats. Intracerebroventricular (i.c.v.) administration of adiponectin significantly reduced the basal plasma AVP concentration in a dose-dependent manner, with a maximal effect being obtained 10 min after administration. The plasma AVP increase in response to either hyperosmolar or hypovolaemic stimulation was also significantly attenuated by an i.c.v. injection of adiponectin. Treatment with AMP-activated protein kinase (AMPK) inhibitor compound C (100 nmol, i.c.v.) partially reversed the inhibitory effects of adiponectin on AVP release. These findings suggest that central adiponectin plays an inhibitory role in the osmoregulation and baroregulation of AVP release, that the AMPK pathway is at least partly involved in the action of adiponectin, and further suggest a novel physiological or pathophysiological role for central adiponectin in water balance via inhibition of AVP release.
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PMID:Central adiponectin functions to inhibit arginine vasopressin release in conscious rats. 1952 67


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