Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin resistance is a key pathophysiologic feature of obesity and type 2 diabetes and is associated with other human diseases, including atherosclerosis, hypertension, hyperlipidemia, and polycystic ovarian disease. Yet, the specific cellular defects that cause insulin resistance are not precisely known. Insulin receptor substrate (IRS) proteins are important signaling molecules that mediate insulin action in insulin-sensitive cells. Recently, serine phosphorylation of IRS proteins has been implicated in attenuating insulin signaling and is thought to be a potential mechanism for insulin resistance. However, in vivo increased serine phosphorylation of IRS proteins in insulin-resistant animal models has not been reported before. In the present study, we have confirmed previous findings in both JCR:LA-cp and Zucker fatty rats, two genetically unrelated insulin-resistant rodent models, that an enhanced serine kinase activity in liver is associated with insulin resistance. The enhanced serine kinase specifically phosphorylates the conserved Ser(789) residue in IRS-1, which is in a sequence motif separate from the ones for MAPK, c-Jun N-terminal kinase, glycogen-synthase kinase 3 (GSK-3), Akt, phosphatidylinositol 3'-kinase, or casein kinase. It is similar to the phosphorylation motif for AMP-activated protein kinase, but the serine kinase in the insulin-resistant animals was shown not to be an AMP-activated protein kinase, suggesting a potential novel serine kinase. Using a specific antibody against Ser(P)(789) peptide of IRS-1, we then demonstrated for the first time a striking increase of Ser(789)-phosphorylated IRS-1 in livers of insulin-resistant rodent models, indicating enhanced serine kinase activity in vivo. Taken together, these data strongly suggest that unknown serine kinase activity and Ser(789) phosphorylation of IRS-1 may play an important role in attenuating insulin signaling in insulin-resistant animal models.
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PMID:In vivo phosphorylation of insulin receptor substrate 1 at serine 789 by a novel serine kinase in insulin-resistant rodents. 1200 86

From the perspective of a muscle physiologist, adipose tissue has long been perceived predominantly as a fuel reservoir that provides muscle and other tissues with NEFA when exogenous nutrients are insufficient for their energy needs. Recently, studies have established that adipose tissue is also an endocrine organ. Among the hormones it releases are adiponectin and leptin, both of which can activate AMP-activated protein kinase and increase fatty acid oxidation in skeletal muscle and probably other tissues. Deficiencies of leptin or leptin receptor, adiponectin and IL-6 are associated with obesity, insulin resistance and a propensity to type 2 diabetes. In addition, a lack of adiponectin has been linked to atherosclerosis. Whether this pathology reflects a deficient activation of AMP-activated protein kinase in peripheral tissues remains to be determined. Finally, recent studies have suggested that skeletal muscle may also function as an endocrine organ when it releases the cytokine IL-6 into the circulation during sustained exercise. Interestingly, one of the apparent effects of IL-6 is to stimulate lipolysis, causing the release of NEFA from the adipocyte. Thus, hormonal communications exist between the adipocyte and muscle that could enable them to talk to each other. The physiological relevance of this cross talk clearly warrants further study.
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PMID:Metabolic and hormonal interactions between muscle and adipose tissue. 1529 59

Because polyphenols may have beneficial effects on dyslipidemia, which accelerates atherosclerosis in diabetes, we examined the effect of polyphenols on hepatocellular AMP-activated protein kinase (AMPK) activity and lipid levels, as well as hyperlipidemia and atherogenesis in type 1 diabetic LDL receptor-deficient mice (DMLDLR(-/-)). In HepG2 hepatocytes, polyphenols, including resveratrol (a major polyphenol in red wine), apigenin, and S17834 (a synthetic polyphenol), increased phosphorylation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC), and they increased activity of AMPK with 200 times the potency of metformin. The polyphenols also prevented the lipid accumulation that occurred in HepG2 cells exposed to high glucose, and their ability to do so was mimicked and abrogated, respectively, by overexpression of constitutively active and dominant-negative AMPK mutants. Furthermore, treatment of DMLDLR(-/-) mice with S17834 prevented the decrease in AMPK and ACC phosphorylation and the lipid accumulation in the liver, and it also inhibited hyperlipidemia and the acceleration of aortic lesion development. These studies 1) reveal that inactivation of hepatic AMPK is a key event in the pathogenesis of hyperlipidemia in diabetes, 2) point to a novel mechanism of action of polyphenols to lower lipids by activating AMPK, and 3) emphasize a new therapeutic avenue to benefit hyperlipidemia and atherosclerosis specifically in diabetes via activating AMPK.
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PMID:Polyphenols stimulate AMP-activated protein kinase, lower lipids, and inhibit accelerated atherosclerosis in diabetic LDL receptor-deficient mice. 1687 80

Adipose tissue plays a critical role in energy homeostasis, not only in storing triglycerides, but also responding to nutrient, neural, and hormonal signals and secreting adipokines that control feeding, thermogenesis, immunity, and neuroendocrine function. A rise in leptin signals satiety to the brain through receptors in hypothalamic and brainstem neurons. Leptin activates tyrosine kinase, Janus kinase 2, and signal transducer and activator of transcription 3, leading to increased levels of anorexigenic peptides, e.g., alpha-melanocyte stimulating hormone and cocaine- and amphetamine-regulated transcript, and inhibition of orexigenic peptides, e.g., neuropeptide Y and agouti-related peptide. Obesity is characterized by hyperleptinemia and hypothalamic leptin resistance, partly caused by induction of suppressor of cytokine signaling-3. Leptin falls rapidly during fasting and potently stimulates appetite, reduces thermogenesis, and mediates the inhibition of thyroid and reproductive hormones and activation of the hypothalamic-pituitary-adrenal axis. These actions are integrated by the paraventicular hypothalamic nucleus. Leptin also decreases glucose and stimulates lipolysis through central and peripheral pathways involving AMP-activated protein kinase (AMPK). Adiponectin is secreted exclusively by adipocytes and has been linked to glucose, lipid, and cardiovascular regulation. Obesity, diabetes, and atherosclerosis have been associated with reduced adiponectin levels, whereas adiponectin treatment reverses these abnormalities partly through activation of AMPK in liver and muscle. Administration of adiponectin in the brain recapitulates the peripheral actions to increase fatty acid oxidation and insulin sensitivity and reduce glucose. Although putative adiponectin receptors are widespread in peripheral organs and brain, it is uncertain whether adiponectin acts exclusively through these targets. As with leptin, adiponectin requires the central melanocortin pathway. Furthermore, adiponectin stimulates fatty acid oxidation and reduces glucose and lipids, at least in part, by activating AMPK in muscle and liver.
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PMID:Adipose tissue as an endocrine organ. 1702 75

Increased oxidative stress in vascular cells is implicated in the pathogenesis of atherosclerosis. Reactive oxygen species (ROS) induce vascular inflammation via the proinflammatory cytokine/NF-kappaB pathway. Several lines of evidence suggest that peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1alpha) is an important regulator of intracellular ROS levels. However, no studies have examined the effects of PGC-1alpha on this process. We investigated the effects of PGC-1alpha on inflammatory molecule expression and activity of the redox-sensitive transcription factor, NF-kappaB, in vascular cells. PGC-1alpha expressed in human aortic smooth (HASMCs) and endothelial cells (HAECs) is upregulated by AMP-activated protein kinase activators, including metformin, rosiglitazone and alpha-lipoic acid. Tumor necrosis factor-alpha (TNF-alpha), a major proinflammatory factor in the development of vascular inflammation, stimulates intracellular ROS production through an increase in both mitochondrial ROS and NAD(P)H oxidase activity. Adenovirus-mediated overexpression of the PGC-1alpha gene in HASMCs and HAECs leads to a significant reduction in intracellular and mitochondrial ROS production as well as NAD(P)H oxidase activity. Consequently, NF-kappaB activity and MCP-1 and VCAM-1 induced by TNF-alpha are suppressed. Our data support the possibility that agents stimulating PGC-1alpha expression in the vasculature aid in preventing the development of atherosclerosis.
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PMID:Effects of PGC-1alpha on TNF-alpha-induced MCP-1 and VCAM-1 expression and NF-kappaB activation in human aortic smooth muscle and endothelial cells. 1718 71

AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that is expressed in most mammalian tissues including cardiac muscle. Among the multiple biological processes influenced by AMPK, regulation of fuel supply and energy-generating pathways in response to the metabolic needs of the organism is fundamental and likely accounts for the remarkable evolutionary conservation of this enzyme complex. By regulating the activity of acetyl-coenzyme A carboxylase, AMPK affects levels of malonyl-coenzyme A, a key energy regulator in the cell. AMPK is generally quiescent under normal conditions but is activated in response to hormonal signals and stresses sufficient to produce an increase in AMP/ATP ratio, such as hypoglycemia, strenuous exercise, anoxia, and ischemia. Once active, muscle AMPK enhances uptake and oxidative metabolism of fatty acids as well as increases glucose transport and glycolysis. Data from AMPK deficiency models suggest that AMPK activity might influence the pathophysiology and therapy of diabetes and increase heart tolerance to ischemia. Effects that are not as well understood include AMPK regulation of transcription. Different AMPK isoforms are found in distinct locations within the cell and have distinct functions in different tissues. A principal mode of AMPK activation is phosphorylation by upstream kinases (eg, LKB1). These kinases have a fundamental role in cell-cycle regulation and protein synthesis, suggesting involvement in a number of human disorders including cardiac hypertrophy, apoptosis, cancer, and atherosclerosis. The physiological role played by AMPK during health and disease is far from being clearly defined. Naturally occurring mutations affecting the nucleotide-sensing modules in the regulatory gamma subunit of AMPK lead to enzyme dysregulation and inappropriate activation under resting conditions. Glycogen accumulation ensues, leading to human disease manifesting as cardiac hypertrophy, accessory atrioventricular connections, and degeneration of the physiological conduction system. Whether AMPK is a key participant or bystander in other disease states and whether its selective manipulation may significantly benefit these conditions remain important questions.
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PMID:AMP-activated protein kinase in the heart: role during health and disease. 1733 38

Adiponectin is known to play a role in fatty acid and glucose metabolism through a change in insulin sensitivity and activation of fuel oxidation by AMP-activated protein kinase. Adiponectin can be considered an important factor able to modulate the adipovascular axis which, through genomic and environmental influences, affects the cardiovascular risk milieu, from the pre-metabolic syndrome-- through the metabolic syndrome--to the overt atherosclerotic process and its clinical manifestations. Hypoadiponectinaemia can be viewed as an early sign of a complex cardiovascular risk factor predisposing to the atherosclerosis process as well as a contributing factor accelerating the progress of the atherosclerotic plaque. In addition, adiponectin per se holds a protective role thanks to its anti-inflammatory and antiatherogenic properties. The early identification of patients "at cardiovascular risk" means in the current practice to search for indexes of metabolic derangements and pro-inflammatory status (adiponectin) from adolescence and childhood.
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PMID:Adiponectin and the cardiovascular system: from risk to disease. 1790 7

Adiponectin is an adipocyte-derived protein with insulin-sensitizing, anti-inflammatory, and anti-atherogenic properties and is abundantly found in plasma. Vascular adventitia is the outermost connective and supporting tissue of vessels. Recently, increasing evidence has shown that infection in the adventitia is one of the causes of atherosclerosis and restenosis. Our previous study indicated that local transferring adenovirus expressing adiponectin gene (Ad-APN) to intima and adventitia can suppress atherosclerosis, but the exact mechanism is still obscure. We speculate that with infection in the adventitia, adiponectin can activate AMP-activated protein kinase (AMPK) through adiponectin receptors in the membranes of adventitial fibroblasts and then inhibit the expression and activity of inducible nitric oxide synthase (iNOS); secretion of adventitial infective factors; division, proliferation and translation of adventitial fibroblasts; and change of adventitial fibroblasts to myofibroblasts, finally decreasing oxidative/nitrative stress to reduce atherosclerotic plaque area and stabilize atherosclerotic plaques. The proposition may provide clues into the development of a novel treatment for atherosclerosis.
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PMID:A hypothesis: adiponectin mediates anti-atherosclerosis via adventitia-AMPK-iNOS pathway. 1791 Sep 91

Adiponectin is an abundantly expressed adipokine in adipose tissue and has direct insulin sensitizing activity. A decrease in the circulating levels of adiponectin by interactions between genetic factors and environmental factors causing obesity has been shown to contribute to the development of insulin resistance, type 2 diabetes, metabolic syndrome and atherosclerosis. In addition to its insulin sensitizing actions, adiponectin has central actions in the regulation of energy homeostasis. Adiponectin enhances AMP-activated protein kinase activity in the arcuate hypothalamus via its receptor AdipoR1 to stimulate food intake and decreases energy expenditure. We propose a hypothesis on the physiological role of adiponectin: a starvation gene in the course of evolution by promoting fat storage on facing the loss of adiposity.
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PMID:The physiological and pathophysiological role of adiponectin and adiponectin receptors in the peripheral tissues and CNS. 1805 35

Cardiovascular diseases continue to be the main cause of death in most industrialized countries. Endothelial dysfunction, a systemic process, is the earliest known marker of atherosclerosis and has become a major focus in acute ischemic disorders. We are investigating the hypothesis that, in these diseases, microvascular and endothelial dysfunctions occur simultaneously and precede the onset of macrovascular disease. We studied, to our knowledge for the first time in the same subjects, microvascular and endothelial functions in 11 patients with type 2 diabetes. 36 metabolic syndrome patients (NCEP-ATPIII criteria) and 25 young obese women matched with healthy controls. Micro vascular morphology and hemodynamics were evaluated non-invasively by means of nailfold videocapillaroscopy. Red blood cell velocity (RBCV, mm/s) was measured at rest and after release from 60 s of arterial occlusion (RBCVmax, mm/s) at the finger base, along with the time to reach RBCVmax (TRBCVmax, s), by video analysis with Cap Image software. Venous occlusion plethysmography was performed after intra-arterial infusions of acetylcholine and sodium nitroprusside to assess endo thelial-dependent and -independent vasodilation, respectively. We found similar results in the three groups of subjects, namely a significant decrease in RBCVmax, an increase in TRBCVmax, and a decrease in endothelial-dependent vasodilation. These findings clearly demonstrate that the two dysfunctions occur simultaneously in these groups of patients. Several mechanisms which could impair micro vascular and endothelial functions are associated with insulin resistance, and drugs that act on insulin resistance might thus be beneficial. Metformin, given to 16 first-degree relatives of patients with type 2 diabetes mellitus, who had the metabolic syndrome and normal glucose tolerance (ADA criteria), improved endothelial-dependent vasodilation and microcirculatory function. Rosiglitazone, given to 18 patients with the metabolic syndrome, enhanced vascular responses by improving endothelial function and increasing adiponectin levels. Increased triglyceride storage is often associated with insulin resistance, contributing to free fatty acid (FFA) overexposure. The two drugs tested here stimulate AMP-activated protein kinase, which promotes FFA oxidation and thus reduces oxidative stress, and might therefore attenuate endothelial lipotoxicity. The results strongly suggest that targeting micro vascular and endothelial dysfunctions in patients with metabolic disorders might help to prevent cardiovascular events, and warrant long-term clinical trials.
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PMID:[Vascular dysfunction in metabolic disorders: evaluation of some therapeutic interventions]. 1807 49


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