Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Abnormal dietary intake of macronutrients is implicated in the development of obesity and fatty liver disease. Steatosis develops in cultured hepatocytes exposed to medium containing either a high concentration of long chain free fatty acids (HFFA) or medium deficient in methionine and choline (MCD). This study examined the mitochondrial reactive oxygen species (ROS)-dependent regulation of the phosphoinositol (PI) 3-kinase pathway in steatosis induced by exposure of AML-12 mouse hepatocytes to MCD or HFFA medium. Exposure to either MCD or HFFA medium resulted in increased production of superoxide anions and H(2)O(2), transduction of the PI 3-kinase pathway and steatosis. Inhibition of PI 3-kinase with LY294002 prevented steatosis. Pharmacologically inhibiting electron transport chain complex III production of ROS prevented activation of PI 3-kinase during macronutrient perturbation, whereas pharmacologically promoting electron transport chain complex III ROS production activated PI 3-kinase independent of nutrient input. The data suggest that H(2)O(2) is the ROS species involved in signal transduction; promoting the rapid conversion of superoxide to H(2)O(2) does not inhibit PI 3-kinase pathway activation during nutrient perturbation, and exogenous H(2)O(2) activates it independent of nutrient input. In addition to transducing PI 3-kinase, the ROS-dependent signal cascade amplifies the PI 3-kinase signal by maintaining phosphatase and tensin homolog in its inactive phosphorylated state. Knockdown of phosphatase and tensin homolog by small interfering RNA independently activated the PI 3-kinase pathway. Our findings suggest a common path for response to altered nutrition involving mitochondrial ROS-dependent PI 3-kinase pathway regulation, leading to steatosis.
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PMID:Mitochondrial reactive oxygen species signal hepatocyte steatosis by regulating the phosphatidylinositol 3-kinase cell survival pathway. 1754 Jul 68

Nutrition in childhood influences both the child's present and future health. Health professionals need to educate parents from all socioeconomic groups about good nutrition for their children from birth onwards. They should give priority to including this during consultations. All parents must be made aware of the nutritional benefits of breast-feeding. Since most babies receive formula at some stage during the first year of life, health professionals also have a responsibility to be aware of current developments in infant formulae (e.g. nucleotides, long chain polyunsaturated fatty acids, prebiotics) so they can give accurate information. Weaning is an important nutritional milestone with implications for present and future health. Advice on good weaning practice should be a priority and can help avoid several nutritional problems later on, such as excessively faddy eating, faltering growth, constipation, iron deficiency anaemia and obesity. The last two are key problems in children in the U.K. today. Families should be encouraged to cook, eat and enjoy food together as often as they can, which in itself has been shown to have nutritional benefits, as well as considering the quality of the food they eat.
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PMID:Does childhood nutrition matter? 1784 71

Abnormal energy regulation may significantly contribute to the pathogenesis of obesity, diabetes mellitus, cardiovascular disease, and cancer. For rapid control of energy homeostasis, allosteric and posttranslational events activate or alter activity of key metabolic enzymes. For longer impact, transcriptional regulation is more effective, especially in response to nutrients such as long chain fatty acids (LCFA). Recent advances provide insights into how poorly water-soluble lipid nutrients [LCFA; retinoic acid (RA)] and their metabolites (long chain fatty acyl Coenzyme A, LCFA-CoA) reach nuclei, bind their cognate ligand-activated receptors, and regulate transcription for signaling lipid and glucose catabolism or storage: (i) while serum and cytoplasmic LCFA levels are in the 200 mircroM-mM range, real-time imaging recently revealed that LCFA and LCFA-CoA are also located within nuclei (nM range); (ii) sensitive fluorescence binding assays show that LCFA-activated nuclear receptors [peroxisome proliferator-activated receptor-alpha (PPARalpha) and hepatocyte nuclear factor 4alpha (HNF4alpha)] exhibit high affinity (low nM KdS) for LCFA (PPARalpha) and/or LCFA-CoA (PPARalpha, HNF4alpha)-in the same range as nuclear levels of these ligands; (iii) live and fixed cell immunolabeling and imaging revealed that some cytoplasmic lipid binding proteins [liver fatty acid binding protein (L-FABP), acyl CoA binding protein (ACBP), cellular retinoic acid binding protein-2 (CRABP-2)] enter nuclei, bind nuclear receptors (PPARalpha, HNF4alpha, CRABP-2), and activate transcription of genes in fatty acid and glucose metabolism; and (iv) studies with gene ablated mice provided physiological relevance of LCFA and LCFA-CoA binding proteins in nuclear signaling. This led to the hypothesis that cytoplasmic lipid binding proteins transfer and channel lipidic ligands into nuclei for initiating nuclear receptor transcriptional activity to provide new lipid nutrient signaling pathways that affect lipid and glucose catabolism and storage.
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PMID:Role of fatty acid binding proteins and long chain fatty acids in modulating nuclear receptors and gene transcription. 1788 63

Fatty acid translocase (FAT/CD36) plays an important role in facilitating long chain fatty acid transport. FAT/CD36 gene deletion protects mice from high fat diet-induced obesity. In this study we have investigated the regulatory mechanism of FAT/CD36 expression at the transcription level. FAT/CD36 expression was activated during 3T3-L1 adipocyte differentiation, and FAT/CD36 protein levels were positively correlated with CCAAT/enhancer-binding protein alpha (C/EBPalpha) and peroxisome proliferator-activated receptor gamma. However, a negative correlation was detected between FAT/CD36 and C/EBPbeta. Overexpression of C/EBPalpha or C/EBPbeta increased FAT/CD36 mRNA and protein levels in several types of cells. Restoration of C/EBPalpha or C/EBPbeta expression in C/EBPalpha- or C/EBPbeta-deficient mouse embryonic fibroblasts increased FAT/CD36 expression. However, in mouse embryonic fibroblasts C/EBPalpha was a more potent activator of FAT/CD36 expression than was C/EBPbeta. Expression of C/EBPalpha robustly increased FAT/CD36 proximal promoter-directed luciferase expression in human embryonic kidney 293 cells. A C/EBP-responsive element was identified in the FAT/CD36 promoter by using 5' and specific site mutations. The binding of C/EBPalpha in the FAT/CD36 promoter was detected by chromatin immunoprecipitation in 3T3-L1 adipocytes. These results demonstrated that C/EBPalpha regulates FAT/CD36 gene expression at the transcriptional level.
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PMID:Transcriptional regulation of fatty acid translocase/CD36 expression by CCAAT/enhancer-binding protein alpha. 1826 77

A histidine-tagged recombinant N-terminal fragment of type-1 mouse liver diacylglycerol acyltransferase (DGAT; EC 2.3.1.20), MmDGAT1(1-95)His6, was expressed in Escherichia coli, and used to investigate possible acyl-CoA-binding properties. Analysis of the purified fragment by MALDI-TOF mass spectrometry revealed a polypeptide with molecular mass of about 11 kDa which was consistent with the calculated molecular mass based on the deduced amino acid sequence. Lipidex-1000 binding assays indicated that MmDGAT1(1-95)His(6) interacted with long chain fatty acyl-CoAs similar to observations on DGAT1 from oilseed rape (Brassica napus). Binding, as a function of acyl-CoA concentration, differed for palmitoyl (16:0), stearoyl (18:0), and erucoyl (cisDelta(13)22:1)-CoA. Binding of stearoyl- or erucoyl-CoA to MmDGAT1(1-95)His(6) as a function of acyl-CoA concentration, however, was sigmoid and displayed positive cooperativity suggesting that MmDGAT1 may be subject to allosteric modulation by acyl-CoAs. An intra-polypeptide segment within the N-terminal region of MmDGAT1 contained remnants of an acyl-CoA-binding signature initially identified in plant DGAT1. The acyl-CoA-binding site in mammalian DGAT1 could represent a potential target for therapeutic interventions for disorders such as type-2 diabetes and obesity.
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PMID:An N-terminal fragment of mouse DGAT1 binds different acyl-CoAs with varying affinity. 1857

The molecular mechanism of fatty acid uptake and utilization is of high medical relevance for the treatment of obesity, diabetes, and cardiovascular disease. Neuronal processes, hormones, and transcription factors are master regulators of these essential processes while their fine-tuning is achieved by modulating the activity and amount of enzymes. Proteins involved in fatty acid uptake and metabolism are important pharmaceutical targets. Only basic research on these molecules will lead to new strategies for therapy. Conceptionally, the intracellular utilization of long chain fatty acids may be subdivided into three steps: uptake across the plasma membrane, activation by esterification with coenzyme A, and subsequent metabolism. Long chain acyl-CoA synthetases (ACSLs) activate fatty acids for intracellular metabolism but are also involved in the regulation of uptake. The predominant pathways for fatty acids are their storage, membrane biosynthesis, and conversion to energy. How activated fatty acids are channeled toward one particular metabolic pathway is not well understood on the molecular level. We have previously shown that ACSLs localized to either the endoplasmic reticulum or to mitochondria can regulate the extent of fatty acid uptake. Multiple different long chain ACSLs are expressed simultaneously in the same cell type but differ in their subcellular localization. The hypothesis we put forward here implies that the spatial organization of ACSL activity is a key factor in channeling fatty acids toward a particular metabolic fate.
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PMID:Acyl-CoA synthetases: fatty acid uptake and metabolic channeling. 1911 50

In addition to its essential role in permitting mitochondrial import and oxidation of long chain fatty acids, carnitine also functions as an acyl group acceptor that facilitates mitochondrial export of excess carbons in the form of acylcarnitines. Recent evidence suggests carnitine requirements increase under conditions of sustained metabolic stress. Accordingly, we hypothesized that carnitine insufficiency might contribute to mitochondrial dysfunction and obesity-related impairments in glucose tolerance. Consistent with this prediction whole body carnitine diminution was identified as a common feature of insulin-resistant states such as advanced age, genetic diabetes, and diet-induced obesity. In rodents fed a lifelong (12 month) high fat diet, compromised carnitine status corresponded with increased skeletal muscle accumulation of acylcarnitine esters and diminished hepatic expression of carnitine biosynthetic genes. Diminished carnitine reserves in muscle of obese rats was accompanied by marked perturbations in mitochondrial fuel metabolism, including low rates of complete fatty acid oxidation, elevated incomplete beta-oxidation, and impaired substrate switching from fatty acid to pyruvate. These mitochondrial abnormalities were reversed by 8 weeks of oral carnitine supplementation, in concert with increased tissue efflux and urinary excretion of acetylcarnitine and improvement of whole body glucose tolerance. Acetylcarnitine is produced by the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT). A role for this enzyme in combating glucose intolerance was further supported by the finding that CrAT overexpression in primary human skeletal myocytes increased glucose uptake and attenuated lipid-induced suppression of glucose oxidation. These results implicate carnitine insufficiency and reduced CrAT activity as reversible components of the metabolic syndrome.
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PMID:Carnitine insufficiency caused by aging and overnutrition compromises mitochondrial performance and metabolic control. 1955 74

Excess body fat is associated with increased cardiovascular disease (CVD) risk. The hypothesis of the study was that physical activity and omega-3 index, a marker of past long chain n-3 polyunsaturated fatty acids consumption, counteract the negative associations between fatness and CVD risk factors in young overweight and obese adults. A total of 324 subjects (20-40 years, body mass index [BMI], 27.5-32.5 kg/m(2), from Iceland, Spain, and Ireland) were investigated cross-sectionally. Dietary intake, anthropometric measurements, blood pressure, CVD risk factors, and fatty acids in erythrocyte membrane were analyzed. Information on physical activity was collected. Linear models were constructed to find out the associations of BMI, physical activity (quartiles), and omega-3 index with CVD risk factors. The most frequently increased risk factors were blood lipids (41.4%) and blood pressure (32.1%); fewer participants experienced disturbed glucose metabolism (11.8%). Body mass index was significantly associated with increased CVD risk factors (P = .001-.029), with the exception of total cholesterol, low-density lipoprotein, and high-density lipoprotein. The highest physical activity quartile had a lower fat mass (P = .005, at a given BMI), leptin (P = .008, in male participants only), and interleukin 6 (P = .021) but higher high-density lipoprotein (P = .020) than other quartiles; however, an approximate dose-response relationship could only be observed for leptin. The omega-3 index was not associated with lower low-density lipoprotein (P = .056), but docosahexaenoic acid in erythrocyte membrane was associated to it (P = .016). It is concluded that physical activity and docosahexaenoic acid diminish some of the negative health effects associated with overweight and obesity; however, body fatness remains the most important variable associated with increased CVD risk factors in young overweight and obese adults.
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PMID:Cardiovascular risk factors in young, overweight, and obese European adults and associations with physical activity and omega-3 index. 1955 11

Fatty acids are a major fuel source used to sustain contractile function in heart and oxidative skeletal muscle. To meet the energy demands of these muscles, the uptake and beta-oxidation of fatty acids must be coordinately regulated in order to ensure an adequate, but not excessive, supply for mitochondrial beta-oxidation. However, imbalance between fatty acid uptake and beta-oxidation has the potential to contribute to muscle insulin resistance. The action of insulin is initiated by binding to its receptor and activation of the intrinsic protein tyrosine kinase activity of the receptor, resulting in the initiation of an intracellular signaling cascade that eventually leads to insulin-mediated alterations in a number of cellular processes, including an increase in glucose transport. Accumulation of fatty acids and lipid metabolites (such as long chain acyl CoA, diacylglycerol, triacylglycerol, and/or ceramide) can lead to alterations in this insulin signaling pathway. An imbalance between fatty acid uptake and oxidation is believed to be responsible for this lipid accumulation, and is thought to be a major cause of insulin resistance in obesity and diabetes, due to lipid accumulation and inhibition of one or more steps in the insulin-signaling cascade. As a result, decreasing muscle fatty acid uptake can improve insulin sensitivity. However, the potential role of increasing fatty acid beta-oxidation in the heart or skeletal muscle in order to prevent cytoplasmic lipid accumulation and decrease insulin resistance is controversial. While increased fatty acid beta-oxidation may lower cytoplasmic lipid accumulation, increasing fatty acid beta-oxidation can decrease muscle glucose metabolism, and incomplete fatty acid oxidation has the potential to also contribute to insulin resistance. In this review, we discuss the proposed mechanisms by which alterations in fatty acid uptake and oxidation contribute to insulin resistance, and how targeting fatty acid uptake and oxidation is a potential therapeutic approach to treat insulin resistance.
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PMID:Role of fatty acid uptake and fatty acid beta-oxidation in mediating insulin resistance in heart and skeletal muscle. 1978 65

Long chain fatty acids (LCFAs) provide 70-80% of the energy for cardiac contractile activity. LCFAs are also essential for many other cellular functions, such as transcriptional regulation of proteins involved in lipid metabolism, modulation of intracellular signalling pathways, and as substrates for membrane constituents. When LCFA uptake exceeds the capacity for their cardiac utilization, the intracellular lipids accumulate and are thought to contribute to contractile dysfunction, arrhythmias, cardiac myocyte apoptosis and congestive heart failure. Moreover, increased cardiac myocyte triacylglycerol, diacylglycerol and ceramide depots are cardinal features associated with obesity and type 2 diabetes. In recent years considerable evidence has accumulated to suggest that, the rate of entry of long chain fatty acids (LCFAs) into the cardiac myocyte is a key factor contributing to a) regulating cardiac LCFA metabolism and b) lipotoxicity in the obese and diabetic heart. In the present review we i) examine the evidence indicating that LCFA transport into the heart involves a protein-mediated mechanism, ii) discuss the proteins involved in this process, including FAT/CD36, FABPpm and FATP1, iii) discuss the mechanisms involved in regulating LCFA transport by some of these proteins (including signaling pathways), as well as iv) the possible interactions of these proteins in regulating LCFA transport into the heart. In addition, v) we discuss how LCFA transport and transporters are altered in the obese/diabetic heart.
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PMID:Protein-mediated Fatty Acid Uptake in the Heart. 1992 73


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