Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Abnormal high density lipoprotein metabolism may contribute to the increased atherosclerosis associated with diabetes and insulin resistance. The ATP-binding cassette transporter ABCA1 mediates cholesterol transport from tissue macrophages to apoA-I, the major high density lipoprotein protein component. Because fatty acids are elevated in diabetes, we examined the effects of fatty acids on ABCA1 activity in cultured macrophages. Results showed that unsaturated fatty acids markedly inhibited ABCA1-mediated cholesterol and phospholipid efflux from macrophages when ABCA1 was induced by a cAMP analog. This was accompanied by a reduction in the membrane content of ABCA1 and a decrease in apoA-I binding to whole cells and to ABCA1. In contrast, saturated fatty acids had no effect on these processes. Fatty acids did not alter ABCA1 mRNA abundance or incorporation of methionine into ABCA1, indicating that decreased ABCA1 transcription, enhanced mRNA decay, or impaired translation efficiency did not account for these inhibitory effects. Unsaturated fatty acids, however, increased ABCA1 turnover when protein synthesis was blocked by cycloheximide. We conclude that unsaturated fatty acids reduce the macrophage ABCA1 content by enhancing its degradation rate. These findings raise the possibility that an increased supply of unsaturated fatty acids in the artery wall promotes atherogenesis by impairing the ABCA1 cholesterol secretory pathway in macrophages.
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PMID:Unsaturated fatty acids inhibit cholesterol efflux from macrophages by increasing degradation of ATP-binding cassette transporter A1. 1174 98

Atherosclerosis is a major vascular complication of diabetes and the primary cause of mortality in persons with this disease. Metabolic abnormalities related to the Insulin Resistance Syndrome or Metabolic Syndrome may importantly contribute to the increased risk of atherosclerosis associated with diabetes. Thiazolidinediones (TZDs) are oral insulin sensitizers in broad clinical use that enhance insulin-stimulated glucose uptake into skeletal muscle. TZDs can also improve cardiovascular risk factors and exert direct effects on vascular cells to potentially retard the atherosclerotic process. Direct vascular effects of TZDs likely result from their activity as ligands for the nuclear receptor, PPARgamma. All of the major cell types in the vasculature express PPARgamma, including intimal macrophages and vascular smooth muscle cells (VSMCs) in human atheroma. TZDs block VSMC growth by inducing cell cycle arrest in G1 through an inhibition of retinoblastoma protein phosphorylation. Migration of monocytes and VSMCs is also inhibited by TZDs, possibly through decreased matrix metalloproteinase production. Activation of PPARgamma by TZDs in macrophages induces ABCA1 transporter expression to promote reverse cholesterol transport. These antiatherogenic activities may also occur in vivo because TZDs have been shown to inhibit lesion formation in several animal models. Thus, TZD activation of PPARgamma may protect against atherosclerosis both by normalizing proatherogenic metabolic abnormalities of the insulin resistance/diabetes milieu and through an inhibition of vascular cell growth and movement.
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PMID:PPARgamma and atherosclerosis: effects on cell growth and movement. 1174 60

The disturbance of lipid metabolism is seen in some inherited diseases and also in patients with some kinds of underlying diseases. The presence of its disturbance can be detected by measuring the concentrations of cholesterol and triglyceride in serum. Although hyperlipidemia or hypolipidemia is the result of abnormal lipid metabolism, hyperlipidemia is of more concern to physicians because of the close association with atherosclerosis. Responsible genes for some primary (or hereditary) hyperlipidemic diseases have been confirmed as follows; LPL or apo C-II for primary chylomicronemia, LDL receptor for familial hypercholesterolemia and apo B-100 for familial defective apo B-100. However, the responsible gene remains controversial for familial combined hyperlipidemia, though AI/CIII/AIV cluster is one of the possible candidate genes. Secondary hyperlipidemia is caused by various diseases such as diabetes mellitus, renal diseases and cholestasis. This type of hyperlipidemia is improved by therapy for the underlying diseases. To date, the mechanism of lipid metabolism has been defined in a molecular basis. In fact, sterol regulatory element-binding protein (SREBP), peroxisome proliferator-activated receptor (PPAR) and ATP-binding cassette transporter subfamily A, member 1(ABCA1) were recently identified and it was demonstrated that these regulate lipid metabolism.
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PMID:[Disturbance of lipid metabolism]. 1198 47

The family of adenosine triphosphate (ATP)-binding cassette (ABC) transporters is the largest gene family known. While some ABC transporters translocate single substances across membranes with high specificity, others transport a wide variety of different lipophilic compounds. They are responsible for many physiological processes and are also implicated in a number of diseases. The present review focuses on ABC transporter genes which are involved in ageing and age-related diseases. Expression of ABCB1 (MDR1, P-glycoprotein) increases with age in CD4(+) and CD8(+) T-lymphocytes indicating that P-glycoprotein may be involved in the secretion of cytokines, growth factors, and cytotoxic molecules. As T cells in aged individuals are hyporesponsive leading to a reduced immunodefence capability, a role of ABCB1 in age-related immunological processes is presumed. The ABCA1 (ABC1) gene product translocates intracellular cholesterol and phospholipids out of macrophages. Genetic aberrations in ABCA1 cause perturbations in lipoprotein metabolism and contribute to atherosclerosis. ABCA4 (ABCR) represents a retina-specific ABC transporter expressed in rod photoreceptor cells. The ABCA4 gene product translocates retinyl-derivatives. Mutations in the ABCA4 gene contribute to age-related macular degeneration. Polymorphisms in the sulfonylurea receptor gene (ABCC8, SUR1) are associated with non-insulin-dependent diabetes mellitus (NIDDM). Sulfonylureas inhibit potassium conductance and are used to treat NIDDM by stimulation of insulin secretion across ATP-sensitive potassium channels in pancreatic beta-cell membranes. Possible diagnostic and therapeutic implications of ABC transporters for age-related diseases are discussed.
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PMID:Adenosine triphosphate-binding cassette transporter genes in ageing and age-related diseases. 1243 93

The ABCA subfamily of ABC transporters includes ten members to date. In this study, we describe an additional gene, ABCA12. Four full-length cDNA sequences have been obtained from human placenta that contain two different polyadenylation sites and two splicing forms, coding for ABCA12 isoforms of 2,595 and 2,516 amino acid residues. Both isoforms are predicted to have two ATP-binding domains (nucleotide binding domain, NBD) and two transmembrane (TM) domains, features shared by all other ABCA subfamily proteins. ABCA12 is most closely related to ABCA1, with an amino acid similarity of 47%. Northern blot analysis demonstrates that a 9.5-kb transcript is mainly expressed in the stom- ach. ABCA12 was mapped to human chromosome 2q34. Two other genes from ABCA subfamily are associated with human inherited diseases, ABCA1 with the cholesterol transport disorders Tangier disease and familial hypoalphalipoproteinemia, and ABCA4 with several retinal degeneration disorders. The ABCA12 gene is located in a region of chromosome 2q34 that harbors the genes for lamellar ichthyosis, polymorphic congenital cataract, and insulin-dependent diabetes mellitus (IDDM13), and therefore is a positional candidate for these pathologies.
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PMID:Identification and characterization of a novel ABCA subfamily member, ABCA12, located in the lamellar ichthyosis region on 2q34. 1269 99

We have employed microarray technology using RNA from normal 3T3-L1 adipocytes and from 3T3-L1 adipocytes made insulin-resistant by treatment with tumor necrosis factor-alpha to identify a new class of insulin-responsive genes. These genes continued to respond normally to insulin even though the adipocytes themselves were metabolically insulin-resistant, i.e. they displayed a significantly decreased rate of insulin-stimulated glucose uptake. Approximately 12,000 genes/expressed sequence tags (ESTs) were screened. Of these, 40 genes/ESTs were identified that became insulin-resistant as expected (e.g. Socs-3, junB, and matrix metalloproteinase-11). However, 61 genes/ESTs continued to respond normally to insulin. Although some of these genes were previously shown to be regulated by insulin (e.g. Glut-1 and beta3-adrenergic receptor), other novel insulin-sensitive genes were also identified (e.g. Egr-1, epiregulin, Fra-1, and ABCA1). Real-time reverse transcription-PCR analysis confirmed the expression patterns of several of the differentially expressed genes. One gene that remained insulin-sensitive in the insulin-resistant adipocytes is the transcription factor Egr-1. Using an antisense strategy, we show that tissue factor and macrophage colony-stimulating factor, two cardiovascular risk factors, are downstream EGR-1 target genes in the adipocyte. Taken together, these data support the hypothesis that some signaling pathways remain insulin-sensitive in metabolically insulin-resistant adipocytes. These pathways may promote abnormal gene expression in hyperinsulinemic states like obesity and type II diabetes and thus may contribute to pathologies associated with these conditions.
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PMID:Expression profiling identifies genes that continue to respond to insulin in adipocytes made insulin-resistant by treatment with tumor necrosis factor-alpha. 1453 Feb 83

Atherosclerosis is well recognized as an inflammatory disease and circulating markers of inflammation such as C-reactive protein and soluble adhesion molecules are strong predictors of atherosclerotic lesion development and future cardiovascular events. Several cells (endothelial, smooth muscle and macrophages) and proteins (inflammatory cytokines and adhesion molecules) contribute to this inflammatory process and lesion development. Although lipid management with statins does reduce levels of circulating inflammatory markers, this appears to be unrelated LDL-lowering. Thus, the recent focus has been shifted to develop molecules that directly affect the atherosclerotic process without effects on plasma lipids. Much of this research was initially focused on cytokine antagonists and adhesion molecule expression inhibitors, which are now at different stages pre-clinical and clinical development. Additional targets have begun gaining prominence in the past few years -- modulation of proteins involved in reverse cholesterol transport and lipid metabolism in the vessel wall such as ApoA1/apoE/ABCA1, ACAT, and LpPLA2 and regulation of molecules involved in matrix remodeling and cell proliferation such as matrix metalloproteinases and heparan sulfate proteoglycans. The current approaches for the treatment of atherosclerosis are 1) reduction of risk factors for the disease -- e.g., lipids, hypertension and diabetes and 2) direct disease modifiers. The purpose of this review is to examine key scientific advances and the prospect of these approaches in the prevention of cardiovascular disease.
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PMID:Atherosclerosis -- new targets and therapeutics. 1532 Jul 83

Abnormal high density lipoprotein (HDL) metabolism among patients with diabetes and insulin resistance may contribute to their increased risk of atherosclerosis. ATP-binding cassette transporter ABCA1 mediates the transport of cholesterol and phospholipids from cells to HDL apolipoproteins and thus modulates HDL levels and atherogenesis. Unsaturated fatty acids, which are elevated in diabetes, impair the ABCA1 pathway in cultured cells by destabilizing ABCA1 protein. Here we examined the cellular pathway that mediates the ABCA1 destabilizing effects of fatty acids. The long-chain acyl-CoA synthetase inhibitor triacsin C completely reversed fatty acid-induced ABCA1 destabilization, indicating that fatty acids need to be activated to their CoA derivatives to enhance ABCA1 degradation. Unsaturated but not saturated fatty acids stimulated phospholipase D (PLD) activity, the PLD inhibitor 1-butanol prevented the unsaturated fatty acid-induced reduction in ABCA1 levels, and the PLD2 activator mastoparan markedly reduced ABCA1 protein levels, implicating a role for PLD2 in the ABCA1 destabilizing effects of fatty acids. Unsaturated fatty acids and mastoparan increased phosphorylation of ABCA1 serines. PLD2 small interfering RNA abolished the ability of unsaturated fatty acids to inhibit lipid transport activity, to reduce protein levels, and to increase serine phosphorylation of ABCA1. The diacylglycerol analog oleoylacetylglycerol also reduced ABCA1 protein levels and increased its serine phosphorylation, suggesting that PLD2-generated diacylglycerols promote the destabilizing phosphorylation of ABCA1. These data provide evidence that intracellular unsaturated acyl-CoA derivatives destabilize ABCA1 by activating a PLD2 signaling pathway.
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PMID:Unsaturated fatty acids phosphorylate and destabilize ABCA1 through a phospholipase D2 pathway. 1611 12

Reduced circulating levels of high density lipoprotein cholesterol (HDL-C) are a frequent lipoprotein disorder in coronary heart disease patients and can be caused by either genetic and/or environmental factors (sedentary lifestyle, diabetes mellitus, smoking, obesity or a diet enriched in carbohydrates). Extremely low serum HDL-C levels occur in patients with Tangier disease (TD), which is caused by mutations in the adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1). Clinical manifestations are related to the storage of cholesteryl esters in reticuloendothelial tissues and to peripheral neuropathy. This review focuses on the genetic and lipid abnormalities of TD, the consequence of these on clinical outcome and the possible treatment options. These abnormalities reflect the importance of HDL in the pathogenesis of vascular disease.
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PMID:Tangier disease four decades of research: a reflection of the importance of HDL. 1661 Oct 66

We examined whether macrophages from men and women with Type 2 diabetes mellitus (T2DM) exhibited differences in expression of key genes involved in fatty acid metabolism and in fatty acid composition compared with macrophages from non-diabetic controls. Peripheral blood monocytes from subjects with T2DM (n=9) and non-diabetic controls (n=10) were differentiated into macrophages in 10% autologous serum and normal (5mM) or high (22mM) glucose. Levels of PPARalpha, PPARgamma, LXRalpha, SCD and ABCA1 mRNAs were similar in macrophages from subjects with T2DM and controls. At 5mM glucose, macrophage stearic acid (C18:0) was 12.6+/-1.0% of total fatty acids for T2DM compared with 18.1+/-2.0% for controls (p=0.03). Macrophage linoleic acid (C18:2) was 15.5+/-0.8% for T2DM and 9.3+/-2.0% for controls (p=0.005). The ratio of macrophage stearic acid (C18:0)/oleic acid (C18:1) was 0.29 [0.25,0.48] for T2DM versus 0.54 [0.36,0.82] for controls (p=0.04). Compared with non-diabetic controls, macrophages from men and women with T2DM had significantly different fatty acid profiles consistent with increased stearoyl-CoA desaturase (SCD) activity and increased C18:2 accumulation. This pattern of altered macrophage fatty acid composition may be relevant to diabetic atherogenesis.
Diabetes Res Clin Pract 2007 Mar
PMID:Monocyte-derived macrophages from men and women with Type 2 diabetes mellitus differ in fatty acid composition compared with non-diabetic controls. 1690 84


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