Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations in the HNF4alpha gene have been correlated with maturity-onset diabetes of the young, which is characterized mainly by pancreatic beta-cell dysfunction and is also associated with mild liver abnormalities. HNF4alpha D126Y and D126H mutations were found in a patient with early-onset type 2 diabetes, and the R324H mutation was found in a common type 2 diabetic nephropathic patient. We investigated whether these mutations, which have not yet been functionally characterized, impair HNF4alpha function in three cell models: HEK 293 embryonal kidney cells, HepG2 hepatoma cells, and betaTC3 pancreatic beta-cells. The R324H mutation had no effect on HNF4alpha function with either the HNF1alpha and L-type pyruvate kinase (LPK) promoters, but the D126Y and D126H mutations impaired HNF4alpha transcriptional activities in all tested cell lines. These impairments by D126Y and D126H mutations, which are located in the T box, are not due to a loss of dimerization but to a loss of DNA binding. Interestingly, the strongest functional consequences of these mutations were observed on the HNF1alpha promoter in betaTC3 cells. Given the key role of the transcription factor HNF1alpha in pancreatic beta-cell function, it can be inferred that impairment of HNF4alpha function by these mutations affects metabolic pathways in pancreatic beta-cells and contributes to development of diabetes. Moreover, the HNF4alpha-mediated activation of the apolipoprotein CIII promoter in HepG2 cells was significantly impaired by D126Y and D126H mutations. These results support clinical findings that liver function can also be impaired in diabetic patients having HNF4alpha mutations.
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PMID:Mutations in hepatocyte nuclear factor 4alpha (HNF4alpha) gene associated with diabetes result in greater loss of HNF4alpha function in pancreatic beta-cells than in nonpancreatic beta-cells and in reduced activation of the apolipoprotein CIII promoter in hepatic cells. 1211 Sep 48

Low levels of high-density lipoproteins cholesterol (HDL-C) as well as impaired postprandial lipemia are known to be associated with the increased risk for coronary artery disease (CAD) in patients with type 2 diabetes mellitus (type 2 DM). HDL are heterogeneous in size and apolipoprotein composition. Recent evidence indicates that among the 2 major HDL subclasses, those without apolipoprotein A-II (LpA-I) are more antiatherogenic compared with those with apoA-II (LpA-I:A-II). Cilostazol, a novel selective phosphodiesterase type III inhibitor, has been shown to inhibit platelet activation and is also a potent vasodilator. Additionally, cilostazol has been shown to modulate lipoprotein profiles by raising HDL-C and lowering plasma triglyceride (TG) levels. The present study investigated the effect of cilostazol on HDL composition (LpA-I and LpA-I:A-II levels) and postprandial lipemia in patients with type 2 DM. Seventeen patients were given cilostazol 200 mg twice daily for 12 weeks. At weeks 0 and 12, fat tolerance tests (30 g/m(2)) were performed to assess postprandial lipemia. Plasma TG and remnant-like lipoprotein particles cholesterol (RLP-C) were significantly decreased by 17% and 26%, respectively (P <.05), and HDL-C was significantly increased by 14% (P <.01). LpA-I was significantly increased by 23% (P <.01) from the mean value of 45 mg/dL to 55 mg/dL. In contrast, LpA-I:A-II remained unchanged, resulting in significantly increased %LpA-I (apoA-I on LpA-I/total apoA-I x 100) from 35% to 40% (P <.01). Areas under the curve for TG and RLP-C after the fat meal were both nonsignificantly decreased by 17%. Patients with higher plasma TG levels had a greater benefit from the treatment with cilostazol as revealed by fasting TG levels and fat tolerance tests. HDL-C responses to cilostazol were independent of baseline plasma TG levels or percentage changes in TG, indicating that the underlying mechanisms for raising HDL and reducing TG levels are distinct. In conclusion, cilostazol selectively increased LpA-I, thus favorably altering HDL towards a more antiatherogenic composition. This finding, together with the improved postprandial lipemia, indicates that cilostazol has a potent antiatherogenic function by modulating HDL and remnant metabolism in patients with type 2 DM.
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PMID:Cilostazol, a potent phosphodiesterase type III inhibitor, selectively increases antiatherogenic high-density lipoprotein subclass LpA-I and improves postprandial lipemia in patients with type 2 diabetes mellitus. 1237 Aug 57

A total of 5 randomized, double-blind trials in patients with hypercholesterolemia were prospectively designed to allow pooling of plasma lipid data after 12 weeks of treatment. The purpose was (1) to compare rosuvastatin 5 and 10 mg with atorvastatin 10 mg (data from 3 of the 5 trials); (2) to compare rosuvastatin 5 and 10 mg with simvastatin 20 mg and pravastatin 20 mg (data from 2 of the 5 trials); and (3) to summarize overall efficacy and subset analyses of rosuvastatin data from all 5 trials. Rosuvastatin 5 mg (n = 390) and 10 mg (n = 389) reduced low-density lipoprotein (LDL) cholesterol significantly more than did atorvastatin 10 mg (n = 393) (41.9% and 46.7% vs 36.4%, both p <0.001). Treatment with rosuvastatin 5 mg (n = 240) and 10 mg (n = 226) also resulted in significantly greater reductions in LDL cholesterol compared with both simvastatin 20 mg (n = 249) and pravastatin 20 mg (n = 252) (40.6% and 48.1% vs 27.1% and 35.7%, all p <0.001). Significant differences favoring rosuvastatin 10 mg were also observed for total cholesterol, high-density lipoprotein (HDL) cholesterol, non-HDL cholesterol, apolipoprotein (apo) B, and apo A-I versus atorvastatin 10 mg, and for total cholesterol, HDL cholesterol, triglycerides, non-HDL cholesterol, and apo B versus simvastatin 20 mg and pravastatin 20 mg. Analyses of all the rosuvastatin 10 mg data (n = 615) from the 5 trials in subgroups defined by age > or =65 years, female sex, postmenopausal status, hypertension, atherosclerosis, type 2 diabetes, and obesity showed that rosuvastatin had consistent efficacy across patient subgroups.
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PMID:Efficacy of rosuvastatin compared with other statins at selected starting doses in hypercholesterolemic patients and in special population groups. 1264 36

Genetic variation in the microsomal triglyceride transfer protein (MTP) affects the secretion pattern and plasma concentration of apolipoprotein (aopB)-containing lipoproteins and a common functional -493 G/T polymorphism has been reported to influence plasma lipids levels. Recent data suggest that carriers of the T allele might be more sensitive to detrimental factors such as features of the insulin resistance syndrome. Since type 2 diabetes is associated with obesity and insulin resistance, the present study investigated the effect of this polymorphism on plasma lipids, apoB and LDL subfractions in 281 Chinese type 2 diabetic subjects and 364 non-diabetic controls. The frequency of the rare T allele was 0.162 and 0.126 in subjects with and without diabetes respectively. There were no differences in the effect of the polymorphism on plasma lipids and apoB in the two groups. However, the TT genotype was associated with a higher concentration of small dense LDL-III than the GT or GG variants in the diabetic subjects (P=0.01) whereas no such effect was observed in the controls. In the diabetic patients, age, plasma triglyceride and the MTP genotype were independent determinants of LDL-III concentrations in linear regression analysis (R(2)=10%, P=0.04) whereas in the controls, only plasma triglyceride and age were important determinants (R(2)=15%, P=0.01). In conclusion, the -493 G/T polymorphism only has a minor effect on LDL subfraction pattern in Chinese and the effect is only apparent in the presence of type 2 diabetes.
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PMID:Effect of the microsomal triglyceride transfer protein -493 G/T polymorphism and type 2 diabetes mellitus on LDL subfractions. 1281 11

Hypertriglyceridemia, low plasma concentrations of high density lipoproteins (HDL) and qualitative changes in low density lipoproteins (LDL) comprise the typical dyslipidemia of insulin resistant states and type 2 diabetes. Although isolated low plasma HDL-cholesterol (HDL-c) and apolipoprotein A-I (apo A-I, the major apolipoprotein component of HDL) can occur in the absence of hypertriglyceridemia or any other features of insulin resistance, the majority of cases in which HDL-c is low are closely linked with other clinical features of insulin resistance and hypertriglyceridemia. We and others have postulated that triglyceride enrichment of HDL particles secondary to enhanced CETP-mediated exchange of triglycerides and cholesteryl ester between HDL and triglyceride-rich lipoproteins, combined with the lipolytic action of hepatic lipase (HL), are driving forces in the reduction of plasma HDL-c and apoA-I plasma concentrations. The present review focuses on these metabolic alterations in insulin resistant states and their important contributions to the reduction of HDL-c and HDL-apoA-I plasma concentrations.
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PMID:Mechanisms of HDL lowering in insulin resistant, hypertriglyceridemic states: the combined effect of HDL triglyceride enrichment and elevated hepatic lipase activity. 1295 Nov 68

The regulation of hepatic VLDL secretion mainly depends on apolipoprotein (apo) B synthesis, on microsomal triglyceride transfer protein, insulin and the availability of triglycerides, free fatty acids (FFA) and cholesteryl ester. Four sources of fatty acids are used for lipoprotein synthesis: de-novo lipogenesis, cytoplasmic triglyceride stores, fatty acids derived from lipoproteins taken up directly by the liver and plasma FFA. Quantitatively, de-novo lipogenesis plays a minor role in regulating VLDL synthesis, but evidently it is elevated under conditions of high carbohydrate feeding. Cytoplasmic triglyceride stores appear to essentially contribute to VLDL triglycerides. Plasma FFA enter the hepatocytes and are either oxidized or esterified. The relationship between oxidation and esterification appears to be important in regulating the VLDL synthesis. An enhanced esterification is accompanied by increased VLDL secretion. The addition of oleic acid to hepatocytes has been shown to stimulate production of VLDL triglyceride and apoB. In human beings, an acute experimental elevation of plasma FFA stimulates VLDL production. In healthy men strong positive relations were found between the late increases in large triglyceride-rich lipoproteins and plasma FFA concentrations after 6 h following a mixed meal. In contrast, n-3 fatty acids impair VLDL assembly and secretion. Chronic hyperinsulinemia seems to stimulate VLDL production. On the other hand, the short-term addition of insulin has been shown to inhibit VLDL-triglyceride and apoB production in vitro. There is in vivo evidence that acute hyperinsulinemia suppresses VLDL-apoB and VLDL-triglyceride production in insulin-sensitive humans. Part of this action is due to suppression of plasma FFA. In patients with impaired glucose tolerance (IGT), VLDL production was increased when compared with subjects with normal glucose (NGT). When infusing a lipid emulsion, VLDL production could not be further stimulated in IGT patients in contrast to NGT persons. Hypertriglyceridemia in type 2 diabetes mellitus is usually the consequence of a VLDL overproduction. In type 2 diabetic patients, in contrast to normal men, insulin failed to suppress VLDL1 particle release. In normal men, an elevation of blood glucose led to a decrease in fatty acid oxidation and an increase in hepatic triglyceride secretion. Under these conditions, approximately 30% of total VLDL triglycerides coming out of the liver did not originate from plasma FFA. In conclusion, plasma FFA seem to play an important role in stimulating hepatic VLDL production. Other factors such as chronic hyperinsulinemia or nutrition modify this effect.
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PMID:Influence of plasma free fatty acids on lipoprotein synthesis and diabetic dyslipidemia. 1295 28

Although postprandial hypertriglyceridemia is a major contributing factor in the development of atherosclerosis, little information is available on the effect of insulin resistance and diabetes on intestinal fat transport. The aim of the present study was to examine intracellular events that govern lipid transport and apolipoprotein (apo) B-48-containing lipoprotein assembly in the small intestine of Psammomys obesus, a model of nutritionally induced insulin resistance and type 2 diabetes. Animals with normoglycemia/hyperinsulinemia and hyperglycemia/hyperinsulinemia exhibited high levels of triglycerides (TGs) in the plasma and intestine and postprandial plasma chylomicrons and apo B-48 compared with normoglycemic/normoinsulinemic animals. In vitro studies, using cultured jejunal explants incubated with either [14C]oleic acid or [35S]methionine, revealed their higher efficiency in de novo TG synthesis, apo B-48 biogenesis, and TG-rich lipoprotein assembly. Accordingly, enhanced monoacylglycerol and diacylglycerol acyltransferase activity was also discernible and concomitant with an increased content of L-fatty acid binding protein and in vivo chylomicron production rates. However, both the I-fatty acid binding protein amount and the apo B-48 proteasomal degradative pathway were decreased. Overall, our findings show that the development of an insulin-resistant/diabetic state in Psammomys obesus triggers the whole intra-enterocyte machinery, leading to lipoprotein assembly and favoring the intestinal oversecretion of apo B-48-lipoproteins, which may contribute to characteristic hypertriglyceridemia.
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PMID:Cellular aspects of intestinal lipoprotein assembly in Psammomys obesus: a model of insulin resistance and type 2 diabetes. 1451 38

Plasma inflammatory cytokines are elevated in obese subjects as well as in those with type 2 diabetes. This presumably results in systemic insulin resistance, characterized by a pro-atherogenic plasma lipid profile and reduced apolipoprotein AI (apoAI) protein levels. To determine how cytokine-mediated insulin resistance suppresses apoAI gene expression, we investigated the effect of tumor necrosis factor alpha (TNF alpha) and interleukin-1beta (IL-1beta) on apoAI protein, mRNA, and transcriptional activity in the human hepatoma cell line HepG2. ApoAI secretion was suppressed in a dose-dependent manner in HepG2 cells treated with both cytokines. ApoAI protein levels were 2892+/-22.0, 2263+/-117, 2458+/-25.0, 3401+/-152, 2333+/-248, 1520+/-41.5 and 956.0+/-11.0 arbitrary units (AU) in cells treated with 0, 0.3, 1.0, 3.0, 10, 30, and 100 ng/ml TNF alpha, achieving statistical significance in the 30 and 100 ng/ml range (P<0.0009). ApoAI protein levels were 4055+/-360, 3697+/-101, 3347+/-327, 1561+/-33.0, 1581+/-182, 810.0+/-59.5, and 1766+/-717 AU in cells treated with similar doses of IL-1beta, achieving statistical significance within the range of 3-100 ng/ml (P<0.02). ApoAI mRNA levels were suppressed 50.8% in HepG2 cells treated with 30 ng/ml TNF alpha for 24 h (P<0.05), and remained suppressed for up to 96 h. Similarly, treatment of cells with 30 ng/ml IL-1beta for 24 h, resulted in 42.9% reduction in apoAI mRNA levels (P<0.05) and remained suppressed for up to 96 h. In order to determine if the effect of TNF alpha and IL-1beta occurs at the transcriptional level, HepG2 cells were transfected with a chloramphenicol acetyltransferase (CAT) reporter gene plasmid containing the full-length apoAI promoter, and after 24 h, treated with TNF alpha (30 ng/ml), IL-1beta (30 ng/ml), or both cytokines. CAT activity was suppressed by both cytokines (24.0+/-1.9% acetylation in control cells vs. 5.6+/-1.2% (P<0.0004), 10.2+/-1.5% (P<0.0006), and 3.9+/-0.9% acetylation (P<0.0002) in cells treated with TNF alpha, IL-1beta, and the combination of both cytokines, respectively) suggesting that cytokine-mediated suppression occurs at the transcriptional level. Using a series of apoAI deletion constructs, the cytokine response element was mapped between nucleotides -325 and -186 (relative to the transcriptional start site). This region contains a previously identified and characterized cis-element, site A, which binds several different transcription factors. Finally, electrophoretic mobility shift assays (EMSA) showed that TNF alpha treatment of HepG2 cells is associated with reduced nuclear factor binding to site A. These studies suggest that inflammatory cytokines down-regulate apoAI expression at least partly through inhibition of binding of the nuclear factors to site A of the apoAI promoter.
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PMID:Suppression of apolipoprotein AI gene expression in HepG2 cells by TNF alpha and IL-1beta. 1457 9

The dyslipidemia and insulin resistance of type 2 diabetes can be improved by aerobic exercise. The effect of 6 months supervised exercise on very low-density lipoprotein (VLDL) apolipoprotein B metabolism was investigated in patients with type 2 diabetes. Moderately obese patients (n = 18) were randomized into supervised (n = 9) and unsupervised (n = 9) exercise groups. All patients were given a training session and a personal exercise program and asked to exercise four times per week at 70% maximal oxygen uptake for 6 months. Patients in the supervised group had a weekly session with an exercise trainer. VLDL apolipoprotein (apo)B metabolism was measured with an infusion of 1-(13)C leucine before and after 6 months of the exercise program. Supervised exercise for 6 months resulted in a significant within-group decrease in percent hemoglobin A1c (P < 0.001), body fat (P < 0.004), nonesterified fatty acid (P < 0.04), and triglycerides (P < 0.05) and an increase in insulin sensitivity (P < 0.01). There was a decrease in VLDL apoB pool size (160.8 +/- 42.6 to 84.9 +/- 23.2 mg, P < 0.01) and VLDL apoB secretion rate (11.3 +/- 2.6 to 5.5 +/- 2.0 mg/kg.d, P < 0.05) with no change in fractional catabolic rate. In a between-group comparison, the decrease in VLDL apoB secretion rate in the supervised group did not achieve significance. This study demonstrates that in type 2 diabetes, a supervised exercise program reduces VLDL apoB pool size, which may be due to a decrease in VLDL apoB secretion rate.
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PMID:The effect of a six-month exercise program on very low-density lipoprotein apolipoprotein B secretion in type 2 diabetes. 1476 82

Type 2 diabetic patients present high triglyceride and low HDL levels, significant determinants for the risk of atherosclerosis. Transgenic mice overproducing human apolipoprotein (apo)A-II, one of the two major apos of HDLs, display the same lipid disorders. Here, we investigated the possible regulation of apoA-II gene expression by glucose. In primary rat hepatocytes and in HepG2 cells, the transcription of the human apoA-II gene was upregulated by glucose. This response was mediated by a hormone-responsive element within the enhancer of the apoA-II promoter and was dependent on hepatocyte nuclear factor-4alpha. Accordingly, in transgenic mice, the human apoA-II gene is stimulated by a high-carbohydrate diet after fasting and at weaning. By contrast, the apoA-II mRNA level is not modified in streptozotocin-induced diabetic rats. In transgenic mice overexpressing the human apoA-II gene, plasma human apoA-II concentration was positively correlated with blood glucose levels. These mice displayed a marked delay in plasma glucose tolerance as compared with control mice. We hypothesize that the following pathogenic pathway might occur in the course of type 2 diabetes: increased apoA-II level causes a rise in plasma triglyceride level and glucose intolerance, resulting in hyperglycemia, which in turn might further increase apoA-II gene transcription.
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PMID:In vitro transcriptional induction of the human apolipoprotein A-II gene by glucose. 1498 51


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