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

Using an expression cloning strategy, we have identified TFE3, a basic helix-loop-helix protein, as a transactivator of metabolic genes that are regulated through an E-box in their promoters. Adenovirus-mediated expression of TFE3 in hepatocytes in culture and in vivo strongly activated expression of IRS-2 and Akt and enhanced phosphorylation of insulin-signaling kinases such as Akt, glycogen synthase kinase 3beta and p70S6 kinase. TFE3 also induced hexokinase II (HK2) and insulin-induced gene 1 (INSIG1). These changes led to metabolic consequences, such as activation of glycogen and protein synthesis, but not lipogenesis, in liver. Collectively, plasma glucose levels were markedly reduced both in normal mice and in different mouse models of diabetes, including streptozotocin-treated, db/db and KK mice. Promoter analyses showed that IRS2, HK2 and INSIG1 are direct targets of TFE3. Activation of insulin signals in both insulin depletion and resistance suggests that TFE3 could be a therapeutic target for diabetes.
 ...
PMID:TFE3 transcriptionally activates hepatic IRS-2, participates in insulin signaling and ameliorates diabetes. 1632 1

In type 2-diabetes and impaired glucose tolerance, the muscle, fat and liver become resistant to insulin, and recent developments place dysregulation of insulin receptor substrate (IRS) expression and activation at the center of such defects. IRS1 and IRS2 are the major insulin receptor substrates leading to glucose homeostasis, and have distinct and overlapping roles in diverse organs. The majority of the published literature in this field suggests that IRS1 is the major substrate leading to stimulation of glucose transport in muscle and adipose tissues, whereas in liver, IRS1 and IRS2 have complementary roles in insulin signaling and metabolism.
 ...
PMID:Tissue-specific roles of IRS proteins in insulin signaling and glucose transport. 1645 27

We hypothesize that the peroxisome proliferator-activated receptor-gamma (PPARgamma) is associated with colorectal cancer given its association with insulin, diabetes, obesity, and inflammation. In this study, we evaluated the association between colorectal cancer and specific tumor mutations and the Pro12Ala (P12A) PPARgamma polymorphism. We also evaluated interactions between the PPARgamma gene and other insulin-related genes and use of aspirin and non-steroidal anti-inflammatory drug use. Data were available from 1,577 cases of colon cancer that were matched to 1,971 population-based controls and 794 cases of rectal cancer that were matched to 1,001 population-based controls. Colon tumors from the case subjects were evaluated for p53 and Ki-ras mutations and microsatellite instability (MSI). Insulin-related genes evaluated were the Bsm1, polyA, and Fok1 polymorphisms of the VDR gene; the G972R IRS1 polymorphism; the G1057D IRS2 polymorphism; the 19CA repeat polymorphism of the IGF1 gene; and the -200A>C IGFBP3 polymorphism. The odds ratio (OR) between the PA/AA genotypes and proximal tumors was 0.83 (95% CI: 0.69-1.01); for distal tumors was 1.00 (95% CI: 0.83-1.21); and for rectal tumors was 1.04 (95% CI: 0.86-1.25). Evaluation of specific types of tumor mutations showed that colon cancer cases with the PA or AA genotypes were less likely to have p53 tumor mutations (OR 0.78; 95% CI: 0.62-0.99), specifically transition mutations (OR 0.74; 95% CI: 0.56-0.97). Colon cancer cases also were less likely to have a tumor with MSI if they had the PA or AA PPARgamma genotype (OR 0.68; 95% CI: 0.47-0.98); differences in Ki-ras mutations were not seen in colon tumors by PPARgamma genotype. Those who did not take ibuprofen-type drugs and had the PA or AA genotypes were at a significantly greater risk of rectal cancer (OR 2.11; 95% CI: 1.52-2.92; p interaction 0.03) than people with the PP genotype regardless of ibuprofen-type drug use. There was a significant interaction between the -200A>C IGFBP3 polymorphism and the Pro12Ala PPARgamma polymorphism and risk of colon cancer (p for interaction = 0.02) with individuals being at significantly lower risk if they had both the CC IGFBP3 genotype and the PA/AA PPARgamma genotype. For rectal cancer there was a significant interaction between the Bsm1/polyA polymorphisms (p = 0.001) of the VDR gene and the PA/AA Pro12Ala PPARgamma polymorphism with the highest risk group being those with both the PA/AA Pro12Ala PPARgamma and the BB/SS VDR genotypes. These data suggest that PPARgamma may be associated with many aspects of colorectal cancer including insulin- and inflammation-related mechanisms.
 ...
PMID:PPARgamma and colon and rectal cancer: associations with specific tumor mutations, aspirin, ibuprofen and insulin-related genes (United States). 1648 31

Inhibition of endosomal acidification disturbs insulin signaling in both liver and adipose cells. In this study we used MIN6 beta cells to determine whether bafilomycin, a potent inhibitor of the proton-translocating vacuolar ATPase, disrupts insulin signaling in islet beta cells. Pretreatment of MIN6 cells with varying concentrations of bafilomycin according to a time course revealed concentration and time-dependent changes in phosphorylation of insulin receptor signaling components. Increased phosphorylation of insulin receptor (IR), IRS2 and Akt was prolonged at low bafilomycin concentrations (10 and 50 nmol/L), whereas at high concentrations (100 and 200 nmol/L) phosphorylation rapidly returned to basal levels or below. Akt activation was demonstrated by transient increases in phosphorylation of BAD, cytoplasmic retention of FoxO1 and increased preproinsulin mRNA. Bcl2 expression was also transiently increased but reduced after 30 min exposure to bafilomycin, and this coincided with reduced cell viability. Thus, in beta cells inhibition of endosomal acidification by low concentrations of bafilomycin transiently increases insulin signaling, whereas high concentrations promote cell death. Bafilomycin and other agents that interfere with insulin signaling may contribute to diabetes development through disturbing homeostatic control of beta cell growth.
 ...
PMID:The plecomacrolide vacuolar-ATPase inhibitor bafilomycin, alters insulin signaling in MIN6 beta-cells. 1655

Obesity is associated with increased morbidity and mortality from cardiovascular disease, diabetes and cancer. Although obesity is a multi-factorial heterogeneous condition, fat accumulation in visceral depots is most highly associated with these risks. Pathological glucocorticoid excess (i.e. in Cushing's syndrome) is a recognised, reversible cause of visceral fat accumulation. The aim of this study was to identify depot-specific glucocorticoid-target genes in adipocyte precursor cells (preadipocytes) using Affymetrix microarray technique. Confluent preadipocytes from subcutaneous (SC) and omental (OM) adipose tissue collected from five female patients were treated for 24 h with 100 nM cortisol (F), RNA was pooled and hybridised to the Affymetrix U133 microarray set. We identified 72 upregulated and 30 downregulated genes by F in SC cells. In OM preadipocytes, 56 genes were increased and 19 were decreased. Among the most interesting were transcription factors, markers of adipocyte differentiation and glucose metabolism, cell adhesion and growth arrest protein factors involved in G-coupled and Wnt signalling. The Affymetrix data have been confirmed by quantitative real-time PCR for ten specific genes, including HSD11B1, GR, C/EBPalpha, C/EBPbeta, IL-6, FABP4, APOD, IRS2, AGTR1 and GHR. One of the most upregulated genes in OM but not in SC cells was HSD11B1. The GR was similarly expressed and not regulated by glucocorticoids in SC and OM human preadipocytes. C/EBPalpha was expressed in SC preadipocytes and upregulated by F, but was below the detection level in OM cells. C/EBPbeta was highly expressed both in SC and in OM preadipocytes, but was not regulated by F. Our results provide insight into the genes involved in the regulation of adipocyte differentiation by cortisol, highlighting the depot specifically in human adipose tissue.
 ...
PMID:Expression profiling of 11beta-hydroxysteroid dehydrogenase type-1 and glucocorticoid-target genes in subcutaneous and omental human preadipocytes. 1703 48

beta-Cell mass is determined by a dynamic balance of proliferation, neogenesis, and apoptosis. The precise mechanisms underlying compensatory beta-cell mass (BCM) homeostasis are not fully understood. To evaluate the processes that maintain normoglycemia and regulate BCM during pancreatic regeneration, C57BL/6 mice were analyzed for 15 days following 60% partial pancreatectomy (Px). BCM increased in Px mice from 2 days onwards and was approximately 68% of the shams by 15 days, partly due to enhanced beta-cell proliferation. A transient approximately 2.8-fold increase in the prevalence of beta-cell clusters/small islets at 2 days post-Px contributed substantially to BCM augmentation, followed by an increase in the number of larger islets at 15 days. To evaluate the signaling mechanisms that may regulate this compensatory growth, we examined key intermediates of the insulin signaling pathway. We found insulin receptor substrate (IRS)2 and enhanced-activated Akt immunoreactivity in islets and ducts that correlated with increased pancreatic duodenal homeobox (PDX)1 expression. In contrast, forkhead box O1 expression was decreased in islets but increased in ducts, suggesting distinct PDX1 regulatory mechanisms in these tissues. Px animals acutely administered insulin exhibited further enhancement in insulin signaling activity. These data suggest that the IRS2-Akt pathway mediates compensatory beta-cell growth by activating beta-cell proliferation with an increase in the number of beta-cell clusters/small islets.
Diabetes 2006 Dec
PMID:Regulation of pancreatic beta-cell regeneration in the normoglycemic 60% partial-pancreatectomy mouse. 1713 Apr 72

Inappropriate adaptation of beta-cell mass is a primary cause of the development of diabetic hyperglycemia. However, the mechanisms underlying regulation of the beta-cell mass in response to insulin resistance or in the development of type 2 diabetes remain unclear. We determined the insulin signaling in the beta-cells and the adaptation of the beta-cell mass in response to the progression of insulin resistance in OLETF rats. By 25 weeks of age, at the onset of diabetes, compared to control LETO rats, OLETF rats developed obesity (Body weight: LETO vs OLETF = 474.0+/-9.5 vs 581.3+/-21.8 g, P < 0.001, n=6), hyperlipidemia (Cholesterol: LETO vs OLETF = 1.67+/-0.07 vs 2.19+/-0.20 mM, P < 0.05, n=6; triglyceride: LETO vs OLETF = 0.36+/-0.05 vs 1.36+/-0.12 mM, P < 0.001, n=6), and impaired glucose tolerance (AUC: LETO vs OLETF = 10.3+/-3.4 vs 29.6+/-7.8 mM, P < 0.001, n=6). Insulin sensitivities as assessed by the insulin sensitivity index (ISI) and the homeostasis model assessment (HOMA) indicated that OLETF rats developed severe insulin resistance. The measurement of plasma insulin levels by ELISA demonstrated, at the onset of diabetes, that fasting insulin levels were increased by 1.2-fold, and 2 hr postprandial insulin levels were increased by 3-fold (P < 0.05, n=6) in OLETF rats compared to age-matched LETO mates which is suggestive of hyperinsulinemia. Immunostaining detected a significant reduction in the insulin receptor substrate 1 (IRS1) (by 54%, P < 0.001) and IRS2 (by 55%, P < 0.001) in the beta-cells of the OLETF rats. Interestingly, while the beta-cell mass was found to be increased (by 2.2-fold; P < 0.001), the beta-cell insulin content as determined by immunostaining was significantly reduced by 32% (P < 0.001) in the OLETF rats when compared to the controls. Our findings suggest that despite increasing beta-cell mass the impaired beta-cell insulin signaling and reduced beta-cell insulin content may contribute to the onset of overt diabetes in OLETF rats.
 ...
PMID:Increased beta-cell apoptosis and impaired insulin signaling pathway contributes to the onset of diabetes in OLETF rats. 1845 52

To determine the role of cholesterol synthesis in pancreatic beta-cells, a transgenic model of in vivo activation of sterol-regulatory element binding protein 2 (SREBP-2) specifically in beta-cells (TgRIP-SREBP-2) was developed and analyzed. Expression of nuclear human SREBP-2 in beta-cells resulted in severe diabetes as evidenced by greater than 5-fold elevations in glycohemoglobin compared with C57BL/6 controls. Diabetes in TgRIP-SREBP-2 mice was primarily due to defects in glucose- and potassium-stimulated insulin secretion as determined by glucose tolerance test. Isolated islets of TgSREBP-2 mice were fewer in number, smaller, deformed, and had decreased insulin content. SREBP-2-expressing islets also contained increased esterified cholesterol and unchanged triglycerides with reduced ATP levels. Consistently, these islets exhibited elevated expression of HMG-CoA synthase and reductase and LDL receptor, with suppression of endogenous SREBPs. Genes involved in beta-cell differentiation, such as PDX1 and BETA2, were suppressed, explaining loss of beta-cell mass, whereas IRS2 expression was not affected. These phenotypes were dependent on the transgene expression. Taken together, these results indicate that activation of SREBP-2 in beta-cells caused severe diabetes by loss of beta-cell mass with accumulation of cholesterol, providing a new lipotoxic model and a potential link of disturbed cholesterol metabolism to impairment of beta-cell function.
 ...
PMID:Cholesterol accumulation and diabetes in pancreatic beta-cell-specific SREBP-2 transgenic mice: a new model for lipotoxicity. 1868 8

Early changes in neuroendocrine pathways are essential in the development of metabolic pathologies. Thus, it is important to have a better understanding of the signals involved in their initiation. Long-term consumption of high-fat diets induces insulin resistance, obesity, diabetes. Here, we have investigated early neural and endocrine events in the hypothalamus and hippocampus induced by a short-term high fat, low carbohydrate diet in adult male Wistar rats. The release of serotonin, which is closely associated with the actions of insulin and leptin, was measured, by electrochemical detection following reverse-phase liquid chromatography (HPLC), in the extracellular space of the medial hypothalamus and the dorsal hippocampus in samples obtained from non-anesthetized animals, by microdialysis. The high-fat diet had a specific effect on the hypothalamus. Serotonin release induced by food intake was reduced after 1 week, and effectively ceased after 6 weeks of the diet. After 1 week, there was an increased gene expression of the insulin receptor and the insulin receptor substrates IRS1 and IRS2, as measured by real-time PCR. After 6 weeks of diet, insulin gene expression increased. Leptinemia increased in all cases. This new data support the concept that high-fat diets, in addition to have peripheral effects, cause a rapid alteration in specific central mechanisms involved in energy and glucose homeostasis. The changes in the gene expression of insulin and signaling elements represent possible adaptations aimed at counterbalancing the reduced responsiveness of the serotonergic system to nutritional signals and maintaining homeostasis.
 ...
PMID:A dietary fat excess alters metabolic and neuroendocrine responses before the onset of metabolic diseases. 1877 89

Heme oxygenase 1 (HO-1) is a representative mediator of antioxidants and cytoprotectants against various stress stimuli including oxidants in vascular cells. Intensive insulin treatment can delay the onset and progression of diabetic retinopathy and other vascularopathies, yet little is known about insulin regulation of anti-apoptotic and antioxidant molecules such as HO-1 in vascular cells. Intravitreous injection or in vitro addition of insulin increased HO-1 protein expression in rat retina and in cultured bovine retinal pericytes, retinal endothelial cells, and retinal pigment epithelial cells. In bovine retinal pericytes, insulin induced mRNA and protein expression of HO-1 in a time- and concentration-dependent manner. Using HO-1 promoter analysis, the luciferase reporter assay showed that induction of HO-1 expression by insulin is mediated by additional response elements in the ho-1 promoter gene, which was not responsive to antioxidants. Insulin-induced HO-1 mRNA expression through activation of PI3-kinase/Akt pathway without affecting ERK and p38 MAPK. Overexpression of an adenoviral vector of native IRS1, IRS2, and Akt dominant negative or small interfering RNA transfection of Akt1 and Akt2 targeted gene demonstrated that insulin regulated HO-1 expression via IRS1 and Akt2 pathway, selectively. Further, insulin treatment prevented H(2)O(2)-induced NF-kappaB and caspase-8 activation and apoptosis via the IRS1/PI3K/Akt2/HO-1 pathway in the pericytes. In conclusion, we suggest that the anti-apoptotic properties of insulin are mediated partly by increasing HO-1 expression at transcriptional level via IRS1/PI3K/Akt2 activation, a potential explanation for how insulin is retarding the progression of microvascular complications induced by diabetes.
 ...
PMID:Selective regulation of heme oxygenase-1 expression and function by insulin through IRS1/phosphoinositide 3-kinase/Akt-2 pathway. 1885 16


<< Previous 1 2 3 4 5 6 7 8 9 Next >>