Glycan changes caused by insulin-deficient diabetes in the mouse liver
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ABSTRACT: To determine the effect of insulin deficiency on global changes to expression of glycan related genes in the liver. See: Joseph R. Bishop,‡ Erin Foley,‡§ Roger Lawrence,‡ and Jeffrey D. Esko‡1 (2010) Insulin-dependent Diabetes Mellitus in Mice Does Not Alter Liver Heparan Sulfate* J Biol Chem. 2010 May 7; 285(19): 14658–14662. We are studying the glycan changes caused by insulin-deficient diabetes in the mouse liver. We would like to determine whether insulin-deficiency causes global changes to expression of glycan-related genes in the liver. Male C57BL/6 mice (4 weeks of age) were purchased from Jackson Laboratory and maintained in a temperature-controlled (25 °C) facility with a 12-h light/dark cycle. The derivation and genotyping of Ndst1f/fAlbCre+ mice have been described previously (16). Mice were fed laboratory rodent chow (Harlan-Teklad) ad libitum except when fasting blood specimens were obtained. Mice were made diabetic by administering 50 mg/kg body weight of streptozotocin (STZ; Sigma) intraperitoneally for 5 consecutive days. Because of variations in plasma triglycerides in females, only male mice were used in this study. Our preliminary results suggest glycosaminoglycan enzymes may be down-regulated, which may affect the turnover of lipids in the plasma. Liver RNA samples from 3 diabetic mice will be compared to 3 wildtype samples for properly controlled analysis.
Project description:To determine the effect of insulin deficiency on global changes to expression of glycan related genes in the liver. See: Joseph R. Bishop,‡ Erin Foley,‡§ Roger Lawrence,‡ and Jeffrey D. Esko‡1 (2010) Insulin-dependent Diabetes Mellitus in Mice Does Not Alter Liver Heparan Sulfate* J Biol Chem. 2010 May 7; 285(19): 14658–14662. We are studying the glycan changes caused by insulin-deficient diabetes in the mouse liver. We would like to determine whether insulin-deficiency causes global changes to expression of glycan-related genes in the liver. Male C57BL/6 mice (4 weeks of age) were purchased from Jackson Laboratory and maintained in a temperature-controlled (25 °C) facility with a 12-h light/dark cycle. The derivation and genotyping of Ndst1f/fAlbCre+ mice have been described previously (16). Mice were fed laboratory rodent chow (Harlan-Teklad) ad libitum except when fasting blood specimens were obtained. Mice were made diabetic by administering 50 mg/kg body weight of streptozotocin (STZ; Sigma) intraperitoneally for 5 consecutive days. Because of variations in plasma triglycerides in females, only male mice were used in this study.
Project description:Type 2 diabetes is a complex disease associated with many underlying pathomechanisms. Epigenetic regulation of gene expression by DNA methylation has become increasingly recognized as an important component in the etiology of type 2 diabetes. We performed genome-wide methylome and transcriptome analysis in liver from severely obese patients with or without type 2 diabetes to discover aberrant pathways underlying the development of insulin resistance. We identified hypomethylation of five key genes involved in hepatic glycolysis, de novo lipogenesis and insulin resistance with concomitant increased mRNA expression and protein content. The CpG-site within the ATF-motif was hypomethylated in four of these genes in liver of non-diabetic and type 2 diabetic obese patients, suggesting epigenetic regulation of transcription by altered ATF-DNA binding. In conclusion, severely obese non-diabetic and type 2 diabetic patients have distinct alterations in the hepatic methylome and transcriptome and genes controlling glucose and lipid metabolism are hypomethylated at a regulatory site. Thus, obesity may epigenetically reprogram the liver towards increased lipid production and exacerbate the development of insulin resistance. To better understand the molecular mechanisms underlying the development of hepatic insulin resistance and type 2 diabetes at a molecular level, we performed a genome-wide methylome and transcriptome analysis of liver from non-obese metabolically healthy, obese non-diabetic and obese type 2 diabetic patients. Distinct DNA methylation and gene expression profiles were identified in liver from the obese and type 2 diabetic patients compared with the non-obese participants.
Project description:Investigation of gene expression level changes in pancreatic and liver tissues of diabetic db/db mice supplemented with selenate, compared to the diabetic db/db mice administered placebo. Fasting blood glucose levels increased continuously in diabetic db/db mice administered placebo (DMCtrl) but decreased gradually in selenate-supplemented diabetic db/db mice (DMSe) and approached normal values when the experiment ended. The size of pancreatic islets increased, causing the plasma insulin concentration to double in DMSe mice compared with that in DMCtrl mice. Two six chip studies using total RNA respectively isolated from pancreatic and liver tissues of three selenate-supplemented diabetic db/db mice, and three diabetic db/db mice administered placebo.
Project description:In an effort to reduce hepatic glucose production and lower plasma glucose levels that are characteristics of diabetes, we have devised a treatment whereby we enhance glycolysis in the liver of a type 2 diabetic mouse model (KK/H1J). We achieve this by raising the levels of a potent regulator of glucose metabolism, fructose-2,6-bisphosphate (F26BP). Treating the mice in this way, we have demonstrated amelioration of the diabetic phenotype in terms of lowering plasma glucose and insulin levels. These treated mice also display reduced weight gain, reduced adiposity, and normalized plasma and hepatic lipid levels. These latter metabolic changes brought about by raising F26BP levels are counterintuitive. A concurrent increase in glycolysis and lipogenesis is expected, however, we observe an increase in glycolysis with a concurrent decrease in lipogenesis. Preliminary analysis of gene expression in these mice has revealed alterations in gene expression of several genes that support the therapeutic effect of raising F26BP levels. To further profile F26BP effects on hepatic gene expression, we have applied a comprehensive approach to identify sets of genes and thereby biological pathways that are differentially regulated when hepatic glycolysis is accelerated in diabetic mice. Comparing diabetic and treated animals, we hope to further clarify the molecular and genetic signature of type 2 diabetes and obesity and elucidate how this signature is affected by raising F26BP levels. Our study examining gene array as well as the hepatic proteome has identified multiple gene and protein expression changes. Of particular relevance, we note that fatty acid metabolism and cholesterol metabolism pathways are significantly down-regulated in diabetic mice treated with a PFK-2 mutant engineered to raise F26BP levels, which underlie the changes we see in the metabolic parameters. 6 KK/H1J mice, a polygenic model of type 2 diabetes and obesity, weighing approximately 35g were used in this study. 3 mice were injected with GFP control adenovirus and 3 mice were injected with bisphosphatase deficient PFK-2 adenovirus (BPD). Mice were followed for 7 days before livers were extracted. Total cellular RNA was extracted from each mouse and analyzed by microarray separately.
Project description:Current treatments for type 1 diabetes (T1D) focus on optimizing insulin replacement. We demonstrate the therapeutic potential of the large secreted protein fraction from brown adipose tissue (BAT), independent of insulin. This secreted fraction mediates insulin receptor-dependent recovery of euglycemia in diabetic nonobese diabetic (NOD) mice by suppressing glucagon secretion. It also promotes white adipocyte differentiation and browning, and enhances glucose uptake in adipose tissue, skeletal muscle, and liver. From this fraction, we identify nidogen-2 as a brown adipocyte-secreted factor that reverses hyperglycemia in T1D NOD, inhibits glucagon secretion from pancreatic α-cells, and mimics other actions of the secreted fraction. These findings provide proof of principle that the pleiotropic effects of BAT-derived peptides represent a novel approach to diabetes management.
Project description:Assembly of HSPGs in the liver is defective in diabetes mellitus. A major consequence is impaired clearance of post-prandial lipoproteins, which ordinarily depends on the binding of these particles to hepatic HSPGs. Impaired clearance leads to prolonged exposure of the arterial wall to these harmful lipoproteins. We pin-pointed suppression of NDST-1 in livers of type 1 diabetic rats as at least a partial explanation for defective HSPG assembly. Dr. Williams' lab examined glycan-related gene expression in the livers of three groups of mice: wild-type, ad-lib-fed type 2 diabetic mice (db/db), and calorically restricted db/db mice (caloric restriction was shown several years ago to correct their clearance of atherogenic post-prandial lipoproteins). The results will indicate the molecular basis for defective HSPG assembly in type 2 diabetes, which is a question of considerable medical importance. RNA preparations from mice livers (wild-type, ad-lib-fed type 2 diabetic mice, and calorically restricted mice) were sent to Microarray Core (E). The RNA was amplified, labeled, and hybridized to GLYCO_v3 microarrays.
Project description:Investigation of gene expression level changes in pancreatic and liver tissues of diabetic db/db mice supplemented with selenate, compared to the diabetic db/db mice administered placebo. Fasting blood glucose levels increased continuously in diabetic db/db mice administered placebo (DMCtrl) but decreased gradually in selenate-supplemented diabetic db/db mice (DMSe) and approached normal values when the experiment ended. The size of pancreatic islets increased, causing the plasma insulin concentration to double in DMSe mice compared with that in DMCtrl mice.
Project description:Metabolic abnormalities underlying diabetes are primarily the result of the lack of adequate insulin action and the associated changes in protein phosphorylation and gene expression. Affymetrix oligonucleotide microarrays were used to study the changes in the transcriptional program of mouse skeletal muscle in insulin-deficient diabetes. Mice which were made diabetic by streptozotocin treatment were compared to controls. Also, the reversibility of these changes was ascertained by treating a subset of the diabetic mice with insulin.
Project description:Quercetin is a food component that may ameliorate the diabetic symptoms. We examined hepatic gene expression of BALB/c mice with streptozotocin (STZ)-induced diabetes to elucidate the mechanism of the protective effect of dietary quercetin on diabetes-associated liver injury. We fed STZ-induced diabetic mice with diets containing 0.1% or 0.5% quercetin for 2 weeks and compared the patterns of hepatic gene expression in these groups of mice using a DNA microarray. Diets containing 0.1% or 0.5% quercetin lowered the STZ-induced increase in blood glucose levels and improved plasma insulin levels. A cluster analysis of the hepatic gene expressions showed that 0.5% quercetin diet suppressed STZ-induced alteration of gene expression. Gene set enrichment analysis (GSEA) and quantitative RT-PCR analysis showed that the quercetin diets had their greatest suppressive effect on the STZ-induced elevation of expression of cyclin dependent kinase inhibitor p21(WAF1/Cip1) (Cdkn1a).
Project description:Appropriate tuning of protein homeostasis through mobilization of the unfolded protein response (UPR) is key to the capacity of pancreatic beta cells to cope with highly variable demand for insulin synthesis. An efficient UPR ensures a sufficient beta cell mass and secretory output but can also affect beta cell resilience to autoimmune aggression. However, the factors regulating protein homeostasis in the face of metabolic and immune challenges are insufficie tly understood. We examined beta cell adaptation to stress in mice deficient for insulin-degrading enzyme (IDE), a ubiquitous protease with high affinity for insulin, a putative ill-defined role in protein homeostasis, and genetic association with type 2 diabetes. IDE deficiency induces a low-level UPR in both standard and autoimmune non-obese diabetic (NOD) mice, associated with rapamycin-sensitive beta cell proliferation, as well as protection from diabetes in NOD mice. Moreover, in NOD islets, IDE deficiency specifically induces strong upregulation of regenerating islet-derived protein 2, a protein attenuating inflammation and protecting from autoimmunity. Our findings establish a role of IDE in islet cell protein homeostasis, corroborate the link between low-level UPR and proliferation, and identify an anti-inflammatory islet cell response uncovered in the absence of IDE of potential interest in autoimmune diabetes.