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Gene expression profile of tungstate-induced beta cell mass increase in STZ rats

ABSTRACT: Background and Aims: It is well demonstrated that in the beta cell population of the pancreas there is a dynamic turnover, which results from the net balance of several processes; beta cell replication, apoptosis and neogenesis. These processes have been studied in partial pancreatectomy and glucagon-like peptide 1 treated animals, where an increase in pancreas regeneration has been observed. Similarly, sodium tungstate, which decreases hyperglycemia in several animal models of diabetes, promotes a rise in the beta cell mass of nSTZ and STZ animals. However, the molecular mechanisms underlying this pancreas regeneration remain unknown. Therefore the objective of this study is to identify which genes are up or down regulated in the increase of the beta cell population of STZ rats treated with sodium tungstate. Materials and methods: Adult male Wistar (225-250 g) rats were kept under a constant 12-hour light-dark cycle and rats were kept under a constant 12-hour light-dark cycle and were allowed to eat and drink freely. Diabetes was induced by a single i.p. injection of streptozotocin (STZ) (70 mg/Kg body weight) in 0.9% NaCl with 100 mmol/L sodium citrate buffer (pH 4.5). Diabetes was confirmed by determination of its hyperglycaemia (>500mg/dL [Reflotron, Roche Diagnostic]). Healthy rats received an i.p. injection of the vehicle. Treatment started 7 days after the STZ or vehicle injection. Diabetic and healthy rats were divided into two groups. In the first (untreated), rats received deionized drinking water; in the second (treated) group, they were given a solution of sodium tungstate. During the first week of treatment, the rats received a solution of 0.7 mg/mL and in the next 4-5 weeks, the concentration was increased to 2 mg/mL. At the end of the experiment, the animals were sacrificed and pancreatic RNA isolated. Three chips (Affymetrix RAE-230A) were hybridized for each of the four experimental groups (untreated and treated healthy rats and untreated and treated diabetic rats). The raw intensity data obtained from the microarrays was normalized and summarized using the Bioconductor package RMA. Keywords = pancreas regeneration Keywords = STZ Keywords = diabetes Keywords = tungstate Keywords = insulin-like agents Keywords = beta cell plasticity Keywords = neogenesis Keywords: ordered

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE2470 | GEO | 2006/04/01

SECONDARY ACCESSION(S): PRJNA91183

REPOSITORIES: GEO

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Project description:Background and Aims: It is well demonstrated that in the beta cell population of the pancreas there is a dynamic turnover, which results from the net balance of several processes; beta cell replication, apoptosis and neogenesis. These processes have been studied in partial pancreatectomy and glucagon-like peptide 1 treated animals, where an increase in pancreas regeneration has been observed. Similarly, sodium tungstate, which decreases hyperglycemia in several animal models of diabetes, promotes a rise in the beta cell mass of nSTZ and STZ animals. However, the molecular mechanisms underlying this pancreas regeneration remain unknown. Therefore the objective of this study is to identify which genes are up or down regulated in the increase of the beta cell population of STZ rats treated with sodium tungstate. Materials and methods: Adult male Wistar (225-250 g) rats were kept under a constant 12-hour light-dark cycle and rats were kept under a constant 12-hour light-dark cycle and were allowed to eat and drink freely. Diabetes was induced by a single i.p. injection of streptozotocin (STZ) (70 mg/Kg body weight) in 0.9% NaCl with 100 mmol/L sodium citrate buffer (pH 4.5). Diabetes was confirmed by determination of its hyperglycaemia (>500mg/dL [Reflotron, Roche Diagnostic]). Healthy rats received an i.p. injection of the vehicle. Treatment started 7 days after the STZ or vehicle injection. Diabetic and healthy rats were divided into two groups. In the first (untreated), rats received deionized drinking water; in the second (treated) group, they were given a solution of sodium tungstate. During the first week of treatment, the rats received a solution of 0.7 mg/mL and in the next 4-5 weeks, the concentration was increased to 2 mg/mL. At the end of the experiment, the animals were sacrificed and pancreatic RNA isolated. Three chips (Affymetrix RAE-230A) were hybridized for each of the four experimental groups (untreated and treated healthy rats and untreated and treated diabetic rats). The raw intensity data obtained from the microarrays was normalized and summarized using the Bioconductor package RMA.

Project description:Patients with long-duration diabetes develop cardiovascular complications resulting in highly increased mortality and complications which affect the kidneys, eyes and peripheral nerves associated with high morbidity. Among the diabetic complications, damage in the eye, diabetic retinopathy, is the most common microvascular complication of diabetes. Diabetic retinopathy is a leading cause of vision-loss globally. It is characterized by a number of different patho-mechanisms including changes in vascular permeability, capillary degeneration, and finally at a late stage overshooting formation of new blood vessels. This expression analysis focused on the use of different experimental models for Diabetes Mellitus and its complications (for a review see 1: Al-Awar et al: Experimental Diabetes Mellitus in Different Animal Models. J Diabetes Res. 2016; doi: 10.1155/2016/9051426). By that, we wanted to uncover the relative contributions of systemic hyperinsulinaemia and/or hyperglycemia to molecular regulations. The following models have been used: As insulinopenic, hyperglycemic model reflecting Type 1 diabetes, male STZ-Wistar rats (60mg/kg BW; i.p.) were used. Wistar rats without STZ injection served as non-diabetic controls. Male obese ZDF rats (Fa/Fa) were used as type-2 diabetes model characterized by persisting hyperglycemia and transient hyperinsulinemia. Male lean ZDF rats (Fa/-) served as non-diabetic controls. Male obese ZF rats (Fa/Fa) hyperglycemia were used reflecting euglycemia and severe insulin resistance. Male lean ZF rats (Fa/-) served as controls. ZDF and ZF rats were obtained in two genotypes, obese (genotype fa/fa) and lean littermates (genotype Fa/?). All rats were housed in standard cages under a normal light-dark cycle for 16 weeks. All animals had free access to food and water. ZF and Wistar rats received a standard chow (Ssniff R/M) and ZDF rats received Purina 5008 chow. A group size of n=8 were used for all study groups. Wistar rats were rendered type-1 like hyperglycemic and hypoinsulinemic via a single injection of streptocotocin (STZ, 60mg/kg; i.p.) at 7 weeks of age. Obese ZDF rats (fa/fa) develop spontaneously a type-2 diabetes phenotype with persisting hyperglycemia and transient hyperinsulinemia (hyperglycemic, hypoinsulinemic). Obese ZF rats (fa/fa) develop insulin resistance with permanent hyperinsulinemia without concomitant hyperglycemia and no overt diabetes phenotype. Non STZ treated Wistar rats, lean ZDF littermates (Fa/?), and lean ZF littermates (Fa/?) served as controls. All groups were kept for 12 weeks on respective conditions together with appropriate age-matched controls. Unbiased gene expression analysis was performed per group using Affymetrix gene arrays.

Project description:Objectives The streptozotocin (STZ) model is widely used in diabetes research. However, the cellular and molecular states of pancreatic endocrine cells in this model remain unclear. This study explored the molecular characteristics of islet cells treated with STZ and re-evaluated β-cell dysfunction and regeneration in the STZ model. Methods We performed single-cell RNA sequencing of pancreatic endocrine cells from STZ-treated mice. High-quality sequencing data from 2,999 cells were used to identify clusters via Louvain clustering analysis. Principal component analysis (PCA), t-distributed stochastic neighbor embedding (t-SNE), uniform manifold approximation and projection (UMAP), force-directed layout (FDL), and differential expression analysis were used to define the heterogeneity and transcriptomic changes in islet cells. In addition, qPCR and immunofluorescence staining were used to confirm findings from the sequencing data. Results Untreated β-cells were divided into two populations at the transcriptomic level, a large high-Glut2 expression (Glut2high) population and a small low-Glut2 expression (Glut2low) population. At the transcriptomic level, Glut2low β-cells in adult mice did not represent a developmentally immature state, although a fraction of genes associated with β-cell maturation and function were downregulated in Glut2low cells. After a single high-dose STZ treatment, most Glut2high cells were killed, but Glut2low cells survived and over time changed to a distinct cell state. We did not observe conversion of Glut2low to Glut2high β-cells up to 9 months after STZ treatment. In addition, we did not detect transcriptomic changes in the non-β endocrine cells or a direct trans-differentiation pathway from the α-cell lineage to the β-cell lineage in the STZ model. Conclusions We identified the heterogeneity of β-cells in both physiological and pathological conditions. However, we did not observe conversion of Glut2low to Glut2high β-cells, transcriptomic changes in the non-β endocrine cells, or direct trans-differentiation from the α-cell lineage to the β-cell lineage in the STZ model. Our results clearly define the states of islet cells treated with STZ and allow us to re-evaluate the STZ model widely used in diabetes studies.

Project description:Relative beta cell deficit and increased beta cell apoptosis are hallmarks of type 2 diabetes (T2D). The Insulin/Insulin Growth Factor (Igf) signaling pathway is an established regulator of beta cell survival and is found downregulated in human T2D islets. The Insulin Receptor Substrate 2 (Irs2) plays a central role in the coordination of this pathway in beta cells. Thus, Irs2 knockout mice (Irs2 -/-) exhibit increased beta cell apoptosis that leads to a progressive decline of beta cell mass and hyperglycaemia. In this study, we sought to determine whether the anti-diabetic compound sodium tungstate could prevent the onset of diabetes in Irs2 -/- mice. Oral administration of tungstate resulted in an overall improvement in whole-body glucose tolerance in Irs2 -/- mice which correlated with increased beta cell mass. Enhanced beta cell mass was due to a dramatic reduction of beta cell apoptosis without changes in proliferation. Whole genome gene profiling analysis of islets isolated from treated Irs2 -/- mice confirmed a broad impact of tungstate on cell death pathways. Mechanistically, tungstate induced Erk1/2 phosphorylation in islets in vitro and, in agreement, treated Irs2 -/- islets exhibited increased basal Erk1/2 phosphorylation. Tungstate also downregulated expression of apoptosis-related genes in Irs2-/- islets in vitro, uncovering a direct effect of this compound in islets. All together, our data demonstrate that tungstate can restore beta cell mass and glucose homeostasis in a context of deficient Insulin/Igf signaling. This study underscores the importance of developing strategies specifically designed to arrest beta cell apoptosis as a means to prevent progressive beta cell failure in diabetes. 10-week old WT and Irs2 -/- mice were randomly divided into two treatment group, in a total of 4 experimental groups. For 21 days one group received distilled water as drinking water (untreated group) whilst the other received ad libitum a solution of 2mg/ml of sodium tungstate in distilled water (treated group). For each experimental group 2 independent samples were analysed, in a total of 8 samples.

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Gene expression profile of tungstate-induced beta cell mass increase in STZ rats

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