Early Peroxisome proliferator-activated receptor gamma regulated genes involved in expansion of pancreatic beta cell mass
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE33647 | GEO | 2012/01/16
SECONDARY ACCESSION(S): PRJNA148653
REPOSITORIES: GEO
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Project description:The progression towards type 2 diabetes depends on the success of the allostatic response of the pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physio and pathological states such as pregnancy, obesity or ageing. The mechanisms, mediating beta cell mass expansion in these scenarios are not well defined. We have recently showed that beta cell mass failed to expand in ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Here we investigate PPAR gamma dependent transcriptional responses occurring during early stages of the adaptation of beta cells to insulin resistance. As it could be expected we have identified genes known to regulate proliferation and survival signals of the beta cells. Moreover we have also identified new pathways induced in ob/ob islets that fail to do so in POKO islets. Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with activation of immune response and is missing in POKO islets. Other PPARγ dependent differentially regulated pathways include cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation. In this study, we used gene expression arrays to investigate differences between four experimental classes by pairs
2012-01-16 | E-GEOD-33647 | biostudies-arrayexpress
Project description:The inability of the beta-cell to meet the demand for insulin brought about by insulin resistance leads to type 2 diabetes. In adults, beta-cell replication is one of the mechanisms thought to cause the expansion of beta-cell mass. Efforts to treat diabetes require knowledge of the pathways that drive facultative beta-cell proliferation in vivo. A robust physiological stimulus of beta-cell expansion is pregnancy, and identifying the mechanisms underlying this stimulus may provide therapeutic leads for the treatment of type 2 diabetes. The peak in beta-cell proliferation during pregnancy occurs on day 14.5 of gestation in mice. Using advanced genomic approaches, we globally characterize the gene expression signature of pancreatic islets on day 14.5 of gestation during pregnancy. We identify a total of 1,907 genes as differentially expressed in the islet during pregnancy. We demonstrate that the islet's ability to compensate for relative insulin deficiency during metabolic stress is associated with the induction of both proliferative and survival pathways. A comparison of the genes induced in three different models of islet expansion suggests that diverse mechanisms can be recruited to expand islet mass. The identification of many novel genes involved in islet expansion during pregnancy provides an important resource for diabetes researchers to further investigate how these factors contribute to the maintenance of not only islet mass, but ultimately beta-cell mass.
2010-06-26 | E-MTAB-120 | biostudies-arrayexpress
Project description:Pancreatic M-CM-^_-cells adapt to compensate for the increased metabolic demand during insulin resistance. While the microRNA pathway has an essential role in the expansion of M-CM-^_-cell mass, the extent of its contribution is unclear. Here we show that miR-184 is silenced in the pancreatic islets of several insulin-resistant mouse models and in the islets of type-2 diabetic human subjects. Reduction of miR-184 promotes the expression of its target Argonaute2 (Ago2), a component of the microRNA-induced silencing complex. While over-expression of Ago2 increased M-CM-^_-cell proliferation, conditional deletion decreased M-CM-^_-cell number. Moreover, restored expression of miR-184 in leptin-deficient ob/ob mice decreased Ago2 and prevented compensatory M-CM-^_-cell expansion. Loss of Ago2 expression during insulin resistance blocked M-CM-^_-cell growth and relieved the regulation of miR-375-targeted genes including the growth suppressor Cadm1. This study identifies the regulation of Ago2 by miR-184 as an essential component of the compensatory response to promote proliferation during insulin resistance. MIN6 cells were transfected with Doxycyline responsive plasmids including the tetO-184 construct in biological triplicates for every time point. The conditions included untransfected control (CTR, induced), Transfected Control (TC, uninduced) along the time points of miR-184 overexpression in 16, 24, 48, and 72 hours of doxycycline treatment.
2014-02-06 | E-GEOD-46623 | biostudies-arrayexpress
Project description:During pregnancy, the energy requirements of the fetus impose changes in maternal metabolism. Increasing insulin resistance in the mother maintains nutrient flow to the growing fetus, while prolactin and placental lactogen counterbalance this resistance and prevent maternal hyperglycemia by driving expansion of the maternal population of insulin-producing beta-cells. However, the exact mechanisms by which the lactogenic hormones drive beta-cell expansion remain uncertain. Here we show that serotonin acts downstream of lactogen signaling to drive beta-cell proliferation. Serotonin synthetic enzyme Tph1 and serotonin production increased sharply in beta-cells during pregnancy or after treatment with lactogens in vitro. Inhibition of serotonin synthesis by dietary tryptophan restriction or Tph inhibition blocked beta-cell expansion and induced glucose intolerance in pregnant mice without affecting insulin sensitivity. Expression of the Gq-linked serotonin receptor Htr2b in maternal islets increased during pregnancy and normalized just prior to parturition, while expression of the Gi-linked receptor Htr1d increased at the end of pregnancy and postpartum. Blocking Htr2b signaling in pregnant mice also blocked beta-cell expansion and caused glucose intolerance. These studies reveal an integrated signaling pathway linking beta-cell mass to anticipated insulin need during pregnancy. Modulators of this pathway, including medications and diet, may affect the risk of gestational diabetes. Analysis of poly(A)+ RNA from 3 biological replicates of pancreatic islets isolated from normal female and pregnant female mice
2010-07-01 | E-GEOD-21860 | biostudies-arrayexpress
Project description:Pancreatic ß-cells adapt to compensate for the increased metabolic demand during insulin resistance. While the microRNA pathway has an essential role in the expansion of ß-cell mass, the extent of its contribution is unclear. Here we show that miR-184 is silenced in the pancreatic islets of several insulin-resistant mouse models and in the islets of type-2 diabetic human subjects. Reduction of miR-184 promotes the expression of its target Argonaute2 (Ago2), a component of the microRNA-induced silencing complex. While over-expression of Ago2 increased ß-cell proliferation, conditional deletion decreased ß-cell number. Moreover, restored expression of miR-184 in leptin-deficient ob/ob mice decreased Ago2 and prevented compensatory ß-cell expansion. Loss of Ago2 expression during insulin resistance blocked ß-cell growth and relieved the regulation of miR-375-targeted genes including the growth suppressor Cadm1. This study identifies the regulation of Ago2 by miR-184 as an essential component of the compensatory response to promote proliferation during insulin resistance.
2014-02-06 | GSE46623 | GEO
Project description:During pregnancy, pancreatic islets undergo structural and functional changes that lead to enhance insulin release in response to increased insulin demand, which is rapidly reversed at parturition. One of the most important changes is expansion of pancreatic β-cell mass mainly by increased proliferation of β cells. We used microarrays to detail the global programme of gene expression and identified distinct up- or down-regulated genes during pregnancy.
2010-06-04 | GSE22125 | GEO
Project description:Loss of functional beta-cell mass is a hallmark of Type 1 and Type 2 diabetes, and methods for restoring these cells are needed. We have previously reported that overexpression of the homeodomain transcription factor Nkx6.1 in rat pancreatic islets induces beta-cell proliferation and enhances glucose-stimulated insulin secretion, but the pathway by which Nkx6.1 activates beta-cell expansion has not been defined. Here we demonstrate that Nkx6.1 induces expression of the Nr4a1 and Nr4a3 orphan nuclear receptors, and that these factors are both necessary and sufficient for Nkx6.1-mediated beta-cell proliferation. Consistent with this finding, global knockout of Nr4a1 results in a decrease in beta-cell area in neonatal and young mice. Overexpression of Nkx6.1 and the Nr4a receptors results in increased expression of key cell cycle inducers E2F1 and cyclin E1. Furthermore, Nkx6.1 and Nr4a receptors induce components of the anaphase-promoting complex, including Ube2c, resulting in degradation of the cell cycle inhibitor p21CIP1. These studies identify a new bipartite pathway for activation of beta-cell proliferation, suggesting several new targets for expansion of functional beta-cell mass. We set up a microarray using primary rat islets that were left untreated or transduced with adenoviruses overexpressing betagal or Nkx6.1 for 48 h.
2014-02-18 | E-GEOD-55077 | biostudies-arrayexpress
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.
2014-01-19 | E-GEOD-43620 | biostudies-arrayexpress
Project description:Pancreatic islet transplantation as a cure for type 1 diabetes (T1D) cannot be scaled up due to a scarcity of human pancreas donors. In vitro expansion of beta cells from mature human pancreatic islets provides an alternative source of insulin-producing cells. The exact nature of the expanded cells produced by diverse expansion protocols, and their potential for differentiation into functional beta cells, remain elusive. We performed a large-scale meta-analysis of gene expression in human pancreatic islet cells, which were processed using three different previously described protocols for expansion and attempted re-differentiation. All three expansion protocols induced dramatic changes in the expression profiles of pancreatic islets; many of these changes are shared among the three protocols. Attempts at re-differentiation of expanded cells induce a limited number of gene expression changes. Nevertheless, these fail to restore a pancreatic islet-like gene expression pattern. Comparison with a collection of public microarray datasets confirmed that expanded cells are highly comparable to mesenchymal stem cells. Genes induced in expanded cells are also enriched for targets of transcription factors important for pluripotency induction. The present data increases our understanding of the active pathways in expanded and re-differentiated islets. Knowledge of the mesenchymal stem cell potential may help development of drug therapeutics to restore beta cell mass in T1D patients. Experiment Overall Design: In this study, we have tested three different protocols to expand human pancreatic islets in monolayer and after attempted maneuvers to re-differentiate the expanded cells back to islets. We have characterized the resulting cells in detail by performing microarray analyses with fresh pancreatic islets, expanded islet cells and re-differentiated cells. Genes modified by either of three protocols have 70 to 80% overlap with the genes changed by the other two protocols. Although there are promising changes in the right direction, none of the three protocols could achieve a return to a functional islet state. The expanded cells highly resemble Mesenchymal Stem Cells (MSC), and similar gene regulatory networks seem to be active in both cell types. On the other hand, the expanded islet cells are different from MSC in that they seem to retain activity of some islet gene modules. The current results highlight the importance of designing new strategies that take into account the MSC potential of expanded cells.
2009-08-07 | E-GEOD-15543 | biostudies-arrayexpress
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.
2014-01-19 | GSE43620 | GEO