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GSE36935
Rattus norvegicus
5 Downloadable Samples
Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
In obesity an increase in -cell mass occurs to cope with the rise in insulin demand. This -cell plasticity is essential to avoid the onset of hyperglycemia, although the molecular mechanisms that regulate this process remain unclear. This study analyzed the role of adipose tissue in the control of -cell replication. Using a diet-induced model of obesity, we obtained conditioned media from three different white adipose tissue depots. Only in the adipose tissue depot surrounding the pancreas did the diet induce changes that led to an increase in INS1E cells and the islet replication rate. To identify the factors responsible for this proliferative effect, adipose tissue gene expression analysis was conducted by microarrays and quantitative RT-PCR. Of all the differentially expressed proteins, only the secreted ones were studied. IGF binding protein 3 (Igfbp3) was identified as the candidate for this effect. Furthermore, in the conditioned media, although the blockage of IGFBP3 led to an increase in the proliferation rate, the blockage of IGF-I receptor decreased it. Taken together, these data show that obesity induces specific changes in the expression profile of the adipose tissue depot surrounding the pancreas, leading to a decrease in IGFBP3 secretion. This decrease acts in a paracrine manner, stimulating the -cell proliferation rate, probably through an IGF-I-dependent mechanism. This cross talk between the visceral-pancreatic adipose tissue and -cells is a novel mechanism that participates in the control of -cell plasticity. (Endocrinology 153: 177187, 2012)
Publication Title
Role of IGFBP-3 in the regulation of β-cell mass during obesity: adipose tissue/β-cell cross talk.
Sample Metadata Fields
Specimen part
View Samples- Rattus norvegicus
- 19 Downloadable Samples
- Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
This SuperSeries is composed of the SubSeries listed below.
Publication Title
Downregulation of Sfrp5 promotes beta cell proliferation during obesity in the rat.
Sample Metadata Fields
Specimen part
View Samples- Rattus norvegicus
- 10 Downloadable Samples
- Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
Obesity is associated with an increase in -cell mass in response tothe rising demand for insulin. -cell plasticity is essential to maintaining glucose homeostasis, however,the cellular and molecular mechanisms by which -cell mass is regulated remain poorly understood.Recently, we described the existence of a crosstalk between the peripancreatic adipose tissue and -cells as a novel mechanism that participates in the regulation of -cell plasticity. Here, we identify the secreted frizzled-related protein (Sfrp) 5 as down-regulated in the pancreatic islets of obese rats as well as in the pancreatic islets of human obese patients. Our results demonstrate that the silencing of Sfrp5 induces an increase in -cell proliferation, which we correlate with the activation of Wnt signaling and of the MAPK and PI3 kinase pathways. Together, these findings expand our understanding of the mechanisms underlying -cell proliferation under conditions of obesity. Furthermore, this study opens new insights into the specific targeting of Sfrp5 as a novel therapeutic strategy for balancing -cell mass.
Publication Title
Downregulation of Sfrp5 promotes beta cell proliferation during obesity in the rat.
Sample Metadata Fields
Specimen part
View Samples- Rattus norvegicus
- 9 Downloadable Samples
- Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
Obesity is associated with an increase in -cell mass in response tothe rising demand for insulin. -cell plasticity is essential to maintaining glucose homeostasis, however,the cellular and molecular mechanisms by which -cell mass is regulated remain poorly understood.Recently, we described the existence of a crosstalk between the peripancreatic adipose tissue and -cells as a novel mechanism that participates in the regulation of -cell plasticity. Here, we identify the secreted frizzled-related protein (Sfrp) 5 as down-regulated in the pancreatic islets of obese rats as well as in the pancreatic islets of human obese patients. Our results demonstrate that the silencing of Sfrp5 induces an increase in -cell proliferation, which we correlate with the activation of Wnt signaling and of the MAPK and PI3 kinase pathways. Together, these findings expand our understanding of the mechanisms underlying -cell proliferation under conditions of obesity. Furthermore, this study opens new insights into the specific targeting of Sfrp5 as a novel therapeutic strategy for balancing -cell mass.
Publication Title
Downregulation of Sfrp5 promotes beta cell proliferation during obesity in the rat.
Sample Metadata Fields
Specimen part
View Samples- Rattus norvegicus
- 9 Downloadable Samples
- Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
Changes in the secretion profile of visceral-pancreatic white adipose tissue (pWAT) due to diet-induced obesity are partially responsible for increased beta cell replication, suggesting that a crosstalk between pWAT and beta cells may play a role in regulating beta cell plasticity. The molecular mechanisms underlying this cross-talk are still not fully understood.
Publication Title
Downregulation of Sfrp5 promotes beta cell proliferation during obesity in the rat.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 8 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
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.
Publication Title
Tungstate promotes β-cell survival in Irs2-/- mice.
Sample Metadata Fields
Sex, Specimen part
View Samples- Rattus norvegicus
- 15 Downloadable Samples
- Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
This SuperSeries is composed of the SubSeries listed below.
Publication Title
Integrative analysis reveals novel pathways mediating the interaction between adipose tissue and pancreatic islets in obesity in rats.
Sample Metadata Fields
Specimen part
View Samples- Rattus norvegicus
- 6 Downloadable Samples
- Affymetrix Rat Genome 230 2.0 Array (rat2302)
Description
Changes in the secretion profile of visceral-pancreatic white adipose tissue due to diet-induced obesity are partially responsible for increased beta cell replication, suggesting that a crosstalk between pWAT and beta cells may play a role in regulating beta cell plasticity. The molecular mechanisms underlying this cross-talk are still not fully understood.
Publication Title
Integrative analysis reveals novel pathways mediating the interaction between adipose tissue and pancreatic islets in obesity in rats.
Sample Metadata Fields
Specimen part
View Samples- Drosophila melanogaster
- 8 Downloadable Samples
- Affymetrix Drosophila Genome 2.0 Array (drosophila2)
Description
Drosophila eye specification an development relies on a collection of transcription factors termed the retinal determination gene network (RDGN). Two members of this network, Eyes absent (EYA) and Sine oculis (SO), form a transcriptional complex in which EYA provides the transactivation function while SO provides the DNA binding activity. EYA also function as a protein tyrosine phosphatase, raising the question of whether transcriptional output is dependent or independent of phosphatase activity. To explore this, we used microarrays together with binding site analysis, quantitative real-time PCR, chromatin immunoprecipitation, genetics, and in vivo expression analysis to identify new EYA-SO targets. In parallel, we examined the expression profiles of tissue expressing phosphatase mutant eya and found that reducing phosphatase activity did not globally impair transcriptional output. Among the targets identified by our analysis was the cell cycle regulatory gene, string (stg), suggesting that EYA and SO may influence cell proliferation through transcriptional regulation of stg. Future investigation into the regulation of stg and other EYA-SO targets identified in this study will help elucidate the transcriptional circuitries whereby output from the RDGN integrates with other signaling inputs to coordinate retinal development.
Publication Title
Identification of transcriptional targets of the dual-function transcription factor/phosphatase eyes absent.
Sample Metadata Fields
No sample metadata fields
View Samples- Mus musculus
- 18 Downloadable Samples
- Affymetrix Mouse Gene 1.0 ST Array (mogene10st)
Description
We have recently demonstrated that mycobacterial ligands engage Toll like receptor 2 (TLR2) on CD4+ T cells and up-regulate T-cell receptor (TCR) triggered- Th1 responses in vitro and in vivo.
Publication Title
Toll like Receptor 2 engagement on CD4<sup>+</sup> T cells promotes TH9 differentiation and function.
Sample Metadata Fields
No sample metadata fields
View Samples