Expression data from 24 hours of Sox17 overexpression in pancreatic islets of a 16-week old mice
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE59928 | GEO | 2014/07/31
SECONDARY ACCESSION(S): PRJNA257072
REPOSITORIES: GEO
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Project description:Secretion of insulin by pancreatic β cells in response to glucose is central for glucose homeostasis, and dysregulation of this process is a hallmark of the early stages of diabetes. We utilized a tetracycline-inducible approach to investigate the immediate impact of a pulse of Sox17 expression on the insulin secretory pathway. Sox17 gain-of-function animals (Sox17-GOF) were generated using an Ins2-rtTA mouse line and a line in which Sox17 expression is regulated by the tetracycline transactivator (tetO-Sox17). Administering doxycycline to 16-week old mice resulted in Sox17 overexpression in mature β cells in the islets. In order to identify the molecular basis by which Sox17 regulates the secretory pathway in β cells, we performed microarray analysis on isolated islets following a 24-hour pulse of Sox17 overexpression. We chose to analyze a 24 hour pulse of Sox17 for islet pancreas RNA extraction and hybridization on Affymetrix microarrays since it was sufficient to stimulate the insulin secretory pathway without causing changes in islet architecture.
2014-07-31 | E-GEOD-59928 | biostudies-arrayexpress
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Project description:Adaptation of the islet β-cell insulin secretory response to changing insulin demand is critical for blood glucose homeostasis, yet the mechanisms underlying this adaptation are unknown. Here, we show that nutrient cues adapt insulin secretion by modulating chromatin state and transcription of genes regulating β-cell nutrient sensing and metabolism. Feeding stimulates histone acetylation at sites occupied by the chromatin-modifying enzyme Lsd1 in islets. We demonstrate that β-cell-specific deletion of Lsd1 leads to insulin hypersecretion, aberrant expression of nutrient response genes, and histone hyperacetylation, features we also observed in the db/db model of chronically increased insulin demand. Moreover, genetic variants associated with fasting glucose levels and type 2 diabetes risk are enriched at LSD1-bound sites in human islets, suggesting interindividual variation in β-cell functional adaptation in humans. These findings reveal nutrient state-dependent modulation of the islet epigenome and identify Lsd1 as a regulator of feeding-stimulated chromatin modification and adaptive insulin secretion.
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Project description:Pancreatic beta-cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair beta-cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion are similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on beta-cell mRNA translation. Prior to induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also of mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex-vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our study uncovered a translational regulatory circuit during beta-cell glucose toxicity that impairs expression of proteins with critical roles in beta-cell function.
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Project description:We found that in rodents, postnatal beta-cell maturation is associated with changes in the expression of several islet microRNAs and discovered that these modifications are driven by changes in the nutrient supply. Mimicking the microRNA changes observed during β-cell maturation in newborn rat islet cells was sufficient to promote glucose-induced insulin release and to achieve a mature β-cell secretory phenotype. Moreover, the modifications in the level of some of these microRNAs reduced the proliferation of newborn β-cells, suggesting that they contribute to the limited proliferative capacity of adult β-cells. These findings demonstrated that miRNAs contribute to postnatal beta-cell maturation and development. Their role is likely to promote beta-cell adaptation to fuel supply and to maintain glucose homeostasis by regulating insulin release and proliferation. Islets from 10-day-old rats (P10) (n=4) or 3-month-old male rat (n=4) were taken. Total RNA was extracted and microRNA profiling was performed with miRNA Agilent arrays.
2014-09-04 | E-GEOD-61090 | biostudies-arrayexpress
Project description:Pancreatic beta-cells are specialized for coupling glucose metabolism to insulin peptide production and secretion. Acute glucose exposure robustly and coordinately increases translation of proinsulin and proteins required for secretion of mature insulin peptide. By contrast, chronically elevated glucose levels that occur during diabetes impair beta-cell insulin secretion and have been shown experimentally to suppress insulin translation. Whether translation of other genes critical for insulin secretion are similarly downregulated by chronic high glucose is unknown. Here, we used high-throughput ribosome profiling and nascent proteomics in MIN6 insulinoma cells to elucidate the genome-wide impact of sustained high glucose on -cell mRNA translation. Prior to induction of ER stress or suppression of global translation, sustained high glucose suppressed glucose-stimulated insulin secretion and downregulated translation of not only insulin, but also of mRNAs related to insulin secretory granule formation, exocytosis, and metabolism-coupled insulin secretion. Translation of these mRNAs was also downregulated in primary rat and human islets following ex-vivo incubation with sustained high glucose and in an in vivo model of chronic mild hyperglycemia. Furthermore, translational downregulation decreased cellular abundance of these proteins. Our study uncovered a translational regulatory circuit during beta-cell glucose toxicity that impairs expression of proteins with critical roles in beta-cell function.
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Project description:Maternal low-protein diet increases the susceptibility of offspring to type 2 diabetes. An insult to the pancreas during development can have long-term consequences on β-cell mass and function. Because nutrients and growth factors signaling converge on mTOR, we hypothesized that mTOR plays a central role in β-cell programming during fetal development. In this study, we revealed that newborns of dams exposed to low-protein diet (LP0.5) throughout pregnancy exhibited decreased insulin levels, β-cell fraction, and mTOR signaling. Adult LP0.5 offspring demonstrated enhanced insulin sensitivity but remained glucose intolerant due to an insulin secretory defect and not reduced β-cell mass. The insulin secretory defect was distal to Ca2+ influx, at the level of proinsulin biosynthesis and insulin content. LP0.5 islets exhibited reduced mTOR protein and increased expression of specific microRNAs. The reductions in mTOR protein and insulin secretion in LP0.5 islets were restored to normal by blockade of microRNAs 199a-3p and 342. Finally, transient activation of mTORC1 signaling in β-cells during the last week of pregnancy rescued the neonatal β-cell fraction defect and metabolic abnormalities in LP0.5 mice. These findings identify a major role of microRNAs and mTOR in β-cell programing by maternal low-protein diet. To investigate which microRNAs are altered in islets isolated from 2-3 months old male offspring of dams fed low-protein diet (LP0.5) or control diet throughout pregnancy
2014-07-11 | GSE59279 | GEO
Project description:ABSTRACT: Furin is a proprotein convertase (PC) responsible for proteolytic activation of a wide array of precursor proteins within the secretory pathway. It maps to the PRC1 locus, a type 2 diabetes susceptibility locus, yet its specific role in pancreatic β cells is largely unknown. The aim of this study was to determine the role of furin in glucose homeostasis. We show that furin is highly expressed in human islets, while PCs that potentially could provide redundancy are expressed at considerably lower levels. β cell-specific furin knockout (βfurKO) mice are glucose intolerant, due to smaller islets with lower insulin content and abnormal dense core secretory granule morphology. RNA expression analysis and differential proteomics on βfurKO islets revealed activation of Activating Transcription Factor 4 (ATF4), which was mediated by mammalian target of rapamycin C1 (mTORC1). βfurKO cells show impaired cleavage of the accessory V-ATPase subunit Ac45, and by blocking this pump in β cells the mTORC1 pathway is activated. Furthermore, βfurKO cells show lack of insulin receptor cleavage and impaired response to insulin. Taken together, these results suggest a model of mTORC1-ATF4 hyperactivation in β cells lacking furin, which causes β cell dysfunction. METHOD: Data obtained for the β cell specific knockout (RIP-Cre+/- furin flox/flox) and control (furin flox/flox) samples were compared to investigate the effect of furin loss on the mRNA profile of islets. Although this method does not directly provide furin targets, the notion of differential gene expression might elucidate affected cellular processes, potentially leading to upstream furin substrates.
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Project description:We found that in rodents, postnatal beta-cell maturation is associated with changes in the expression of several islet microRNAs and discovered that these modifications are driven by changes in the nutrient supply. Mimicking the microRNA changes observed during β-cell maturation in newborn rat islet cells was sufficient to promote glucose-induced insulin release and to achieve a mature β-cell secretory phenotype. Moreover, the modifications in the level of some of these microRNAs reduced the proliferation of newborn β-cells, suggesting that they contribute to the limited proliferative capacity of adult β-cells. These findings demonstrated that miRNAs contribute to postnatal beta-cell maturation and development. Their role is likely to promote beta-cell adaptation to fule supply and to maintain glucose homeostasis by regulating insulin release and proliferation. Islets from 10-day-old rats (P10) (n=3) or 3-month-old male rat (n=3) were taken. Total RNA was extracted and mRNA profiling via Illumina single-end sequencing of mRNA-seq libraries was performed.
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