ABSTRACT: Insm1 cooperates with Neurod1 and Foxa2 to maintain mature pancreatic β-cell function (Expression data from islets of control and Insm1 conditional deleted adult pancreatic islets)
Project description:Insm1 cooperates with Neurod1 and Foxa2 to maintain mature pancreatic β-cell function (Insm1, Neurod1 and Foxa2 ChipSeq data from pancreatic beta cell)
Project description:Genome-wide Insm1 binding sites analysis revealed an overrepresentation of sequences predicted to bind bHLH and/or forkhead factors, and further analyses demonstrated that most Insm1 sites in the genome are co-occupied by Neurod1 and Foxa2. Binding regions co-occupied by all three factors but not single Insm1 sites explained a significant fraction of gene expression changes in Insm1 mutant β-cells. Together, our data provide evidence that an Insm1, Neurod1 and Foxa2 network maintains a mature gene expression program in β-cells. 6 samples include, replicates of Insm1 and Foxa2, IgG pull down as a control
Project description:Genome-wide Insm1 binding sites analysis revealed an overrepresentation of sequences predicted to bind bHLH and/or forkhead factors, and further analyses demonstrated that most Insm1 sites in the genome are co-occupied by Neurod1 and Foxa2. Binding regions co-occupied by all three factors but not single Insm1 sites explained a significant fraction of gene expression changes in Insm1 mutant β-cells. Together, our data provide evidence that an Insm1, Neurod1 and Foxa2 network maintains a mature gene expression program in β-cells.
Project description:The zinc finger factor Insm1 is known to regulate differentiation of pancreatic ? cells during development, Here we show that Insm1 is essential for the maintenance of functionally mature pancreatic ? cells in mice. We used microarrays to analyse the global gene expression after deletion of insm1 in adult pancreatic ? cells and identified functional important genes and immature islets releated genes deregulated in the mutatant islets. We used 8 mutant and 8 litter matched control mice for the islets preparation.
Project description:The zinc finger factor Insm1 is known to regulate differentiation of pancreatic β cells during development, Here we show that Insm1 is essential for the maintenance of functionally mature pancreatic β cells in mice. We used microarrays to analyse the global gene expression after deletion of insm1 in adult pancreatic β cells and identified functional important genes and immature islets releated genes deregulated in the mutatant islets.
Project description:We anticipated that the identification of cis-regulatory regions active in pancreatic islets would help increase our understanding of islet biology and the pathology of diabetes. Towards this end we used histone H3 lysine 4 monomethylation-based nucleosome predictions genome-wide, in conjunction with binding data for PDX1, FOXA2, MAFA, and NEUROD1, to identify 3,654 putative enhancers that are H3K4me1-enriched uniquely in islets as compared to 14 other tissue or cell-types. We show that these islet-specific enhancers are associated with genes with significantly higher islet specificity than genes associated with non-specific enhancers. Further, islet-specific enhancers were not enriched for typical active or repressive histone methylations in embryonic stem cells and liver, suggesting they are formed by de novo histone methylation during pancreas development. We also identify a subset of enhancers bivalently marked by both H3K4me1 and H3K27me3 in adult pancreatic islets. Further, we show that islet-specific enhancers triple- or quadruple- bound by PDX1, MAFA, NEUROD1 and/or FOXA2 are associated with genes with particularly high islet-specificity, and that these loci are enriched in regions with functional activity in islet cell types. Finally, we demonstrate that cytokines reduce H3K4me1 enrichment levels at selected triple- or quadruple-bound islet-specific enhancers, suggesting that epigenetic changes may contribute to cytokine-induced b-cell dysfunction. In conjunction with data from Hoffman et al Genome Research 2010, an analysis of histone modifications and transcription factor binding sites to identify enhancer regions
Project description:Nkx6.1 target genes were identified in mature pancreatic islets by comparing gene expression in conditional Nkx6.1-ablated islets versus control islets using microarray analysis.
Project description:This experiment used RNA-Seq technology to explore gene expression in mouse Insm1GFP.Cre/+ controls and Insm1 (Insm1GFP.Cre/GFP.Cre), Neurod1 (Insm1GFP.Cre/+; Neurod1LacZ/LacZ), or Pax6 (Insm1GFP.Cre/+; Pax6fl/fl) knockout FACS sorted pancreatic endocrine cells at E15.5. Comparison of Insm1GFP.Cre+/- and knockout animals revealed sets of differentially expressed genes that are required for endocrine cell specification and development.
Project description:Nkx6.1 target genes were identified in mature pancreatic islets by comparing gene expression in conditional Nkx6.1-ablated islets versus control islets using microarray analysis. Nkx6.1 was conditionally ablated in mature pancreatic islets by recombination of a Nkx6.1-flox allele using the tamoxifen-inducible Pdx1-CreERTM allele (Gu et al 2002). Mice were injected with 2 mg/25 g tamoxifen in corn oil four times between 4 and 6 weeks of age. Islets were isolated after the final tamoxifen injection. Total RNA was isolated and pooled from pancreata of 6 week old Nkx6.1fl/-;Pdx1-CreERTM (mutant) versus Nkx6.1fl/+;Pdx1-CreERTM (control) littermates for 3 biological replicates.
Project description:We anticipated that the identification of cis-regulatory regions active in pancreatic islets would help increase our understanding of islet biology and the pathology of diabetes. Towards this end we used histone H3 lysine 4 monomethylation-based nucleosome predictions genome-wide, in conjunction with binding data for PDX1, FOXA2, MAFA, and NEUROD1, to identify 3,654 putative enhancers that are H3K4me1-enriched uniquely in islets as compared to 14 other tissue or cell-types. We show that these islet-specific enhancers are associated with genes with significantly higher islet specificity than genes associated with non-specific enhancers. Further, islet-specific enhancers were not enriched for typical active or repressive histone methylations in embryonic stem cells and liver, suggesting they are formed by de novo histone methylation during pancreas development. We also identify a subset of enhancers bivalently marked by both H3K4me1 and H3K27me3 in adult pancreatic islets. Further, we show that islet-specific enhancers triple- or quadruple- bound by PDX1, MAFA, NEUROD1 and/or FOXA2 are associated with genes with particularly high islet-specificity, and that these loci are enriched in regions with functional activity in islet cell types. Finally, we demonstrate that cytokines reduce H3K4me1 enrichment levels at selected triple- or quadruple-bound islet-specific enhancers, suggesting that epigenetic changes may contribute to cytokine-induced b-cell dysfunction.
