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Insm1 cooperates with Neurod1 and Foxa2 to maintain mature pancreatic β-cell function.

Jia S, Ivanov A, Blasevic D, Müller T, Purfürst B, Sun W, Chen W, Poy MN, Rajewsky N, Birchmeier C - EMBO J. (2015)

Bottom Line: We defined Insm1, Neurod1 and Foxa2 binding sites associated with genes deregulated in Insm1 mutant β-cells.Human genomic sequences corresponding to the murine sites occupied by Insm1/Neurod1/Foxa2 were enriched in single nucleotide polymorphisms associated with glycolytic traits.Thus, our data explain part of the mechanisms by which β-cells maintain maturity: Combinatorial Insm1/Neurod1/Foxa2 binding identifies regulatory sequences that maintain the mature gene expression program in β-cells, and disruption of this network results in functional failure.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany cbirch@mdc-berlin.de jshiqi@mdc-berlin.de.

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Sites co-occupied by Insm1, Neurod1 and Foxa2 correspond to high affinity sites and are enriched in intergenic and intronic sequencesA Peak heights at sites occupied by individual factors, factor combinations and Insm1/Neurod1/Foxa2; median value (black line), quartiles (boxes) and errors (dashed lines) are shown (R package). Peak heights are largest at Insm1/Neurod1/Foxa2 sites (P < 2.2 × 10−16).B Pie charts showing the distribution of Insm1 only sites (top) and Insm1/Neurod1/Foxa2 sites (bottom).C, D ChIP-PCR analyses of Insm1, Neurod1 and Foxa2 binding in chromatin from SJ β-cells and isolated islets. Shown is the enrichment of precipitated chromatin; representative examples of three experiments are shown.
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fig06: Sites co-occupied by Insm1, Neurod1 and Foxa2 correspond to high affinity sites and are enriched in intergenic and intronic sequencesA Peak heights at sites occupied by individual factors, factor combinations and Insm1/Neurod1/Foxa2; median value (black line), quartiles (boxes) and errors (dashed lines) are shown (R package). Peak heights are largest at Insm1/Neurod1/Foxa2 sites (P < 2.2 × 10−16).B Pie charts showing the distribution of Insm1 only sites (top) and Insm1/Neurod1/Foxa2 sites (bottom).C, D ChIP-PCR analyses of Insm1, Neurod1 and Foxa2 binding in chromatin from SJ β-cells and isolated islets. Shown is the enrichment of precipitated chromatin; representative examples of three experiments are shown.

Mentions: Next, we compared the number of reads obtained in Insm1, Neurod1 or Foxa2 ChIP-seq experiments and observed that read numbers were highest at sites co-occupied by all three factors (Fig 6A). Comparison of the distribution of co-occupied and ‘Insm1 only’ sites in the genome demonstrated that co-occupied sites were depleted of promoter and enriched in intergenic and intronic sequences (Fig 6B). The co-recruitment of Insm1, Neurod1 and Foxa2 was also experimentally tested by ChIP-PCR in both SJ β-cells and murine islets. Indeed, all tested sites were enriched (Fig 6C and D). Thus, Insm1, Neurod1 and Foxa2 frequently bind in close proximity in chromatin of pancreatic β-cells, and high affinity binding sites are enriched in sites co-occupied by all three factors.


Insm1 cooperates with Neurod1 and Foxa2 to maintain mature pancreatic β-cell function.

Jia S, Ivanov A, Blasevic D, Müller T, Purfürst B, Sun W, Chen W, Poy MN, Rajewsky N, Birchmeier C - EMBO J. (2015)

Sites co-occupied by Insm1, Neurod1 and Foxa2 correspond to high affinity sites and are enriched in intergenic and intronic sequencesA Peak heights at sites occupied by individual factors, factor combinations and Insm1/Neurod1/Foxa2; median value (black line), quartiles (boxes) and errors (dashed lines) are shown (R package). Peak heights are largest at Insm1/Neurod1/Foxa2 sites (P < 2.2 × 10−16).B Pie charts showing the distribution of Insm1 only sites (top) and Insm1/Neurod1/Foxa2 sites (bottom).C, D ChIP-PCR analyses of Insm1, Neurod1 and Foxa2 binding in chromatin from SJ β-cells and isolated islets. Shown is the enrichment of precipitated chromatin; representative examples of three experiments are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4492000&req=5

fig06: Sites co-occupied by Insm1, Neurod1 and Foxa2 correspond to high affinity sites and are enriched in intergenic and intronic sequencesA Peak heights at sites occupied by individual factors, factor combinations and Insm1/Neurod1/Foxa2; median value (black line), quartiles (boxes) and errors (dashed lines) are shown (R package). Peak heights are largest at Insm1/Neurod1/Foxa2 sites (P < 2.2 × 10−16).B Pie charts showing the distribution of Insm1 only sites (top) and Insm1/Neurod1/Foxa2 sites (bottom).C, D ChIP-PCR analyses of Insm1, Neurod1 and Foxa2 binding in chromatin from SJ β-cells and isolated islets. Shown is the enrichment of precipitated chromatin; representative examples of three experiments are shown.
Mentions: Next, we compared the number of reads obtained in Insm1, Neurod1 or Foxa2 ChIP-seq experiments and observed that read numbers were highest at sites co-occupied by all three factors (Fig 6A). Comparison of the distribution of co-occupied and ‘Insm1 only’ sites in the genome demonstrated that co-occupied sites were depleted of promoter and enriched in intergenic and intronic sequences (Fig 6B). The co-recruitment of Insm1, Neurod1 and Foxa2 was also experimentally tested by ChIP-PCR in both SJ β-cells and murine islets. Indeed, all tested sites were enriched (Fig 6C and D). Thus, Insm1, Neurod1 and Foxa2 frequently bind in close proximity in chromatin of pancreatic β-cells, and high affinity binding sites are enriched in sites co-occupied by all three factors.

Bottom Line: We defined Insm1, Neurod1 and Foxa2 binding sites associated with genes deregulated in Insm1 mutant β-cells.Human genomic sequences corresponding to the murine sites occupied by Insm1/Neurod1/Foxa2 were enriched in single nucleotide polymorphisms associated with glycolytic traits.Thus, our data explain part of the mechanisms by which β-cells maintain maturity: Combinatorial Insm1/Neurod1/Foxa2 binding identifies regulatory sequences that maintain the mature gene expression program in β-cells, and disruption of this network results in functional failure.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany cbirch@mdc-berlin.de jshiqi@mdc-berlin.de.

Show MeSH