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- Ameri, Jacqueline, et al.
(författare)
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FGF2 Specifies hESC-Derived Definitive Endoderm into Foregut/Midgut Cell Lineages in a Concentration-Dependent Manner.
- 2010
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 28, s. 45-56
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Tidskriftsartikel (refereegranskat)abstract
- Fibroblast growth factor (FGF) signaling controls axis formation during endoderm development. Studies in lower vertebrates have demonstrated that FGF2 primarily patterns the ventral foregut endoderm into liver and lung, whereas FGF4 exhibits broad anterior-posterior and left-right patterning activities. Furthermore, an inductive role of FGF2 during dorsal pancreas formation has been shown. However, whether FGF2 plays a similar role during human endoderm development remains unknown. Here, we show that FGF2 specifies hESC-derived definitive endoderm (DE) into different foregut lineages in a dosage-dependent manner. Specifically, increasing concentrations of FGF2 inhibits hepatocyte differentiation, whereas intermediate concentration of FGF2 promotes differentiation towards a pancreatic cell fate. At high FGF2 levels specification of midgut endoderm into small intestinal progenitors is increased at the expense of PDX1+ pancreatic progenitors. High FGF2 concentrations also promote differentiation towards an anterior foregut pulmonary cell fate. Finally, by dissecting the FGF receptor intracellular pathway that regulates pancreas specification, we demonstrate for the first time to our knowledge that induction of PDX1+ pancreatic progenitors relies on FGF2-mediated activation of the MAPK signaling pathway. Altogether, these observations suggest a broader gut endodermal patterning activity of FGF2 that corresponds to what has previously been advocated for FGF4, implying a functional switch from FGF4 to FGF2 during evolution. Thus, our results provide new knowledge of how cell fate specification of human DE is controlled - facts that will be of great value for future regenerative cell therapies.
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| 2. |
- Artner, Isabella, et al.
(författare)
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MafA and MafB Regulate Genes Critical to beta-Cells in a Unique Temporal Manner
- 2010
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 59:10, s. 2530-2539
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-Several transcription factors are essential to pancreatic islet beta-cell development, proliferation, and activity, including MafA and MafB. However, MafA and MafB are distinct from others in regard to temporal and islet cell expression pattern, with beta-cells affected by MafB only during development and exclusively by MafA in the adult. Our aim was to define the functional relationship between these closely related activators to the beta-cell. RESEARCH DESIGN AND METHODS-The distribution of MafA and MafB in the beta-cell population was determined immunohistochemically at various developmental and perinatal stages in mice. To identify genes regulated by MafB, microarray profiling was performed on wild-type and MafB(-/-) pancreata at embryonic day 18.5, with candidates evaluated by quantitative RT-PCR and in situ hybridization. The potential role of MafA in the expression of verified targets was next analyzed in adult islets of a pancreas-wide MafA mutant (termed MafA(Delta Panc)). RESULTS-MafB was produced in a larger fraction of beta-cells than MafA during development and found to regulate potential effectors of glucose sensing, hormone processing, vesicle formation, and insulin secretion. Notably, expression from many of these genes was compromised in MafA(Delta Panc) islets, suggesting that MafA is required to sustain expression in adults. CONCLUSIONS-Our results provide insight into the sequential manner by which MafA and MafB regulate islet beta-cell formation and maturation. Diabetes 59:2530-2539, 2010
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| 5. |
- Raum, Jeffrey C, et al.
(författare)
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Islet {beta}-cell-specific MafA transcription requires the 5'-flanking conserved Region 3 control domain.
- 2010
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Ingår i: Molecular and Cellular Biology. - 0270-7306. ; 30:17, s. 4234-4244
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Tidskriftsartikel (refereegranskat)abstract
- MafA is a key transcriptional activator of islet beta cells and its exclusive expression within beta cells of the developing and adult pancreas is distinct amongst pancreatic regulators. Region 3 (base pairs -8118/-7750 relative to the transcription start site), one of six conserved 5' cis-domains of the MafA promoter, is capable of directing beta-cell-line-selective expression. Transgenic reporters of Region 3 alone (R3), sequences spanning Regions 1-6 (R1-6; base pairs -10428/+230), and R1-6 lacking Region 3 (R1-6(DeltaR3)) were generated. Only the R1-6 transgene was active in MafA(+) insulin(+) cells during development and in adults. R1-6 also mediated glucose-induced MafA expression. Conversely, pancreatic expression was not observed with the R3 or R1-6(DeltaR3) lines, although much of the non-pancreatic expression pattern was shared between the R1-6 and R1-6(DeltaR3) lines. Further support for the importance of Region 3 was shown as the islet regulators Nkx6.1 and Pax6, but not NeuroD1 activated MafA using gel shift, chromatin immunoprecipitation (ChIP), transfection assays, and in vivo mouse knockout models. Lastly ChIP demonstrated that Pax6 and Pdx-1 bound also to Regions 1 and 6, potentially functioning in pancreatic and non-pancreatic expression. These data highlight the nature of the cis- and trans-acting factors controlling the beta-3cell-specific expression of MafA.
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