Project description:Multipotent pancreatic progenitors (MPC) are defined as Ptf1a+, Mychigh, Cpa+ cells. During the transition from MPC to unipotent acinar progenitors, c-Myc is down-regulated whereas Ptf1a is up-regulated, leading to the deployment of the acinar program. Here, we show that c-Myc and Ptf1a interact directly and c-Myc binds to, and represses, the transcriptional activity of the PTF1 complex in vitro and in vivo. Using Ela1-Myc mice, in which c-Myc is overexpressed in acinar cells starting at E14.5, we find that acinar cells fail to undergo normal maturation at P1 and this is followed by a massive subsequent repression of the acinar programme. Lineage tracing with Ptf1aCreERT2;Rosa26YFP and Ela1-Myc;Ptf1aCreERT2;Rosa26YFP mice receiving TMX at E15.5 and analyzed at E18.5 revealed that c-Myc overexpression is associated with activation of a hepatic programme but not with pancreatic lineage misspecification At 8 weeks, the silencing of the acinar program is associated with increased expression of the PRC2 complex in a c-Myc dependent manner. Genome wide studies show that Ptf1a and c-Myc display partially overlapping chromatin occupancy patterns and DNA binding competition. We conclude that c-Myc down-regulation during development is crucial for the maturation of pre-acinar to acinar cells. c-Myc overexpression may contribute to pancreatic carcinogenesis by restraining cell differentiation and rendering cells susceptible to transformation.
Project description:Multipotent pancreatic progenitors (MPC) are defined as Ptf1a+, Mychigh, Cpa+ cells. During the transition from MPC to unipotent acinar progenitors, c-Myc is down-regulated whereas Ptf1a is up-regulated, leading to the deployment of the acinar program. Here, we show that c-Myc and Ptf1a interact directly and c-Myc binds to, and represses, the transcriptional activity of the PTF1 complex in vitro and in vivo. Using Ela1-Myc mice, in which c-Myc is overexpressed in acinar cells starting at E14.5, we find that acinar cells fail to undergo normal maturation at P1 and this is followed by a massive subsequent repression of the acinar programme. Lineage tracing with Ptf1aCreERT2;Rosa26YFP and Ela1-Myc;Ptf1aCreERT2;Rosa26YFP mice receiving TMX at E15.5 and analyzed at E18.5 revealed that c-Myc overexpression is associated with activation of a hepatic programme but not with pancreatic lineage misspecification At 8 weeks, the silencing of the acinar program is associated with increased expression of the PRC2 complex in a c-Myc dependent manner. Genome wide studies show that Ptf1a and c-Myc display partially overlapping chromatin occupancy patterns and DNA binding competition. We conclude that c-Myc down-regulation during development is crucial for the maturation of pre-acinar to acinar cells. c-Myc overexpression may contribute to pancreatic carcinogenesis by restraining cell differentiation and rendering cells susceptible to transformation.
Project description:We first used RNA-Seq technology to explore gene expression in mouse Ptf1a^YFP/+ [het] FACS sorted cells at E11.5 (early pancreatic Multipotent Progenitor Cells) and E15.5 (nascent acinar cells) as well as in Ptf1a^YFP/YFP [null] at E11.5 (delayed early MPC): this is deposited with accession number E-MTAB-449. We then examined 376 selected genes identified as differentially expressed between early pancreatic MPC and nascent acinar cells or between early pancreatic and delayed early MPCs by Taqman Low Density Arrays (TLDAs) with Real Time RT-PCR for each 1-day time point from E10.5 to E15. 5 in Ptf1a^YFP/+ [het] and for E10.5 and E11.5 in Ptf1aYFP/YFP [null] . Finally, 94 genes identified in the first phase of TLDAs (including 2 endogenous control, Gapdh and 18S) were analyzed in a second TLDA phase for each 1-day time point from E10.5 to -E18.5 in Ptf1a^YFP/+ [het] and for E11.5 in Ptf1aYFP/YFP [null] with biological replicates (n>=3) for each time point.
Project description:This experiment used RNA-Seq technology to explore gene expression in mouse Ptf1a^YFP/+ [het] FACS sorted cells at E11.5 (early pancreatic Multipotent Progenitor Cells) and E15.5 (nascent acinar cells) as well as in Ptf1a^YFP/YFP [null] at E11.5 (delayed early MPC). 376 selected genes identified as differentially expressed between early pancreatic MPC and nascent acinar cells or between early pancreatic and delayed early MPCs have then been examined by Taqman Low Density Arrays (TLDAs) with Real Time RT-PCR for each 1-day time point from E10.5 to E15. 5 in Ptf1a^YFP/+ [het] and for E10.5 and E11.5 in Ptf1aYFP/YFP [null] . Finally, 94 genes identified in the first phase of TLDAs (including 2 endogenous control, Gapdh and 18S) were analyzed in a second TLDA phase for each 1-day time point from E10.5 to -E18.5 in Ptf1a^YFP/+ [het] and for E11.5 in Ptf1aYFP/YFP [null] with biological replicates (n>=3) for each time point.
Project description:The Ptf1a gene has essential functions during several stages of pancreas development. It is expressed in the naïve endoderm and required pancreas cell fate specification; it is also required later in the differentiation and maintenance of acinar cells. To identify the regulatory genetic program downstream of Ptf1a required for early pancreatic fate acquisition, we used microarrays to perform a comprehensive gene expression analysis of Ptf1a overexpressing endodermal tissue at NF32 and NF36. The results revealed an up-regulation on 1142 probe sets over 2-fold. Additional analyses, by in situ hybridizations, identified 9 genes that were endodermally expressed after the onset of endogenous Ptf1a; STXBP1, putative transmembrane protein TA-2, C25H, IGFBP1, IRF1, HALPN3, Hey1, sestrin 1, syndecan-4. These results provide insight into the regulatory network activated by Ptf1a during early pancreas development.
Project description:The Ptf1a gene has essential functions during several stages of pancreas development. It is expressed in the naM-CM-/ve endoderm and required pancreas cell fate specification; it is also required later in the differentiation and maintenance of acinar cells. To identify the regulatory genetic program downstream of Ptf1a required for early pancreatic fate acquisition, we used microarrays to perform a comprehensive gene expression analysis of Ptf1a overexpressing endodermal tissue at NF32 and NF36. The results revealed an up-regulation on 1142 probe sets over 2-fold. Additional analyses, by in situ hybridizations, identified 9 genes that were endodermally expressed after the onset of endogenous Ptf1a; STXBP1, putative transmembrane protein TA-2, C25H, IGFBP1, IRF1, HALPN3, Hey1, sestrin 1, syndecan-4. These results provide insight into the regulatory network activated by Ptf1a during early pancreas development. In order to identify downstream targets of Ptf1a, two microarrays were performed at different time-points. The two microarrays compared control pancreatic tissue (GFP) and pancreatic tissue over-expressing Ptf1a (Ptf1a+GFP). The first microarray was performed at NF32, hence renamed MA32, 8 hours after the initial expression of endogenous Ptf1a. A second microarray was performed at NF36 (MA36), 8 hours after the first one. Ptf1a+gfp mRNA or gfp mRNA alone was injected into the two dorso-vegetal blastomeres of eight-cell embryos, targeting the anterior endoderm, and 40/48 hours later the anterior endoderm was dissected out. Approximated 15 endoderm explants were pooled for each RNA preparation, and both control and experimental samples were collected from the same batch of embryos; this was done in triplicate at NF32 and in quadruplicate at NF36 (Fig. 1A). For the NF32 microarray, we used the Affymetrix 3M-bM-^@M-^Y Xenopus laevis Genome 2.0 GeneChip, whereas for the NF36 microarray we used the Affymetrix 3M-bM-^@M-^Y Xenopus laevis Genome 1.0 GeneChip; the NF36 microarray was performed prior to the release of the 2.0 GeneChip.
Project description:Purpose: The goal of the study was to determine the effects of forced expression of the acinar transcription factors MIST1 and PTF1a in PDAC cells. Methods: Doxycycline inducible MIST1myc and PTF1amyc Panc-1 cells were generated using Clontech's Tetone System and subjected to RNA-Sequencing following doxycycline treatment. Results: 50 million sequence reads were mapped to the human genome. Data suggests acinar associated molecules were induced upon doxycyline treatment. Conclusions: MIST1 and PTF1a retain functional activity and can promote acinar gene expression in the context of pancreatic cancer cells.