Project description:Although early developmental processes involve cell fate decisions that define the body axes and establish progenitor cell pools, development does not cease once cells are specified. Instead, most cells undergo specific maturation events where changes in the cell transcriptome ensure that the proper gene products are expressed to carry out unique physiological functions. Pancreatic acinar cells mature post-natally to handle an extensive protein synthetic load, establsih organized apical-basal polarity for zymogen granule trafficking, and assemble gap-junctions to perimt efficient cell-cell communication. Despite significant progress in defining transcriptional networks that control initial acinar cell specification and differentiation decisions, little is know regarding the role of transcription factors in the specification and maintenance of maturation events. One candidate maturation effector is MIST1, a secretory cell-restricted transcription factor that has been implicated in controlling regulated exocytosis events in a number of cell types. Embryonic knock-out of MIST1 generates acinar cells that fail to establish an apical-basal organization, fail to properly localize zymogen granule and fail to communicate intra-cellularly, making the exocrine organ highly suceptible to pancreatic diseases. In an effort to identify the gene expression differences responsible for MIST1 regulating mature acinar properties. We generated a tamoxifen-inducible mouse model where MIST1 expression could be activated in vivoand performed gene expression arrays on wildtype, MIST1-null, and induced MIST1 pancreatic RNA. RNA was isolated from pancreata of 8 week old mice using the Qiagen RNeasy Midi kit. Pancreta of wildtype, MIST1-null, and MIST1-null with a tamoxifen inducible MIST1-expressing transgene were harvested 36 hours post-tamoxifen administration. Therefore, this experiment provides information on steady-state gene expression differences between wildtype and MIST1-null mice as well as immediate gene expression changes induced by MIST1 expression.
Project description:Although early developmental processes involve cell fate decisions that define the body axes and establish progenitor cell pools, development does not cease once cells are specified. Instead, most cells undergo specific maturation events where changes in the cell transcriptome ensure that the proper gene products are expressed to carry out unique physiological functions. Pancreatic acinar cells mature post-natally to handle an extensive protein synthetic load, establsih organized apical-basal polarity for zymogen granule trafficking, and assemble gap-junctions to perimt efficient cell-cell communication. Despite significant progress in defining transcriptional networks that control initial acinar cell specification and differentiation decisions, little is know regarding the role of transcription factors in the specification and maintenance of maturation events. One candidate maturation effector is MIST1, a secretory cell-restricted transcription factor that has been implicated in controlling regulated exocytosis events in a number of cell types. Embryonic knock-out of MIST1 generates acinar cells that fail to establish an apical-basal organization, fail to properly localize zymogen granule and fail to communicate intra-cellularly, making the exocrine organ highly suceptible to pancreatic diseases. In an effort to identify the gene expression differences responsible for MIST1 regulating mature acinar properties. We generated a tamoxifen-inducible mouse model where MIST1 expression could be activated in vivoand performed gene expression arrays on wildtype, MIST1-null, and induced MIST1 pancreatic RNA.
Project description:Epigenetic profile of tissues is reprogrammed under diseased conditions. H3K4Me3 and H3K27Me3 represent active and repressive epigenetic marks, respectively. ChIP-seq is an effective tool to study global protein-DNA interactions. To study global epigenetic differences, we used H3K4Me3 antibody to evaluate its enrichment in pancreatic acinar cells of WT and Mist1-/- mice followed by next generation sequencing. We found specific hotspots that showed differential enrichment for H3K4Me3 both in WT and Mist1-/- mice. The data show that pancreatic acinar cells are epigenetically reprogrammed under stressed cellular conditions. Global H3K4Me3 profiling of WT and Mist1-/- pancreatic acinar cells using ChIP-seq.
Project description:Pancreatitis is triggered by environmental or cellular stress and is the leading contributor to pancreatic ductal adenocarcinoma. Altered gene expression in response to acinar cell stress determines the severity and duration of pancreatitis. However, it is unclear what factors contribute to this phenomenon. Here, we define a novel role for Activating Transcription Factor 3 (ATF3) during pancreatic injury. ATF3, a key mediator in the unfolded protein response, is robustly expressed in acinar cells during pancreatitis. Targeted deletion of Atf3 altered the molecular response to injury, with Atf3-/- acinar cells maintaining cell organization in response to cerulein, a well-established inducer of pancreatitis. Characterization of the mechanism using chromatin immunoprecipitation followed by Next Generation sequencing (ChIP-seq) identified 11,771 enrichment spots for ATF3, with known transcriptional start sites for >3,000 genes within 5 kb of ATF3 enrichment. Gene ontology analysis revealed a significant representation of ATF3 enrichment to genes affecting cell organization, including Mist1, a molecule required for establishing acinar cell organization. We confirmed a direct interaction of ATF3 to the Mist1 promoter during pancreatitis, and showed that ATF3 is required for altered Mist1 expression in response to injury. Finally, we demonstrate that ATF3 repression of Mist1 involves HDAC5. These findings suggest that ATF3 is a key transcriptional regulator during pancreatitis and promotes loss of the mature acinar cell phenotype in response to pancreatic injury. Two samples were produced from male mice 4 hours after CIP initiation from intraparitoneal injections of cerulein, a ChIP sample using an ATF3 antibody and an IP control.
Project description:Epigenetic profile of tissues is reprogrammed under diseased conditions. H3K4Me3 and H3K27Me3 represent active and repressive epigenetic marks, respectively. ChIP-seq is an effective tool to study global protein-DNA interactions. To study global epigenetic differences, we used H3K4Me3 antibody to evaluate its enrichment in pancreatic acinar cells of WT and Mist1-/- mice followed by next generation sequencing. We found specific hotspots that showed differential enrichment for H3K4Me3 both in WT and Mist1-/- mice. The data show that pancreatic acinar cells are epigenetically reprogrammed under stressed cellular conditions.
Project description:Pancreatitis is triggered by environmental or cellular stress and is the leading contributor to pancreatic ductal adenocarcinoma. Altered gene expression in response to acinar cell stress determines the severity and duration of pancreatitis. However, it is unclear what factors contribute to this phenomenon. Here, we define a novel role for Activating Transcription Factor 3 (ATF3) during pancreatic injury. ATF3, a key mediator in the unfolded protein response, is robustly expressed in acinar cells during pancreatitis. Targeted deletion of Atf3 altered the molecular response to injury, with Atf3-/- acinar cells maintaining cell organization in response to cerulein, a well-established inducer of pancreatitis. Characterization of the mechanism using chromatin immunoprecipitation followed by Next Generation sequencing (ChIP-seq) identified 11,771 enrichment spots for ATF3, with known transcriptional start sites for >3,000 genes within 5 kb of ATF3 enrichment. Gene ontology analysis revealed a significant representation of ATF3 enrichment to genes affecting cell organization, including Mist1, a molecule required for establishing acinar cell organization. We confirmed a direct interaction of ATF3 to the Mist1 promoter during pancreatitis, and showed that ATF3 is required for altered Mist1 expression in response to injury. Finally, we demonstrate that ATF3 repression of Mist1 involves HDAC5. These findings suggest that ATF3 is a key transcriptional regulator during pancreatitis and promotes loss of the mature acinar cell phenotype in response to pancreatic injury.
Project description:Pancreatic acinar cell reprogramming is described as a common hallmark in pancreatic regeneration and carcinogenesis, although the regulatory mechanisms are barely understood. To overcome limitations of cellular diversity posed by heterogeneous cell compositions and high stroma density in pathogenic tissue specimens, we have established a pure in vitro system mimicking the pancreatic carcinogenic sequence. With this model, we globally profiled for epigenetic and transcriptional alterations and demonstrate that regulatory key players and structural genes are extensively regulated by epigenetic mechanisms. A conditional knockout of the epigenetic repressor Ring1b showed that particularly the epigenetic silencing of acinar differentiation genes is a crucial step in acinar cell reprogramming and pancreatic cancer development. Moreover, a persistent epigenetic repression of these genes manifests tumor cell malignancy. Depletion or drug-dependent inhibition of Ring1b promoted tumor cell reprogramming towards a less aggressive phenotype offering new options for therapeutic intervention. Simone,Benitz
Project description:Pancreatic acinar cell reprogramming is described as a common hallmark in pancreatic regeneration and carcinogenesis, although the regulatory mechanisms are barely understood. To overcome limitations of cellular diversity posed by heterogeneous cell compositions and high stroma density in pathogenic tissue specimens, we have established a pure in vitro system mimicking the pancreatic carcinogenic sequence. With this model, we globally profiled for epigenetic and transcriptional alterations and demonstrate that regulatory key players and structural genes are extensively regulated by epigenetic mechanisms. A conditional knockout of the epigenetic repressor Ring1b showed that particularly the epigenetic silencing of acinar differentiation genes is a crucial step in acinar cell reprogramming and pancreatic cancer development. Moreover, a persistent epigenetic repression of these genes manifests tumor cell malignancy. Depletion or drug-dependent inhibition of Ring1b promoted tumor cell reprogramming towards a less aggressive phenotype offering new options for therapeutic intervention.