Project description:Androgenic steroids are increasingly used for hormone therapy of postmenopausal women and abused as life style drugs and for doping purposes, though knowledge about associated health risks in females is very limited. In order to understand more about short- and long-term androgen effects on a molecular level, we have analyzed hepatic gene expression in female C57BL/6 mice immediately after subcutaneous treatment with testosterone for 3 weeks and after 12 weeks hormone withdrawal using Affymetrix array technology and quantitative real-time RT-PCR. Among about 14,000 genes examined, 48 were up- and 65 genes were downregulated by testosterone after 3-weeks treatment and about 50% of these changes persisted even 12 weeks after testostrone withdrawal. In addition to obvious risks such as induction of hepatocellular carcinomas and virilization of liver metabolism, testosterone induced a series of changes, as e.g. dysregulation of hepatic gene expression due to incomplete conversion of female to male phenotype â in particular downregulation of cytochrom P450 isoforms and sulfotransferases. As a long-term testosterone effect, transcripts emerged in the liver that are normally specific for the exocine pancreas including amylase 2, ribonuclease 1, and several trypsin-, chymotrypsin-, and elastase-like proteases. This transdifferentiation of hepatic to exocrine pancreatic tissue indicates that testosterone can initiate long-lasting differentiation programs, which â once induced â progress even after androgen withdrawal. This may have far-reaching consequences difficult to foresee implying long-term hazards of testosterone-treatment for female health that have not been taken into account yet. Mice were treated with testosterone or sesame oil (vehicle) for three weeks twice a week. Gene expression in the liver was analyzed either directly after treatment or after three weeks of hormone/vehicle withdrawal. For each of these four groups, three individual mice were used as biological replicates.
Project description:Androgenic steroids are increasingly used for hormone therapy of postmenopausal women and abused as life style drugs and for doping purposes, though knowledge about associated health risks in females is very limited. In order to understand more about short- and long-term androgen effects on a molecular level, we have analyzed hepatic gene expression in female C57BL/6 mice immediately after subcutaneous treatment with testosterone for 3 weeks and after 12 weeks hormone withdrawal using Affymetrix array technology and quantitative real-time RT-PCR. Among about 14,000 genes examined, 48 were up- and 65 genes were downregulated by testosterone after 3-weeks treatment and about 50% of these changes persisted even 12 weeks after testostrone withdrawal. In addition to obvious risks such as induction of hepatocellular carcinomas and virilization of liver metabolism, testosterone induced a series of changes, as e.g. dysregulation of hepatic gene expression due to incomplete conversion of female to male phenotype – in particular downregulation of cytochrom P450 isoforms and sulfotransferases. As a long-term testosterone effect, transcripts emerged in the liver that are normally specific for the exocine pancreas including amylase 2, ribonuclease 1, and several trypsin-, chymotrypsin-, and elastase-like proteases. This transdifferentiation of hepatic to exocrine pancreatic tissue indicates that testosterone can initiate long-lasting differentiation programs, which – once induced – progress even after androgen withdrawal. This may have far-reaching consequences difficult to foresee implying long-term hazards of testosterone-treatment for female health that have not been taken into account yet.
Project description:Early postnatal overnutrition causes persistent dysregulation of endocrine pancreas function. We used genome-scale DNA methylation profiling in the suckling-period small litter (SL) mouse model to test whether this occurs via persistent epigenetic changes in pancreatic islets. Although SL islets showed DNA methylation changes directly after weaning and in adulthood, few of these were present at both ages, contrary to our hypothesis. Most interestingly, we discovered that genomic regions that are hypermethylated in exocrine relative to endocrine pancreas tend to gain methylation in islets during aging. Focusing on a subset of genes relevant to β cell function, we showed that these methylation differences are strongly correlated with expression. Together, our results provide the novel insight that DNA methylation changes that occur as islets age indicate an overall epigenetic drift toward the exocrine pancreas epigenome. These concerted shifts in the islet methylome could contribute to the age-associated decline in endocrine pancreas function. Pancreatic islets were isolated from P21/P180 SL or C mice. To ensure purity of islets, 3 rounds of manual picking were performed in each samples. Whole pancreas samples, ~98% of which is exocrine pancreas, were used as exocrine pancreas. There are 5 mice per group.
Project description:deBack2012 - Lineage Specification in Pancreas Development
This model of two neighbouring pancreas precursor cells, describes the exocrine versus endocrine lineage specification process. To account for the tissue scale patterns, this couplet model has been extended to hundreds of coupled cells.
This model is described in the article:
On the role of lateral stabilization during early patterning in the pancreas
de Back W., Zhou JX, Brusch L
J. R. Soc. Interface 6 February 2013 vol. 10 no. 79 20120766
Abstract:
The cell fate decision of multi-potent pancreatic progenitor cells between the exocrine and endocrine lineages is regulated by Notch signalling, mediated by cell–cell interactions. However, canonical models of Notch-mediated lateral inhibition cannot explain the scattered spatial distribution of endocrine cells and the cell-type ratio in the developing pancreas. Based on evidence from acinar-to-islet cell transdifferentiation in vitro, we propose that lateral stabilization, i.e. positive feedback between adjacent progenitor cells, acts in parallel with lateral inhibition to regulate pattern formation in the pancreas. A simple mathematical model of transcriptional regulation and cell–cell interaction reveals the existence of multi-stability of spatial patterns whose simultaneous occurrence causes scattering of endocrine cells in the presence of noise. The scattering pattern allows for control of the endocrine-to-exocrine cell-type ratio by modulation of lateral stabilization strength. These theoretical results suggest a previously unrecognized role for lateral stabilization in lineage specification, spatial patterning and cell-type ratio control in organ development.
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Project description:We have determined the cistrome and transcriptome for the nuclear receptor liver receptor homolog-1 (LRH-1) in the exocrine pancreas. Chromatin immunoprecipitation (ChIP)-seq and RNA-seq analyses reveal that LRH-1 directly induces expression of genes encoding digestive enzymes and secretory and mitochrondrial proteins. LRH-1 cooperates with the pancreas transcription factor 1-L complex (PTF1-L) in regulationg exocrine pancreas-specific gene expression. Elimination of LRH-1 in adult mice reduced the concentration of several lipases and proteases in pancreatic fluid and impaired pancreatic fluid secretion in response to cholecystokinin. Thus, LRH-1 is a key regulator of the exocrine pancreas-specific transcriptional network required for the production and secretion of pancreatic fluid. input and Lrh1 ChIP
Project description:We found that BAP1 (BRCA1 Associated Protein-1) shows loss of heterozygosity in over 25% of pancreatic cancer patients and functions as tumor suppressor. Conditional deletion of Bap1 in murine pancreas led to genomic instability, accumulation of DNA damage, and an inflammatory response that evolved to pancreatitis with full penetrance. Concomitant expression of oncogenic KrasG12D led to malignant transformation and development of invasive and metastatic pancreatic cancer. At the molecular level, BAP1 maintains the integrity of the exocrine pancreas by regulating genomic stability and its loss confers sensitivity to radio- and platinum-based therapies.
Project description:Testosterone (T) is known to masculinize the female phenotype of the liver evidenced as upregulated gene expression of male- and downregulated expression of female-predominant genes. To explore the a possibly T epigenetic control, we here screen genome-wide the liver for T-induced changes of the DNA methylation status of gene promoters. by methylated DNA immunoprecipitation and Nimblegen microarrays. Female C57BL/6 mice are treated with T for 3 weeks and, then, T treatment is discontinued for 12 weeks. The T-induced changes found suggest a functional impact since T induces under the same experimental conditions as used here persistent susceptibility to blood-stage malaria of Plasmodium chabaudi. We hypothesize that T epigenetically dys-regulates initial steps of liver-inherent innate immune mechanisms leading to dys-balanced host responses eventually causing the lethal outcome of otherwise self-healing infections.
Project description:Early postnatal overnutrition causes persistent dysregulation of endocrine pancreas function. We used genome-scale DNA methylation profiling in the suckling-period small litter (SL) mouse model to test whether this occurs via persistent epigenetic changes in pancreatic islets. Although SL islets showed DNA methylation changes directly after weaning and in adulthood, few of these were present at both ages, contrary to our hypothesis. Most interestingly, we discovered that genomic regions that are hypermethylated in exocrine relative to endocrine pancreas tend to gain methylation in islets during aging. Focusing on a subset of genes relevant to β cell function, we showed that these methylation differences are strongly correlated with expression. Together, our results provide the novel insight that DNA methylation changes that occur as islets age indicate an overall epigenetic drift toward the exocrine pancreas epigenome. These concerted shifts in the islet methylome could contribute to the age-associated decline in endocrine pancreas function.
Project description:We have determined the cistrome and transcriptome for the nuclear receptor liver receptor homolog-1 (LRH-1) in the exocrine pancreas. Chromatin immunoprecipitation (ChIP)-seq and RNA-seq analyses reveal that LRH-1 directly induces expression of genes encoding digestive enzymes and secretory and mitochrondrial proteins. LRH-1 cooperates with the pancreas transcription factor 1-L complex (PTF1-L) in regulationg exocrine pancreas-specific gene expression. Elimination of LRH-1 in adult mice reduced the concentration of several lipases and proteases in pancreatic fluid and impaired pancreatic fluid secretion in response to cholecystokinin. Thus, LRH-1 is a key regulator of the exocrine pancreas-specific transcriptional network required for the production and secretion of pancreatic fluid.