Ehmt2 Inactivation in Pancreatic Epithelial Cells Shapes the Transcriptional Landscape and Inflammation Response of the Whole Pancreas [Spatial transcriptomics]
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ABSTRACT: The Euchromatic Histone Methyl Transferase Protein 2 (EHMT2), also known as G9a, deposits transcriptionally repressive chromatin marks that play pivotal roles in the maturation and homeostasis of multiple organs.Recently, we have shown that Ehmt2 inactivation in the mouse pancreas alters growth and immune gene expression networks, antagonizing Kras-mediated pancreatic cancer initiation and promotion. Here, we elucidate the essential role of Ehmt2 in maintaining a transcriptional landscape that protects organs from inflammation. Comparative RNA-seq studies between normal postnatal and young adult pancreatic tissue from Ehmt2 conditional knockout animals (Ehmt2 fl/fl ) targeted to the exocrine pancreatic epithelial cells (Pdx1-Cre and P48 Cre/+ ), reveal alterations in gene expression networks in the whole organ related to injury-inflammationrepair, suggesting an increased predisposition to damage. Thus, we induced an inflammation repair response in the Ehmt2 fl/fl pancreas and used a data science-based approach to integrate RNA-seq-derived pathways and networks, deconvolution digital cytology, and spatial transcriptomics. We also analyzed the tissue response to damage at the morphological, biochemical, and molecular pathology levels. The Ehmt2 fl/fl pancreas displays an enhanced injury-inflammation-repair response, offering insights into fundamental molecular and cellular mechanisms involved in this process. More importantly, these data show that conditional Ehmt2 inactivation in exocrine cells reprograms the local environment to recruit mesenchymal and immunological cells needed to mount an increased inflammatory response. Mechanistically, this response is an enhanced injury-inflammationrepair reaction with a small contribution of specific Ehmt2-regulated transcripts. Thus, this new knowledge extends the mechanisms underlying the role of the Ehmt2-mediated pathway in suppressing pancreatic cancer initiation and modulating inflammatory pancreatic diseases.
Project description:The Euchromatic Histone Methyl Transferase Protein 2 (EHMT2), also known as G9a, deposits transcriptionally repressive chromatin marks that play pivotal roles in the maturation and homeostasis of multiple organs.Recently, we have shown that Ehmt2 inactivation in the mouse pancreas alters growth and immune gene expression networks, antagonizing Kras-mediated pancreatic cancer initiation and promotion. Here, we elucidate the essential role of Ehmt2 in maintaining a transcriptional landscape that protects organs from inflammation. Comparative RNA-seq studies between normal postnatal and young adult pancreatic tissue from Ehmt2 conditional knockout animals (Ehmt2 fl/fl ) targeted to the exocrine pancreatic epithelial cells (Pdx1-Cre and P48 Cre/+ ), reveal alterations in gene expression networks in the whole organ related to injury-inflammationrepair, suggesting an increased predisposition to damage. Thus, we induced an inflammation repair response in the Ehmt2 fl/fl pancreas and used a data science-based approach to integrate RNA-seq-derived pathways and networks, deconvolution digital cytology, and spatial transcriptomics. We also analyzed the tissue response to damage at the morphological, biochemical, and molecular pathology levels. The Ehmt2 fl/fl pancreas displays an enhanced injury-inflammation-repair response, offering insights into fundamental molecular and cellular mechanisms involved in this process. More importantly, these data show that conditional Ehmt2 inactivation in exocrine cells reprograms the local environment to recruit mesenchymal and immunological cells needed to mount an increased inflammatory response. Mechanistically, this response is an enhanced injury-inflammationrepair reaction with a small contribution of specific Ehmt2-regulated transcripts. Thus, this new knowledge extends the mechanisms underlying the role of the Ehmt2- mediated pathway in suppressing pancreatic cancer initiation and modulating inflammatory pancreatic diseases.
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:Pancreatic ductal adenocarcinoma (PDAC) is an aggressive, painful disease with a 5-year survival rate of only 9%. Recent evidence indicates that distinct epigenomic landscapes underlie PDAC progression, identifying the H3K9me pathway as important to its pathobiology. Here, we delineate the role of Euchromatic Histone-lysine N-Methyltransferase 2 (EHMT2), the enzyme that generates H3K9me, as a downstream effector of oncogenic KRAS during PDAC initiation and pancreatitis-associated promotion. EHMT2 inactivation in pancreatic cells reduces H3K9me2 and antagonizes KrasG12D mediated acinar-to-ductal metaplasia (ADM) and PanIN formation in both the Pdx1-Cre and P48+/-Cre KrasG12D mouse models. Ex vivo acinar explants also show impaired EGFR-KRAS-MAPK pathway mediated ADM upon EHMT2 deletion. Notably, KrasG12D increases EHMT2 protein levels and EHMT2-EHMT1-WIZ complex formation. Transcriptome analysis reveals that EHMT2 inactivation upregulates a cell cycle inhibitory gene expression network that converges on the Cdkn1a/p21-Chek2 pathway. Congruently, pancreas tissue from KrasG12D animals with EHMT2 inactivation have increased P21 protein levels and enhanced senescence. Furthermore, loss of EHMT2 reduces inflammatory cell infiltration typically induced during KrasG12D-mediated initiation. The inhibitory effect on KrasG12D-induced growth is maintained in the pancreatitis-accelerated model, while simultaneously modifying immunoregulatory gene networks that also contribute to carcinogenesis. This study outlines the existence of a novel KRAS-EHMT2 pathway that is critical for mediating the growth-promoting and immunoregulatory effects of this oncogene in vivo, extending human observations to support a pathophysiological role for the H3K9me pathway in PDAC.
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.
Project description:The present study was constructed to confirm previous findings that mice on a high fat diet (HFD) treated by subcutaneous injection with exenatide (EXE) at 3µg/kg once daily for 6 weeks develop exocrine pancreatic injury (Rouse et al. 2014). The present study included 12 weeks of EXE exposure at multiple concentrations (3, 10, or 30 μg/kg) with multiple endpoints (histopathology evaluations, immunoassay for cytokines, immunostaining of the pancreas, serum chemistries and measurement of trypsin, amylase, and, lipase, and gene expression profiles). Time- and dose-dependent exocrine pancreatic injury was observed in mice associated with EXE exposure in a HFD environment. The time- and dose-dependent morphological changes identified in the pancreas involved acinar cell injury and death (autophagy, apoptosis, necrosis, and atrophy), cell adaptations (hypertrophy and hyperplasia), and cell survival (regeneration) accompanied with varying degrees of inflammatory response leading to secondary injury in pancreatic blood vessels, ducts, and adipose tissues. Gene expression profiles supported the presence of increased signaling for cell survival and altered lipid metabolism. The potential for EXE to cause acute or early chronic pancreatic injury was identified in a HFD environment. In human disease, the influence of pancreatitis risk factors or pre-existing chronic pancreatitis on this injury potential requires further investigation.
Project description:Pancreatic ducts form an intricate network of tubules that secrete bicarbonate and drive acinar secretions into the duodenum. This network is formed by centroacinar cells, terminal, intercalated, intracalated ducts, and the main pancreatic duct. Ductal heterogeneity at the single-cell level has been poorly characterized. Here, we used scRNA-seq to comprehensively characterize mouse ductal heterogeneity at single-cell resolution of the entire ductal epithelium from centroacinar cells to the main duct. Moreover, we used organoid cultures, injury models and pancreatic tumor samples to interrogate the role of novel ductal populations in pancreas regeneration and exocrine pathogenesis. In our study, we have identified the coexistence of 15 ductal populations within the healthy pancreas and characterized their organoid formation capacity and endocrine differentiation potential. Cluster isolation and subsequent culturing let us identify ductal cell populations with high organoid formation capacity and endocrine and exocrine differentiation potential in vitro, including Wnt-responsive-population, ciliated-population and FLRT3+ cells. Moreover, we have characterized the location of these novel ductal populations in healthy pancreas, chronic pancreatitis and tumor samples, hightlihgting a putative role of WNT-responsive, IFN-responsive and EMT-populations in pancreatic exocrine pathogenesis as their expression inceases in chronic pancreatitis and PanIN lesions. In light of our discovery of previously unidentified ductal populations, we unmask the potential roles of specific ductal populations in pancreas regeneration and exocrine pathogenesis.
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:Sox9 target genes were identified by comparing gene expression in Sox9-ablated versus wild-type pancreata using microarray analysis. Sox9 was conditionally ablated in the developing pancreas via recombination of a Sox9-flox allele (Kist et al., 2002) using the Pdx1-Cre transgene (Gu et al., 2002). Total RNA was isolated and pooled from dorsal pancreatic epithelia of e12.5 Sox9fl/fl; Pdx1-Cre (mutant) versus Sox9fl/fl (wild-type) littermates for three biological replicates.
Project description:Dysbiosis of the gut microbiota has been linked to disease pathogenesis in type 1 diabetes (T1D), yet the functional consequences to the host of this dysbiosis is unknown. Here, we have performed a metaproteomic analysis of 103 stool samples from subjects that either had recent-onset T1D, were high-risk autoantibody positive or low-risk autoantibody negative relatives of individuals with beta cell autoimmunity or healthy individuals to identify signatures in host and microbial proteins associated with disease risk. Multivariate modelling analysis demonstrated that both human host proteins and microbial derived proteins could be used to differentiate new-onset and seropositive individuals from low-risk and healthy controls. Significant alterations were identified between subjects with T1D or islet autoimmunity versus autoantibody negative and control subjects in the prevalence of individual host proteins associated with exocrine pancreas function, inflammation and mucosal function. Data integrationIntegrative analysis combining the metaproteomic data with bacterial abundance showed that taxa that were depleted in new-onset T1D patients were positively associated with host proteins involved in maintaining function of the mucous barrier, microvilli adhesion and exocrine pancreas. These data support the notion that T1D patients have increased intestinal inflammation and decreased barrier function. They also confirmed that pancreatic exocrine dysfunction occurs in new-onset T1D patients and show for the first time that this dysfunction is present in high-risk individuals prior to disease onset. Our data has identified a unique T1D-associated signature in stool that may be useful as a means to monitor disease progression or response to therapies aimed at restoring a healthy microbiota.
Project description:The goal of this study is to obtain an expression profile of regenerating mouse livers. We used microarray analysis to study the gene groups coordinately expressed temporally during mouse a liver regeneration. One of the syn-expression groups that showed a sharp rise in gene expression immediately after hepatectomy contains a set pancreatic exocrine genes. The syn-expression profile of pancreatic genes and the pancreatic-specific transcription factors Ptf1a and Ipf1 was confirmed using real-time PCR. Electron microscopic examination showed the presence of morphological features reminiscent of pancreatic acinar cells with the presence of characteristic zymogen granules and ER organization. These results indicate that there is a transient liver-to-pancreas transdifferentiation event at the beginning of liver regeneration. A strong coordinated up-regulation of pancreatic genes was found to accompany the injury response in the pancreas, suggesting a compensatory mechanism for pancreatic functions. There seems to be a relationship between the induction of pancreatic genes and acute phase response at the beginning of liver regeneration. Keywords: gene expression array-based (RNA / in situ oligonucleotide)