Pancreatic regeneration in chronic pancreatitis requires activation of the Notch signaling pathway
ABSTRACT Chronic pancreatitis as an inflammatory process characterized by morphological changes, pancreatic dysfunction, and pain. During pancreatic injury and repair the Notch signaling pathway is reinstated. The current study analyzed this pathway in chronic pancreatitis and characterized its influence on fibrogenesis. Real-time quantitative PCR and immunohistochemistry were used for expression studies. Notch activation was determined by a specific luciferase-HES-1-reporter gene constructs. Cells were stimulated with alcohol, glucose, bile acids, and steroids. Notch-2, -3, and -4 mRNA, were overexpressed in chronic pancreatitis specimens. The ligands Jagged-1, -2, and Delta-1 were highly overexpressed. Jagged-1 and Notch receptors were observed in nerves, regenerating exocrine cells, and endocrine cells. Delta staining was present in ductal but not in acinus cells and not in nerves. Activation of Notch signaling was detectable upon cell stimulation with glucose, steroids, and bile acids. High glucose levels were further associated with increased collagen-I production. The Notch pathway is reactivated during chronic pancreatitis. Among the stimuli activating the Notch pathway are steroids, high glucose levels, and bile acids. These findings suggest a possible role of the Notch pathway during pancreatic regeneration since Jagged-1 inhibits inducible collagen-1 production, suggesting a new mechanism of tissue repair in this disease.
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ABSTRACT: Pancreatic adenocarcinoma, one of the worst malignancies of exocrine pancreas, is a solid tumor with increasing incidence and mortality in industrialized countries. It is usually driven by oncogenic Kras point mutations and evolves into a highly aggressive metastatic carcinoma due to secondary gene mutations and specific signaling pathways unbalance. To examine in vivo the effects of Kras(G12D) during pancreatic cancer progression and time correlation with cancer signaling pathways activities, we have generated a zebrafish model of Pancreatic adenocarcinoma in which eGFP-Kras(G12D) expression was specifically driven to the pancreatic tissue by using the GAL4/UAS conditional expression system. Outcrossing the inducible oncogenic Kras(G12D) line with transgenic zebrafish reporters harboring specific signaling responsive elements of transcriptional effectors, we were able to follow TGFβ, Notch, Bmp and Shh activities during tumor development. Zebrafish transgenic lines expressing eGFP-Kras(G12D) showed normal exocrine pancreas development till 3 weeks post fertilization (wpf). From 4 to 24 wpf we observed several degree of acinar lesions, characterized by an increase of mesenchymal cells and mixed acinar/ductal features followed by progressive bowel and liver infiltrations finally bringing to highly aggressive carcinoma. Moreover, live imaging analysis of the exocrine pancreatic tissue revealed an increasing number of Kras positive cells and progressive activation of TGFβ; and Notch pathways. Increase of TGFβ, following Kras(G12D) activation, was confirmed in a concomitant model of medulloblastoma (MDB). Notch and Shh signaling activities during tumor onset were different between MDB and pancreatic adenocarcinoma indicating a tissue specific regulation of cell signaling pathways. Moreover, our results shows that a living model of pancreatic adenocarcinoma joined with cell signaling reporters is a suitable tool to describe in vivo the signaling cascades and molecular mechanisms involved in tumor development and a potential platform to screen for novel oncostatic drugs.Disease Models and Mechanisms 05/2014; DOI:10.1242/dmm.014969 · 5.54 Impact Factor
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ABSTRACT: Type 1 Diabetes (T1D) is a chronic multifactorial disease with a strong genetic component, which, through interactions with specific environmental factors, triggers disease onset. T1D typically manifests in early to mid childhood through the autoimmune destruction of pancreatic β cells resulting in a lack of insulin production. Historically, prior to genome-wide association studies (GWAS), six loci in the genome were fully established to be associated with T1D. With the advent of high-throughput single nucleotide polymorphism (SNP) genotyping array technologies, enabling investigators to perform high-density GWAS, many additional T1D susceptibility genes have been discovered. Indeed, recent meta-analyses of multiple datasets from independent investigators have brought the tally of well-validated T1D disease genes to almost 60. In this mini-review, we address recent advances in the genetics of T1D and provide an update on the latest susceptibility loci added to the list of genes involved in the pathogenesis of T1D.09/2013; 4(3):499-521. DOI:10.3390/genes4030499
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ABSTRACT: Notch family members were first identified as cell adhesion molecules by cell aggregation assays in Drosophila studies. However, they are generally recognized as signaling molecules, and it was unclear if their adhesion function was restricted to Drosophila. We previously demonstrated that a mouse Notch ligand, Delta-like 1 (Dll1) functioned as a cell adhesion molecule. We here investigated whether this adhesion function was conserved in the diversified mammalian Notch ligands consisted of two families, Delta-like (Dll1, Dll3 and Dll4) and Jagged (Jag1 and Jag2). The forced expression of mouse Dll1, Dll4, Jag1, and Jag2, but not Dll3, on stromal cells induced the rapid and enhanced adhesion of cultured mast cells (MCs). This was attributed to the binding of Notch1 and Notch2 on MCs to each Notch ligand on the stromal cells themselves, and not the activation of Notch signaling. Notch receptor-ligand binding strongly supported the tethering of MCs to stromal cells, the first step of cell adhesion. However, the Jag2-mediated adhesion of MCs was weaker and unlike other ligands appeared to require additional factor(s) in addition to the receptor-ligand binding. Taken together, these results demonstrated that the function of cell adhesion was conserved in mammalian as well as Drosophila Notch family members. Since Notch receptor-ligand interaction plays important roles in a broad spectrum of biological processes ranging from embryogenesis to disorders, our finding will provide a new perspective on these issues from the aspect of cell adhesion.PLoS ONE 09/2014; 9(9):e108535. DOI:10.1371/journal.pone.0108535 · 3.53 Impact Factor