Project description:We developed a FACS-platform for the isolation of highly purified endocrine subsets from mouse islets, based on specific differential expression of CD24 on delta-cells and CD71 on beta-cells.
Project description:Identification of protein complexes for the synaptotagmin 13 protein from MDCK cells by Strep affinity purificaiton and LFQ mass spectrometry. Epithelial cell egression is important for organ development and cell differentiation, but also drives cancer metastasis. The tightly connected pancreatic epithelial differentiation and morphogenesis generate islets of Langerhans. However, the morphogenetic drivers and molecular mechanisms are largely unresolved. Here we identify the uncharacterized Synaptotagmin 13 (Syt13) as a major regulator of endocrine cell egression and islet morphogenesis and differentiation. We detected upregulation of Syt13 in endocrine precursors that associates with increased expression of several unique cytoskeletal components. High-resolution imaging reveals a previously unidentified apical-basal to front-rear repolarization during endocrine cell egression. Strikingly, Syt13 directly interacts with acetylated tubulin and phosphoinositide phospholipids to be recruited to the leading edge of egressing cells. Knockout of Syt13 discloses the impairment in endocrine cell egression and skews the α-to-β-cell ratio. At mechanistic levels, Syt13 regulates protein endocytosis to remodel the basement membrane and modulate cell-matrix adhesion at the leading edge of egressing endocrine cells. Altogether, these findings implicate that Ca2+-independent atypical Syt13 vesicular protein functions in regulating cell polarity to orchestrate endocrine cell egression and tissue morphogenesis.
Project description:The aim of this study was to determine the effect of transgenic Aire expression on the transcriptional profile of a tissue that normally does not express Aire: pancreatic islets. The transcriptional profile of transgenic RIP-Aire27 islets was compared to non-transgenic littermate islets as well as to archival NOD thymic medullary epithelial cells (MEC) data. All data were from non-obese diabetic (NOD) mice Experiment Overall Design: 3-wk-old individual male RIP-Aire27 or non-transgenic littermates islets were isolated by gradient purification followed by hanpicking under a microscope for subsequent RNA purification, labeling and hybridization to Affymetrix arrays.
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:Identification of protein intreactions for the synaptotagmin 13 protein from MDCK cells by BioID-based proximity labelling and LFQ mass spectrometry. Epithelial cell egression is important for organ development and cell differentiation, but also drives cancer metastasis. The tightly connected pancreatic epithelial differentiation and morphogenesis generate islets of Langerhans. However, the morphogenetic drivers and molecular mechanisms are largely unresolved. Here we identify the uncharacterized Synaptotagmin 13 (Syt13) as a major regulator of endocrine cell egression and islet morphogenesis and differentiation. We detected upregulation of Syt13 in endocrine precursors that associates with increased expression of several unique cytoskeletal components. High-resolution imaging reveals a previously unidentified apical-basal to front-rear repolarization during endocrine cell egression. Strikingly, Syt13 directly interacts with acetylated tubulin and phosphoinositide phospholipids to be recruited to the leading edge of egressing cells. Knockout of Syt13 discloses the impairment in endocrine cell egression and skews the α-to-β-cell ratio. At mechanistic levels, Syt13 regulates protein endocytosis to remodel the basement membrane and modulate cell-matrix adhesion at the leading edge of egressing endocrine cells. Altogether, these findings implicate that Ca2+-independent atypical Syt13 vesicular protein functions in regulating cell polarity to orchestrate endocrine cell egression and tissue morphogenesis.
Project description:To define genetic pathways that regulate development of the endocrine pancreas, we generated transcriptional profiles of enriched cells isolated from four biologically significant stages of endocrine pancreas development: endoderm before pancreas specification, early pancreatic progenitor cells, endocrine progenitor cells and adult islets of Langerhans. These analyses implicate new signaling pathways in endocrine pancreas development, and identified sets of known and novel genes that are temporally regulated, as well as genes that spatially define developing endocrine cells from their neighbors. The differential expression of several genes from each time point was verified by RT-PCR and in situ hybridization. Moreover, we present preliminary functional evidence suggesting that one transcription factor encoding gene (Myt1), which was identified in our screen, is expressed in endocrine progenitors and may regulate alpha, beta and delta cell development. In addition to identifying new genes that regulate endocrine cell fate, this global gene expression analysis has uncovered informative biological trends that occur during endocrine differentiation.
Project description:To gain insights into how pancreatic cells are programmed in vivo, we profiled Ring1b in embryonic stem cells and pancreatic islets
Project description:In this study, we achieved integrated transcriptomic and proteomic profiles of GK islets in a time-course fashion at different stages of T2D. Subsequent bioinformatics analysis revealed the chronological order of T2D-related molecular events during the deterioration of pancreatic islets. Our large quantitative dataset provide a valuable resource to obtain a comprehensive picture of the mechanisms responsible for islet dysfunction and to identify potential interventions to prevent beta-cell failure in human T2D.
Project description:To gain insights into how pancreatic cells are programmed in vivo, we profiled RNA expression in pancreatic islets of pancreatic Ring1b conditional KO mice (conditional using a pancreas specfic Cre; Pdx1-Cre) and their littermate controls