Project description:β-cell proliferation is a rare event in adult pancreatic islets. To study the replication-related β-cell biology we designed a replicating β-cells sorting system based on EdU incorporation for gene expression experiments. The global transcriptome of replicating and quiescent pancreatic β-cells was analysed using gene expression arrays.
Project description:We employed single-cell RNA sequencing of islets in young mice subjected to partial pancreatectomy (PPTx). Four clusters of pancreatic beta cells including a subpopulation of replicating beta cells. Pseudo-time course analysis clarified the gradual changes in gene expression from non-replicating beta cells to replicating ones. Upstream analysis visualized the transcriptional networks associated with beta cell replication by PPTx.
Project description:β-cell proliferation is a rare event in adult pancreatic islets. To study the replication-related β-cell biology we designed a replicating β-cells sorting system for gene expression experiments. Replicating β-cells were identified by EdU incorporation and purified by flow cytometry. For β-cell separation islet cells were sorted by size, granularity and Newport Green fluorescence emission that was combined with emitted fluorescence for EdU-labelled replicating cells sorting. The purity of the resulting sorted populations was evaluated by insulin staining and EdU for β-cell identification and for replicating cells, respectively. Total RNA was isolated from purified cell-sorted populations for gene expression analysis. Cell sorting of dispersed islet cells resulted in 96.2% purity for insulin positivity in the collected β-cell fraction and 100% efficiency of the EdU-based cell separation. RNA integrity was similar between FACS-sorted replicating and quiescent β-cells. Global transcriptome analysis of replicating vs quiescent β-cells showed the expected enrichment of categories related to cell division and DNA replication. Indeed, key genes in the spindle check-point were the most upregulated genes in replicating β-cells. This work provides a method that allows for the isolation of replicating β-cells, a very scarce population in adult pancreatic islets.
Project description:We employed single-cell RNA sequencing of islets in young mice subjected to partial pancreatectomy (PPTx). Four clusters of pancreatic beta cells including a subpopulation of replicating beta cells. Pseudo-time course analysis clarified the gradual changes in gene expression from non-replicating beta cells to replicating ones. Upstream analysis visualized the transcriptional networks associated with beta cell replication by PPTx.
Project description:The aim of the present study was to explore the transcriptome of pancreatic islets and, based on this information, to prepare a comprehensive and open access inventory of insulin-producing ?-cell gene expression, the beta-Cell Gene Atlas (BCGA). INS-1 cells, primary rat beta-cells (>87% beta-cells) and non-beta-cells (<3% beta cells, mostly alpha) were isolated by FACS mediated purification of two different rat islet preparations.
Project description:The NF-κB pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic beta cell dysfunction in the metabolic syndrome. While canonical NF-κB signaling is well studied, there is little information on the divergent non-canonical NF-κB pathway in the context of pancreatic islet dysfunction in diabetes. Here, we demonstrate that pharmacological activation of the non-canonical NF-κB inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. Further, we identify NIK as a critical negative regulator of beta cell function as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of non-canonical NF-κB components p100 to p52, and accumulation of RelB. Tumor necrosis factor α (TNFα) and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive beta cell intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the non-canonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to beta cell failure. These studies reveal that NIK contributes a central mechanism for beta cell failure in diet-induced obesity. We identify a role for Nuclear Factor inducing κB (NIK) in pancreatic beta cell failure. NIK activation disrupts glucose homeostasis in zebrafish in vivo and impairs glucose-stimulated insulin secretion in mouse and human islets in vitro. NIK activation also perturbs beta cell insulin secretion in a diet-induced obesity mouse model. These studies reveal that NIK contributes a central mechanism for beta cell failure in obesity. To uncover the role of NIK in pancreatic beta cells, we performed a gene expression microarray analysis comparing pancreatic islets with constitutive beta cell intrinsicNIK activation from the 16 week old mice (beta cell specific TRAF2 and TRAF2 knockout mice) to their controls (n=3 per group).
Project description:Pancreatic beta cells have well-developed endoplasmic reticulum (ER) to accommodate for the massive production and secretion of insulin. ER homeostasis is vital for normal beta cell function. Perturbation of ER homeostasis contributes to beta cell dysfunction in both type 1 and type 2 diabetes. To systematically identify the molecular machinery responsible for proinsulin biogenesis and maintenance of beta cell ER homeostasis, a widely used mouse pancreatic beta cell line, MIN6 cell was used to purify rough ER. Two different purification schemes were utilized. In each experiment, the ER pellets were solubilized and analyzed by one dimensional SDS-PAGE coupled with HPLC-MS/MS. A total of 1467 proteins were identified in three experiments with ≥95% confidence, among which 1117 proteins were found in at least two separate experiments. Gene ontology analysis revealed a comprehensive profile of known and novel players responsible for proinsulin biogenesis and ER homeostasis. This dataset defines a molecular environment in the ER for proinsulin synthesis, folding and export and laid a solid foundation for further characterizations of altered ER homeostasis under diabetes-causing conditions.