Project description:Pancreatic islets depend on cytosolic calcium to trigger the secretion of glucoregulatory hormones and the transcriptional regulation of genes important for islet response to stimuli. To date, there has not been an attempt to profile calcium-regulated gene expression in all islet cell types. To address this, we generated a large single cell transcriptomic dataset from healthy human islets exposed to conditions that would acutely induce or inhibit intracellular calcium signaling, while preserving biological heterogeneity. Our aim was to use this dataset to identify acutely calcium-regulated genes in each islet cell type, while simulataneously exploring markers of islet heterogeneity.
Project description:Islet transplantation is an ideal option for diabetes while early graft lose serves as a major obstacle. Human umbilical cord mesenchymal stem cells (hucMSC) have multiple functions including the maintenance of cellular homeostasis. However, it is unknown whether extracellular vesicles (EVs) derived from hucMSC (hucMSC-EVs) provide protective effects against transplant-related trauma-induced islet injury. Here, we isolated and purified hucMSC-EVs, and found that hucMSC-EVs promoted grafted islet survival, and enhanced glycemic control following co-transplantation in a syngeneic streptozotocin (STZ)-induced mouse model of diabetes. After co-cultured for 12 h or 24 h, labelled hucMSC-EVs with PKH67 were readily internalized by NIT-1 β cells and islets. In tunicamycin (Tm) and thapsigargin (Tg) induced specific endoplasmic reticulum stress (ERS) cell injury models, hucMSC-EVs treatment improved cell viability and β cells function both in NIT-1 cells and ex vivo primary islets. Bulk RNA-seq demonstrated that hucMSC-EVs treatment significantly involved in ERS and the negative regulated mitochondrial apoptotic pathway. While ERS promoted interactions between endoplasmic reticulum (ER) and mitochondria, hucMSC-EVs alleviated ERS, maintained calcium homeostasis, and improved mitochondrial energy metabolism. Notably, the downregulation of XBP1 by hucMSC-EVs fine-tuned ER-mitochondria communication via reducing inositol-1,4,5-trisphosphate receptors at mitochondria-associated membranes (MAMs). Reduced XBP1 also activated Nrf2, restoring mitochondrial calcium homeostasis under ERS. miRNA analysis identified miR-182-5p enriched in hucMSC-EVs that specifically targeted XBP1 mRNA, leading to its degradation and downregulation. These findings demonstrate that hucMSC-EVs protect grafted islets by blocking XBP1 and restoring calcium homeostasis, thus suggesting their potential as a cell-free therapy for improving islet transplantation outcomes.
Project description:Immune-mediated beta cell destruction and lack of alpha cell responsiveness to hypoglycaemia are hallmarks of type 1 diabetes pathology. The incretin hormone glucose-dependent insulinotropic polypeptide (GIP) may hold therapeutic potential for type 1 diabetes due to its insulinotropic and glucagonotropic effects as well as its beta cell protective effects shown in rodent islets. Here, we examined the functional and transcriptomic effects of GIP treatment upon diabetogenic cytokine exposure to interleukin (IL)-1β ± interferon (IFN)-γ in human EndoC-βH5 beta cells and isolated human islets, respectively. GIP dose-dependently augmented glucose-stimulated insulin secretion from EndoC-βH5 cells and increased insulin and glucagon secretion from human islets during high and low glucose concentrations, respectively. The insulinotropic effect of GIP in EndoC-βH5 cells was abrogated by KN-93, an inhibitor of calcium/calmodulin-dependent protein kinase 2 (CaMK2). GIP did not prevent cytokine-induced apoptosis or cytokine-induced functional impairment of human EndoC-βH5 cells. GIP also did not prevent cytokine-induced apoptosis in human islets. GIP treatment of human islets with or without cytokines for 24 hours did not significantly impact the transcriptome. GIP potentiated cytokine-induced secretion of IL-10 and c-c motif chemokine ligand (CCL)-2 from human islets while decreasing the secretion of c-x-c motif chemokine ligand (CXCL)-8. In EndoC-βH5 cells, GIP reduced IFN-γ-induced secretion of tumor necrosis factor (TNF)-α, IL-2, IL-6, and IL-10, but increased the secretion of CXCL8, CCL2, CCL4, and CCL11. In conclusion, our results suggest that the insulinotropic effect of GIP is CaMK2-dependent. Furthermore, our results indicate that GIP does not provide substantial cytoprotective effects against diabetogenic cytokine challenge or significantly modulate the transcriptome of human islets when applied at a supraphysiological level. GIP may, however, still exert selective inflammation-modulatory effects upon diabetogenic cytokine exposure.
Project description:We have used RNA-seq to identify transcripts expressed in human islets harboring beta cells transduced to overexpress STX4 and induce chemokine ligand by adenoviral transduction
Project description:Intrauterine growth restriction is a common complication of pregnancy. We induce IUGR in rats by bilateral uterine artery ligation at e18 of a 23 day gestation. This mimics placental insufficiency. This array experiment compares gene expression changes in isolated pancreatic islets from e19, 24 hours post-surgery , or sham operated animals. RNA from isolated pancreatic islets from e19 fetuses, pooled from an entire litter. There are 4 control (sham) operated litters and 4 IUGR litters.
Project description:Calcium acts as a universal second messenger to regulate gene expression in both developmental processes and responses to environmental stresses. Previous studies showed that a number of stimuli can induce calcium increases in the cytoplasm and nucleus, independently. However, the gene expression network deciphering [Ca2+]cyt and/or [Ca2+]nuc signaling pathway remain obscure. Using transgenic Arabidopsis containing a fusion protein, comprising rat parvalbumin (PV) with either a nuclear export sequence (PV-NES) or a nuclear localization sequence (NLS-PV), to selectively buffer the cytosolic or nucleosolic calcium, we identified the [Ca2+]cyt- or /and [Ca2+]nuc-regulated ABA- and MeJA-responsible genes with the Arabidopsis Genome Oligo array.
Project description:Intramuscular fat (IMF) in pork holds significant importance for economic performance within the pig industry and dietary calcium supplementation enhances the accumulation of intramuscular fat. Additionally, calcium ions inhibit translation and reduce protein synthesis. However, the mechanism by which calcium regulates IMF deposition in muscle through translation remains largely unknown. In this study, we compared the ribosome profiles of the longissimus dorsi muscles of trigram pigs from the normal calcium (NC) group or calcium supplement (HC) group by Ribo-seq, and RNA-seq. By integrating multiple-omics analysis, we further discovered 437 genes that were transcriptionally unchanged but translationally altered and these genes