Project description:We aimed to assess whether Wnt-modulation could contribute to mature hiPSC-derived insulin-producing cells in vitro. Building our hypothesis on our previous findings of Wnt activation in immature hiPSC-derived insulin-producing cells compared to adult human islets and with recent data reporting a link between Wnt/PCP and in vitro beta-cell maturation. In this study we stimulated hiPSC-derived insulin-producing cells with syntetic proteins including WNT3A, WNT4, WNT5A and WNT5B as well as inhibiting endogeneous Wnt signaling with Tankyrase inhibitor G007-LK.
Project description:Transgenerational epigenetic inheritance is a subject of immense current interest. In a newly developed Drosophila model in the laboratory, genetic ablation of insulin-producing cells (IPCs) was found to affect whole -body triglyceride levels not only in the ablated flies but also in their male-line derived, non-ablated future generations. To further characterize this genetic-factor-induced transgenerational inheritance model, we have now performed whole body microarray gene expression profiling of adult males and females with genetically ablated IPCs, and of three consecutive, paternally derived non-ablated generations of adult males and females originating from ablated males. Interestingly, like altered levels of triglycerides, transcriptomic alterations are found not only in the ablated flies but also in their male-line-derived, non-ablated future generations.
Project description:A Drosophila microRNA (dme-miR-14) is involved in regulating the levels of insulin-like peptides (ilps) from the neuronal insulin-producing cells (IPCs). This is crucial for regulation of fat content in adult flies. Finding the target of this microRNA is crucial for understanding the regulation of ilp gene expression. We used microarrays to identify genes that are upregulated specifically in the neuronal IPCs in the microRNA mutants.
Project description:A Drosophila microRNA (dme-miR-14) is involved in regulating the levels of insulin-like peptides (ilps) from the neuronal insulin-producing cells (IPCs). This is crucial for regulation of fat content in adult flies. Finding the target of this microRNA is crucial for understanding the regulation of ilp gene expression. We used microarrays to identify genes that are upregulated specifically in the neuronal IPCs in the microRNA mutants. Drosophila adult head RNA was extracted and hybridized on Affymetrix microarrays. We reared animals from early larval stages in controlled growth and feeding conditions. RNA was extracted from 5-day-old adult males. We collected RNA from control, homozygous dme-miR-14 mutants and mutants expressing dme-miR-14 microRNA specifically in the IPCs (rescue). We were interested in genes that were upregulated in the mutants and were restored or reduced to control levels in the rescue condition. Two biological replicates per sample type were performed.
Project description:Purpose: Hnf1a is an important regulator of pancreas development. Mutation in this gene in humans lead to Maturity Onset Diabetes of the Young 3. Previous studies have shown that Hnf1a is important in function of insulin producing cells. However, they have not payed attention to islet cell identity, which we have focused on. Methods: Male WT mice or mice carrying either a single (htz) or both (hmz) floxed alles of the Hnf1a gene specifically in insulin producing beta-cells controlled by RIP-cre were maintainted in normal housing condition and glyceamia were monitored twice a week. Islet cells were isolated from 12 or 24 weeks old mice of each group and mRNA were extracted before shipping to Qiagen for analysis. Results: Mice carrying the floxed Hnf1a in beta-cells were mildly hyperglyceamic with alterations in expression of important cell identiy genes, potentially more sever with age.
Project description:Insulin and IGF signaling (IIS) is a complex system that controls diverse processes including growth, development, metabolism, stress responses and aging. Drosophila melanogaster IIS is propagated by eight Drosophila insulin-like peptides (DILPs), homologues of both mammalian insulin and IGFs, with various spatiotemporal expression patterns and functions. DILPs 1-7 are thought to act through a single Drosophila insulin/IGF receptor, InR, but it is unclear how the DILPs thereby mediate a range of physiological phenotypes. We determined the distinct cell signaling effects of DILP2 and DILP5 stimulation upon Drosophila S2 cells. DILP2 and DILP5 induced similar transcriptional patterns, but differed in signal transduction kinetics. DILP5 induced sustained phosphorylation of Akt, while DILP2 produced acute, transient Akt phosphorylation. Accordingly, we used phosphoproteomic analysis to identify distinct patterns of non-genomic signaling induced by DILP2 and DILP5. Across all treatments and replicates, 5250 unique phosphopeptides were identified, representing 1575 proteins. Among these peptides, DILP2, but not DILP5, dephosphorylated Ser15 on glycogen phosphorylase (GlyP), and DILP2, but not DILP5, was subsequently shown to repress enzymatic GlyP activity in S2 cells. The functional consequences of this difference were evaluated in adult Drosophila dilp mutants: dilp2 null adults have elevated GlyP enzymatic activity relative to wildtype, while dilp5 mutants have reduced GlyP activity.
Project description:β cell proliferation rates decline with age and adult β cells have limited self-duplicating activity for regeneration, which predisposes to diabetes. Here we show that, among MYC family members, Mycl was expressed preferentially in proliferating immature endocrine cells. Genetic ablation of Mycl caused a modest reduction in cell proliferation of pancreatic endocrine cells in neonatal mice. By contrast, systemic expression of Mycl in mice stimulated proliferation in pancreatic islet cells and resulted in expansion of pancreatic islets without forming tumors in other organs. Single-cell RNA sequencing and genetic tracing experiments revealed that the expression of Mycl provoked transcription signatures associated with immature proliferating endocrine cells and stimulated self-duplication in adult hormone-expressing cells. The expanded hormone-expressing cells ceased proliferation but persisted after withdrawal of Mycl expression. Remarkably, a subset of the expanded α cells gave rise to insulin-producing cells after the withdrawal. Moreover, transient Mycl expression in vivo was sufficient to normalize increased blood glucose levels in diabetic mice evoked by chemical ablation of β cells. In vitro expression of Mycl similarly provoked active replication without inducing apoptosis in adult hormone-expressing islet cells, even those from aged mice. Furthermore, the expanded islet cells functioned in diabetic mice after transplantation. Finally, we show that MYCL stimulated self-duplication of human adult cadaveric islet cells. Collectively, these results demonstrate that sole induction of Mycl expands adult β cells both in vivo and in vitro. Moreover, islet cell-specific reprogramming via transient Mycl transduction elicits endogenous expansion of insulin-producing cells in adult pancreas through both self-duplication of β cells and transdifferentiation ofα cells into insulin-producing cells, which may provide a regenerative strategy of β cells.
Project description:β cell proliferation rates decline with age and adult β cells have limited self-duplicating activity for regeneration, which predisposes to diabetes. Here we show that, among MYC family members, Mycl was expressed preferentially in proliferating immature endocrine cells. Genetic ablation of Mycl caused a modest reduction in cell proliferation of pancreatic endocrine cells in neonatal mice. By contrast, systemic expression of Mycl in mice stimulated proliferation in pancreatic islet cells and resulted in expansion of pancreatic islets without forming tumors in other organs. Single-cell RNA sequencing and genetic tracing experiments revealed that the expression of Mycl provoked transcription signatures associated with immature proliferating endocrine cells and stimulated self-duplication in adult hormone-expressing cells. The expanded hormone-expressing cells ceased proliferation but persisted after withdrawal of Mycl expression. Remarkably, a subset of the expanded α cells gave rise to insulin-producing cells after the withdrawal. Moreover, transient Mycl expression in vivo was sufficient to normalize increased blood glucose levels in diabetic mice evoked by chemical ablation of β cells. In vitro expression of Mycl similarly provoked active replication without inducing apoptosis in adult hormone-expressing islet cells, even those from aged mice. Furthermore, the expanded islet cells functioned in diabetic mice after transplantation. Finally, we show that MYCL stimulated self-duplication of human adult cadaveric islet cells. Collectively, these results demonstrate that sole induction of Mycl expands adult β cells both in vivo and in vitro. Moreover, islet cell-specific reprogramming via transient Mycl transduction elicits endogenous expansion of insulin-producing cells in adult pancreas through both self-duplication of β cells and transdifferentiation ofα cells into insulin-producing cells, which may provide a regenerative strategy of β cells.
Project description:In this study, we demonstrate that insulin is produced not only in the mammalian pancreas but also in adult neuronal cells derived from hippocampus and olfactory bulb. Paracrine Wnt3 plays an essential role in promoting the active expression of insulin in both hippocampus and olfactory bulb-derived neural stem cells. Our analysis indicates that the balance between Wnt3, which triggers the expression of insulin via NeuroD1 transcription factor, and IGFBP-4, which inhibits the original Wnt3 action, is regulated depending on the diabetic status. We also show that adult neural progenitors derived from diabetic animals retain the ability to give rise to insulin-producing cells and that grafting neuronal progenitors into the pancreas of diabetic animals reduces glucose levels. This study provides an example of a simple and direct use of adult stem cells from one organ to another, without introducing additional inductive genes. In this study, we demonstrate that insulin is produced not only in the mammalian pancreas but also in adult neuronal cells derived from hippocampus and olfactory bulb. Paracrine Wnt3 plays an essential role in promoting the active expression of insulin in both hippocampus and olfactory bulb-derived neural stem cells. Our analysis indicates that the balance between Wnt3, which triggers the expression of insulin via NeuroD1 transcription factor, and IGFBP-4, which inhibits the original Wnt3 action, is regulated depending on the diabetic status. We also show that adult neural progenitors derived from diabetic animals retain the ability to give rise to insulin-producing cells and that grafting neuronal progenitors into the pancreas of diabetic animals reduces glucose levels. This study provides an example of a simple and direct use of adult stem cells from one organ to another, without introducing additional inductive genes.