Project description:Aims/hypothesis: Duct cells isolated from adult human pancreas can be reprogrammed to express islet beta cell genes by adenoviral transduction of the developmental transcription factor neurogenin3 (Ngn3). In this study we aimed to fully characterize the extent of this reprogramming and intended to improve it. Methods: The extent of the Ngn3-mediated duct-to-endocrine cell reprogramming was measured employing genome wide mRNA profiling. By modulation of the Delta-Notch signaling or addition of pancreatic endocrine transcription factors Myt1, MafA and Pdx1 we intended to improve the reprogramming. Results: Ngn3 stimulates duct cells to express a focused set of genes that are abundant in islet endocrine cells and/or neural tissues. This neuro-endocrine shift, however, covers a minor fraction (5%) of the estimated genome-wide transcriptome difference between duct and islet endocrine cells. Interestingly, transduction of exogenous Ngn3 activates endogenous Ngn3 suggesting auto-activation of this gene. Furthermore, pancreatic endocrine reprogramming of human duct cells can be moderately enhanced by inhibition of Delta-Notch signaling as well as by co-expressing the transcription factor Myt1, but not MafA and Pdx1. Conclusions/interpretation: The results provide further insight into the plasticity of adult human duct cells and suggest measurable routes to enhance Ngn3-mediated in vitro reprogramming protocols for regenerative beta cell therapy in diabetes. We used Affymetrix HG133A and HG133B to get a comprehensive view on the reprogramming potential in vitro of human pancreatic duct cell cultures (n=3-4) at 3 and 14/20 days after ectopic adenoviral expression of murine neurogenin 3 as compared to GFP-expressing control vectors. The microarray analysis was performed on 3 independent samples that each contained RNA extracted from a pool of 3 independent donor pancreata. The total number of non-selected donor organs is 9. Transcripts were considered as differentially regulated by Ngn3 when 1.5 fold (LCB, unpaired P < 0.05) up- or down-regulated in AdGFP-Ngn3 versus AdGFP controls, at 3 and/or 14 dpi. Transcripts that showed differential expression between day 3 and day 14 in AdGFP-Ngn3 duct cells but not in AdGFP control cells, were also considered Ngn3-regulated

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 ofα cells into insulin-producing cells, which may provide a regenerative strategy of β cells.

			Action	DRS
	Phosphoproteomics_phospho.zip	Other
	Phosphoproteomics_phospho_output.zip	Other
	Phosphoproteomics_proteome.zip	Other
	Phosphoproteomics_proteome_output.zip	Other
	Proteomics.zip	Other

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Decoding pancreatic islet cell diversity through cell type-resolved proteomics and phosphoproteomics

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