Project description:After their destruction in adult mice, insulin-producing pancreatic beta-cells slowly regenerate from other islet cells, like glucagon-producing alpha-cells. However the molecular basis of this conversion is unknown. Moreover it remains unclear if this intra-islet cell conversion is relevant to human diseases with extensive beta-cell loss, like in type 1 diabetes (T1D). Here, we show that subsets of glucagon-expressing cells in subjects with T1D produce Insulin and other molecular features of beta-cells, accompanied by loss of the alpha-cell regulators DNA methyltransferase 1 (Dnmt1) and Aristaless-related homeobox (Arx). We generated mice permitting lineage tracing and inactivation of Dnmt1 and Arx in adult alpha-cells. Within 3 months of Dnmt1 and Arx loss, 50% of alpha-cells converted into cells producing insulin protein but not glucagon, changes not observed in alpha-cells after only Arx or Dnmt1 loss. Single cell isolation and high-throughput RNA sequencing revealed efficient and extensive alpha-cell conversion into progeny indistinguishable by global gene expression from native beta-cells. Our work reveals pathways regulated by Arx and Dnmt1 sufficient for achieving targeted generation of beta-cells from adult pancreatic alpha-cells.
Project description:Type 1 diabetes is characterized by the destruction of pancreatic beta cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising approach is transdifferentiation of developmentally related pancreatic cell types including glucagon-producing alpha cells. In a genetic model, overexpression of the master regulatory transcription factor Pax4 or loss of its counterplayer Arx are sufficient to induce the conversion of alpha cells to functional beta-like cells. Here we identify artemisinins as small molecules that functionally repress Arx and induce beta-cell characteristics in alpha cells. We show that the protein gephyrin is the mammalian target of these antimalaria drugs. Finally, we demonstrate that gephyrin-mediated enhancement of GABAA receptor signaling is the mechanism of action of these molecules in pancreatic transdifferentiation. Our results indicate that gephyrin is a novel druggable target for the regeneration of pancreatic beta cell mass from alpha cells.
Project description:Type 1 diabetes is characterized by the destruction of pancrea tic beta cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising approach is transdifferentiation of developmentally related pancreatic cell types including glucagon-producing alpha cells. In a genetic model, loss of the master regulatory transcription factor Arx is sufficient to induce the conversion of alpha cells to functional beta-like cells. Here we identify artemisinins as small molecules that functionally repress Arx by causing its translocation to the cytoplasm. We show that the protein gephyrin is the mammalian target of these antimalaria drugs, and that enhancement of GABAA receptor signaling contributes to the mechanism of action of these molecules in pancreatic transdifferentiation. Our results in zebrafish, rodents and primary human pancreatic islets indicate that gephyrin is a novel druggable target for the regeneration of pancreatic beta cell mass from alpha cells.
Project description:Islet-enriched transcription factors (TFs) exert broad control over cellular processes in pancreatic α and β cells and changes in their expression are associated with developmental state and diabetes. However, the implications of heterogeneity in TF expression across islet cell populations are not well understood. To define this TF heterogeneity and its consequences for cellular function, we profiled >40,000 cells from normal human islets by scRNA-seq and stratified α and β cells based on combinatorial TF expression. Subpopulations of islet cells co-expressing ARX/MAFB (α cells) and MAFA/MAFB (β cells) exhibited greater expression of key genes related to glucose sensing and hormone secretion relative to subpopulations expressing only one or neither TF. Moreover, all subpopulations were identified in native pancreatic tissue from multiple donors. By Patch-seq, MAFA/MAFB co-expressing β cells showed enhanced electrophysiological activity. Thus, these results indicate combinatorial TF expression in islet α and β cells predicts highly functional, mature subpopulations.
Project description:Transcriptional profiling of a directed differentiation time course converting human embryonic stem cells (hES) into immature pancreatic beta cell precursors.
Project description:miRNA transcript profiling of a directed differentiation time course converting human embryonic stem cells (hES) into immature pancreatic beta cell precursors.
Project description:<p>Most pancreatic neuroendocrine tumors (PNETs) do not produce symptoms of hormonal excess and are hence considered “non-functional”. Their clinical behaviors vary widely, emphasizing the need for a robust classification with prognostic power. Using enhancer maps to infer regulatory programs, we find that the large majority of non-functional PNETs fall into two major sub-types that reflect alpha and beta endocrine cell ontogeny, respectively. Tumors of the different subtypes have similar clinical presentations and histology, but express distinct lineage-specifying transcription factors, ARX or PDX1. Here we provide the raw ChIP-seq and RNA-seq data of the PNET cohort in this study, as well as ChIP-seq data of ileal carcinoids.</p>
Project description:H3K4me3 ChIP-Seq profiling of a directed differentiation time course converting human embryonic stem cells (hES) into immature pancreatic beta cell precursors. CyT49, a Viacyte proprietary male hESC line with normal karyotype was used.