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:The process of regeneration by in vivo transdifferentiation in mammals is poorly understood. Here, using pancreatic β cell regeneration as a paradigm, we performed a single-cell transcriptomic study of in vivo transdifferentiation from adult mouse acinar cells to induced β cells.
Project description:Insulin-secreting β cells and glucagon-secreting α cells maintain physiological blood glucose levels, and their malfunction drives diabetes development. Using ChIP sequencing and RNA sequencing analysis, we determined the epigenetic and transcriptional landscape of human pancreatic α, β, and exocrine cells. We found that, compared with exocrine and β cells, differentiated α cells exhibited many more genes bivalently marked by the activating H3K4me3 and repressing H3K27me3 histone modifications. This was particularly true for β cell signature genes involved in transcriptional regulation. Remarkably, thousands of these genes were in a monovalent state in β cells, carrying only the activating or repressing mark. Our epigenomic findings suggested that α to β cell reprogramming could be promoted by manipulating the histone methylation signature of human pancreatic islets. Indeed, we show that treatment of cultured pancreatic islets with a histone methyltransferase inhibitor leads to colocalization of both glucagon and insulin and glucagon and insulin promoter factor 1 (PDX1) in human islets and colocalization of both glucagon and insulin in mouse islets. Thus, mammalian pancreatic islet cells display cell-type–specific epigenomic plasticity, suggesting that epigenomic manipulation could provide a path to cell reprogramming and novel cell replacement-based therapies for diabetes. Pancreatic islets were collected post-mortem from 6 human donors and subjected to FACS to separate populations of alpha, beta, and exocrine cells. Depending on the availability of resulting material, sorted islet cell populations were used for H3K4me3, H3K27me3 ChIP-seq, or RNA-seq analysis. All ChIP-seq samples have a corresponding input from the same sample.
Project description:Insulin-secreting β cells and glucagon-secreting α cells maintain physiological blood glucose levels, and their malfunction drives diabetes development. Using ChIP sequencing and RNA sequencing analysis, we determined the epigenetic and transcriptional landscape of human pancreatic α, β, and exocrine cells. We found that, compared with exocrine and β cells, differentiated α cells exhibited many more genes bivalently marked by the activating H3K4me3 and repressing H3K27me3 histone modifications. This was particularly true for β cell signature genes involved in transcriptional regulation. Remarkably, thousands of these genes were in a monovalent state in β cells, carrying only the activating or repressing mark. Our epigenomic findings suggested that α to β cell reprogramming could be promoted by manipulating the histone methylation signature of human pancreatic islets. Indeed, we show that treatment of cultured pancreatic islets with a histone methyltransferase inhibitor leads to colocalization of both glucagon and insulin and glucagon and insulin promoter factor 1 (PDX1) in human islets and colocalization of both glucagon and insulin in mouse islets. Thus, mammalian pancreatic islet cells display cell-type–specific epigenomic plasticity, suggesting that epigenomic manipulation could provide a path to cell reprogramming and novel cell replacement-based therapies for diabetes.
Project description:MicroRNAs (miRNAs) are non-coding RNAs that play a fundamental role in regulation of gene expression affecting differentiation and development. In particular, miRNAs have been described to regulate genes important for pancreatic development and islet function. The aim of this work was to determine the miRNA expression signature in human pancreatic alpha and beta cells. miRNA stability to fixation allowed the study of microRNA in pure populations of human alpha and beta cells sorted by FACS after intracellular staining with glucagon and insulin, respectively. The determination of the specific group of miRNAs expressed in the human pancreatic alpha and beta cells may further the understanding of gene expression regulation of the islet differentiation process.
Project description:MicroRNAs (miRNAs) are non-coding RNAs that play a fundamental role in regulation of gene expression affecting differentiation and development. In particular, miRNAs have been described to regulate genes important for pancreatic development and islet function. The aim of this work was to determine the miRNA expression signature in human pancreatic alpha and beta cells. miRNA stability to fixation allowed the study of microRNA in pure populations of human alpha and beta cells sorted by FACS after intracellular staining with glucagon and insulin, respectively. The determination of the specific group of miRNAs expressed in the human pancreatic alpha and beta cells may further the understanding of gene expression regulation of the islet differentiation process. The alpha and beta cells come from 6 different preparations of human pancreatic islets from donors. In this study we define expression profiles of a total of 665 miRNAs for pancreatic alpha and beta cells. For this purpose, cells were fixed with paraformaldehyde, 7AAD was applied to exclude dead cells. Then, cells were sorted after intracellular staining with C peptide to detect beta cells and glucagon to detect alpha cells. After sorting, we confirmed enriched beta cells have a purity of on average over 98%. Enriched alpha cells have a purity of on average over 98%. To determine the miRNA expression profiles, we used human miRNA TLDAs version 2. For each sample card A and card B were run after cDNA synthesis and 12 cycles of preamplification according to the manufacturer protocol. Each TLDA card A contains 1 probe for the endogenous control RNU48 while each TLDA card B contains 4 replicates of the RNU48 probe. Analysis of these controls allows calculating the intra- and inter-assay variation. Quantitative values (RQ) were calculated measuring the ddCt between the Ct values of each miRNA and the Ct value of the small nucleolar RNU48 RNA comparing the target sample and the control sample.
Project description:<p>The involvement of membrane-bound solute carriers (SLCs) in neoplastic transdifferentiation processes is poorly defined. Here, we examined changes in the SLC landscape during epithelial-mesenchymal transition (EMT) of pancreatic cancer cells. We show that two SLCs from the organic anion/cation transporter family, SLC22A10 and SLC22A15, favor EMT via interferon (IFN) α and γ signaling activation of receptor tyrosine kinase-like orphan receptor 1 (ROR1) expression. In addition, SLC22A10 and SLC22A15 allow tumor cell accumulation of glutathione to support EMT via the IFNα/γ-ROR1 axis. Moreover, a pan-SLC22A inhibitor lesinurad reduces EMT-induced metastasis and gemcitabine chemoresistance to prolong survival in mouse models of pancreatic cancer, thus identifying new vulnerabilities for human PDAC.</p>
Project description:To guide the beta cell differentiation process in vitro, a complete understanding of the transcriptome and their regulatory network during the differentiation process is essential. Using RNA-seq, we have performed the transcriptome profiling of human embryonic stem cells (ESCs), purified ESC-derivate definitive endoderm (DE), pancreatic progenitors (PP), as well as sorted human primary pancreatic alpha cells, beta cells and exocrine cells.