1. Dysregulation of the Pdx1/Ovol2/Zeb2 axis in dedifferentiated β-cells triggers the induction of genes associated with epithelial–mesenchymal transition in diabetes
- Author
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Pauline Chabosseau, Victoria Salem, Tracy C S Mak, Guy A. Rutter, Eva Kane, Walter Distaso, Catherine M Chahrour, Alejandra Tomas, Yi-Fang Wang, Yorrick von Ohlen, Ying Bai, Markus Stoffel, Daniel S de Jesus, Mathieu Latreille, Diabetes UK, and Lee Kong Chian School of Medicine (LKCMedicine)
- Subjects
Male ,0301 basic medicine ,microRNA, miRNA ,0601 Biochemistry and Cell Biology ,Mice ,GSIS, glucose-induced stimulated-insulin secretion ,UPR, unfolded protein response ,0302 clinical medicine ,GSEA, gene set enrichment analysis ,Fibrosis ,Insulin-Secreting Cells ,FACS, fluorescence-activated cell sorting ,Insulin ,Internal medicine ,Cells, Cultured ,scRNA-seq, single-cell RNA sequencing ,geography.geographical_feature_category ,microRNA ,Diabetes ,Islet ,ECM, extracellular matrix ,Cell biology ,T2D, type2 diabetes ,PDX1 ,Female ,Original Article ,T1D, type 1 diabetes ,Dedifferentiation ,Epithelial-Mesenchymal Transition ,Down-Regulation ,Mice, Transgenic ,030209 endocrinology & metabolism ,Biology ,03 medical and health sciences ,Downregulation and upregulation ,medicine ,Animals ,Humans ,Medicine [Science] ,Epithelial–mesenchymal transition ,β-TFs, β-cell transcription factors ,Pancreatic b-cells ,Epithelial-to-mesenchymal transition ,Molecular Biology ,Transcription factor ,Zinc Finger E-box Binding Homeobox 2 ,Homeodomain Proteins ,geography ,Sequence Analysis, RNA ,Mesenchymal stem cell ,Cell Biology ,medicine.disease ,0606 Physiology ,RC31-1245 ,Pancreatic β-cells ,Mice, Inbred C57BL ,HEK293 Cells ,030104 developmental biology ,Diabetes Mellitus, Type 2 ,Trans-Activators ,Transcription Factors - Abstract
Objective: β-cell dedifferentiation has been revealed as a pathological mechanism underlying pancreatic dysfunction in diabetes. We previously showed that increased miR-7 levels trigger β-cell dedifferentiation and diabetes. We used β-cell-specific miR-7 overexpressing mice (Tg7) to test the hypothesis that loss of β-cell identity triggered by miR-7 overexpression alters islet gene expression and islet microenvironment in diabetes. Methods: We performed bulk and single-cell RNA sequencing (RNA-seq) in islets obtained from β-cell-specific miR-7 overexpressing mice (Tg7). We carried out loss- and gain-of-function experiments in MIN6 and EndoC-bH1 cell lines. We analysed previously published mouse and human T2D data sets. Results: Bulk RNA-seq revealed that β-cell dedifferentiation is associated with the induction of genes associated with epithelial-to-mesenchymal transition (EMT) in prediabetic (2-week-old) and diabetic (12-week-old) Tg7 mice. Single-cell RNA-seq (scRNA-seq) indicated that this EMT signature is enriched specifically in β-cells. These molecular changes are associated with a weakening of β-cell: β-cell contacts, increased extracellular matrix (ECM) deposition, and TGFβ-dependent islet fibrosis. We found that the mesenchymal reprogramming of β-cells is explained in part by the downregulation of Pdx1 and its inability to regulate a myriad of epithelial-specific genes expressed in β-cells. Notable among genes transactivated by Pdx1 is Ovol2, which encodes a transcriptional repressor of the EMT transcription factor Zeb2. Following compromised β-cell identity, the reduction in Pdx1 gene expression causes a decrease in Ovol2 protein, triggering mesenchymal reprogramming of β-cells through the induction of Zeb2. We provided evidence that EMT signalling associated with the upregulation of Zeb2 expression is a molecular feature of islets in T2D subjects. Conclusions: Our study indicates that miR-7-mediated β-cell dedifferentiation induces EMT signalling and a chronic response to tissue injury, which alters the islet microenvironment and predisposes to fibrosis. This research suggests that regulators of EMT signalling may represent novel therapeutic targets for treating β-cell dysfunction and fibrosis in T2D., Molecular Metabolism, 53
- Published
- 2021