Project description:Stem cell-derived β (SC-β) cells are an emerging regenerative therapy to compensate for loss of functional β cell mass in diabetes. Glucose-stimulated insulin secretion in SC-β cells is variable in vitro but stabilizes after transplantation and maturation under the kidney capsule of mice. We identified mechanisms correlated with functional maturation using RNA-sequencing and co-expression network analysis. In vivo maturation enhanced glucose-stimulated but not basal insulin secretion, up-regulated β cell hormones IAPP and ADCYAP1, increased expression of maturation markers MAFA, UCN3, and SIX2, and resolved endocrine identity of incompletely specified polyhormonal cells produced during differentiation. Transplantation promoted calcium signalling, induced exocytotic machinery supporting hormone secretion and improved stimulus-secretion coupling that fine-tunes insulin secretion. Growth hormone signalling emerged as candidate driver of in vivo maturation and was confirmed in vitro. Also, a large co-expression module correlated with HbA1c and was enriched in genes up-regulated during in vivo maturation but down-regulated in hyperglycaemic and palmitate stress conditions, suggesting that transcriptional maturation of SC-β cells in vivo mirrors processes lost in diabetic β cells.
Project description:Islet transplantation for treatment of diabetes is limited by availability of donor islets and requirements for immunosuppression. Stem cell-derived islets might circumvent these issues. SC-islets effectively control glucose metabolism post transplantation, but do not yet achieve full function in vitro with currently published differentiation protocols. We aimed to identify markers of mature subpopulations of SC-β cells by studying transcriptional changes associated with in vivo maturation of SC-β cells using RNA-seq and co-expression network analysis. The β cell-specific hormone islet amyloid polypeptide (IAPP) emerged as the top candidate to be such a marker. IAPP+ cells had more mature β cell gene expression and higher cellular insulin content than IAPP- cells in vitro. IAPP+ INS+ cells were more stable in long-term culture than IAPP- INS+ cells and retained insulin expression after transplantation into mice. Finally, we conducted a small molecule screen to identify compounds that enhance IAPP expression. Aconitine up-regulated IAPP and could help to optimize differentiation protocols.
Project description:The goal of this study was to identify transcriptional changes in SC-beta and SC-endothelial cells pre and post IFN-gamma stimulation. Specifically, to characterize the differential expression of immune cell ligands in these cells with respect to a partial inflammatory stimulus.
Project description:We found that in rodents, postnatal beta-cell maturation is associated with changes in the expression of several islet microRNAs and discovered that these modifications are driven by changes in the nutrient supply. Mimicking the microRNA changes observed during β-cell maturation in newborn rat islet cells was sufficient to promote glucose-induced insulin release and to achieve a mature β-cell secretory phenotype. Moreover, the modifications in the level of some of these microRNAs reduced the proliferation of newborn β-cells, suggesting that they contribute to the limited proliferative capacity of adult β-cells. These findings demonstrated that miRNAs contribute to postnatal beta-cell maturation and development. Their role is likely to promote beta-cell adaptation to fuel supply and to maintain glucose homeostasis by regulating insulin release and proliferation. Islets from 10-day-old rats (P10) (n=4) or 3-month-old male rat (n=4) were taken. Total RNA was extracted and microRNA profiling was performed with miRNA Agilent arrays.
Project description:Pancreatic β-cell failure induced by WFS1 deficiency is manifested in wolfram syndrome (WS). The lack of a suitable human model in WS has hampered the progress in developing new treatments. Here, human pluripotent stem cell derived pancreatic β cells (SC-β cells) harboring WFS1-deficiency and mouse model of β cell-specific Wfs1 knockout were applied to model β-cell failure in WS. Single-cell RNA sequencing of WFS1-deficient SC-β cells revealed two cell fates along pseudotime trajectory including maturation and stress branch. WFS1 deficiency blocked β-cell fate trajectory to maturation but pushed it towards stress trajectory leading to β-cell failure.
Project description:The weaning period consist of a critical postnatal window for structural and physiologic maturation of rat beta cells. To investigate transcriptome changes involved in the maturation of beta cells neighboring this period we performed microarray analysis in FACS beta cell enriched populations to detail the global programme of gene expression to identify its changes during this process. Male Wistar rats were selected at the initial point of a postnatal critical period (postnatal 20d) for pancreatic maturation for RNA extraction and hybridization on Affymetrix microarrays. We obtained immature and mature beta cell-enriched populations from postnatal 20d and 2 months animals in order to compare their expression profiles. To that end, we used primary cultured FACS-enriched beta cell populations according to their FSC, SSC and autoflourescence. We used three replicates for each condition.
Project description:In stem cell-derived β (SC-β) cells, metabolic abnormalities persist as obstacles to glucose responsiveness and functional maturation, with the primary metabolic bottlenecks yet to be identified. This study demonstrated that restoring pyruvate kinase 1 (PKM1) re-established pyruvate kinase activity, effectively reversing the SC-β-cell identity loss and functional impairment associated with phosphoenolpyruvate (PEP) accumulation. 13C-glucose labeling metabolomics revealed a disruption in glucose-stimulated metabolite production beginning at the glycolytic PEP stage in stem cell-derived islets (SC-islets). Uniquely, elevated PEP prevented glycolytic metabolite-dependent increase of exocytosis and significantly increased intracellular calcium levels through a KATP channel-independent pathway, even under basal glucose condition. Furthermore, exposure to PEP led to downregulated expression of genes involved in the TCA cycle and respiratory electron transport. This PEP accumulation in SC-islets was associated with markedly reduced pyruvate kinase activity. Overexpression of PKM1 rescued the transcriptional changes induced by PEP accumulation and improved both glucose-stimulated calcium responses and insulin secretion. These findings suggest that PKM1 plays a pivotal role in promoting SC-β cell differentiation and functional maturation by regulating PEP metabolism, offering potential improvements for SC-β cell replacement in diabetes treatment.
Project description:Mediator, a co-regulator required for RNA pol II activity, interacts with tissue-specific transcription factors to regulate development and maintain homeostasis. We sought to understand whether Mediator subunit MED15 acts as a node that controls tissue-specific gene expression, using pancreatic insulin-producing β-cell maturation as a model. We found Med15 to be expressed during mouse pancreatic organogenesis and β-cell maturation; moreover, islets from human T2D donors feature reduced MED15 expression. Loss of Med15 in mouse β-cells caused defects in maturation without affecting β-cell mass or insulin expression. ChIP-seq and co-immunoprecipitation analyses determined that Med15 binds β-cell transcription factors Nkx6-1 and NeuroD1 to regulate key β-cell maturation genes. Human embryonic stem cell derived β-like cells, genetically engineered to express high levels of MED15, had increased maturation markers and improved insulin secretion. We provide the first evidence of the importance of Mediator in β-cell maturation and demonstrate an additional layer of control that tunes transcription factor function.