Maladaptive Positive Feedback Production of ChREBPβ Drives Glucotoxic β-Cell Failure
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ABSTRACT:
ORGANISM(S): Rattus norvegicus
PROVIDER: GSE197864 | GEO | 2022/06/02
REPOSITORIES: GEO
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2022-05-20 | GSE197449 | GEO
Project description:Dedifferentiation of pancreatic beta cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown. We employed single-cell RNAseq to detail the maturation program of alpha and beta cells during human ontogeny. We show that although both alpha and beta cells mature in part by repressing non-endocrine genes, alpha-cells retain hallmarks of an immature state, while beta-cells attain a full beta-cell specific gene expression program. In islets from T2D donors, both alpha- and beta-cells return to a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes while increasing expression of exocytosis, inflammation and stress response signaling pathways. These changes support the increased proportion of beta-cells displaying suboptimal function observed in T2D islets. These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.
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2007-09-11 | E-CBIL-35 | biostudies-arrayexpress
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Project description:In this study, we investigated the molecular and cellular mechanisms of verapamil treatment on β-cell function and survival using MIN6 cells. Verapamil's molecular processes were studied using transcriptomic data. MTT, cell count, and flow cytometry assessed cell proliferation, growth, and cycle. MIN6 cell function was assessed by glucose-stimulated insulin release and total insulin content. Seahorse and metabolic stress kits examined metabolic activity and oxygen consumption rate. The protective impact of verapamil on MIN6 cells was evaluated by challenging the verapamil treated cell with streptozotocin, T1D-cytomix, or T2D-cytomix cocktail. Our results demonstrate that verapamil treatment induced higher proliferation of MIN6 cells, altered expression of various proteins and genes, improved insulin secretion in hyperglycemic conditions, increased basal and maximal respiration levels, along with β-cell survival against streptozotocin, T1D-, or T2D-cytomix-induced toxicity, and rendered a protective effect.
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Project description:Whether amino acids act on cellular insulin signaling remains unclear, given that increased circulating amino acid levels are associated with the onset of type 2 diabetes (T2D). Here, we report that phenylalanine modifies insulin receptor beta (IRβ) and inactivates insulin signaling and glucose uptake. Mice fed phenylalanine-rich chow or phenylalanine-producing aspartame or overexpressing human phenylalanyl-tRNA synthetase (hFARS) developed insulin resistance and T2D symptoms. Mechanistically, FARS phenylalanylated lysine 1057/1079 of IRβ (F-K1057/1079), inactivating IRβ and preventing insulin from promoting glucose uptake by cells. SIRT1 reversed F-K1057/1079 and counteracted the insulin-inactivating effects of hFARS and phenylalanine. F-K1057/1079 and SIRT1 levels in white blood cells from T2D patients wereare positively and negatively correlated with T2D onset, respectively. Blocking F-K1057/1079 with phenylalaninol sensitizeds insulin signaling and relieveds T2D symptoms in hFARS-transgenic and db/db mice. These findings shed light on the activation of insulin signaling and T2D progression through inhibition of phenylalanylation.
2022-07-22 | PXD035076 | Pride
Project description:Recent advances in the understanding of the genetics of type 2 diabetes (T2D) susceptibility have focused attention on the regulation of transcriptional activity within the pancreatic beta-cell. MicroRNAs (miRNAs) represent an important component of regulatory control, and have proven roles in the development of human disease and control of glucose homeostasis. We set out to establish the miRNA profile of human pancreatic islets and of enriched beta-cell populations, and to explore their potential involvement in T2D susceptibility. We used Illumina small RNA sequencing to profile the miRNA fraction in three preparations each of primary human islets and of enriched beta-cells generated by fluorescence-activated cell sorting. In total, 366 miRNAs were found to be expressed (i.e. >100 cumulative reads) in islets and 346 in beta-cells; of the total of 384 unique miRNAs, 328 were shared. A comparison of the islet-cell miRNA profile with those of 15 other human tissues identified 40 miRNAs predominantly expressed (i.e. >50% of all reads seen across the tissues) in islets. Several highly-expressed islet miRNAs, such as miR-375, have established roles in the regulation of islet function, but others (e.g. miR-27b-3p, miR-192-5p) have not previously been described in the context of islet biology. As a first step towards exploring the role of islet-expressed miRNAs and their predicted mRNA targets in T2D pathogenesis, we looked at published T2D association signals across these sites. We found evidence that predicted mRNA targets of islet-expressed miRNAs were globally enriched for signals of T2D association (p-values <0.01, q-values <0.1). At six loci with genome-wide evidence for T2D association (AP3S2, KCNK16, NOTCH2, SCL30A8, VPS26A, and WFS1) predicted mRNA target sites for islet-expressed miRNAs overlapped potentially causal variants. In conclusion, we have described the miRNA profile of human islets and beta-cells and provide evidence linking islet miRNAs to T2D pathogenesis. Examination of the miRNA profiles in 3 preparations of isolated pancreatic islets and 3 preparations of FACS-enriched pancreatic beta-cells
2013-06-07 | E-GEOD-47720 | biostudies-arrayexpress
Project description:We found PAX5 to be overexpressed in human pancreatic islets of donors from donors with type 2 diabetes compared to islets from non-diabetic individuals. Functional follow-up showed that Pax5 overexpression in rat clonal beta-cells (832/13 INS1) results in impaired insulin secretion. Microarrays were used to investigate if overexpression of Pax5 alters the gene expression profile of 832/13 INS1 beta-cells.
2023-01-11 | GSE211310 | GEO
Project description:Objective Notch signaling is re-activated in β cells from obese mice, and is causal to β cell dysfunction. Notch activity is determined in part by expression of transmembrane ligand availability in a neighboring cell. We hypothesized that β cell expression of Jagged1 determines the maladaptive Notch response and resultant β cell dysfunction in obese mice. Methods We assessed expression of Notch pathway components in diet-induced obese (DIO) or leptin receptor-deficient (db/db) mice, and performed single cell RNA sequencing (scRNAseq) in islets from patients with and without type 2 diabetes (T2D). We generated and performed glucose tolerance testing in inducible, β cell-specific Jagged1 gain-of- and loss-of-function mice. We also tested effects of monoclonal neutralizing antibodies to Jagged1 in glucose-stimulated insulin secretion (GSIS) assays in isolated islets. Results Jag1 was the only Notch ligand that tracked with increased Notch activity in DIO and db/db mice. Consistently, JAG1 tracked with Notch activity in metabolically inflexible β cells enriched in patients with T2D. Neutralizing antibodies to block Jagged1 in islets isolated from DIO and db/db mice potentiated GSIS ex vivo. To demonstrate if β cell Jagged1 is sufficient to cause glucose tolerance in vivo, we generated inducible β cell-specific Jag1 transgenic mice (β-Jag1TG), which showed impaired glucose intolerance due to reduced GSIS. However, β cell-specific Jagged1 loss-of-function (β-Jag1KO) did not protect against HFD-induced insulin secretory defects or glucose intolerance. Conclusions Jagged1 is increased in islets from obese mice and in patients with T2D, and neutralizing Jagged1 antibodies lead to improved GSIS, suggesting that inhibition of Jagged1-Notch signaling may have therapeutic benefit. However, genetic loss-of-function experiments suggest that β cells are not a likely source of the Jagged1 signal.
2024-02-23 | GSE249170 | GEO
Project description:Altered islet architecture is associated with β cell dysfunction and Type 2 Diabetes (T2D) progression, but molecular effectors of islet spatial organization remain mostly unknown. Although Notch signaling is known to regulate pancreatic development, we observed “re-activated” β cell Notch activity in obese mouse models. To test the repercussions and reversibility of Notch effects, we generated doxycycline-dependent, β cell-specific Notch gain-of-function mice. As predicted, we found that Notch activation in post-natal β cells impaired glucose stimulated insulin secretion (GSIS) and glucose intolerance, but we observed a surprising remnant glucose intolerance after doxycycline withdrawal and cessation of Notch activity, associated with a marked disruption of normal islet architecture. Transcriptomic screening of Notch-active islets revealed increased Ephrin signaling. Commensurately, exposure to Ephrin ligands increased β cell repulsion, and impaired murine and human pseudo-islet formation. Consistent with our mouse data, Notch and Ephrin signaling are increased in metabolically-inflexible β cells in patients with T2D. These studies suggest than islet architecture can be permanently altered by β cell Notch/Ephrin signaling during a morphogenetic window in early life.
2022-02-21 | GSE193888 | GEO