An inhibitor-mediated beta cell dedifferentiation model reveals distinct roles for FoxO1 in glucagon repression and insulin maturation
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE184210 | GEO | 2021/09/16
REPOSITORIES: GEO
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Project description:ObjectiveThe loss of forkhead box protein O1 (FoxO1) signaling in response to metabolic stress contributes to the etiology of type II diabetes, causing the dedifferentiation of pancreatic beta cells to a cell type reminiscent of endocrine progenitors. Lack of methods to easily model this process in vitro, however, have hindered progress into the identification of key downstream targets and potential inhibitors. We therefore aimed to establish such an in vitro cellular dedifferentiation model and apply it to identify novel agents involved in the maintenance of beta-cell identity.MethodsThe murine beta-cell line, Min6, was used for primary experiments and high-content screening. Screens encompassed a library of small-molecule drugs representing the chemical and target space of all FDA-approved small molecules with an automated immunofluorescence readout. Validation experiments were performed in a murine alpha-cell line as well as in primary murine and human diabetic islets. Developmental effects were studied in zebrafish and C. elegans models, while diabetic db/db mouse models were used to elucidate global glucose metabolism outcomes.ResultsWe show that short-term pharmacological FoxO1 inhibition can model beta-cell dedifferentiation by downregulating beta-cell-specific transcription factors, resulting in the aberrant expression of progenitor genes and the alpha-cell marker glucagon. From a high-content screen, we identified loperamide as a small molecule that can prevent FoxO inhibitor-induced glucagon expression and further stimulate insulin protein processing and secretion by altering calcium levels, intracellular pH, and FoxO1 localization.ConclusionsOur study provides novel models, molecular targets, and drug candidates for studying and preventing beta-cell dedifferentiation.
| S-EPMC8476777 | biostudies-literature
Project description:An inhibitor-mediated beta cell dedifferentiation model reveals distinct roles for FoxO1 in glucagon repression and insulin maturation
| PRJNA763583 | ENA
Project description:Pancreatic beta-cell dysfunction contributes to onset and progression of type 2 diabetes. In this state beta-cells become metabolically inflexible, losing the ability to select between carbohydrates and lipids as substrates for mitochondrial oxidation. These changes lead to beta-cell dedifferentiation. We have proposed that FoxO proteins are activated through deacetylation-dependent nuclear translocation to forestall the progression of these abnormalities. However, how deacetylated FoxO exert their actions remains unclear. To address this question, we analyzed islet function in mice homozygous for knock-in alleles encoding deacetylated FoxO1 (6KR). Islets expressing 6KR mutant FoxO1 have enhanced insulin secretion in vivo and ex vivo, and decreased fatty acid oxidation ex vivo. Remarkably, the gene expression signature associated with FoxO1 deacetylation differs from wild-type by only ~2% of the > 4,000 genes regulated in response to re-feeding. But this narrow swath includes key genes required for beta-cell identity, lipid metabolism, and mitochondrial fatty acid and solute transport. The data support the notion that deacetylated FoxO1 protects beta-cell function by limiting mitochondrial lipid utilization, and raise the possibility that inhibition of fatty acid oxidation in β-cells is beneficial to diabetes treatment.
2016-05-10 | GSE77652 | GEO
Project description:Tight regulation of Toll-like receptor (TLR)-mediated inflammatory responses is important in innate immunity. Here, we show that T cell death-associated gene 51 (TDAG51/PHLDA1) is a novel coactivator of the transcription factor FoxO1, regulating inflammatory mediator production in the lipopolysaccharide (LPS)-induced inflammatory response. TDAG51 induction by LPS stimulation was mediated by the TLR2/4 signaling pathway in bone marrow-derived macrophages (BMMs). LPS-induced inflammatory mediator production was significantly decreased in TDAG51-deficient BMMs. In TDAG51-deficient mice, LPS- or pathogenic Escherichia coli infection-induced lethal shock was reduced by decreasing serum proinflammatory cytokine levels. The recruitment of 14-3-3 to FoxO1 was competitively inhibited by the TDAG51-FoxO1 interaction, leading to blockade of FoxO1 cytoplasmic translocation and thereby strengthening FoxO1 nuclear accumulation. TDAG51/FoxO1 double-deficient BMMs showed significantly reduced inflammatory mediator production compared with TDAG51- or FoxO1-deficient BMMs. TDAG51/FoxO1 double deficiency protected mice against LPS- or pathogenic E. coli infection-induced lethal shock by weakening the systemic inflammatory response. Thus, these results indicate that TDAG51 acts as a coactivator of the transcription factor FoxO1, leading to strengthened FoxO1 activity in the LPS-induced inflammatory response.
2023-06-24 | PXD039815 | Pride
Project description:In the pathogenesis of type 2 diabetes development of insulin resistance triggers an increase in pancreatic β-cell insulin secretion capacity and β-cell number. Failure of this compensatory mechanism is caused by a dedifferentiation of β-cells, which leads to insufficient insulin secretion and diabetic hyperglycemia. The β-cell factors that normally protect against dedifferentiation remain poorly defined. Here, through a systems biology approach, we identify the transcription factor Klf6 as a regulator of β-cell adaptation to metabolic stress. We show that inactivation of Klf6 in mouse β-cells blunts their proliferation induced by the insulin resistance of pregnancy, high-fat high-sucrose feeding, and insulin receptor antagonism. Transcriptomic analysis showed that Klf6 controls the expression of β-cell proliferation genes and, in the presence of insulin resistance, it prevents the down-expression of genes controlling mature β-cell identity and the induction of disallowed genes that impair insulin secretion; its expression also limits the transdifferentiation of β-cells into alpha cells. Our study identifies a new transcription factor that protects β-cells against dedifferentiation and which may be targeted to prevent diabetes development.
2020-03-01 | GSE137187 | GEO
Project description:PAX3-FOXO1 is a fusion transcription factor that is the main driver of tumorigenesis leading to the development of alveolar rhabdomyosarcoma (aRMS). Since aRMS cells are addicted to PAX3-FOXO1 activity, the fusion protein also represents a major target for therapeutic interference, which is however challenging as transcription factors usually cannot be inhibited directly by small molecules. Hence, characterization of the biology of PAX3-FOXO1 might lead to the discovery of new possibilities for an indirect inhibition of its activity. Here, our goal was to characterize the proteomic neighborhood of PAX3-FOXO1 and to find candidates potentially affecting its activity and tumor cell viability. Towards this aim, we expressed BirA fused versions of PAX3-FOXO1 (N- and C-terminal) in HEK293T cells under presence of biotin. In the control setup, we expressed the BirA enzyme alone. After Streptavidin purification of biotinylated proteins, we performed mass spectrometry and quantified relative abundances compared to control conditions. This enabled us to determine PAX3-FOXO1 proximal proteins, which we investigated further in orthogonal endogenous systems.
2021-09-16 | PXD022187 | Pride
Project description:Analysis of transcriptional changes upon silencing of endothelial VEGF. Because transcription factor Foxo1 levels increase under VEGF silencing, we hypothesized that Foxo1 transcriptional activity would be apparent in a whole-genome microarray. Double-silencing of VEGF+Foxo1 was also performed to determine which transcriptional changes are Foxo1-dependent in a VEGF-deficient background.
2015-12-31 | E-MTAB-2515 | biostudies-arrayexpress
Project description:Klf6 protects β-cells against insulin resistance-induced dedifferentiation
| PRJNA564774 | ENA
Project description:Plant development is characterised by the capacity to reprogram differentiated cells to initiate asexual reproduction and to produce new organs such as lateral roots. To test whether HIRA could be involved in aspects of developmental reprogramming we studied the effect of HIRA during de-differentiation Arabidopsis root tissue was digested with enzyme to generate protoplast. This process would induce plant cell dedifferentiation. Experiments were performed in WT and hira background to understand how hira affect plant dedifferentiation process.
2014-10-01 | E-GEOD-57044 | biostudies-arrayexpress
Project description:The pathways regulating the formation of the germinal center (GC) dark- (DZ) and light- (LZ) zones are unknown. We show that FOXO1 expression is restricted to the GC DZ and is required for DZ formation, since its absence in mice leads to the complete loss of DZ gene programs and the formation of LZ-only GCs. FOXO1-negative GC B-cells display normal somatic hypermutation, but defective affinity maturation and class switch recombination. The function of FOXO1 in sustaining the DZ program involves the transactivation of the chemokine receptor CXCR4, and the cooperation with BCL6 in the trans-repression of genes involved in immune activation, DNA-repair and plasma cell differentiation. These results have also implications for understanding the role of FOXO1 mutations in lymphomagenesis. We used microarrays to determine the consequences of FOXO1 deletion in the GC B cell comparment, and correlate these data with phenotypic changes GC B cell subpopulations were collected by Fluorescence Activated Cell Sorting (FACS) from B cell enriched fractions of splenic mononuclear cell pools (12 days after SRBC immunization). 20ng of total RNA (RIN>9) for each sample was used as a template for linear cDNA amplification (Ovation RNA amplification Kit, NuGen). cDNA was labeled using the Encore Biotin Labeling Kit (NuGen) and hybridized to Affymetrix Mouse 430.2 gene expression arrays
2015-12-04 | E-GEOD-69216 | biostudies-arrayexpress