Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1215456 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Glucolipotoxicity is known to cause beta-cell failure and type 2 diabetes (T2D) via stress response-related mechanisms. Yet the detailed mechanisms are not known. This study examine the roles of activating transcription factor 4 (Atf4) in glucolipotoxicity. Using beta-cell specific gene knockout in mice, we show here that Atf4 is dispensable in young mice for glucose homeostasis. But it is required for beta-cell function during aging and under long-term obesity-related metabolic stress. Henceforth, aged Atf4-deficient beta-cells display compromised function under acute hyperglycemia. In contrast, these mutant beta-cells are resistant to acute free fatty acid-induced dysfunction. Corresponding to these phenotypes, Atf4-deficient beta-cells down-regulate genes involved in protein translation, reducing beta-cell identity gene products under high glucose. They also upregulate several genes involved in lipid metabolism or signaling, likely contributing to their resistance to free fatty acid-induced dysfunction. These results suggest that although Atf4 activation is required for beta-cell identity and function under high glucose, this activation induces beta-cell failure in the presence of high levels of free fatty acids.
2025-04-30 | GSE288277 | GEO
Project description:Neonatal beta-cells undergo a maturation process to acquire glucose responsiveness. We hypothesize that in later life, a partial reversal of this maturation might promote beta-cell dysfunction. We previously ascertained that fetuin-A, a fetal glycoprotein downregulated at birth but increasingly secreted when fatty liver develops, inhibits insulin secretion. Here, we evaluate fetuin-A’s impact on beta-cell maturation. In vitro maturation of neonatal porcine islet cell clusters (NICCs) promoted expression of beta-cell markers and TGFBR/SMAD signaling. Fetuin-A reduced both functional and proliferative gene expression and SMAD phosphorylation. Consequently, fetuin-A impaired glucose- and forskolin-dependent secretion, and reduced adaptive beta-cell proliferation. In adult human islets, fetuin-A abolished glucose responsiveness, diminished SMAD phosphorylation and downregulated functional and proliferative genes. Our findings suggest that perinatal decline of fetuin-A relieves TGFBR signaling in neonatal beta-cells, thereby facilitating the onset of postnatal maturation. However, this program remains revocable during adulthood, since fatty liver-derived fetuin-A reverses beta-cells’ maturity, conferring them a neonatal-like phenotype and contributing to their failure.
2020-12-07 | GSE144950 | GEO
Project description:Pancreatic beta-cell dysfunction and eventual beta-cell loss are key steps in the course of type 2 diabetes (T2D). Endoplasmic reticulum (ER) stress, in particular the PERK-ATF4 pathway, has been implicated in promoting these beta-cell pathologies. However, the exact molecular events surrounding the PERK-ATF4 pathway in beta-cell dysfunction remain unknown. Here, we discovered that ATF4 transcriptionally promotes expression of PDE4D, which results in beta-cell dysfunction via downregulation of cAMP signaling. Beta-cell-specific transgenic expression of ATF4 resulted in early beta-cell dysfunction and loss, resembling accelerated T2D. ATF4 expression, rather than CHOP, promoted PDE4D expression, decreased cAMP signaling, and attenuated responses to incretins and elevated glucose. Further, beta-cells of leptin receptor-deficient diabetic (db/db) mice expressed increased levels of ATF4 and PDE4D, accompanying impaired beta-cell function. Moreover, inhibiting PDE4D activity with selective pharmacological inhibitors significantly ameliorated beta-cell dysfunction in both db/db mice and beta-cell-specific ATF4 transgenic mice. In summary, our findings support that ER stress causes beta-cell failure via ATF4-mediated PDE4D production, and this is a highly promising therapeutic target for protecting beta-cell function during progression of T2D.
2023-09-25 | GSE199534 | GEO
Project description:Type-2 diabetes (T2D) mellitus results from a complex interplay of genetic and environmental factors leading to deficient insulin secretion from pancreatic islet beta cells. Here, we provide a the first comprehensive study of the human islet state of metabolically profiled pancreatectomized living human donors in relationship to glycemic control integrating clinical traits with multiple in situ islet and pre-operative blood omics datasets across the glycemia continuum from non diabetic healthy to overt T2D levels. Our transcriptomics and proteomics data suggest that progressive dysregulation of islet gene expression associated with increasing glucose intolerance is a disharmonic process resembling a non-linear trajectory of mature beta cell states towards trans-differentiation. Furthermore, we identify a unique islet gene set altered already in early-onset glucose intolerance and that, which correlates well across HbA1c levels - the gold-standard in clinical monitoring. Our findings reach beyond conventional clinical thresholds and can serve as direct or indirect prognostic markers for beta cell failure.
2021-10-12 | PXD022561 | Pride
Project description:Generation of mature cells with stable functional identities is crucial for developing cell-based replacement therapies. Current global efforts to produce insulin-secreting beta-like cells to treat diabetes are hampered by the lack of tools to reliably assess cellular identity. We conducted a thorough single-cell transcriptomics meta-analysis to generate robust genesets defining the identity of human adult alpha-, beta-, gamma- and delta-cells. After extensive validation, we showed the efficacy of the novel genesets to define changes in islet cell identity, whether during embryonic development or in different experimental setups aimed at developing new functional glucose-responsive insulin-secreting cells, such as through pluripotent stem-cell differentiation or islet cell reprogramming protocols. Finally, we evaluated whether the perturbed metabolic conditions typical of diabetes influence islet cell identity. We observed that alpha-cells from diabetic donors exhibit an altered phenotype. In conclusion, these novel genesets represent valuable tools that robustly benchmark gain and loss in islet cell identity traits.
2021-06-26 | GSE150724 | GEO
Project description:Objective: Transcriptional complex activity drives the development and function of pancreatic islet cells to allow for proper glucose regulation. Our prior work highlighted that the LIM-homeodomain transcription factor (TF), Islet-1 (Isl1), and its interacting co-regulator, Ldb1, are vital effectors of developing and adult β-cells. We further found that a member of the Single Stranded DNA-Binding Protein (SSBP) co-regulator family, SSBP3, interacts with Isl1 and Ldb1 in β-cells and primary islets (mouse and human) to impact β-cell target genes MafA and Glp1R. Members of the SSBP family stabilize TF complexes by binding directly to Ldb1 and protecting the complex from ubiquitin-mediated turnover. In this study, we hypothesized that SSBP3 would have critical roles in pancreatic islet cell development and function in vivo, similar to the Isl1::Ldb1 complex. Methods: We first generated a novel SSBP3 LoxP allele mouse line, where Cre-mediated recombination imparts a predicted early protein termination. We bred this mouse to constitutive Cre lines (Pdx1- and Pax6-driven) to recombine of SSBP3 in the developing pancreas and islet (SSBP3DeltaPanc and SSBP3DeltaIslet), respectively. We assessed glucose tolerance and used immunofluorescence to detect changes in islet cell abundance and markers of β-cell identity and function. Using an inducible Cre system we also deleted SSBP3 in the adult β-cell, a model termed SSBP3Deltaβ-cell. We measured glucose tolerance as well as glucose-stimulated insulin secretion (GSIS), both in vivo and in isolated islets in vitro. Using islets from control and SSBP3Deltaβ-cell we conducted RNA-Seq and compared our results to published datasets for similar β-cell specific Ldb1 and Isl1 knockouts to identify commonly regulated target genes. Results: SSBP3DeltaPanc and SSBP3DeltaIslet neonates present with hyperglycemia. SSBP3DeltaIslet mice are glucose intolerant by P21 and exhibit a reduction of β-cell maturity markers MafA, Pdx1, and UCN3. We observe disruptions in islet cell architecture with an increase in glucagon+ α-cells and ghrelin+ ε-cells at P10. Inducible loss of β-cell SSBP3 in SSBP3Deltaβ-cell causes hyperglycemia, glucose intolerance, and reduced GSIS. Transcriptomic analysis of 14-week SSBP3Deltaβ-cell islets revealed a decrease in β-cell function gene expression (Ins, MafA, Ucn3), increased stress and dedifferentiation markers (Neurogenin-3, Aldh1a3, Gastrin), and shared differentially expressed genes between SSBP3, Ldb1, and Isl1 in adult β-cells. Conclusions: SSBP3 drives proper islet development and identity, where its loss causes altered islet-cell abundance and glucose regulatory function. β-cell SSBP3 is required for GSIS and glucose homeostasis, at least partially through shared regulation of Ldb1 and Isl1 target genes.
2023-08-16 | GSE232750 | GEO
Project description:Background: Long-term exposure to elevated levels of free fatty acids (FFAs) is deleterious for beta-cell function and may contribute to development of type 2 diabetes mellitus (T2DM). Whereas mechanisms of impaired glucose-stimulated insulin secretion (GSIS) in FFA-treated beta-cells have been intensively studied, biological events preceding the secretory failure, when GSIS is accentuated, are poorly investigated. To identify these early events, we performed genome-wide analysis of gene expression in isolated human islets exposed to fatty acid palmitate for different time periods. Results: Palmitate-treated human islets showed decline in beta-cell function starting from day two. Affymetrix Human Transcriptome Array 2.0 identified 903 differentially expressed genes (DEGs). Mapping of the genes onto pathways using KEGG pathway enrichment analysis predicted four islet biology-related pathways enriched prior but not after the decline of islet function and three pathways enriched both prior and after the decline of islet function. DEGs from these pathways were analyzed at the transcript level. The results propose that in palmitate-treated human islets, at early time points, protective events, including up-regulation of metallothioneins, tRNA synthetases and fatty acid-metabolising proteins, dominate over deleterious events, including inhibition of fatty acid detoxification enzymes, which contributes to the enhanced GSIS. After prolonged exposure of islets to palmitate, the protective events are outweighed by the deleterious events, which leads to impaired GSIS. Conclusions: The study identifies temporal order between different cellular events, which either promote or protect from beta-cell failure. The sequence of these events should be considered when developing strategies for prevention and treatment of the disease.
2018-08-19 | GSE118230 | GEO
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:Pancreatic beta-cell dysfunction and death are central in the pathogenesis of type 2 diabetes. Saturated fatty acids cause beta-cell failure and contribute to diabetes development in genetically predisposed individuals. Here we used RNA-sequencing to map transcripts expressed in five palmitate-treated human islet preparations, observing 1,325 modified genes. Palmitate induced fatty acid metabolism and endoplasmic reticulum (ER) stress. Functional studies identified novel mediators of adaptive ER stress signaling. Palmitate modified genes regulating ubiquitin and proteasome function, autophagy and apoptosis. Inhibition of autophagic flux and lysosome function contributed to lipotoxicity. Palmitate inhibited transcription factors controlling beta-cell phenotype including PAX4 and GATA6. 59 type 2 diabetes candidate genes were expressed in human islets, and 11 were modified by palmitate. Palmitate modified expression of 17 splicing factors and shifted alternative splicing of 3,525 transcripts. Ingenuity Pathway Analysis of modified transcripts and genes confirmed that top changed functions related to cell death. DAVID analysis of transcription binding sites in palmitate-modified transcripts revealed a role for PAX4, GATA and the ER stress response regulators XBP1 and ATF6. This human islet transcriptome study identified novel mechanisms of palmitate-induced beta-cell dysfunction and death. The data point to crosstalk between metabolic stress and candidate genes at the beta-cell level. 5 human islet of Langerhans preparations examined under 2 conditions (control and palmitate treatment)
2014-01-09 | E-GEOD-53949 | biostudies-arrayexpress
Project description:Free fatty acids (FFAs) are often stored in lipid droplet (LD) depots for eventual metabolic and/or synthetic use in many cell types, such a muscle, liver, and fat. In pancreatic islets, overt LD accumulation was detected in humans but not mice. LD buildup in islets was principally observed after roughly 11 years of age, increasing throughout adulthood under physiologic conditions, and also enriched in type 2 diabetes. To obtain insight into the role of LDs in human islet β cell function, the levels of a key LD scaffold protein, perilipin2 (PLIN2), were manipulated by lentiviral-mediated knock-down (KD) or over-expression (OE) in EndoCβH2-Cre cells, a human cell line with adult islet β-like properties. Glucose stimulated insulin secretion was blunted in PLIN2KD cells and improved in PLIN2OE cells. An unbiased transcriptomic analysis revealed that limiting LD formation induced effectors of endoplasmic reticulum (ER) stress that compromised the expression of critical β cell function and identity genes. These changes were essentially reversed by PLIN2OE or using the ER stress inhibitor, tauroursodeoxycholic acid. These results strongly suggest that LDs are essential for adult human islet β cell activity by preserving FFA homeostasis.
2021-09-15 | GSE184016 | GEO