Checkpoint Kinase 2 Controls Insulin Secretion and Glucose Homeostasis
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE239335 | GEO | 2023/10/25
REPOSITORIES: GEO
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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:The pancreas plays a critical role in maintaining glucose homeostasis through the secretion of hormones from the islets of Langerhans. Glucose-stimulated insulin secretion (GSIS) by the pancreatic beta-cell is the main mechanism for reducing elevated plasma glucose.
Here we present a systematic modeling workflow for the development of kinetic pathway models using the Systems Biology Markup Language (SBML). An important factor was the reproducibility and exchangeability of the model, which allowed the use of various existing tools.
The workflow was applied to construct a novel data-driven kinetic model of GSIS in the pancreatic beta-cell based on experimental and clinical data from 39 studies spanning 50 years of pancreatic, islet, and beta-cell research in humans, rats, mice, and cell lines. The model consists of detailed glycolysis and phenomenological equations for insulin secretion coupled to cellular energy state, ATP dynamics and (ATP/ADP ratio).
Key findings of our work are that in GSIS there is a glucose-dependent increase in almost all intermediates of glycolysis. This increase in glycolytic metabolites is accompanied by an increase in energy metabolites, especially ATP and NADH. One of the few decreasing metabolites is ADP, which, in combination with the increase in ATP, results in a large increase in ATP/ADP ratios in the beta-cell with increasing glucose. Insulin secretion is dependent on ATP/ADP, resulting in glucose-stimulated insulin secretion.
2024-01-18 | MODEL2401110001 | BioModels
Project description:Insulin secreted by pancreatic β cells is essential for maintaining the level of blood glucose. Diabetes is mainly caused by the loss of β cells or impaired β cell function. The previous study performed a whole transcriptome analysis on the islets of T2D and the control group, and the results showed that the splicing disorder of the splicing event was about 25%, breast carcinoma amplified sequence 2(BCAS2) is one of the components of the spliceosome, and its function in islet β cell is unclear. Here we report that knockdown of Bcas2 decreases in glucose and KCl-stimulated insulin secretion in the NIT-1 cell line. The pancreas weight, glucose tolerance and insulin sensitivity were detected in normal chow-fed and high-fat diet-fed Bcas2 f/f-βKO mice, and β cell mass and islet size was analyzed by immunohistochemistry. Glucose intolerance developed in Bcas2 f/f-βKO mice, but there were no significant differences in pancreas weight, insulin sensitivity, β cell mass and islet size. Further, GSIS and observation of insulin secretion granules were performed on normal chow-fed mice, and it was found that the insulin level in serum decreased and the number of insulin secretion granules decreased in Bcas2 f/f-βKO mice, which was related to the abnormal splicing of Syt7 and Tcf7l2 pre-mRNA. Taken together, these results demonstrate that BCAS2 is involved in alternative splicing during insulin synthesis and secretion. Elisa,islet isolation,insulin secretion
2024-06-01 | GSE224490 | GEO
Project description:The Ras-related Rap1A GTPase is implicated in pancreas β-cell insulin secretion, and is stimulated by the cAMP sensor Epac2, a guanine exchange factor and activator of Rap1 GTPase. In this study we examined the differential proteomic profiles by nanoLC-ESI-MS/MS of pancreata from C57BL/6 Rap1A-deficient (Null) and control wild-type (WT) mice, to assess targets of Rap1A potentially involved in insulin regulation. We identified 77 overlapping identifier proteins in both groups, 8 distinct identifier proteins in Null versus 56 distinct identifier proteins in WT mice pancreas. Functional enrichment analysis showed 4 of the 8 Null unique proteins, ERO1-like protein β (Ero1lβ), triosephosphate isomerase (TP1), 14-3-3 protein γ and kallikrein-1, were exclusively involved in insulin biogenesis, with role in insulin metabolism. Specifically, the mRNA expression of Ero1lβ and TP1 was significantly (p<0.05) increased in Null versus WT pancreas. Rap1A-deficiency significantly affected glucose tolerance during the first 15-30 min of glucose challenge, but showed no impact on insulin sensitivity. Ex vivo glucose-stimulated insulin secretion (GSIS) studies on isolated Null islets showed significantly impaired GSIS. Furthermore, in GSIS-impaired islets, the cAMP-Epac2-Rap1A pathway was significantly compromised as compared to WT. Altogether, these studies underscore an essential role of Rap1A GTPase in pancreas physiological function
2024-10-17 | PXD052896 | Pride
Project description:Objectives: Glycine acts in an autocrine positive feedback loop in human β cells through its ionotropic receptors (GlyRs). In type 2 diabetes (T2D), islet GlyR activity is impaired by unknown mechanisms. We sought to investigate if the GlyR dysfunction in T2D is replicated by hyperglycemia per se, and to further characterize its action in β cells and the islets. Methods: GlyR-mediated currents were measured using whole-cell patch-clamp in human β cells from donors with or without T2D, or after high glucose culture. We also correlated glycine-induced current amplitude with transcript expression levels through patch-seq. The expression of the GlyR α1, α3, and β subunit mRNA splice variants was compared between islets from donors with and without T2D, and after high glucose culture. Insulin secretion from human islets was measured in the presence or absence of the GlyR antagonist strychnine. Results: Gene expression of GlyRs was decreased in islets from T2D donors along with smaller GlyR-mediated currents in the β cells. Glycine-induced currents are also reduced in islets from donors without diabetes after 48 hours of culture in high glucose, along with reducedα1 subunit expression and increased α3 subunit expression. Glycine-evoked currents are highly heterogeneous between different β cells within and between donors; inversely correlated with donor HbA1c; and significantly correlated to the expression of 99 different transcripts. Finally, glucose-stimulated insulin secretion is decreased in the presence of strychnine.
2024-12-02 | GSE280267 | 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
Project description:Deterioration of functional islet β-cell mass is the final step in progression to Type 2 diabetes. We previously reported that overexpression of Nkx6.1 in rat islets has the dual effects of enhancing glucose-stimulated insulin secretion (GSIS) and increasing β-cell replication. Here we show that Nkx6.1 strongly upregulates the prohormone VGF in rat islets and that VGF is both necessary and sufficient for Nkx6.1-mediated enhancement of GSIS. Moreover, the VGF-derived peptide TLQP-21 potentiates GSIS in rat and human islets and improves glucose tolerance in vivo. Chronic injection of TLQP-21 in pre-diabetic ZDF rats preserves islet mass and slows diabetes onset. TLQP-21 prevents islet cell apoptosis by a pathway similar to that used by GLP-1, but independent of the GLP-1, GIP, or VIP receptors. Unlike GLP-1, TLQP-21 does not inhibit gastric emptying or increase heart rate. We conclude that a TLQP-21 is a novel agent for enhancing islet β-cell survival and function.
2012-05-10 | GSE37852 | GEO
Project description:Blunted first-phase insulin secretion and insulin deficiency are indicators of β-cell dysfunction and diabetes manifestation. Thus, insights into molecular mechanisms that regulate insulin homeostasis might provide entry sites to replenish insulin content and restore β-cell function. Here, we identify the insulin inhibitory receptor (short: inceptor; encoded by the gene IIR) as an insulin-binding receptor that regulates insulin stores by lysosomal degradation. Using human induced pluripotent stem cell (iPSC)-derived islets, we show that IIR knockout (KO) results in enhanced stem cell (SC)-β-cell differentiation and survival. Strikingly, extended in vitro culture of IIR KO SC-β-cells leads to greatly increased insulin content and glucose-stimulated insulin secretion (GSIS). We find that inceptor localises to clathrin-coated vesicles (CCVs) close to the plasma membrane (PM) and in the trans-Golgi network (TGN), as well as in secretory granules (SGs), where it acts as a sorting receptor to direct proinsulin and insulin towards lysosomal degradation. Targeting inceptor using a monoclonal antibody (mAB) increases proinsulin and insulin content and improves SC-β-cell GSIS.
2024-09-16 | GSE226346 | GEO
Project description:Glucose-stimulated insulin secretion (GSIS) is suppressed through α-adrenergic receptor stimulation by catecholamines, epinephrine and norepinephrine, in pancreatic β-cells. Previous work has elucidated a bevy of adrenergic regulatory mechanisms beyond traditional Gi-coupled signaling including regulation of ion channels and interactions with exocytotic machinery. Glucose oxidation may also be an important site for adrenergic regulation of GSIS, but the link between epinephrine and glucose oxidation in β-cells is undefined. Here, we evaluate whether adrenergic stimulation decreases oxidative metabolism in β cells. Oxygen consumption rates were determined for Min6 and isolated rat islets in 20mM glucose complete media, then epinephrine was added at either 0 nM (vehicle control) or 100nM, followed by 10uM yohimbine (a selective Adrα2A antagonist). To identify glucose oxidation as the primary metabolic pathway affected by epinephrine, oxidation of 14C(U)-labeled glucose was determined in Min6 cells with epinephrine or vehicle. Oxygen consumption and glucose oxidation experiments were conducted in the presence of cAMP and insulin secretion blockers, respectively. Proteomics was performed on Min6 cells exposed to epinephrine for 4 hours and compared to controls. Epinephrine, but not vehicle, reduced (P<0.01) oxygen consumption rates in rat islets and Min6 cells to 64 ± 6% and 65 ± 1% of baseline, respectively, and yohimbine restored oxygen consumption to rates not different from baseline. In Min6 cells incubated with epinephrine rates of 14C glucose oxidation were reduced (P<0.01) 66 ± 4% compared to vehicle controls. These results demonstrate that acute epinephrine exposure suppresses glucose oxidation in β cells via the specific adrenergic receptor, Adrα2A, and indicate a new role for adrenergic regulation in GSIS.
2019-11-08 | PXD006330 | Pride
Project description:SHP (small heterodimer partner; NR0B2) belongs to the nuclear hormone receptor superfamily, which regulates numerous developmental and metabolic cellular functions. To study physiological function of SHP, we generated congenic SHP-/- mice on C57Bl/6 background. When the congenic SHP-/- mice were challenged with a western diet (high fat, hgih sucrose, high cholesterol) for 20 weeks, they were resistant to diet induced obesity but severely glucose intolerant compared to wild type control mice. However, their overall peripheral tissue insulin sensitivity was normal when assessed by insulin tolerance test. Next, we examined the glucose stimulated insulin secretion (GSIS) in isolated islets from these animals. Islets from SHP-/- mice showed strongly impaired GSIS especially fed the western diet, which is believed to be a major factor causing the whole body glucose intolerance in SHP-/- mice. Therefore, we explored gene expression in islets using illumina beadchip array to understand mechanisms underneath the impaired GSIS.
2010-02-24 | GSE20518 | GEO