Toll-like receptors 2 and 4 control adaptive β-cell expansion in diet-induced obesity
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE101392 | GEO | 2019/03/21
REPOSITORIES: GEO
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Project description:Core diet-induced obesity networks were constructed using Ingenuity pathway analysis (IPA) based on 332 high-fat diet responsive genes identified in liver by time-course microarray analysis (8 time-points over 24 weeks) of high-fat diet fed mice compared to normal diet fed mice. IPA identified five core diet-induced obesity networks with time-dependent gene expression changes in liver. When we merged core diet-induced obesity networks, Tlr2, Cd14 and Ccnd1 emerged as hub genes associated with both liver steatosis and inflammation and were altered in a time-dependent manner. Further protein-protein interaction network analysis revealed Tlr2, Cd14 and Ccnd1 were inter-related through the ErbB/insulin signaling pathway. Dynamic changes occur in molecular networks underlying diet-induced obesity. Tlr2, Cd14 and Ccnd1 appear to be hub genes integrating molecular interactions associated with the development of NASH. Therapeutics targeting hub genes and core diet-induced obesity networks may help ameliorate diet-induced obesity and NASH. Total RNA obtained from isolated liver of C57BL/6J mice fed normal diet or high fat diet for 0, 2, 4, 6, 8, 12, 16, 20 and 24 weeks.
2014-03-01 | E-GEOD-40481 | biostudies-arrayexpress
Project description:Core diet-induced obesity networks were constructed using Ingenuity pathway analysis (IPA) based on 332 high-fat diet responsive genes identified in liver by time-course microarray analysis (8 time-points over 24 weeks) of high-fat diet fed mice compared to normal diet fed mice. IPA identified five core diet-induced obesity networks with time-dependent gene expression changes in liver. When we merged core diet-induced obesity networks, Tlr2, Cd14 and Ccnd1 emerged as hub genes associated with both liver steatosis and inflammation and were altered in a time-dependent manner. Further protein-protein interaction network analysis revealed Tlr2, Cd14 and Ccnd1 were inter-related through the ErbB/insulin signaling pathway. Dynamic changes occur in molecular networks underlying diet-induced obesity. Tlr2, Cd14 and Ccnd1 appear to be hub genes integrating molecular interactions associated with the development of NASH. Therapeutics targeting hub genes and core diet-induced obesity networks may help ameliorate diet-induced obesity and NASH.
2014-03-01 | GSE40481 | GEO
Project description:Obesity-linked type 2 diabetes (T2D) is a major health problem of global epidemic proportions. The onset of T2D is marked by an eventual failure in pancreatic β-cell function and mass that is no longer able to compensate for the inherent insulin resistance and increased metabolic load intrinsic to obesity. However, β-cells have an inbuilt adaptive flexibility enabling them to effectively adjust insulin production rates relative to the metabolic demand. In a commonly used model of obesity-linked T2D, the db/db mouse, we have recently shown that so-called β-cell dysfunction is symptomatic of a marked increase in insulin production attempting to compensate for increased metabolic load. Pancreatic β-cells from these animals have markedly reduced intracellular insulin stores, yet high rates of (pro)insulin secretion (illustrated by severe chronic hyperinsulinemia), together with a substantial increase in proinsulin biosynthesis highlighted by expanded rough endoplasmic reticulum and Golgi apparatus. However, when the metabolic overload and/or hyperglycemia is normalized, β-cells from db/db mice quickly restore their insulin stores and normalize secretory function. This demonstrates the β-cell’s adaptive flexibility and indicates that therapeutic approaches applied to encourage β-cell rest are capable of restoring endogenous β-cell function. However, mechanisms that regulate β-cell adaptive flexibility are essentially unknown. To gain deeper mechanistic insight into the molecular events underlying β-cell adaptive flexibility in db/db β-cells, we conducted a combined proteomic and post-translational modification specific proteomic (PTMomics) approach on islets from db/db mice and wild-type controls (WT) with or without prior exposure to normal glucose levels. We identified differential modifications of proteins involved in cell redox homeostasis, protein refolding, protein K48-linked deubiquitination, mRNA/protein export along the microtubules, focal adhesion, ERK1/2 signaling, and renin-angiotensin-aldosterone signaling, as well as phosphorylation-regulated sialyltransferase activity, associated with β-cell adaptive flexibility. These proteins are all related to proinsulin biosynthesis and processing, maturation of insulin secretory granules, and vesicular trafficking—core pathways involved in the adaptation of insulin production to meet metabolic demand. Collectively, this study outlines a novel and comprehensive global proteome and PTMome signaling map that highlights important molecular mechanisms related to the adaptive flexibility of β-cell function, providing improved insight into disease pathogenesis of T2D.
2020-05-18 | PXD016392 | panorama
Project description:Overnutrition contributes to insulin resistance, obesity and metabolic stress, initiating a loss of functional beta-cells and diabetes development. Whether these damaging effects are amplified in advanced age is barely investigated. Therefore, New Zealand Obese (NZO) mice, a well-established model for the investigation of human obesity-associated type 2 diabetes, were fed a metabolically challenging diet with a high-fat, carbohydrate restricted period followed by a carbohydrate intervention in young as well as advanced age. Interestingly, while young NZO mice developed massive hyperglycemia in response to carbohydrate feeding, leading to beta-cell dysfunction and cell death, aged counterparts compensated the increased insulin demand by persistent beta-cell function and beta-cell mass expansion. Beta-cell loss in young NZO islets was linked to increased expression of thioredoxin-interacting protein (TXNIP), presumably initiating an apoptosis-signaling cascade via caspase-3 activation. In contrast, islets of aged NZOs exhibited a sustained redox balance without changes in TXNIP expression, associated with higher proliferative potential by cell cycle activation. These findings support the relevance of a maintained proliferative potential and redox homeostasis for preserving islet functionality under metabolic stress, with the peculiarity that this adaptive response emerged with advanced age in diabetes-prone NZO mice.
2020-11-02 | GSE150281 | GEO
Project description:Obesity is associated with an increase in β-cell mass in response to the rising demand for insulin. β-cell plasticity is essential to maintaining glucose homeostasis, however, the cellular and molecular mechanisms by which β-cell mass is regulated remain poorly understood. Recently, we described the existence of a crosstalk between the peripancreatic adipose tissue and β-cells as a novel mechanism that participates in the regulation of β-cell plasticity. Here, we identify the secreted frizzled-related protein (Sfrp) 5 as down-regulated in the pancreatic islets of obese rats as well as in the pancreatic islets of human obese patients. Our results demonstrate that the silencing of Sfrp5 induces an increase in β-cell proliferation, which we correlate with the activation of Wnt signaling and of the MAPK and PI3 kinase pathways. Together, these findings expand our understanding of the mechanisms underlying β-cell proliferation under conditions of obesity. Furthermore, this study opens new insights into the specific targeting of Sfrp5 as a novel therapeutic strategy for balancing β-cell mass. Adult male Wistar rats (Charles River Laboratories, Wilmington, MA), 7 wk old (weighing 225–250 g), were caged individually in a 12-h light, 12-h dark cycle in a temperature- and humidity-controlled environment. Animals were divided into two dietary sets for 10 days. One group was fed with standard chow diet (supplying 8% of calories as fat; type AO4 from Panlab, Barcelona, Spain). The second group was fed with a cafeteria diet (66% of calories as fat), as previously described (Endocrinology 2012;153:177-87). Pancreatic islets were isolated through collagenase perfusion of the pancreas, Histopaque gradient and hand-picking under microscopic guidance. Ten micrograms of total RNA from islets were converted into cRNA, biotinylated, fragmented, and hybridized to GeneChip Rat Genome 230 2.0 (Affymetrix, Santa Clara, CA). Ten microarrays were hybridized, five with independent samples coming from rats fed with standard chow (lean group) and five with independent samples coming from rats fed with the cafeteria diet (obese group).
2014-10-10 | E-GEOD-44045 | biostudies-arrayexpress
Project description:The NF-κB pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic beta cell dysfunction in the metabolic syndrome. While canonical NF-κB signaling is well studied, there is little information on the divergent non-canonical NF-κB pathway in the context of pancreatic islet dysfunction in diabetes. Here, we demonstrate that pharmacological activation of the non-canonical NF-κB inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. Further, we identify NIK as a critical negative regulator of beta cell function as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of non-canonical NF-κB components p100 to p52, and accumulation of RelB. Tumor necrosis factor α (TNFα) and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive beta cell intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the non-canonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to beta cell failure. These studies reveal that NIK contributes a central mechanism for beta cell failure in diet-induced obesity. We identify a role for Nuclear Factor inducing κB (NIK) in pancreatic beta cell failure. NIK activation disrupts glucose homeostasis in zebrafish in vivo and impairs glucose-stimulated insulin secretion in mouse and human islets in vitro. NIK activation also perturbs beta cell insulin secretion in a diet-induced obesity mouse model. These studies reveal that NIK contributes a central mechanism for beta cell failure in obesity. To uncover the role of NIK in pancreatic beta cells, we performed a gene expression microarray analysis comparing pancreatic islets with constitutive beta cell intrinsicNIK activation from the 16 week old mice (beta cell specific TRAF2 and TRAF2 knockout mice) to their controls (n=3 per group).
2015-06-18 | E-GEOD-68317 | biostudies-arrayexpress
Project description:Although persistent elevations in circulating glucose concentrations promote compensatory increases in pancreatic islet mass, unremitting insulin resistance causes a deterioration in beta cell function that disrupts glucose balance and signals the progression to diabetes 1. Glucagon like Peptide 1 (GLP1) agonists improve glucose tolerance in insulin resistance, although some individuals are unresponsive to treatment. Here we show that increases in GLP1 during feeding promote beta cell function in part through the PKA-mediated activation of CREB and its coactivator CRTC2 2. Mice with a knockout of CRTC2 in beta cells have impaired oral glucose tolerance due to decreases in circulating insulin concentrations. CRTC2 was found to promote beta cell function in part by stimulating the expression of the transcription factor MafA. Chronic hyperglycemia associated with high fat or high carbohydrate diet feeding disrupted cAMP signaling in pancreatic islets. Indeed, prolonged elevations in circulating glucose concentrations interfered with CREB signaling by activating the mTOR pathway and triggering the hypoxia inducible factor (HIF1)-dependent induction of the Protein Kinase A Inhibitor beta (PKIB), a potent inhibitor of PKA catalytic activity 3. As disruption of the PKIB gene restored glucose tolerance and insulin secretion in obesity, our results demonstrate how cross-talk between nutrient and hormonal pathways contributes to loss of pancreatic islet function in insulin resistance. Rat insulinoma cells were used to interrogate the impact of glucose exposure and CREB activity on cAMP dependent gene regulation in the pancreatic beta cells
2015-02-23 | E-GEOD-60158 | biostudies-arrayexpress
Project description:Maternal low-protein diet increases the susceptibility of offspring to type 2 diabetes. An insult to the pancreas during development can have long-term consequences on β-cell mass and function. Because nutrients and growth factors signaling converge on mTOR, we hypothesized that mTOR plays a central role in β-cell programming during fetal development. In this study, we revealed that newborns of dams exposed to low-protein diet (LP0.5) throughout pregnancy exhibited decreased insulin levels, β-cell fraction, and mTOR signaling. Adult LP0.5 offspring demonstrated enhanced insulin sensitivity but remained glucose intolerant due to an insulin secretory defect and not reduced β-cell mass. The insulin secretory defect was distal to Ca2+ influx, at the level of proinsulin biosynthesis and insulin content. LP0.5 islets exhibited reduced mTOR protein and increased expression of specific microRNAs. The reductions in mTOR protein and insulin secretion in LP0.5 islets were restored to normal by blockade of microRNAs 199a-3p and 342. Finally, transient activation of mTORC1 signaling in β-cells during the last week of pregnancy rescued the neonatal β-cell fraction defect and metabolic abnormalities in LP0.5 mice. These findings identify a major role of microRNAs and mTOR in β-cell programing by maternal low-protein diet. To investigate which microRNAs are altered in islets isolated from 2-3 months old male offspring of dams fed low-protein diet (LP0.5) or control diet throughout pregnancy
2014-07-11 | GSE59279 | GEO
Project description:The progression towards type 2 diabetes depends on the success of the allostatic response of the pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physio and pathological states such as pregnancy, obesity or ageing. The mechanisms, mediating beta cell mass expansion in these scenarios are not well defined. We have recently showed that beta cell mass failed to expand in ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Here we investigate PPAR gamma dependent transcriptional responses occurring during early stages of the adaptation of beta cells to insulin resistance. As it could be expected we have identified genes known to regulate proliferation and survival signals of the beta cells. Moreover we have also identified new pathways induced in ob/ob islets that fail to do so in POKO islets. Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with activation of immune response and is missing in POKO islets. Other PPARγ dependent differentially regulated pathways include cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation. In this study, we used gene expression arrays to investigate differences between four experimental classes by pairs
2012-01-16 | E-GEOD-33647 | biostudies-arrayexpress