Gene expression profiles from islets of a β-cell-specific CB1-knockout mice
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE102027 | GEO | 2018/03/07
REPOSITORIES: GEO
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Project description:Inhibition of cannabinoid receptor 1 (CB1) has shown efficacy in reducing body weight and improving metabolic parameters, with the effects correlating with target engagement in the brain. Recently, the peripheral effects of inhibiting the CB1 receptor has been appreciated through studies in diet-induced obese and liver-specific CB1 KO mice. In this report, we systematically investigated gene expression changes in peripheral tissues of DIO mice treated with the CB1 inverse agonist AM251. CB1 receptor inhibition led to down-regulation of genes within the de novo fatty acid and cholesterol synthetic pathways, including SREBP-1 and -2, and their downstream targets in both liver and adipose tissue. In addition, genes involved in fatty acid Beta-oxidation were up-regulated with AM251 treatment, probably through the activation of PPARalpha. In adipose tissue, CB1 receptor inhibition led to the down-regulation of genes in the TNFalpha signal transduction pathway and possibly to the activation of PPARgamma, both of which would result in improved insulin sensitivity.
2010-06-21 | GSE21069 | GEO
Project description:Inhibition of cannabinoid receptor 1 (CB1) has shown efficacy in reducing body weight and improving metabolic parameters, with the effects correlating with target engagement in the brain. Recently, the peripheral effects of inhibiting the CB1 receptor has been appreciated through studies in diet-induced obese and liver-specific CB1 KO mice. In this report, we systematically investigated gene expression changes in peripheral tissues of DIO mice treated with the CB1 inverse agonist AM251. CB1 receptor inhibition led to down-regulation of genes within the de novo fatty acid and cholesterol synthetic pathways, including SREBP-1 and -2, and their downstream targets in both liver and adipose tissue. In addition, genes involved in fatty acid Beta-oxidation were up-regulated with AM251 treatment, probably through the activation of PPARalpha. In adipose tissue, CB1 receptor inhibition led to the down-regulation of genes in the TNFalpha signal transduction pathway and possibly to the activation of PPARgamma, both of which would result in improved insulin sensitivity. CB1-/- mice were obtained from A. Zimmer (University of Bonn) (Zimmer et al., 1999) and back-crossed onto C57BL/6J genetic background for ten generations by A. Zimmer before homozygous CB1-/- mice were re-derived at Taconic Farms (German Town, NY) onto the C57BL/6N genetic background. Male CB1-/- mice and control littermates (n=5-7 in each group) at 2 months of age were fed with regular chow (Teklad 7012, 13 % kcal from fat, 3.41 kcal/g, Harlan Laboratories, Indianapolis, IN, USA) or high fat diet (S3282, 59.4% kcal from fat; 24.5% kcal from carbohydrate; 16.2% kcal from protein; 5.29 kcal/g, Bio-Serv, Frenchtown, NJ, USA) for 14 weeks, and were individually caged 1 week before drug treatment. Vehicle (0.5% methylcellulose) or AM251 (10 mg/kg, Sigma, St Louis, MO, USA) were dosed by oral gavage at 5:00 PM daily for 2 days. Body weight was measured at 5:00 PM on day 1 and 2, and at 10:00 AM on day 3 before tissue collection. Food was measured at 5:00 PM on day 1 and at 10:00 AM on day 3 before tissue collection. Food intake is calculated as the difference in food weight at the start minus at the end of the study. Mice were euthanized by CO2 asphyxiation at 10:00 AM following the second dose.
2010-06-21 | E-GEOD-21069 | biostudies-arrayexpress
Project description:Although the cannabinoid CB1 receptor has been implicated in atherosclerosis, its cellspecific effects in this disease are not well understood. Here, we report that male mice with myeloid-specific Cnr1 deficiency on atherogenic background developed smaller lesions and necrotic cores than controls, while only minor genotype differences were observed in females. Male Cnr1 deficient mice showed reduced arterial monocyte recruitment and macrophage proliferation with less inflammatory phenotype. The sexspecific differences in proliferation were dependent on estrogen receptor (ER)α estradiol signaling. Kinase activity profiling revealed a CB1-dependent regulation of p53 and cyclin-dependent kinases. Transcriptomic profiling further unveiled chromatin modifications, mRNA processing and mitochondrial respiration among the key processes affected by CB1 signaling, which was supported by metabolic flux assays. Chronic administration of the peripherally-restricted CB1 antagonist JD5037 inhibited plaque progression and macrophage proliferation, but only in male mice. Finally, CNR1 expression was detectable in human carotid endarterectomy plaques and inversely correlated with proliferation, oxidative metabolism and inflammatory markers, hinting to a possible implication of CB1-dependent regulation in human pathophysiology. In conclusion, impaired macrophage CB1 signaling is atheroprotective by limiting their arterial recruitment, proliferation and inflammatory reprogramming. The importance of macrophage CB1 signaling seems to be more pronounced in male mice.
2023-12-07 | GSE249503 | GEO
Project description:In the setting of obesity and insulin resistance, glycemia is controlled in part by beta cell compensation and subsequent hyperinsulinemia. Weight loss improves glycemia and decreases hyperinsulinemia, whereas weight cycling worsens glycemic control. The mechanisms responsible for weight cycling-induced deterioration in glucose homeostasis are poorly understood. Thus, we aimed to pinpoint the main regulatory junctions at which weight cycling alters glucose homeostasis in mice. Using in vivo and ex vivo procedures we show that despite having worsened glucose tolerance, weight-cycled mice do not manifest impaired whole-body insulin action. Instead, weight cycling reduces insulin secretory capacity in vivo during clamped hyperglycemia and ex vivo in perifused islets. Islets from weight-cycled mice have reduced expression of drivers of b-cell identity (Mafa, Pdx1, Nkx6.1, Ucn3) and lower islet insulin content, compared to those from obese mice, suggesting inadequate transcriptional and posttranscriptional response to repeated nutrient overload. Collectively, these data support a model in which pancreatic plasticity is challenged in the face of large fluctuations in body weight resulting in a mismatch between glycemia and insulin secretion in mice.
2022-11-09 | GSE202697 | GEO
Project description:Peripherally restricted cannabinoid CB1 receptor antagonists without central side effects hold promise for treating metabolic disorders including diabetes and obesity. In atherosclerosis, the specific effects of peripheral CB1 signaling in vascular endothelial cells (ECs) remain incompletely understood.We performed en face in situ hybridization of Cnr1 in murine aortas, revealing a significantly increased expression of the CB1 encoding gene in ECs within atheroprone compared to atheroresistant regions. In vitro, CNR1 was upregulated by oscillatory shear stress in human aortic endothelial cells (HAoECs). Endothelial CB1 deficiency (Cnr1EC-KO) in female mice on atherogenic background resulted in pronounced endothelial phenotypic changes, with reduced vascular inflammation and permeability. This translated into attenuated plaque development with reduced lipid content as well as reduced white and brown adipose tissue mass and liver steatosis. Ex vivo imaging of carotid arteries via two-photon microscopy revealed less DIL-LDL uptake in Cnr1EC-KO. This was accompanied by a significant reduction of aortic endothelial caveolin-1 (CAV1) expression, a key structural protein involved in lipid transcytosis in female Cnr1EC-KO mice. In vitro, pharmacological blocking with CB1 antagonist AM281 reproduced the inhibition of CAV1 expression and LDL uptake in response to atheroprone shear stress in human aortic endothelial cells (HAoECs), which was dependent on cAMP-mediated PKA activation. Conversely, the CB1 agonist ACEA increased DIL-LDL uptake and CAV1 expression in HAoECs. Finally, treatment of atherosclerotic mice with the peripheral CB1 antagonist JD-5037 reduced plaque progression, CAV1 and endothelial adhesion molecule expression in female mice. These results confirm an essential role of endothelial CB1 to the pathogenesis of atherosclerosis.
2024-04-04 | GSE260826 | GEO
Project description:Hyperinsulinemia often precedes type 2 diabetes but its role in disease progression is unknown. Palmitoylation, a protein modification implicated in regulated exocytosis, is reversed by acyl-protein thioesterase 1 (APT1). We found altered APT1 biology in pancreatic islets from humans with type 2 diabetes, and APT1 knockdown in nondiabetic human islets caused insulin hypersecretion. Chow fed global and islet specific APT1 knockout mice had enhanced glucose tolerance due to islet autonomous increased glucose-stimulated insulin secretion. APT1 deficiency did not affect islet calcium dynamics but prolonged insulin granule fusion. Using palmitoylation proteomics, we identified Scamp1 as an APT1 substrate that localized to insulin secretory granules. Knockdown of Scamp1 caused insulin hypersecretion. APT1 deficient insulinoma cells subjected to nutrient excess had increased apoptosis, and expression of a mutated Scamp1 incapable of being palmitoylated in APT1 deficient cells rescued insulin hypersecretion and nutrient induced apoptosis. Compared to APT1 sufficient controls, high fat fed islet specific APT1 knockout mice and global APT1 deficient db/db mice showed increased -cell failure. These findings suggest that the depalmitoylation enzyme APT1 is regulated in human islets, and that APT1 deficiency causes insulin hypersecretion leading to -cell failure, modeling the evolution of some forms of human type 2 diabetes.
2023-11-05 | PXD038554 | Pride
Project description:Adult pancreatic β cells are refractory to proliferation, a roadblock for the treatment of insulin-deficient diabetes. Consumption of energy-dense Western or high-fat diet (HFD) triggers mild adaptive β cell mass expansion to compensate for peripheral insulin resistance; however, the underlying molecular mechanism remains unclear. Here we show that Toll-like receptors (TLR) 2/TLR4 act as molecular “brakes” for diet-induced β cell replication in both mice and humans. The combined loss of TLR2/TLR4, but not individually, dramatically increases facultative β, not α, cell replication, leading to progressively enlarged islet mass and hyperinsulinemia in diet-induced obesity. Mechanistically, loss of TLR2/TLR4 increases β cell proliferation and nuclear abundance of Cyclin D2 and CDK4 in an extracellular signal-regulated kinase (ERK)-dependent manner. These data reveal a novel mechanism governing adaptive β cell mass expansion in diet-induced obesity and suggest that selective targeting of TLR2/TLR4 pathways may hold promise for reversing β cell failure in diabetic patients.
2019-03-21 | GSE101392 | GEO
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:Long-lasting forms of postsynaptic plasticity commonly involve protein synthesis-dependent structural changes of dendritic spines. However, the relationship between protein synthesis and presynaptic structural plasticity remains unclear. Here, we investigated structural changes in cannabinoid-receptor 1 (CB1)-mediated long-term depression of inhibitory transmission (iLTD), a form of presynaptic plasticity that requires protein synthesis and involves a long-lasting reduction in GABA release. We found that CB1-iLTD in acute rat hippocampal slices was associated with protein synthesis-dependent presynaptic structural changes. Using proteomics, we determined that CB1 activation in hippocampal neurons resulted in increased ribosomal proteins and initiation factors, but decreased levels of proteins involved in regulation of the actin cytoskeleton, such as Arp2/3, and presynaptic release. Moreover, while CB1-iLTD increased ubiquitin/proteasome activity, ubiquitination but not proteasomal degradation was critical for structural and functional presynaptic CB1-iLTD. Thus, CB1-iLTD relies on both protein synthesis and ubiquitination to elicit structural changes that underlie long-term reduction of GABA release.
2020-09-23 | PXD020008 | Pride
Project description:We previously demonstrated that antisense oligonucleotide (ASO)-mediated knockdown of Mboat7, the gene encoding Membrane Bound O-Acyltransferase 7, in the liver and adipose tissue of mice promoted high fat diet-induced hepatic steatosis, hyperinsulinemia, and systemic insulin resistance. Thereafter, other groups showed that hepatocyte-specific genetic deletion of Mboat7 promoted striking fatty liver and NAFLD progression in mice but does not alter insulin sensitivity, suggesting the potential for cell autonomous roles. Here, we show that MBOAT7 function in adipocytes contributes to diet-induced metabolic disturbances including hyperinsulinemia and systemic insulin resistance. We generated floxed Mboat7 mice and created hepatocyte- and adipocyte-specific knockout mice using Cre-recombinase mice under the control of the albumin and adiponectin promoter, respectively. After chow and high fat diet feeding (60% kCal fat), mice were subjected to metabolic phenotyping and tissues to molecular workup and analysis. Here, we show that MBOAT7 function in adipocytes contributes to diet-induced metabolic disturbances including hyperinsulinemia and systemic insulin resistance. The expression of Mboat7 in white adipose tissue closely correlates with diet-induced obesity across a panel of ~100 inbred strains of mice fed a high fat/high sucrose diet. Moreover, we found that adipocyte-specific genetic deletion of Mboat7 is sufficient to promote hyperinsulinemia, systemic insulin resistance, and mild fatty liver. Unlike in the liver, where Mboat7 plays a relatively minor role in maintaining arachidonic acid (AA)-containing PI pools, Mboat7 is the major source of AA-containing PI pools in adipose tissue. Our data demonstrate that MBOAT7 is a critical regulator of adipose tissue PI homeostasis, and adipocyte MBOAT7-driven PI biosynthesis is closely linked to hyperinsulinemia and insulin resistance in mice.
2023-05-10 | PXD039894 | Pride