Enhanced glucose uptake in adipocytes despite deteriorating insulin signaling and increased autophagic flux with high fat feeding in mice
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PROVIDER: PRJNA415808 | ENA |
REPOSITORIES: ENA
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Project description:Background: Systemic glucose homeostasis is affected by adipose cell function. Still, the cellular events preceding the onset of insulin resistance in adipocytes are not yet resolved. To capture the immediate cellular changes during diet-induced expansion of cell volume and number, we characterized the initial changes in mature adipocytes during a short high fat diet (HFD) intervention. Methods: C57BL6/J male mice were fed chow diet, and switched to HFD for 2, 4, 6 or 14 days. Systemic glucose clearance was assessed by glucose tolerance test. Adipose tissue was dissected for RNA seq analysis and cell size distribution analyzed using coulter counter technique. Insulin response in isolated adipocytes was measured by glucose uptake and Western blotting of insulin signaling intermediates. Confocal microscopy was used to assess autophagic flux in cells pre-incubated with rapamycin and chloroquine. Results: Switching to HFD was accompanied by an immediate adipose cell size expansion followed by recruitment of new adipocytes. Despite an increase in both basal and insulin-stimulated glucose uptake in adipocytes, we observed a progressive decrease in insulin-stimulated activation of Protein Kinase B (PKB) Ser473, PKB Thr308 and Akt substrate of 160 (AS160) Tyr642, and onset of systemic insulin-resistance already after two days. Moreover, RNA-seq analysis of adipose tissue revealed marked changes in gene expression at day four, of which the most significant included genes directly involved in autophagy (Trp53Inp2 and Beclin1). Enhanced autophagy was observed in isolated adipocytes from HFD-fed mice, detected as an increased density of LC3-positive puncta by confocal microscopy, and increase of LC3II. Conclusions: HFD rapidly caused impaired insulin signal transduction in adipocytes, while both basal and insulin-stimulated glucose uptake increased, which support the concept of spare signaling. Interestingly, our data suggests autophagy as one of the early cellular events that could contribute to insulin resistance.
2018-10-25 | GSE106174 | GEO
Project description:Miz1 is required to maintain autophagic flux
| PRJNA210788 | ENA
Project description:Doxorubicin (DOX) cardiotoxicity is an important factor of heart failure. The only clinically approved drug is dexrazoxane, while its side effect of secondary malignancies severely limited its application. It is urgent to find other alternative efficacious molecular for these chemotherapy patients. Colchicine is a safe and well tolerated anti-inflammation drug which also functions in attenuating the reactive oxygen species (ROS) generation. High dose of colchicine was reported block the autophagosome-lysosome fusion in cancer cells due to its destabilization effect to the microtubule system, while how colchicine affects the autophagic flux in cardiomyocytes is largely unknown. Recent years low dose of colchicine administration was reported helpful to the patients with pericarditis, postprocedural atrial fibrillation and coronary artery disease, most of the research attributed it to its anti-inflammation effect. Whether the autophagic flux regulated by colchicine also benefits to DOX induced heart failure remains unclear. Doxorubicin (DOX) administration was used to establish heart failure models in vivo and in vitro. Results showed that DOX blocked the autophagic vacuoles degradation, leading to damaged mitochondria and ROS accumulation. Heart failure characteristics were obviously improved after low dose of colchicine administration. Mechanistically, low dose of colchicine promoted the autolysosome degradation, cleared the damaged mitochondria, and ROS accumulation induced by the DOX and as a result attenuated DOX cardiotoxicity.
2024-06-20 | GSE247345 | GEO
Project description:Diosmin inhibits glioma growth through inhibition of autophagic flux
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Project description:Miz1 is a zinc finger protein that regulates expression of cell cycle inhibitors as part of a complex with Myc. Cell cycle-independent functions of Miz1 are poorly understood. Here, we use a Nestin-Cre transgene to delete an essential domain of Miz1 in the central nervous system (Miz1M-NM-^TPOZNes). Miz1M-NM-^TPOZNes mice display cerebellar neurodegeneration characterized by the progressive loss of Purkinje cells. Chromatin immunoprecipitation sequencing and biochemical analyses show that Miz1 activates transcription upon binding to a non-palindromic sequence present in core promoters. Target genes of Miz1 encode regulators of autophagy and proteins involved in vesicular transport that are required for autophagy. Miz1M-NM-^TPOZ neuronal progenitors and fibroblasts show reduced autophagic flux. Consistently, polyubiquitinated proteins and p62/Sqtm1 accumulate in the cerebella of Miz1M-NM-^TPOZNes mice, characteristic features of defective autophagy. Our data suggest that Miz1 may link cell growth and ribosome biogenesis to the transcriptional regulation of vesicular transport and autophagy. ChIP-Seq with H190 and G18 on an Illumina Genome Analyzer IIx.
2013-09-27 | E-GEOD-48602 | biostudies-arrayexpress
Project description:Autophagy plays an important role in preserving cellular homeostasis in pancreatic beta cells. However, the extent of autophagic flux induced in various physiological settings in vivo is unclear. In this study, we generated transgenic mice expressing pHluorin-LC3-mCherry reporter for monitoring systemic autophagic flux. Our findings revealed that autophagic flux in pancreatic islets enhanced after starvation, although suppression of the flux after short-term refeeding needs more prolonged restarvation in islets than in liver and skeletal muscle. Furthermore, heterogeneity of autophagic flux in beta cells manifested after increasing insulin resistance and intracellular calcium influx by glucose stimulation increased more in high- than low-flux beta cells, with differential gene expression based on the flux. Thus, our monitor mouse enables us to reveal physiological response and biological insight of heterogeneity in autophagic flux in pancreatic beta cells.
2023-03-15 | PXD036390 | JPOST Repository
Project description:Miz1 is a zinc finger protein that regulates expression of cell cycle inhibitors as part of a complex with Myc. Cell cycle-independent functions of Miz1 are poorly understood. Here, we use a Nestin-Cre transgene to delete an essential domain of Miz1 in the central nervous system (Miz1ΔPOZNes). Miz1ΔPOZNes mice display cerebellar neurodegeneration characterized by the progressive loss of Purkinje cells. Chromatin immunoprecipitation sequencing and biochemical analyses show that Miz1 activates transcription upon binding to a non-palindromic sequence present in core promoters. Target genes of Miz1 encode regulators of autophagy and proteins involved in vesicular transport that are required for autophagy. Miz1ΔPOZ neuronal progenitors and fibroblasts show reduced autophagic flux. Consistently, polyubiquitinated proteins and p62/Sqtm1 accumulate in the cerebella of Miz1ΔPOZNes mice, characteristic features of defective autophagy. Our data suggest that Miz1 may link cell growth and ribosome biogenesis to the transcriptional regulation of vesicular transport and autophagy.
2013-09-27 | GSE48602 | GEO
Project description:MICU1 orchestrates the autophagic flux in a SPGL1- and VPS39-dependent manner
| PRJNA714052 | ENA
Project description:Autophagic flux is associated with chemoresistance, the leading cause of chemotherapeutic failure. Here, we showed that HAX-1 promotes chemoresistance by effectively blocking the fusion of autophagosomes with lysosomes. Mass spectrometric and functional studies demonstrated that HAX-1 recruited NEDD4 to promote Rab7a degradation and inhibited the binding of Rab7a with SNAREs by competitively binding to it. Furthermore, HAX-1 could bind to IGF2BP1 mRNA, thereby contributing to its stability and translation. Moreover, IGF2BP1 enhanced HAX-1 m6A methylation, thereby enhancing its stability. Via in vivo and in vitro experiments, we confirmed the positive role of the IGF2BP1-HAX-1 feedback loop in chemoresistance. Our data provide evidence that HAX-1, IGF2BP1, and SQSTM1 levels are useful predictors of clinical outcome and chemoresistance risk. In addition, our data provide new insights into the clinical applications of therapies related to autophagic flux and its associated molecular network in targeting cisplatin chemoresistance in nasopharyngeal carcinoma.
2023-09-30 | GSE244097 | GEO
Project description:To capture immediate cellular changes during diet-induced expansion of adipocyte cell volume and number, we characterized mature adipocytes during a short-term high-fat diet (HFD) intervention. Male C57BL6/J mice were fed chow diet, and then switched to HFD for 2, 4, 6 or 14 days. Systemic glucose clearance was assessed by glucose tolerance test. Adipose tissue was dissected for RNA-seq and cell size distribution analysis using coulter counting. Insulin response in isolated adipocytes was monitored by glucose uptake assay and Western blotting, and confocal microscopy was used to assess autophagic activity. Switching to HFD was accompanied by an immediate adipocyte size expansion and onset of systemic insulin resistance already after two days, followed by recruitment of new adipocytes. Despite an initially increased non-stimulated and preserved insulin-stimulated glucose uptake, we observed a decreased phosphorylation of insulin receptor substrate-1 (IRS-1) and protein kinase B (PKB). After 14 days of HFD, both the insulin-stimulated phosphorylation of Akt substrate of 160?kDa (AS160) and glucose uptake was blunted. RNA-seq analysis of adipose tissue revealed transient changes in gene expression at day four, including highly significant upregulation of Trp53inp, previously demonstrated to be involved in autophagy. We confirmed increased autophagy, measured as an increased density of LC3-positive puncta and decreased p62 expression after 14 days of HFD. In conclusion, HFD rapidly induced systemic insulin resistance, whereas insulin-stimulated glucose uptake remained intact throughout 6 days of HFD feeding. We also identified autophagy as an early cellular process that potentially influences adipocyte function upon switching to HFD.
| S-EPMC7459392 | biostudies-literature