scholarly journals TCONS_00230836 silencing restores stearic acid-induced β cell dysfunction through alleviating endoplasmic reticulum stress rather than apoptosis

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Rui Guo ◽  
Yunjin Zhang ◽  
Yue Yu ◽  
Shenghan Su ◽  
Qingrui Zhao ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Insulin Secretion ◽  
Endoplasmic Reticulum Stress ◽  
Stearic Acid ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Acid Diet ◽  
High Stearic Acid ◽  
Mouse Islets

Abstract Background Chronic exposure of pancreatic β cells to high levels of stearic acid (C18:0) leads to impaired insulin secretion, which accelerates the progression of type 2 diabetes mellitus (T2DM). Recently, long noncoding RNAs (lncRNAs) were found to participate in saturated fatty acid-induced metabolism dysfunction. However, their contribution to stearic acid-induced β-cell dysfunction remains largely unknown. This study evaluated the possible role of the lncRNA TCONS_00230836 in stearic acid-stimulated lipotoxicity to β cells. Method Using high-throughput RNA-sequencing, TCONS_00230836 was screened out as being exclusively differentially expressed in stearic acid-treated mouse β-TC6 cells. Co-expression network was constructed to reveal the potential mRNAs targeted for lncRNA TCONS_00230836. Changes in this lncRNA’s and candidate mRNAs’ levels were further assessed by real-time PCR in stearic acid-treated β-TC6 cells and islets of mice fed a high-stearic-acid diet (HSD). The localization of TCONS_00230836 was detected by fluorescent in situ hybridization. The endogenous lncRNA TCONS_00230836 in β-TC6 cells was abrogated by its Smart Silencer. Results TCONS_00230836 was enriched in mouse islets and mainly localized in the cytoplasm. Its expression was significantly increased in stearic acid-treated β-TC6 cells and HSD-fed mouse islets. Knockdown of TCONS_00230836 significantly restored stearic acid-impaired glucose-stimulated insulin secretion through alleviating endoplasmic reticulum stress. However, stearic acid-induced β cell apoptosis was not obviously recovered. Conclusion Our findings suggest the involvement of TCONS_00230836 in stearic acid-induced β-cell dysfunction, which provides novel insight into stearic acid-induced lipotoxicity to β cells. Anti-lncRNA TCONS_00230836 might be a new therapeutic strategy for alleviating stearic acid-induced β-cell dysfunction in the progression of T2DM.

scholarly journals TCONS_00230836 silencing restores stearic acid-induced β-cell dysfunction through alleviating endoplasmic reticulum stress via a PERK/eIF2α-dependent pathway rather than apoptosis

2020 ◽  
Author(s):  
Rui Guo ◽  
Yunjin Zhang ◽  
Yue Yu ◽  
Shenghan Su ◽  
Qingrui Zhao ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Stearic Acid ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Acid Diet ◽  
High Stearic Acid ◽  
Mouse Islets ◽  
Dependent Pathway

Abstract Background: Chronic exposure of pancreatic β cells to high levels of stearic acid (C18:0) leads to impaired insulin secretion, which accelerates the progression of type 2 diabetes mellitus (T2DM). Recently, long noncoding RNAs (lncRNAs) were found to participate in saturated fatty acid-induced metabolism dysfunction. However, their contribution to stearic acid-induced β-cell dysfunction remains largely unknown. This study evaluated the possible role of the lncRNA TCONS_00230836 in stearic acid-stimulated lipotoxicity to β cells. Method: Using high-throughput RNA-sequencing, TCONS_00230836 was screened out as being exclusively differentially expressed in stearic acid-treated mouse β-TC6 cells. Co-expression network was constructed to reveal the potential mRNAs targeted for lncRNA TCONS_00230836. Changes in this lncRNA’s and candidate mRNAs’levels were further assessed by real-time PCR in stearic acid-treated β-TC6 cells and islets of mice fed a high-stearic-acid diet (HSD). The localization of TCONS_00230836 was detected by fluorescent in situ hybridization. The endogenous lncRNA TCONS_00230836 in β-TC6 cells was abrogated by its Smart Silencer. Results: The lncRNA TCONS_00230836 was enriched in mouse islets and mainly localized in the cytoplasm. Its expression was significantly increased in stearic acid-treated β-TC6 cells and HSD-fed mouse islets. Knockdown of TCONS_00230836 apparently restored stearic acid-impaired GSIS through alleviating endoplasmic reticulum stress via a PERK/eIF2α-dependent pathway. However, stearic acid-induced β-cell apoptosis was not obviously recovered. Conclusion: Our findings suggest the involvement of the lncRNA TCONS_00230836 in stearic acid-induced β-cell dysfunction, which provides novel insight into stearic acid-induced lipotoxicity to β cells. Anti-lncRNA TCONS_00230836 might be a new therapeutic strategy for alleviating stearic acid-induced β-cell dysfunction in the progression of T2DM.

Effects of pharmacological inhibition of NADPH oxidase or iNOS on pro-inflammatory cytokine, palmitic acid or H2O2-induced mouse islet or clonal pancreatic β-cell dysfunction

2010 ◽  
Vol 30 (6) ◽  
pp. 445-453 ◽  
Author(s):  
Marta Michalska ◽  
Gabriele Wolf ◽  
Reinhard Walther ◽  
Philip Newsholme
Keyword(s):  
Fatty Acids ◽  
Insulin Secretion ◽  
Nadph Oxidase ◽  
Inflammatory Cytokine ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Mouse Islets ◽  
Pro Inflammatory Cytokines

Various pancreatic β-cell stressors including cytokines and saturated fatty acids are known to induce oxidative stress, which results in metabolic disturbances and a reduction in insulin secretion. However, the key mechanisms underlying dysfunction are unknown. We investigated the effects of prolonged exposure (24 h) to pro-inflammatory cytokines, H2O2 or PA (palmitic acid) on β-cell insulin secretion, ATP, the NADPH oxidase (nicotinamide adenine dinucleotide phosphate oxidase) component p47phox and iNOS (inducible nitric oxide synthase) levels using primary mouse islets or clonal rat BRIN-BD11 β-cells. Addition of a pro-inflammatory cytokine mixture [IL-1β (interleukin-1β), TNF-α (tumour necrosis factor-α) and IFN-γ (interferon-γ)] or H2O2 (at sub-lethal concentrations) inhibited chronic (24 h) levels of insulin release by at least 50% (from islets and BRIN-BD11 cells), while addition of the saturated fatty acid palmitate inhibited acute (20 min) stimulated levels of insulin release from mouse islets. H2O2 decreased ATP levels in the cell line, but elevated p47phox and iNOS levels as did cytokine addition. Similar effects were observed in mouse islets with respect to elevation of p47phox and iNOS levels. Addition of antioxidants SOD (superoxide dismutase), Cat (catalase) and NAC (N-acetylcysteine) attenuated H2O2 or the saturated fatty acid palmitate-dependent effects, but not cytokine-induced dysfunction. However, specific chemical inhibitors of NADPH oxidase and/or iNOS appear to significantly attenuate the effects of cytokines, H2O2 or fatty acids in islets. While pro-inflammatory cytokines are known to increase p47phox and iNOS levels in β-cells, we now report that H2O2 can increase levels of the latter two proteins, suggesting a key role for positive-feedback redox sensitive regulation of β-cell dysfunction.

scholarly journals Overexpression of miR-297b-5p protects against stearic acid-induced pancreatic β-cell apoptosis by targeting LATS2

2020 ◽  
Vol 318 (3) ◽  
pp. E430-E439 ◽  
Author(s):  
Rui Guo ◽  
Yue Yu ◽  
Yunjin Zhang ◽  
Yinling Li ◽  
Xia Chu ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Stearic Acid ◽  
Palmitic Acid ◽  
Cell Apoptosis ◽  
Control Group ◽  
Β Cell ◽  
Cell Dysfunction ◽  
High Stearic Acid ◽  
Mouse Islets

Chronic exposure to high concentrations of stearic acid (C18:0) can result in β -cell dysfunction, leading to development of type 2 diabetes. However, the molecular mechanisms underlying the destructive effects of stearic acid on β-cells remain largely unknown. In this study, we aimed to investigate the role of miR-297b-5p on stearic acid-induced β-cell apoptosis. Differential expression of microRNAs (miRNAs) was assessed in a β-TC6 cell line exposed to stearic acid, palmitic acid, or a normal culture medium by high-throughput sequencing. The apoptosis rate was measured by flow cytometry after miR-297b-5p mimic/inhibitor transfection, and large-tumor suppressor kinase 2 (LATS2) was identified as a target of miR-297b-5p using a luciferase activity assay. In vivo, C57BL/6 mice were fed with normal and high-stearic-acid diet, respectively. Mouse islets were used for similar identification of miR-297b-5p and Lats2 in β-TC6 cell. We selected two differentially expressed miRNAs in stearic acid compared with those in the palmitic acid and control groups. miR-297b-5p expression was significantly lower in β-TC6 cells and mouse islets in stearic acid than in control group. Upregulation of miR-297b-5p alleviated the stearic acid-induced cell apoptosis and reduction in insulin secretion by inhibiting Lats2 expression in vitro. Meanwhile, silencing Lats2 significantly reversed the stearic acid-stimulated β-cell dysfunction in both β-TC6 cells and islets. Our findings indicate a suppressive role for miR-297b-5p in stearic acid-induced β-cell apoptosis, which may reveal a potential target for the treatment of β-cell dysfunction in the pathogenesis of type 2 diabetes.

scholarly journals Insulin secretion in health and disease: nutrients dictate the pace

2015 ◽  
Vol 75 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Romano Regazzi ◽  
Adriana Rodriguez-Trejo ◽  
Cécile Jacovetti
Keyword(s):  
Fatty Acids ◽  
Insulin Secretion ◽  
Cell Mass ◽  
Insulin Biosynthesis ◽  
Β Cells ◽  
Β Cell ◽  
Altered Expression ◽  
Cell Dysfunction ◽  
Dietary Nutrients ◽  
Underlying Mechanisms

Insulin is a key hormone controlling metabolic homeostasis. Loss or dysfunction of pancreatic β-cells lead to the release of insufficient insulin to cover the organism needs, promoting diabetes development. Since dietary nutrients influence the activity of β-cells, their inadequate intake, absorption and/or utilisation can be detrimental. This review will highlight the physiological and pathological effects of nutrients on insulin secretion and discuss the underlying mechanisms. Glucose uptake and metabolism in β-cells trigger insulin secretion. This effect of glucose is potentiated by amino acids and fatty acids, as well as by entero-endocrine hormones and neuropeptides released by the digestive tract in response to nutrients. Glucose controls also basal and compensatory β-cell proliferation and, along with fatty acids, regulates insulin biosynthesis. If in the short-term nutrients promote β-cell activities, chronic exposure to nutrients can be detrimental to β-cells and causes reduced insulin transcription, increased basal secretion and impaired insulin release in response to stimulatory glucose concentrations, with a consequent increase in diabetes risk. Likewise, suboptimal early-life nutrition (e.g. parental high-fat or low-protein diet) causes altered β-cell mass and function in adulthood. The mechanisms mediating nutrient-induced β-cell dysfunction include transcriptional, post-transcriptional and translational modifications of genes involved in insulin biosynthesis and secretion, carbohydrate and lipid metabolism, cell differentiation, proliferation and survival. Altered expression of these genes is partly caused by changes in non-coding RNA transcripts induced by unbalanced nutrient uptake. A better understanding of the mechanisms leading to β-cell dysfunction will be critical to improve treatment and find a cure for diabetes.

scholarly journals Diazoxide-induced β-cell rest reduces endoplasmic reticulum stress in lipotoxic β-cells

2008 ◽  
Vol 199 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Ernest Sargsyan ◽  
Henrik Ortsäter ◽  
Kristofer Thorn ◽  
Peter Bergsten
Keyword(s):  
Endoplasmic Reticulum ◽  
Insulin Secretion ◽  
Er Stress ◽  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Eukaryotic Translation ◽  
Β Cell Function ◽  
Activating Transcription Factor ◽  
The Unfolded Protein Response

Elevated levels of glucose and lipids are characteristics of individuals with type 2 diabetes mellitus (T2DM). The enhanced nutrient levels have been connected with deterioration of β-cell function and impaired insulin secretion observed in these individuals. A strategy to improve β-cell function in individuals with T2DM has been intermittent administration of KATP channel openers. After such treatment, both the magnitude and kinetics of insulin secretion are markedly improved. In an attempt to further delineate mechanisms of how openers of KATP channels improve β-cell function, the effects of diazoxide on markers of endoplasmic reticulum (ER) stress was determined in β-cells exposed to the fatty acid palmitate. The eukaryotic translation factor 2-alpha kinase 3 (EIF2AK3; also known as PERK) and endoplasmic reticulum to nucleus signaling 1 (ERN1; also known as IRE1) pathways, but not the activating transcription factor (ATF6) pathway of the unfolded protein response, are activated in such lipotoxic β-cells. Inclusion of diazoxide during culture attenuated activation of the EIF2AK3 pathway but not the ERN1 pathway. This attenuation was associated with reduced levels of DNA-damage inducible transcript 3 (DDIT3; also known as CHOP) and β-cell apoptosis was decreased. It is concluded that reduction of ER stress may be a mechanism by which diazoxide improves β-cell function.

scholarly journals Inhibition of Forkhead Box O1 Protects Pancreatic β-Cells against Dexamethasone-Induced Dysfunction

Endocrinology ◽  
2009 ◽  
Vol 150 (9) ◽  
pp. 4065-4073 ◽  
Author(s):  
Xiongfei Zhang ◽  
Wei Yong ◽  
Jinghuan Lv ◽  
Yunxia Zhu ◽  
Jingjing Zhang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Types ◽  
Pancreatic Β Cell ◽  
Rinm5f Cells ◽  
Β Cells ◽  
Β Cell ◽  
Rat Islets ◽  
Cell Dysfunction ◽  
Forkhead Box ◽  
Glucose Stimulated Insulin Secretion

Abstract Forkhead Box O1 (FoxO1) is a key transcription regulator of insulin/IGF-I signaling pathway, and its activity can be increased by dexamethasone (DEX) in several cell types. However, the role of FoxO1 in DEX-induced pancreatic β-cell dysfunction has not been fully understood. Therefore, in this study, we investigated whether FoxO1 could mediate DEX-induced β-cell dysfunction and the possible underlying mechanisms in pancreatic β-cell line RINm5F cells and primary rat islet. We found that DEX markedly increased FoxO1 mRNA and protein expression and decreased FoxO1 phosphorylation through the Akt pathway, which resulted in an increase in active FoxO1 in RINm5F cells and isolated rat islets. Activated FoxO1 subsequently inhibited pancreatic duodenal homeobox-1 expression and induced nuclear exclusion of pancreatic duodenal homeobox-1. Knockdown of FoxO1 by RNA interference restored the expression of pancreatic duodenal homeobox-1 and prevented DEX-induced dysfunction of glucose-stimulated insulin secretion in rat islets. Together, the results of present study demonstrate that FoxO1 is integrally involved in DEX-induced inhibition of pancreatic duodenal homeobox-1 and glucose-stimulated insulin secretion dysfunction in pancreatic islet β-cells. Inhibition of FoxO1 can effectively protect β-cells against DEX-induced dysfunction.

scholarly journals The Orphan Nuclear Receptor NR4A1 Protects Pancreatic β-Cells from Endoplasmic Reticulum (ER) Stress-mediated Apoptosis

2015 ◽  
Vol 290 (34) ◽  
pp. 20687-20699 ◽  
Author(s):  
Cong Yu ◽  
Shang Cui ◽  
Chen Zong ◽  
Weina Gao ◽  
Tongfu Xu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Survivin Promoter ◽  
Min6 Cells ◽  
Chop Expression ◽  
Mouse Islets

The role of NR4A1 in apoptosis is controversial. Pancreatic β-cells often face endoplasmic reticulum (ER) stress under adverse conditions such as high free fatty acid (FFA) concentrations and sustained hyperglycemia. Severe ER stress results in β-cell apoptosis. The aim of this study was to analyze the role of NR4A1 in ER stress-mediated β-cell apoptosis and to characterize the related mechanisms. We confirmed that upon treatment with the ER stress inducers thapsigargin (TG) or palmitic acid (PA), the mRNA and protein levels of NR4A1 rapidly increased in both MIN6 cells and mouse islets. NR4A1 overexpression in MIN6 cells conferred resistance to cell loss induced by TG or PA, as assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and TUNEL assays indicated that NR4A1 overexpression also protected against ER stress-induced apoptosis. This conclusion was further confirmed by experiments exploiting siRNA to knockdown NR4A1 expression in MIN6 cells or exploiting NR4A1 knock-out mice. NR4A1 overexpression in MIN6 cells reduced C/EBP homologous protein (CHOP) expression and Caspase3 activation induced by TG or PA. NR4A1 overexpression in MIN6 cells or mouse islets resulted in Survivin up-regulation. A critical regulatory element was identified in Survivin promoter (−1872 bp to −1866 bp) with a putative NR4A1 binding site; ChIP assays demonstrated that NR4A1 physically associates with the Survivin promoter. In conclusion, NR4A1 protects pancreatic β-cells against ER stress-mediated apoptosis by up-regulating Survivin expression and down-regulating CHOP expression, which we termed as “positive and negative regulation.”

scholarly journals Antagonistic epistasis of Hnf4α and FoxO1 networks through enhancer interactions in β-cell function

2020 ◽  
Author(s):  
Taiyi Kuo ◽  
Wen Du ◽  
Yasutaka Miyachi ◽  
Prasanna K. Dadi ◽  
David A. Jacobson ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Functional Restoration ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Gene Environment ◽  
Genome Wide ◽  
Β Cell Function ◽  
Acquired Abnormalities

AbstractGenetic and acquired abnormalities contribute to pancreatic β-cell failure in diabetes. Transcription factors Hnf4α (MODY1) and FoxO1 are respective examples of these two components, and are known to act through β-cell-specific enhancers. However, their relationship is unclear. Here we show by genome-wide interrogation of chromatin modifications that FoxO1 ablation in mature β-cells leads to increased selection of FoxO1 enhancers by Hnf4α. To model the functional significance we generated single and compound knockouts of FoxO1 and Hnf4α in β-cells. Single knockout of either gene impaired insulin secretion in mechanistically distinct fashions. Surprisingly, the defective β-cell secretory function of either single mutant in hyperglycemic clamps and isolated islets treated with various secretagogues, was completely reversed in double mutants. Gene expression analyses revealed the reversal of β-cell dysfunction with an antagonistic network regulating glycolysis, including β-cell “disallowed” genes; and that a synergistic network regulating protocadherins emerged as likely mediators of the functional restoration of insulin secretion. The findings provide evidence of antagonistic epistasis as a model of gene/environment interactions in the pathogenesis of β-cell dysfunction.

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