Selective Inhibition of Eukaryotic Translation Initiation Factor 2α Dephosphorylation Potentiates Fatty Acid-induced Endoplasmic Reticulum Stress and Causes Pancreatic β-Cell Dysfunction and Apoptosis

Cnop, Miriam; Ladrière, Laurence; Hekerman, Paul; Ortis, Fernanda; Cardozo, Alessandra K; Dogusan, Zeynep; Flamez, Daisy; Boyce, Michael; Yuan, Junying; Eizirik, Décio L.

doi:10.1074/jbc.m607627200

Cited by 272 publications

(302 citation statements)

References 59 publications

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“…However, due to the deleterious effects of prolonged increased XBP1s level, this mechanism has to be closely regulated in beta cells, resulting in a limited XPB1 splicing as shown by previous studies [2,12] and the present data. These observations, together with other studies showing detrimental effects of prolonged eukaryotic translation initiation factor 2 alpha (eIF2α) or ATF6α activation in beta cells [24,49], suggest that tight control of ER homeostasis is crucial to maintain beta cell function and survival.…”

Section: Discussionmentioning

confidence: 80%

Sustained production of spliced X-box binding protein 1 (XBP1) induces pancreatic beta cell dysfunction and apoptosis

et al. 2010

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Aims/hypothesis Pro-inflammatory cytokines involved in the pathogenesis of type 1 diabetes deplete endoplasmic reticulum (ER) Ca 2+ stores, leading to ER-stress and beta cell apoptosis. However, the cytokine-induced ER-stress response in beta cells is atypical and characterised by induction of the pro-apoptotic PKR-like ER kinase (PERK)-C/EBP homologous protein (CHOP) branch of the unfolded protein response, but defective X-box binding protein 1 (XBP1) splicing and activating transcription factor 6 activation. The purpose of this study was to overexpress spliced/active Xbp1 (XBP1s) to increase beta cell resistance to cytokine-induced ER-stress and apoptosis.Methods Xbp1s was overexpressed using adenoviruses and knocked down using small interference RNA in rat islet cells. In selected experiments, Xbp1 was also knocked down in FACS-purified rat beta cells and rat fibroblasts. Expression and production of XBP1s and key downstream genes and proteins was measured and beta cell function and viability were evaluated.

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Section: Discussionmentioning

confidence: 80%

Sustained production of spliced X-box binding protein 1 (XBP1) induces pancreatic beta cell dysfunction and apoptosis

et al. 2010

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“…Although this strategy might be beneficial for treating cardiac hyper trophy in mice 198 , different cell types were found to respond differently to salubrinal. In pancreatic β cells, salubrinal has proapoptotic effects 199 , whereas anti apoptotic and cardioprotective effects were found in the heart 20,200 .…”

Section: Pharmacological Modulation Of Pqcmentioning

confidence: 99%

Proteostasis in cardiac health and disease

Henning

Brundel²

2017

Nat Rev Cardiol

132

113

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The worldwide increase in life expectancy gives rise to an increasing prevalence of cardiac diseases, which remain the leading cause of disability and death in the developed world [1][2][3] . Currently, the mechanisms under lying how ageing contributes to the initiation or acceler ation of cardiac diseases are essentially unresolved. Prevailing theories of ageing centre on gradual derail ment of cellular protein homeostasis -proteostasis -either by design (genetically) or by 'wear and tear' (environmentally) 3 . Central to the role of proteostasis derailment as a major factor in ageing is the observation that protein function declines over time.Proteins are the most versatile and complex macro molecules and are involved in the proper functioning of every biological process 4 . After synthesis as a poly peptide chain from the genetic code, proper function of a protein relies heavily on its correct folding into a 3D native state and on various post translational modifi cations, mostly involving the addition of chem ical groups (including phosphate, acetate, and carbo hydrate). Protein maturation, transport, and ultimately breakdown is monitored and supported by various classes of proteins, collectively called 'protein quality control' (PQC) [3][4][5] . Balanced proteostasis, therefore, depends on proper PQC and is crucial for cellular and organismal health 6 . The intricate network making up the PQC involves numerous proteins, of which the main players are the chaperones and their regula tors 4,7-9 (assisting in folding and refolding of proteins) and the pathways that clear irreversibly misfolded and aggregation prone proteins (the ubiquitin-proteasome system [UPS] and autophagy systems) 9-11 . With ageing, the gradual accumulation of misfolded or damaged pro teins, together with concomitant failure of PQC, results in proteotoxic stress and compromised defence against reactive oxygen species (ROS) 10 , a process that is likely to be accelerated in various age related diseases includ ing neurodegenerative diseases 12,13 , type 2 diabetes mel litus 14 , cancer 15 , and cardiac diseases [16][17][18][19][20] . In addition to the accumulation of misfolded proteins, ageing is accompanied by an imbalance in the proteome, as indi cated by lowered expression of chaperone, proteaso mal, ribosomal, and mitochondrial proteins, whereas proteins related to oxidative stress are upregulated 21,22 . Although mild impairment of proteostasis extends lifespan in Caenorhabditis elegans, referred to as hormesis, sustained impairment is accompanied by loss of PQC to neutralize this effect 3,5 . Importantly, evidence indicates that the amount of soluble, aggregate prone protein oligomers, rather than the abundance of pro tein aggregates, correlates with disease severity 23,24 . Therefore, protein aggregates, which contain both misfolded proteins and elevated levels of chaper ones, constitute an adequate PQC response, aimed at sequestering potentially harmful protein oligomers, rather than embodying the ultimate cellular threat 25 . This ...

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“…The mechanisms causing the loss of beta cell function and mass in type 2 diabetes are still debated [8][9][10]. It has been recently proposed that alterations of endoplasmic reticulum (ER) function in the beta cell contribute to cell dysfunction and death [10][11][12][13][14][15][16]. The ER is central to several important cellular functions, including post-translational modifications, folding and assembly of newly synthesised secretory proteins, and calcium storage [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Because beta cells need to synthesise and secrete large quantities of insulin they have a well developed ER and a remarkable production of proteins involved in ER function [14][15][16]. When ER function is impaired, due for example to accumulation of mutant folding-incompetent proteins, calcium depletion, over-production of proteins, or viral infection, ER stress develops [10,11,14,15]. Similarly, a mutation in insulin that causes its mal-folding leads to ER stress, beta cell death and diabetes in the Akita mouse [17].…”

Section: Introductionmentioning

confidence: 99%

The endoplasmic reticulum in pancreatic beta cells of type 2 diabetes patients

et al. 2007

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Aims/hypothesis Pancreatic beta cells have highly developed endoplasmic reticulum (ER) due to their role in insulin secretion. Since ER stress has been associated with beta cell dysfunction, we studied several features of beta cell ER in human type 2 diabetes. Methods Pancreatic samples and/or isolated islets from non-diabetic controls (ND) and type 2 diabetes patients were evaluated for insulin secretion, apoptosis (electron microscopy and ELISA), morphometric ER assessment (electron microscopy), and expression of ER stress markers in beta cell prepared by laser capture microdissection and in isolated islets.Results Insulin release was lower and beta cell apoptosis higher in type 2 diabetes than ND islets. ER density volume was significantly increased in type 2 diabetes beta cells. Expression of alpha-mannosidase (also known as mannosidase, alpha, class 1A, member 1) and UDP-glucose glycoprotein glucosyl transferase like 2 (UGCGL2), assessed by microarray and/or real-time reverse transcriptase polymerase chain reaction (RT-PCR), differed between ND and type 2 diabetes beta cells. Expression of immunoglobulin heavy chain binding protein (BiP, also known as heat shock 70 kDa protein 5 [glucose-regulated protein, 78 kDa] [HSPA5]), X-box binding protein 1 (XBP-1, also known as XBP1) and C/EBP homologous protein (CHOP, also known as damage-inducible transcript 3 [DDIT3]) was not higher in type 2 diabetes beta cell or isolated islets cultured at 5.5 mmol/l glucose (microarray and real-time RT-PCR) than in ND samples. When islets were cultured for 24 h at 11

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Selective Inhibition of Eukaryotic Translation Initiation Factor 2α Dephosphorylation Potentiates Fatty Acid-induced Endoplasmic Reticulum Stress and Causes Pancreatic β-Cell Dysfunction and Apoptosis

Cited by 272 publications

References 59 publications

Sustained production of spliced X-box binding protein 1 (XBP1) induces pancreatic beta cell dysfunction and apoptosis

Sustained production of spliced X-box binding protein 1 (XBP1) induces pancreatic beta cell dysfunction and apoptosis

Proteostasis in cardiac health and disease

The endoplasmic reticulum in pancreatic beta cells of type 2 diabetes patients

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