Cytokines Downregulate the Sarcoendoplasmic Reticulum Pump Ca2+ ATPase 2b and Deplete Endoplasmic Reticulum Ca2+, Leading to Induction of Endoplasmic Reticulum Stress in Pancreatic β-Cells

• Published in: Diabetes (New York, N.Y.) Vol. 54; no. 2; pp. 452 - 461
• Main Authors: Cardozo, Alessandra K, Ortis, Fernanda, Storling, Joachim, Feng, Ying-Mei, Rasschaert, Joanne, Tonnesen, Morten, Van Eylen, Françoise, Mandrup-Poulsen, Thomas, Herchuelz, André, Eizirik, Décio L
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Diabetes Association 01.02.2005
• Subjects: Animals; Base Sequence; Biological and medical sciences; Calcium - physiology; Calcium-Transporting ATPases - genetics; Cytokines - pharmacology; Diabetes. Impaired glucose tolerance; DNA Primers; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum - enzymology; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Gene Expression Regulation, Enzymologic - drug effects; Islets of Langerhans - drug effects; Islets of Langerhans - enzymology; Islets of Langerhans - physiology; Medical sciences; Medicin och hälsovetenskap; Oxidative Stress - physiology; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Sarcoplasmic Reticulum - drug effects; Sarcoplasmic Reticulum - enzymology; Thapsigargin - pharmacology; Endocrinopathy; Calcium; Enzyme; Diabetes mellitus; Langerhans islet; Adenosinetriphosphatase; Cytokine; Inorganic element; Pump; Stress; Hydrolases; β Cell; Endoplasmic reticulum; Endocrine pancreas
• ISSN: 0012-1797; 1939-327X
• DOI: 10.2337/diabetes.54.2.452

Cytokines Downregulate the Sarcoendoplasmic Reticulum Pump Ca 2+ ATPase 2b and Deplete Endoplasmic Reticulum Ca 2+ , Leading to Induction of Endoplasmic Reticulum Stress in Pancreatic β-Cells Alessandra K. Cardozo 1 , Fernanda Ortis 1 , Joachim Storling 2 , Ying-Mei Feng 1 , Joanne Rasschaert 1 , Morten Tonnesen 2 , Françoise Van Eylen 3 , Thomas Mandrup-Poulsen 2 4 , André Herchuelz 2 and Décio L. Eizirik 1 1 Laboratory of Experimental Medicine, Université Libre de Bruxelles, Brussels, Belgium 2 Steno Diabetes Center, Gentofte, Denmark 3 Laboratory of Pharmacology, Université Libre de Bruxelles, Brussels, Belgium 4 Department of Molecular Medicine, Karoliska Institute, Stockholm, Sweden Address correspondence and reprint requests to Dr. Alessandra K. Cardozo Laboratory of Experimental Medicine, Université Libre de Bruxelles, Route de Lennik, 808 CP-618, 1070 Brussels, Belgium. E-mail: akupperc{at}ulb.ac.be Abstract Cytokines and free radicals are mediators of β-cell death in type 1 diabetes. Under in vitro conditions, interleukin-1β (IL-1β) + γ-interferon (IFN-γ) induce nitric oxide (NO) production and apoptosis in rodent and human pancreatic β-cells. We have previously shown, by microarray analysis of primary β-cells, that IL-1β + IFN-γ decrease expression of the mRNA encoding for the sarcoendoplasmic reticulum pump Ca 2+ ATPase 2b (SERCA2b) while inducing expression of the endoplasmic reticulum stress–related and proapoptotic gene CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein). In the present study we show that cytokine-induced apoptosis and necrosis in primary rat β-cells and INS-1E cells largely depends on NO production. IL-1β + IFN-γ, via NO synthesis, markedly decreased SERCA2b protein expression and depleted ER Ca 2+ stores. Of note, β-cells showed marked sensitivity to apoptosis induced by SERCA blockers, as compared with fibroblasts. Cytokine-induced ER Ca 2+ depletion was paralleled by an NO-dependent induction of CHOP protein and activation of diverse components of the ER stress response, including activation of inositol-requiring ER-to-nucleus signal kinase 1α (IRE1α) and PRK (RNA-dependent protein kinase)-like ER kinase (PERK)/activating transcription factor 4 (ATF4), but not ATF6. In contrast, the ER stress–inducing agent thapsigargin triggered these four pathways in parallel. In conclusion, our results suggest that the IL-1β + IFN-γ–induced decrease in SERCA2b expression, with subsequent depletion of ER Ca 2+ and activation of the ER stress pathway, is a potential contributory mechanism to β-cell death. ATF, activating transcription factor BiP, immunoglobulin heavy-chain binding protein [Ca2+]i, intracellular Ca2+ concentration CHOP, C/EBP (CCAAT/enhancer binding protein) homologous protein CPA, cyclopiazonic acid eIF2α, eukaryotic translation initiation factor 2α ER, endoplasmic reticulum FACS, fluorescence-activated cell sorting GAPDH, glyceraldehyde-3-phosphate dehydrogenase IFN-γ, γ-interferon IL, interleukin iNOS, inducible nitric oxide synthase IRE1α, inositol-requiring ER-to-nucleus signal kinase 1α JNK, c-Jun NH2-terminal kinase LMA, NG-methyl-l-arginine PERK, PRK (RNA-dependent protein kinase)-like ER kinase SERCA, sarcoendoplasmic reticulum Ca2+ ATPase xbp-1, X-box binding protein-1 Footnotes T.M.-P. is employed by, holds stock in, and has received grant/research support from Novo Nordisk. Accepted October 19, 2004. Received April 7, 2004. DIABETES