Abstract
Accumulation of excess hepatic lipids contributes to insulin resistance and liver disease associated with endoplasmic reticulum (ER) stress. Exendin-4 is an agonist of the glucagon-like peptide 1 receptor and plays a role in improving insulin resistance and liver disease by increasing silent mating type information regulation 2 homolog (SIRT) 1. However, the effects and mechanism of action of exendin-4 on responses to palmitic acid (PA)-induced ER stress in hepatocytes have not been clearly defined. We investigated whether exendin-4 attenuates PA-induced ER stress via SIRT1 in HepG2 cells. PA treatment induced increased expression of PRKR-like endoplasmic reticulum kinase, inositol-requiring kinase 1α (IRE1α), activating transcription factor 6 (ATF6), and C/EBP homologous protein (CHOP) mRNA. Exendin-4 decreased the expression of P-IRE1α, ATF6, X-box binding protein-1 and CHOP, and increased the expression of SERCA2b. A significant decrease in the hepatic expression of PUMA, BAX, cytochrome c, and cleaved caspase-3 were observed in hepatocytes treated with exendin-4. The TUNEL assay consistently showed that exendin-4 reversed hepatocyte apoptosis induced by treatment with PA. Inhibition of SIRT1 by nicotinamide and siRNA significantly increased the expression of ER stress marker genes in cells treated with both PA and exendin-4. In conclusion, increased SIRT1 by exendin-4 attenuates PA-induced ER stress and mitochondrial dysfunction in hepatocytes.
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References
Akazawa Y, Cazanave S, Mott JL, Elmi N, Bronk SF, Kohno S, Charlton MR, Gores GJ (2010) Palmitoleate attenuates palmitate-induced Bim and PUMA up-regulation and hepatocyte lipoapoptosis. J Hepatol 52(4):586–593. doi:10.1016/j.jhep.2010.01.003
Araki K, Nagata K (2011) Protein folding and quality control in the ER. Cold Spring Harb Perspect Biol 3(11):a007526. doi:10.1101/cshperspect.a007526
Ashby MC, Tepikin AV (2001) ER calcium and the functions of intracellular organelles. Semin Cell Dev Biol 12(1):11–17. doi:10.1006/scdb.2000.0212
Canto C, Gerhart-Hines Z, Feige JN, Lagouge M, Noriega L, Milne JC, Elliott PJ, Puigserver P, Auwerx J (2009) AMPK regulates energy expenditure by modulating NAD + metabolism and SIRT1 activity. Nature 458(7241):1056–1060. doi:10.1038/nature07813
Certo M, Del Gaizo MV, Nishino M, Wei G, Korsmeyer S, Armstrong SA, Letai A (2006) Mitochondria primed by death signals determine cellular addiction to antiapoptotic BCL-2 family members. Cancer Cell 9(5):351–365. doi:10.1016/j.ccr.2006.03.027
Clark JM, Diehl AM (2002) Hepatic steatosis and type 2 diabetes mellitus. Curr Diabetes Rep 2(3):210–215
Cohen HY, Miller C, Bitterman KJ, Wall NR, Hekking B, Kessler B, Howitz KT, Gorospe M, de Cabo R, Sinclair DA (2004) Calorie restriction promotes mammalian cell survival by inducing the SIRT1 deacetylase. Science 305(5682):390–392. doi:10.1126/science.1099196
Eizirik DL, Cardozo AK, Cnop M (2008) The role for endoplasmic reticulum stress in diabetes mellitus. Endocr Rev 29(1):42–61. doi:10.1210/er.2007-0015
Festi D, Colecchia A, Sacco T, Bondi M, Roda E, Marchesini G (2004) Hepatic steatosis in obese patients: clinical aspects and prognostic significance. Obes Rev: Off J Int Assoc Study Obes 5(1):27–42
Flamment M, Kammoun HL, Hainault I, Ferre P, Foufelle F (2010) Endoplasmic reticulum stress: a new actor in the development of hepatic steatosis. Curr Opin Lipidol 21(3):239–246. doi:10.1097/MOL.0b013e3283395e5c
Fu S, Yang L, Li P, Hofmann O, Dicker L, Hide W, Lin X, Watkins SM, Ivanov AR, Hotamisligil GS (2011) Aberrant lipid metabolism disrupts calcium homeostasis causing liver endoplasmic reticulum stress in obesity. Nature 473(7348):528–531. doi:10.1038/nature09968
Gentile CL, Frye MA, Pagliassotti MJ (2011) Fatty acids and the endoplasmic reticulum in nonalcoholic fatty liver disease. Biofactors 37(1):8–16. doi:10.1002/biof.135
Hayashi T, Saito A, Okuno S, Ferrand-Drake M, Dodd RL, Chan PH (2005) Damage to the endoplasmic reticulum and activation of apoptotic machinery by oxidative stress in ischemic neurons. J Cereb Blood Flow Metab: Off J Int Soc Cereb Blood Flow Metabol 25(1):41–53. doi:10.1038/sj.jcbfm.9600005
Hirabara SM, Curi R, Maechler P (2010) Saturated fatty acid-induced insulin resistance is associated with mitochondrial dysfunction in skeletal muscle cells. J Cell Physiol 222(1):187–194. doi:10.1002/jcp.21936
Hou X, Xu S, Maitland-Toolan KA, Sato K, Jiang B, Ido Y, Lan F, Walsh K, Wierzbicki M, Verbeuren TJ, Cohen RA, Zang M (2008) SIRT1 regulates hepatocyte lipid metabolism through activating AMP-activated protein kinase. J Biol Chem 283(29):20015–20026. doi:10.1074/jbc.M802187200
Jeong SY, Seol DW (2008) The role of mitochondria in apoptosis. BMB Rep 41(1):11–22
Jung TW, Lee KT, Lee MW, Ka KH (2012a) SIRT1 attenuates palmitate-induced endoplasmic reticulum stress and insulin resistance in HepG2 cells via induction of oxygen-regulated protein 150. Biochem Biophys Res Commun 422(2):229–232. doi:10.1016/j.bbrc.2012.04.129
Jung TW, Lee MW, Lee YJ, Kim SM (2012b) Metformin prevents endoplasmic reticulum stress-induced apoptosis through AMPK-PI3K-c-Jun NH2 pathway. Biochem Biophys Res Commun 417(1):147–152. doi:10.1016/j.bbrc.2011.11.073
Kim JE, Kim YW, Lee IK, Kim JY, Kang YJ, Park SY (2008) AMP-activated protein kinase activation by 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) inhibits palmitate-induced endothelial cell apoptosis through reactive oxygen species suppression. J Pharmacol Sci 106(3):394–403
Kim DS, Jeong SK, Kim HR, Kim DS, Chae SW, Chae HJ (2010) Metformin regulates palmitate-induced apoptosis and ER stress response in HepG2 liver cells. Immunopharmacol Immunotoxicol 32(2):251–257. doi:10.3109/08923970903252220
Lee YS, Shin S, Shigihara T, Hahm E, Liu MJ, Han J, Yoon JW, Jun HS (2007) Glucagon-like peptide-1 gene therapy in obese diabetic mice results in long-term cure of diabetes by improving insulin sensitivity and reducing hepatic gluconeogenesis. Diabetes 56(6):1671–1679. doi:10.2337/db06-1182
Lee JW, Kim WH, Yeo J, Jung MH (2010) ER stress is implicated in mitochondrial dysfunction-induced apoptosis of pancreatic beta cells. Mol Cells 30(6):545–549. doi:10.1007/s10059-010-0161-5
Lee J, Hong SW, Chae SW, Kim DH, Choi JH, Bae JC, Park SE, Rhee EJ, Park CY, Oh KW (2012) Exendin-4 improves steatohepatitis by increasing Sirt1 expression in high-fat diet-induced obese C57BL/6J mice. PloS one 7(2):e31394
Leem J, Koh EH (2012) Interaction between mitochondria and the endoplasmic reticulum: implications for the pathogenesis of type 2 diabetes mellitus. Exp Diabetes Res 2012:242984. doi:10.1155/2012/242984
Li Y, Xu S, Giles A, Nakamura K, Lee JW, Hou X, Donmez G, Li J, Luo Z, Walsh K, Guarente L, Zang M (2011) Hepatic overexpression of SIRT1 in mice attenuates endoplasmic reticulum stress and insulin resistance in the liver. FASEB J: Off Publ Fed Am Soc Exp Biol 25(5):1664–1679. doi:10.1096/fj.10-173492
Liu J, Jin X, Yu CH, Chen SH, Li WP, Li YM (2010) Endoplasmic reticulum stress involved in the course of lipogenesis in fatty acids-induced hepatic steatosis. J Gastroenterol Hepatol 25(3):613–618. doi:10.1111/j.1440-1746.2009.06086.x
Maria DA, de Souza JG, Morais KL, Berra CM, Zampolli HD, Demasi M, Simons SM, de Freitas SR, Chammas R, Chudzinski-Tavassi AM (2012) A novel proteasome inhibitor acting in mitochondrial dysfunction, ER stress and ROS production. Investig New Drugs. doi:10.1007/s10637-012-9871-1
Nemoto S, Fergusson MM, Finkel T (2004) Nutrient availability regulates SIRT1 through a forkhead-dependent pathway. Science 306(5704):2105–2108. doi:10.1126/science.1101731
Ozcan L, Tabas I (2012) Role of endoplasmic reticulum stress in metabolic disease and other disorders. Annu Rev Med 63:317–328. doi:10.1146/annurev-med-043010-144749
Park SW, Zhou Y, Lee J, Lee J, Ozcan U (2010) Sarco(endo)plasmic reticulum Ca2+−ATPase 2b is a major regulator of endoplasmic reticulum stress and glucose homeostasis in obesity. Proc Natl Acad Sci U S A 107(45):19320–19325. doi:10.1073/pnas.1012044107
Ricchi M, Odoardi MR, Carulli L, Anzivino C, Ballestri S, Pinetti A, Fantoni LI, Marra F, Bertolotti M, Banni S, Lonardo A, Carulli N, Loria P (2009) Differential effect of oleic and palmitic acid on lipid accumulation and apoptosis in cultured hepatocytes. J Gastroenterol Hepatol 24(5):830–840. doi:10.1111/j.1440-1746.2008.05733.x
Ron D, Walter P (2007) Signal integration in the endoplasmic reticulum unfolded protein response. Nat Rev Mol Cell Biol 8(7):519–529. doi:10.1038/nrm2199
Szegezdi E, Logue SE, Gorman AM, Samali A (2006) Mediators of endoplasmic reticulum stress-induced apoptosis. EMBO Rep 7(9):880–885. doi:10.1038/sj.embor.7400779
Tsunekawa S, Yamamoto N, Tsukamoto K, Itoh Y, Kaneko Y, Kimura T, Ariyoshi Y, Miura Y, Oiso Y, Niki I (2007) Protection of pancreatic beta-cells by exendin-4 may involve the reduction of endoplasmic reticulum stress; in vivo and in vitro studies. J Endocrinol 193(1):65–74. doi:10.1677/JOE-06-0148
Vangheluwe P, Raeymaekers L, Dode L, Wuytack F (2005) Modulating sarco(endo)plasmic reticulum Ca2+ ATPase 2 (SERCA2) activity: cell biological implications. Cell Calcium 38(3–4):291–302. doi:10.1016/j.ceca.2005.06.033
Wang K, Yin XM, Chao DT, Milliman CL, Korsmeyer SJ (1996) BID: a novel BH3 domain-only death agonist. Genes Dev 10(22):2859–2869
Wang D, Wei Y, Pagliassotti MJ (2006) Saturated fatty acids promote endoplasmic reticulum stress and liver injury in rats with hepatic steatosis. Endocrinology 147(2):943–951. doi:10.1210/en.2005-0570
Xiang JN, Chen DL, Yang LY (2012) Effect of PANDER in betaTC6-cell lipoapoptosis and the protective role of exendin-4. Biochem Biophys Res Commun 421(4):701–706. doi:10.1016/j.bbrc.2012.04.065
Zhang Y, Yang X, Shi H, Dong L, Bai J (2011) Effect of alpha-linolenic acid on endoplasmic reticulum stress-mediated apoptosis of palmitic acid lipotoxicity in primary rat hepatocytes. Lipids Health Dis 10:122. doi:10.1186/1476-511X-10-122
Acknowledgments
This study was supported by a grant from Daewoong Pharmaceutical (# MRI-110907-004) and the Korea Science and Engineering Foundation by the Ministry of Education, Science and Technology # S-2010-1115-000 (http://www.mest.go.kr). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Lee, J., Hong, SW., Park, S.E. et al. Exendin-4 attenuates endoplasmic reticulum stress through a SIRT1-dependent mechanism. Cell Stress and Chaperones 19, 649–656 (2014). https://doi.org/10.1007/s12192-013-0490-3
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DOI: https://doi.org/10.1007/s12192-013-0490-3