Cell Stress and Chaperones

, Volume 23, Issue 4, pp 629–638 | Cite as

Exendin-4 improves ER stress-induced lipid accumulation and regulates lipin-1 signaling in HepG2 cells

  • Jinmi Lee
  • Seok-Woo Hong
  • Hyemi Kwon
  • Se Eun Park
  • Eun-Jung Rhee
  • Cheol-Young Park
  • Ki-Won Oh
  • Sung-Woo Park
  • Won-Young LeeEmail author
Original Paper


Lipin-1 performs dual function during lipid metabolism, i.e., it functions as a transcriptional coactivator and as a phosphatidate phosphatase during triglyceride biosynthesis. We investigated whether exendin-4 prevented endoplasmic reticulum (ER) stress-induced hepatic steatosis and whether the protective effects of exendin-4 were associated with lipin-1 signaling. Tunicamycin and thapsigargin, ER stress inducers, increased triglycerides (TG) content and expression of genes encoding lipid droplet surface proteins. Exendin-4 decreased the expression of ER stress markers phosphorylated PKR like ER kinase (PERK), phosphorylated inositol-requiring enzyme 1 alpha (IRE1α), and glucose-regulated protein 78 kDa (GRP78) proteins and spliced X-box binding protein 1 (XBP-1s) mRNA and increased the expression of genes encoding lipolytic enzymes hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MGL) and VLDL assembly-associated proteins microsomal triglyceride transfer protein (MTP) and apolipoprotein B (APOB) in tunicamycin-pretreated cells. Moreover, exendin-4 significantly decreased lipin-1β/α ratio by increasing SFRP10 and increased lipin-1 nuclear localization. The decrease in lipin-1β/α ratio was also observed in SIRT1 and AMPK agonist-treated cells. These data suggest that exendin-4 improves ER stress-induced hepatic lipid accumulation by increasing lipolysis and VLDL assembly, which is partially mediated by the regulation of lipin-1 signaling.


Exendin-4 ER stress Lipid accumulation Lipolysis VLDL assembly Lipin-1 



AMP-activated protein kinase


Apolipoprotein B


Adipose tissue triglyceride lipase


Cell death-inducing DFFA-like effector c


Endoplasmic reticulum


Glucagon-like protein-1


Glucose-regulated protein 78 kDa


Hormone-sensitive lipase


Inositol-requiring enzyme 1 alpha


Monoacylglycerol lipase


Microsomal triglyceride transfer protein


Nonalcoholic fatty liver disease


Nonalcoholic steatohepatitis


Palmitic acid


PKR like ER kinase


Protein kinase A




Serine-arginine-rich splicing factor 10


Silent mating-type information regulation 2 homolog 1


Sterol regulatory element-binding protein 1




Very-low-density lipoprotein


X-box binding protein 1



This study was supported by Samsung Biomedical Research Institute (SBRI) (, the Medical Research Funds from Kangbuk Samsung Hospital, and the National Research Foundation (NRF), which is funded by the Korean government (NRF-2016R1A6A3A11930792) ( The funders had no role in the study design, data collection, and analysis, the decision to publish, or preparation of the manuscript.

Supplementary material

12192_2017_872_MOESM1_ESM.pdf (200 kb)
ESM 1 (PDF 199 kb)


  1. Ameen C, Edvardsson U, Ljungberg A, Asp L, Akerblad P, Tuneld A, Olofsson SO, Linden D, Oscarsson J (2005) Activation of peroxisome proliferator-activated receptor alpha increases the expression and activity of microsomal triglyceride transfer protein in the liver. J Biol Chem 280(2):1224–1229. CrossRefPubMedGoogle Scholar
  2. Bou Khalil M, Sundaram M, Zhang HY, Links PH, Raven JF, Manmontri B, Sariahmetoglu M, Tran K, Reue K, Brindley DN, Yao Z (2009) The level and compartmentalization of phosphatidate phosphatase-1 (lipin-1) control the assembly and secretion of hepatic VLDL. J Lipid Res 50(1):47–58. CrossRefPubMedGoogle Scholar
  3. Castro G, MF CA, Weissmann L, Quaresma PG, Katashima CK, Saad MJ, Prada PO (2013) Diet-induced obesity induces endoplasmic reticulum stress and insulin resistance in the amygdala of rats. FEBS Open Bio 3(1):443–449. CrossRefPubMedPubMedCentralGoogle Scholar
  4. Chen Z, Gropler MC, Mitra MS, Finck BN (2012) Complex interplay between the lipin 1 and the hepatocyte nuclear factor 4 alpha (HNF4alpha) pathways to regulate liver lipid metabolism. PLoS One 7(12):e51320. CrossRefPubMedPubMedCentralGoogle Scholar
  5. Ding X, Saxena NK, Lin S, Gupta NA, Anania FA (2006) Exendin-4, a glucagon-like protein-1 (GLP-1) receptor agonist, reverses hepatic steatosis in ob/ob mice. Hepatology 43(1):173–181. CrossRefPubMedPubMedCentralGoogle Scholar
  6. Dong Q, Giorgianni F, Deng X, Beranova-Giorgianni S, Bridges D, Park EA, Raghow R, Elam MB (2014) Phosphorylation of sterol regulatory element binding protein-1a by protein kinase A (PKA) regulates transcriptional activity. Biochem Biophys Res Commun 449(4):449–454. CrossRefPubMedPubMedCentralGoogle Scholar
  7. Donkor J, Sparks LM, Xie H, Smith SR, Reue K (2008) Adipose tissue lipin-1 expression is correlated with peroxisome proliferator-activated receptor alpha gene expression and insulin sensitivity in healthy young men. J Clin Endocrinol Metab 93(1):233–239. CrossRefPubMedGoogle Scholar
  8. Dowman JK, Tomlinson JW, Newsome PN (2010) Pathogenesis of non-alcoholic fatty liver disease. QJM: Month J Assoc Phys 103(2):71–83. CrossRefGoogle Scholar
  9. Gentile CL, Pagliassotti MJ (2008) The endoplasmic reticulum as a potential therapeutic target in nonalcoholic fatty liver disease. Curr Opin Investig Drugs 9(10):1084–1088PubMedPubMedCentralGoogle Scholar
  10. Harris TE, Finck BN (2011) Dual function lipin proteins and glycerolipid metabolism. Trends Endocrinol Metab 22(6):226–233. CrossRefPubMedPubMedCentralGoogle Scholar
  11. Ishimoto K (2011) Lipin 1 in lipid metabolism. Yakugaku zasshi J Pharm Soc Jpn 131(8):1189–1194. CrossRefGoogle Scholar
  12. Jo H, Choe SS, Shin KC, Jang H, Lee JH, Seong JK, Back SH, Kim JB (2013) Endoplasmic reticulum stress induces hepatic steatosis via increased expression of the hepatic very low-density lipoprotein receptor. Hepatology 57(4):1366–1377. CrossRefPubMedGoogle Scholar
  13. Kammoun HL, Chabanon H, Hainault I, Luquet S, Magnan C, Koike T, Ferre P, Foufelle F (2009) GRP78 expression inhibits insulin and ER stress-induced SREBP-1c activation and reduces hepatic steatosis in mice. J Clin Invest 119(5):1201–1215. CrossRefPubMedPubMedCentralGoogle Scholar
  14. Kawano Y, Cohen DE (2013) Mechanisms of hepatic triglyceride accumulation in non-alcoholic fatty liver disease. J Gastroenterol 48(4):434–441. CrossRefPubMedPubMedCentralGoogle Scholar
  15. Kawasaki N, Asada R, Saito A, Kanemoto S, Imaizumi K (2012) Obesity-induced endoplasmic reticulum stress causes chronic inflammation in adipose tissue. Sci Rep 2(1):799. CrossRefPubMedPubMedCentralGoogle Scholar
  16. Lee AH, Scapa EF, Cohen DE, Glimcher LH (2008) Regulation of hepatic lipogenesis by the transcription factor XBP1. Science 320(5882):1492–1496. CrossRefPubMedPubMedCentralGoogle Scholar
  17. Lee JS, Mendez R, Heng HH, Yang ZQ, Zhang K (2012a) Pharmacological ER stress promotes hepatic lipogenesis and lipid droplet formation. Am J Transl Res 4(1):102–113PubMedPubMedCentralGoogle Scholar
  18. Lee JS, Zheng Z, Mendez R, Ha SW, Xie Y, Zhang K (2012b) Pharmacologic ER stress induces non-alcoholic steatohepatitis in an animal model. Toxicol Lett 211(1):29–38. CrossRefPubMedPubMedCentralGoogle Scholar
  19. 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 25(5):1664–1679. CrossRefPubMedPubMedCentralGoogle Scholar
  20. Lindegaard B, Larsen LF, Hansen AB, Gerstoft J, Pedersen BK, Reue K (2007) Adipose tissue lipin expression levels distinguish HIV patients with and without lipodystrophy. Int J Obes 31(3):449–456. CrossRefGoogle Scholar
  21. Linden D, Lindberg K, Oscarsson J, Claesson C, Asp L, Li L, Gustafsson M, Boren J, Olofsson SO (2002) Influence of peroxisome proliferator-activated receptor alpha agonists on the intracellular turnover and secretion of apolipoprotein (Apo) B-100 and ApoB-48. J Biol Chem 277(25):23044–23053. CrossRefPubMedGoogle Scholar
  22. Malhi H, Kaufman RJ (2011) Endoplasmic reticulum stress in liver disease. J Hepatol 54(4):795–809. CrossRefPubMedGoogle Scholar
  23. Mensenkamp AR, Van Luyn MJ, Havinga R, Teusink B, Waterman IJ, Mann CJ, Elzinga BM, Verkade HJ, Zammit VA, Havekes LM, Shoulders CC, Kuipers F (2004) The transport of triglycerides through the secretory pathway of hepatocytes is impaired in apolipoprotein E deficient mice. J Hepatol 40(4):599–606. CrossRefPubMedGoogle Scholar
  24. Minehira K, Young SG, Villanueva CJ, Yetukuri L, Oresic M, Hellerstein MK, Farese RV Jr, Horton JD, Preitner F, Thorens B, Tappy L (2008) Blocking VLDL secretion causes hepatic steatosis but does not affect peripheral lipid stores or insulin sensitivity in mice. J Lipid Res 49(9):2038–2044. CrossRefPubMedPubMedCentralGoogle Scholar
  25. Ozcan U, Cao Q, Yilmaz E, Lee AH, Iwakoshi NN, Ozdelen E, Tuncman G, Gorgun C, Glimcher LH, Hotamisligil GS (2004) Endoplasmic reticulum stress links obesity, insulin action, and type 2 diabetes. Science 306(5695):457–461. CrossRefPubMedGoogle Scholar
  26. Peterfy M, Phan J, Reue K (2005) Alternatively spliced lipin isoforms exhibit distinct expression pattern, subcellular localization, and role in adipogenesis. J Biol Chem 280(38):32883–32889. CrossRefPubMedGoogle Scholar
  27. Peterson TR, Sengupta SS, Harris TE, Carmack AE, Kang SA, Balderas E, Guertin DA, Madden KL, Carpenter AE, Finck BN, Sabatini DM (2011) mTOR complex 1 regulates lipin 1 localization to control the SREBP pathway. Cell 146(3):408–420. CrossRefPubMedPubMedCentralGoogle Scholar
  28. Pihlajamaki J, Lerin C, Itkonen P, Boes T, Floss T, Schroeder J, Dearie F, Crunkhorn S, Burak F, Jimenez-Chillaron JC, Kuulasmaa T, Miettinen P, Park PJ, Nasser I, Zhao Z, Zhang Z, Xu Y, Wurst W, Ren H, Morris AJ, Stamm S, Goldfine AB, Laakso M, Patti ME (2011) Expression of the splicing factor gene SFRS10 is reduced in human obesity and contributes to enhanced lipogenesis. Cell Metab 14(2):208–218. CrossRefPubMedPubMedCentralGoogle Scholar
  29. Reue K, Dwyer JR (2009) Lipin proteins and metabolic homeostasis. J Lipid Res 50(Suppl):S109–S114. CrossRefPubMedPubMedCentralGoogle Scholar
  30. Reue K, Zhang P (2008) The lipin protein family: dual roles in lipid biosynthesis and gene expression. FEBS Lett 582(1):90–96. CrossRefPubMedGoogle Scholar
  31. Sapiro JM, Mashek MT, Greenberg AS, Mashek DG (2009) Hepatic triacylglycerol hydrolysis regulates peroxisome proliferator-activated receptor alpha activity. J Lipid Res 50(8):1621–1629. CrossRefPubMedPubMedCentralGoogle Scholar
  32. Schweitzer GG, Chen Z, Gan C, McCommis KS, Soufi N, Chrast R, Mitra MS, Yang K, Gross RW, Finck BN (2015) Liver-specific loss of lipin-1-mediated phosphatidic acid phosphatase activity does not mitigate intrahepatic TG accumulation in mice. J Lipid Res 56(4):848–858. CrossRefPubMedPubMedCentralGoogle Scholar
  33. Seo MH, Lee J, Hong SW, Rhee EJ, Park SE, Park CY, Oh KW, Park SW, Lee WY (2016) Exendin-4 inhibits hepatic lipogenesis by increasing beta-catenin signaling. PLoS One 11(12):e0166913. CrossRefPubMedPubMedCentralGoogle Scholar
  34. Tanaka K, Masaki Y, Tanaka M, Miyazaki M, Enjoji M, Nakamuta M, Kato M, Nomura M, Inoguchi T, Kotoh K, Takayanagi R (2014) Exenatide improves hepatic steatosis by enhancing lipid use in adipose tissue in nondiabetic rats. World J Gastroenterol: WJG 20(10):2653–2663. CrossRefPubMedGoogle Scholar
  35. van Schadewijk A, van't Wout EF, Stolk J, Hiemstra PS (2012) A quantitative method for detection of spliced X-box binding protein-1 (XBP1) mRNA as a measure of endoplasmic reticulum (ER) stress. Cell Stress Chaperones 17(2):275–279. CrossRefPubMedGoogle Scholar
  36. Xu F, Li Z, Zheng X, Liu H, Liang H, Xu H, Chen Z, Zeng K, Weng J (2014) SIRT1 mediates the effect of GLP-1 receptor agonist exenatide on ameliorating hepatic steatosis. Diabetes 63(11):3637–3646. CrossRefPubMedGoogle Scholar
  37. Xu Y, Zalzala M, Xu J, Li Y, Yin L, Zhang Y (2015) A metabolic stress-inducible miR-34a-HNF4alpha pathway regulates lipid and lipoprotein metabolism. Nat Commun 6:7466. CrossRefPubMedPubMedCentralGoogle Scholar
  38. Yin H, Hu M, Liang X, Ajmo JM, Li X, Bataller R, Odena G, Stevens SM Jr, You M (2014) Deletion of SIRT1 from hepatocytes in mice disrupts lipin-1 signaling and aggravates alcoholic fatty liver. Gastroenterology 146(3):801–811. CrossRefPubMedGoogle Scholar
  39. Zhang W, Hietakangas V, Wee S, Lim SC, Gunaratne J, Cohen SM (2013) ER stress potentiates insulin resistance through PERK-mediated FOXO phosphorylation. Genes Dev 27(4):441–449. CrossRefPubMedPubMedCentralGoogle Scholar
  40. Zhang ZF, Fan SH, Zheng YL, Lu J, Wu DM, Shan Q, Hu B (2014) Troxerutin improves hepatic lipid homeostasis by restoring NAD(+)-depletion-mediated dysfunction of lipin 1 signaling in high-fat diet-treated mice. Biochem Pharmacol 91(1):74–86. CrossRefPubMedGoogle Scholar

Copyright information

© Cell Stress Society International 2018

Authors and Affiliations

  • Jinmi Lee
    • 1
  • Seok-Woo Hong
    • 1
  • Hyemi Kwon
    • 2
  • Se Eun Park
    • 2
  • Eun-Jung Rhee
    • 2
  • Cheol-Young Park
    • 2
  • Ki-Won Oh
    • 2
  • Sung-Woo Park
    • 2
  • Won-Young Lee
    • 2
    • 3
    Email author
  1. 1.Institute of Medical Research, Kangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoulRepublic of Korea
  2. 2.Department of Endocrinology and Metabolism, Kangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoulRepublic of Korea
  3. 3.Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoulRepublic of Korea

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