Saturated fatty acids entrap PDX1 in stress granules and impede islet beta cell function



Failure of pancreatic and duodenal homeobox factor 1 (PDX1) to localise in the nucleus of islet beta cells under high-fat diet (HFD) conditions may be an early functional defect that contributes to beta cell failure in type 2 diabetes; however, the mechanism of PDX1 intracellular mislocalisation is unclear. Stress granules (SGs) are membrane-less cytoplasmic structures formed under stress that impair nucleocytoplasmic transport by sequestering nucleocytoplasmic transport factors and components of the nuclear pore complex. In this study, we investigated the stimulators that trigger SG formation in islet beta cells and the effects of SGs on PDX1 localisation and beta cell function.


The effect of palmitic acid (PA) on nucleocytoplasmic transport was investigated by using two reporters, S-tdTomato and S-GFP. SG assembly in rat insulinoma cell line INS1 cells, human islets under PA stress, and the pancreas of diet-induced obese mice was analysed using immunofluorescence and immunoblotting. SG protein components were identified through mass spectrometry. SG formation was blocked by specific inhibitors or genetic deletion of essential SG proteins, and then PDX1 localisation and beta cell function were investigated in vitro and in vivo.


We showed that saturated fatty acids (SFAs) are endogenous stressors that disrupted nucleocytoplasmic transport and stimulated SG formation in pancreatic beta cells. Using mass spectrometry approaches, we revealed that several nucleocytoplasmic transport factors and PDX1 were localised to SGs after SFA treatment, which inhibited glucose-induced insulin secretion. Furthermore, we found that SFAs induced SG formation in a phosphoinositide 3-kinase (PI3K)/eukaryotic translation initiation factor 2α (EIF2α) dependent manner. Disruption of SG assembly by PI3K/EIF2α inhibitors or genetic deletion of T cell restricted intracellular antigen 1 (TIA1) in pancreatic beta cells effectively suppressed PA-induced PDX1 mislocalisation and ameliorated HFD-mediated beta cell dysfunction.


Our findings suggest a link between SG formation and beta cell dysfunction in the presence of SFAs. Preventing SG formation may be a potential therapeutic strategy for treating obesity and type 2 diabetes.

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Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.



Amyotrophic lateral sclerosis


Eukaryotic translation initiation factor 2α


Endoplasmic reticulum


GAP SH3 binding protein 1


Glucose-stimulated insulin secretion


High-fat diet


Integrated stress response inhibitor


Nuclear export sequence


Nuclear localisation signal


Palmitic acid


Pancreatic and duodenal homeobox factor 1


Phosphoinositide 3-kinase


Stalled (preinitiation) translation complex


Ran GTPase


Saturated fatty acid


Stress granule


Small interfering RNA


T cell restricted intracellular antigen 1


TIA1 cytotoxic granule associated RNA binding protein like 1


Whole cell lysate




  1. 1.

    Hou J, Li Z, Zhong W et al (2017) Temporal Transcriptomic and proteomic landscapes of deteriorating pancreatic islets in type 2 diabetic rats. Diabetes 66(8):2188–2200.

    CAS  Article  PubMed  Google Scholar 

  2. 2.

    Barnes AS (2011) The epidemic of obesity and diabetes: Trends and treatments. Tex Heart Inst J 38(2):142–144

    PubMed  PubMed Central  Google Scholar 

  3. 3.

    Robertson RP, Harmon J, Tran POT, Poitout V (2004) Beta-cell glucose toxicity, lipotoxicity, and chronic oxidative stress in type 2 diabetes. Diabetes 53(Suppl 1):S119–S124

    CAS  Article  Google Scholar 

  4. 4.

    Oh YS, Bae GD, Baek DJ, Park E-Y, Jun H-S (2018) Fatty acid-induced lipotoxicity in pancreatic Beta-cells during development of type 2 diabetes. Front Endocrinol 9:384

    Article  Google Scholar 

  5. 5.

    Newsholme P, Keane D, Welters HJ, Morgan NG (2007) Life and death decisions of the pancreatic beta-cell: The role of fatty acids. Clin Sci 112(1):27–42.

    CAS  Article  Google Scholar 

  6. 6.

    López S, Bermúdez B, Abia R, Muriana FJG (2010) The influence of major dietary fatty acids on insulin secretion and action. Curr Opin Lipidol 21(1):15–20.

    CAS  Article  PubMed  Google Scholar 

  7. 7.

    Itami N, Shirasuna K, Kuwayama T, Iwata H (2018) Palmitic acid induces ceramide accumulation, mitochondrial protein hyperacetylation, and mitochondrial dysfunction in porcine oocytes. Biol Reprod 98(5):644–653.

    Article  PubMed  Google Scholar 

  8. 8.

    Yu G, Luo H, Zhang N et al (2019) Loss of p53 Sensitizes Cells to Palmitic Acid-Induced Apoptosis by Reactive Oxygen Species Accumulation. Int J Mol Sci 20(24).

  9. 9.

    Borradaile NM, Han X, Harp JD, Gale SE, Ory DS, Schaffer JE (2006) Disruption of endoplasmic reticulum structure and integrity in lipotoxic cell death. J Lipid Res 47(12):2726–2737.

    CAS  Article  PubMed  Google Scholar 

  10. 10.

    Hagman DK, Hays LB, Parazzoli SD, Poitout V (2005) Palmitate inhibits insulin gene expression by altering PDX-1 nuclear localization and reducing MafA expression in isolated rat islets of Langerhans. J Biol Chem 280(37):32413–32418.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  11. 11.

    Ritz-Laser B, Meda P, Constant I et al (1999) Glucose-induced preproinsulin gene expression is inhibited by the free fatty acid palmitate. Endocrinology 140(9):4005–4014.

    CAS  Article  PubMed  Google Scholar 

  12. 12.

    Jonsson J, Carlsson L, Edlund T, Edlund H (1994) Insulin-promoter-factor 1 is required for pancreas development in mice. Nature 371(6498):606–609.

    CAS  Article  PubMed  Google Scholar 

  13. 13.

    Brissova M, Shiota M, Nicholson WE et al (2002) Reduction in pancreatic transcription factor PDX-1 impairs glucose-stimulated insulin secretion. J Biol Chem 277(13):11225–11232.

    CAS  Article  PubMed  Google Scholar 

  14. 14.

    Stoffers DA, Ferrer J, Clarke WL, Habener JF (1997) Early-onset type-II diabetes mellitus (MODY4) linked to IPF1. Nat Genet 17(2):138–139.

    CAS  Article  PubMed  Google Scholar 

  15. 15.

    Stoffers DA, Stanojevic V, Habener JF (1998) Insulin promoter factor-1 gene mutation linked to early-onset type 2 diabetes mellitus directs expression of a dominant negative isoprotein. J Clin Invest 102(1):232–241.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  16. 16.

    Hagman DK, Latour MG, Chakrabarti SK et al (2008) Cyclical and alternating infusions of glucose and intralipid in rats inhibit insulin gene expression and Pdx-1 binding in islets. Diabetes 57(2):424–431.

    CAS  Article  PubMed  Google Scholar 

  17. 17.

    Reimer MK, Ahrén B (2002) Altered beta-cell distribution of pdx-1 and GLUT-2 after a short-term challenge with a high-fat diet in C57BL/6J mice. Diabetes 51(Suppl 1):S138–S143

    CAS  Article  Google Scholar 

  18. 18.

    Spector DL (2006) SnapShot: Cellular bodies. Cell 127(5):1071.

    Article  PubMed  Google Scholar 

  19. 19.

    Protter DSW, Parker R (2016) Principles and properties of stress granules. Trends Cell Biol 26(9):668–679.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  20. 20.

    Anderson P, Kedersha N (2002) Stressful initiations. J Cell Sci 115(Pt 16):3227–3234

    CAS  PubMed  Google Scholar 

  21. 21.

    Li YR, King OD, Shorter J, Gitler AD (2013) Stress granules as crucibles of ALS pathogenesis. J Cell Biol 201(3):361–372.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  22. 22.

    Ramaswami M, Taylor JP, Parker R (2013) Altered ribostasis: RNA-protein granules in degenerative disorders. Cell 154(4):727–736.

    CAS  Article  PubMed  Google Scholar 

  23. 23.

    Gao X, Jiang L, Gong Y et al (2019) Stress granule: A promising target for cancer treatment. Br J Pharmacol 176(23):4421–4433.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  24. 24.

    Zhang K, Daigle JG, Cunningham KM et al (2018) Stress granule assembly disrupts Nucleocytoplasmic transport. Cell 173(4):958–971 e917.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  25. 25.

    Wang Y, Danielson KK, Ropski A et al (2013) Systematic analysis of donor and isolation factor's impact on human islet yield and size distribution. Cell Transplant 22(12):2323–2333.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  26. 26.

    Yang CH, Mangiafico SP, Waibel M et al (2020) E2f8 and Dlg2 genes have independent effects on impaired insulin secretion associated with hyperglycaemia. Diabetologia 63(7):1333–1348.

    CAS  Article  PubMed  Google Scholar 

  27. 27.

    Wan X-M, Zhang M, Zhang P et al (2016) Jiawei Erzhiwan improves menopausal metabolic syndrome by enhancing insulin secretion in pancreatic β cells. Chin J Nat Med 14(11):823–834.

    CAS  Article  PubMed  Google Scholar 

  28. 28.

    Jain S, Wheeler JR, Walters RW, Agrawal A, Barsic A, Parker R (2016) ATPase-modulated stress granules contain a diverse proteome and substructure. Cell 164(3):487–498.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  29. 29.

    Zhang K, Donnelly CJ, Haeusler AR et al (2015) The C9orf72 repeat expansion disrupts nucleocytoplasmic transport. Nature 525(7567):56–61.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  30. 30.

    Morgan NG (2009) Fatty acids and beta-cell toxicity. Curr Opin Clin Nutr Metab Care 12(2):117–122.

    CAS  Article  PubMed  Google Scholar 

  31. 31.

    Woerner AC, Frottin F, Hornburg D et al (2016) Cytoplasmic protein aggregates interfere with nucleocytoplasmic transport of protein and RNA. Science 351(6269):173–176.

  32. 32.

    Steggerda SM, Paschal BM (2002) Regulation of nuclear import and export by the GTPase ran. Int Rev Cytol 217:41–91

    CAS  Article  Google Scholar 

  33. 33.

    Kedersha NL, Gupta M, Li W, Miller I, Anderson P (1999) RNA-binding proteins TIA-1 and TIAR link the phosphorylation of eIF-2 alpha to the assembly of mammalian stress granules. J Cell Biol 147(7):1431–1442.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  34. 34.

    Sidrauski C, Acosta-Alvear D, Khoutorsky A et al (2013) Pharmacological brake-release of mRNA translation enhances cognitive memory. Elife 2:e00498.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  35. 35.

    Sidrauski C, McGeachy AM, Ingolia NT, Walter P (2015) The small molecule ISRIB reverses the effects of eIF2α phosphorylation on translation and stress granule assembly. eLife 4.

  36. 36.

    Heberle AM, Razquin Navas P, Langelaar-Makkinje M et al (2019) The PI3K and MAPK/p38 pathways control stress granule assembly in a hierarchical manner. Life Sci Alliance 2(2).

  37. 37.

    Guo S, Dai C, Guo M et al (2013) Inactivation of specific β cell transcription factors in type 2 diabetes. J Clin Invest 123(8):3305–3316.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  38. 38.

    Ash PEA, Vanderweyde TE, Youmans KL, Apicco DJ, Wolozin B (2014) Pathological stress granules in Alzheimer's disease. Brain Res 1584:52–58.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  39. 39.

    Nolan CJ, Prentki M (2008) The islet beta-cell: Fuel responsive and vulnerable. Trends Endocrinol Metab 19(8):285–291.

    CAS  Article  PubMed  Google Scholar 

  40. 40.

    Panas MD, Ivanov P, Anderson P (2016) Mechanistic insights into mammalian stress granule dynamics. J Cell Biol 215(3):313–323.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  41. 41.

    Cnop M, Toivonen S, Igoillo-Esteve M, Salpea P (2017) Endoplasmic reticulum stress and eIF2α phosphorylation: The Achilles heel of pancreatic β cells. Mol Metab 6(9):1024–1039.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  42. 42.

    Kim H-J, Raphael AR, LaDow ES et al (2014) Therapeutic modulation of eIF2α phosphorylation rescues TDP-43 toxicity in amyotrophic lateral sclerosis disease models. Nat Genet 46(2):152–160.

    CAS  Article  PubMed  Google Scholar 

  43. 43.

    Elden AC, Kim H-J, Hart MP et al (2010) Ataxin-2 intermediate-length polyglutamine expansions are associated with increased risk for ALS. Nature 466(7310):1069–1075.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  44. 44.

    Apicco DJ, Ash PEA, Maziuk B et al (2018) Reducing the RNA binding protein TIA1 protects against tau-mediated neurodegeneration in vivo. Nat Neurosci 21(1):72–80.

    CAS  Article  PubMed  Google Scholar 

  45. 45.

    Dember LM, Kim ND, Liu KQ, Anderson P (1996) Individual RNA recognition motifs of TIA-1 and TIAR have different RNA binding specificities. J Biol Chem 271(5):2783–2788.

    CAS  Article  PubMed  Google Scholar 

  46. 46.

    Reyes R, Alcalde J, Izquierdo JM (2009) Depletion of T-cell intracellular antigen proteins promotes cell proliferation. Genome Biol 10(8):R87.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  47. 47.

    Izquierdo JM, Alcalde J, Carrascoso I, Reyes R, Ludeña MD (2011) Knockdown of T-cell intracellular antigens triggers cell proliferation, invasion and tumour growth. Biochem J 435(2):337–344.

    CAS  Article  PubMed  Google Scholar 

  48. 48.

    Vanderweyde T, Apicco DJ, Youmans-Kidder K et al (2016) Interaction of tau with the RNA-binding protein TIA1 regulates tau pathophysiology and toxicity. Cell Rep 15(7):1455–1466.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  49. 49.

    Heck MV, Azizov M, Stehning T, Walter M, Kedersha N, Auburger G (2014) Dysregulated expression of lipid storage and membrane dynamics factors in Tia1 knockout mouse nervous tissue. Neurogenetics 15(2):135–144.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  50. 50.

    Lewerenz J, Baxter P, Kassubek R et al (2014) Phosphoinositide 3-kinases upregulate system xc(−) via eukaryotic initiation factor 2α and activating transcription factor 4 - a pathway active in glioblastomas and epilepsy. Antioxid Redox Signal 20(18):2907–2922.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  51. 51.

    Lee KS, Jeong JS, Kim SR et al (2016) Phosphoinositide 3-kinase-δ regulates fungus-induced allergic lung inflammation through endoplasmic reticulum stress. Thorax 71(1):52–63.

    Article  PubMed  Google Scholar 

  52. 52.

    Hsu HS, Liu CC, Lin JH et al (2017) Involvement of ER stress, PI3K/AKT activation, and lung fibroblast proliferation in bleomycin-induced pulmonary fibrosis. Sci Rep 7(1):14272.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  53. 53.

    Kim HK, Lee GH, Bhattarai KR et al (2018) PI3Kδ contributes to ER stress-associated asthma through ER-redox disturbances: The involvement of the RIDD-RIG-I-NF-κB axis. Exp Mol Med 50(2):e444.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  54. 54.

    Backlund M, Paukku K, Kontula KK, Lehtonen JY (2016) Endoplasmic reticulum stress increases AT1R mRNA expression via TIA-1-dependent mechanism. Nucleic Acids Res 44(7):3095–3104.

    CAS  Article  PubMed  Google Scholar 

  55. 55.

    Preston AM, Gurisik E, Bartley C, Laybutt DR, Biden TJ (2009) Reduced endoplasmic reticulum (ER)-to-Golgi protein trafficking contributes to ER stress in lipotoxic mouse beta cells by promoting protein overload. Diabetologia 52(11):2369–2373.

    CAS  Article  PubMed  Google Scholar 

  56. 56.

    Ando Y, Inada-Inoue M, Mitsuma A et al (2014) Phase I dose-escalation study of buparlisib (BKM120), an oral pan-class I PI3K inhibitor, in Japanese patients with advanced solid tumors. Cancer Sci 105(3):347–353.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

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The S-GFP plasmid was a kind gift from F. U. Hartl (Department of Cellular Biochemistry, the Max Planck Institute of Biochemistry, Germany). We thank W. Liu (Institute of Translational Medicine, Nanjing Medical University, China) for valuable suggestions. We thank J. Zhang (The Second Xiangya Hospital of Central South University, China) for technical support with INS1 cell culture.

Authors’ relationships and activities

The authors declare that there are no relationships or activities that might bias, or be perceived to bias, their work.


This work was supported by the National Key R&D Program of China (grant no. 2016YFC1305000), the National Natural Science Foundation of China (grant no. 81803750, 81770778), the Key Medical Talents Project of Jiangsu Province (grant no. ZDRCA2016088), the Key Project of Jiangsu Science and Technology Plan (grant no. BE2017738) and the Jiangsu Province Innovative and Entrepreneurial Team Grant. This project was also supported by the Project Program of State Key Laboratory of Natural Medicines, China Pharmaceutical University (SKLNMZZCX201820) and the “Double First-Class” University Project (CPU2018GF04).

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YuL, CQ and MuZ conceived and designed the work. MuZ, CQ and CJY performed the cell experiments and acquired data. XJX and HMC performed the animal experiments and acquired data. MengZ, LQ, YanL and RG contributed to sample preparation and data acquisition. MuZ and CQ interpreted the data and wrote the manuscript. CJY, XJX, HMC, MengZ, LQ, YanL and RG made contributions to revising the article for important intellectual content. YuL revised the manuscript critically. All authors gave final approval of the version to be published. YuL is the guarantor of this work, has full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

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Correspondence to Xiaojun Xu or Cheng Qian or Yu Liu.

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Zhang, M., Yang, C., Zhu, M. et al. Saturated fatty acids entrap PDX1 in stress granules and impede islet beta cell function. Diabetologia (2021).

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  • Glucose-stimulated insulin secretion
  • Pancreatic and duodenal homeobox factor 1
  • Saturated fatty acids
  • Stress granules
  • Type 2 diabetes