Endoplasmic Reticulum Stress Contributes to Beta Cell Apoptosis in Type 2 Diabetes
Overview
Affiliations
Aims/hypothesis: Increased lipid supply causes beta cell death, which may contribute to reduced beta cell mass in type 2 diabetes. We investigated whether endoplasmic reticulum (ER) stress is necessary for lipid-induced apoptosis in beta cells and also whether ER stress is present in islets of an animal model of diabetes and of humans with type 2 diabetes.
Methods: Expression of genes involved in ER stress was evaluated in insulin-secreting MIN6 cells exposed to elevated lipids, in islets isolated from db/db mice and in pancreas sections of humans with type 2 diabetes. Overproduction of the ER chaperone heat shock 70 kDa protein 5 (HSPA5, previously known as immunoglobulin heavy chain binding protein [BIP]) was performed to assess whether attenuation of ER stress affected lipid-induced apoptosis.
Results: We demonstrated that the pro-apoptotic fatty acid palmitate triggers a comprehensive ER stress response in MIN6 cells, which was virtually absent using non-apoptotic fatty acid oleate. Time-dependent increases in mRNA levels for activating transcription factor 4 (Atf4), DNA-damage inducible transcript 3 (Ddit3, previously known as C/EBP homologous protein [Chop]) and DnaJ homologue (HSP40) C3 (Dnajc3, previously known as p58) correlated with increased apoptosis in palmitate- but not in oleate-treated MIN6 cells. Attenuation of ER stress by overproduction of HSPA5 in MIN6 cells significantly protected against lipid-induced apoptosis. In islets of db/db mice, a variety of marker genes of ER stress were also upregulated. Increased processing (activation) of X-box binding protein 1 (Xbp1) mRNA was also observed, confirming the existence of ER stress. Finally, we observed increased islet protein production of HSPA5, DDIT3, DNAJC3 and BCL2-associated X protein in human pancreas sections of type 2 diabetes subjects.
Conclusions/interpretation: Our results provide evidence that ER stress occurs in type 2 diabetes and is required for aspects of the underlying beta cell failure.
Protective effect of CK2 against endoplasmic reticulum stress in pancreatic β cells.
Takai T, Asahara S, Ikushiro H, Kobayashi K, Yano T, Kido Y Diabetol Int. 2025; 16(1):131-144.
PMID: 39877448 PMC: 11769914. DOI: 10.1007/s13340-024-00775-w.
Januario E, Barakat A, Rajsundar A, Fatima Z, Nanda Palienkar V, Bullapur A Cureus. 2025; 16(12):e75677.
PMID: 39807459 PMC: 11725408. DOI: 10.7759/cureus.75677.
Yu J, Lalwani A, Gunton J Int J Mol Sci. 2025; 25(24.
PMID: 39769216 PMC: 11676740. DOI: 10.3390/ijms252413451.
Role of Autophagy in Type 2 Diabetes Mellitus: The Metabolic Clash.
Alanazi Y, Al-Kuraishy H, Al-Gareeb A, Alexiou A, Papadakis M, Bahaa M J Cell Mol Med. 2024; 28(23):e70240.
PMID: 39656379 PMC: 11629865. DOI: 10.1111/jcmm.70240.
Liu Y, Yang X, Zhou J, Yang H, Yang R, Zhu P Nat Commun. 2024; 15(1):10479.
PMID: 39622811 PMC: 11612026. DOI: 10.1038/s41467-024-54905-8.