Novel Insights into the Global Proteome Responses of Insulin-Producing INS-1E Cells To Different Degrees of Endoplasmic Reticulum Stress

Abstract

Exposure of insulin-secreting β-cells to inflammatory cytokines or high concentrations of free fatty acids, factors involved in the pathogenesis of type 1 and type 2 diabetes, leads to endoplasmic reticulum (ER) stress, β-cell dysfunction, and eventually apoptotic β-cell death. The aim of this study was to investigate the impact of ER stress on β-cells at the protein level to evaluate the contribution of post-transcriptional and post-translational changes in ER stress-induced β-cell damage. INS-1E cells were exposed in vitro to the ER-stress inducer cyclopiazonic acid (CPA) at two concentrations, and protein changes were evaluated using 2D-DIGE. CPA, 25 μM, led to massive apoptosis, accompanied by a near complete protein translation shut-down. CPA, 6.25 μM, led to adaptation of the β-cells to ER stress. Identification of the differentially expressed proteins in the two conditions led to the discovery of a clear pattern of defense pathways, with post-translational modifications playing a crucial role. Key alterations included inhibition of insulin translation and post-translational modifications in ER chaperones HYOU1 and HSPA5. Also, a central role for 14-3-3 proteins is suggested. In conclusion, INS-1E cells are highly sensitive to ER stress, leading to important post-transcriptional and post-translational modifications that may contribute to β-cell dysfunction and death.

Dissociation of NSC606985 induces atypical ER-stress and cell death in prostate cancer cells

“…3). Although a decrease in GRP78 protein levels is unusual, such ER-stress associated GRP78 reduction has been reported by other investigators in different cells (47,48). It is obvious that the decrease in GRP78 protein is not due to a decrease in GRP78 mRNA since NSC induced a time-dependent increase in GRP78 mRNA levels.…”

Optimal Elevation of β-Cell 11β-Hydroxysteroid Dehydrogenase Type 1 Is a Compensatory Mechanism That Prevents High-Fat Diet–Induced β-Cell Failure

“…Further, a direct interaction between GR and PKA has been proposed in other cellular systems (40,44), suggesting a novel mechanism for functional augmentation of β-cells that can now be fully explored. Heat shock protein induction is consistent with increased GR activation (45,46) and, along with p21 in islets (29), is associated with cell survival and protection from apoptosis (28,47), echoing critical processes activated in β-cells that successfully adapt to ER stress (30,45). Note the impact of elevated 11β-HSD1 on β-cell apoptosis will need careful future exploration in model systems other than the HF-fed C57BL/KsJ mice where this process is more evident and quantifiable.…”

“…3 E , right, and F and G ) and the mitogen-activated protein kinase/extracellular signal–related kinase (ERK) ( B-raf , Max , and Cdkn1a/p21 ) and Jak/Stat pathways ( Ccnd2 and Jak1 ), indicative of maintained differentiation versus proliferation commitment (24–27) and protection from apoptosis (28,29). MIP-HSD1 tg/+ islets also exhibited higher mRNA levels of genes related to protection from cellular stress ( hspa1a , - a1b , - a4 , and trib3 ) (30). Key gene expression changes were validated by real-time PCR (Fig.…”

Pancreatic islet proteome profile in Zucker fatty rats chronically treated with a grape seed procyanidin extract

“…GSPE decreased protein levels of the chaperones Hspd1, Hsp90b1, and Hspa5, proteins that promote protein folding and degradation (Kriegenburg, Ellgaard, & Hartmann-Petersen, 2011); and of protein disulfide-isomerase A3 (Pdia3), involved in ER-associated degradation. Chaperones Hspa5 and Hsp90b1, as well as Pdia3, were also decreased in the beta-cell line INS-1E when severe ER stress was induced or when they were treated with high glucose, indicating a defective UPR (Ahmed et al, 2010;D'Hertog et al, 2010;Maris et al, 2010). GSPE treatment also increased Polyubiquitin-B (Ubb), a molecule that targets misfolded proteins for degradation (Kriegenburg et al, 2011).…”