Activation of the unfolded protein response in aged human lenses

Tang,He‑Zhen; Yang,Li‑Min

doi:10.3892/mmr.2015.3417

Activation of the unfolded protein response in aged human lenses

Authors:
- He‑Zhen Tang
- Li‑Min Yang
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Affiliations: Department of Ophthalmology, Liaocheng People's Hospital, Liaocheng, Shandong 252000, P.R. China
Published online on: March 4, 2015 https://doi.org/10.3892/mmr.2015.3417
Pages: 389-393

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Abstract

Cataract formation is a multifactorial disease, induced by a variety of stressors. The endoplasmic reticulum (ER) stress‑induced unfolded protein response (UPR) is known to produce reactive oxygen species (ROS) leading to apoptosis. The present study aimed to investigate whether activation of the UPR occurs in human lenses, using human lens epithelial cell (HLEC) lines and lenses obtained from an eye bank, from individuals aged between 50 and 90 years. In vitro analysis was performed using calcimycin (10 µM) as an ER stressor. The level of ER stress was measured by the production of ROS, staining for cell death, detection of binding immunoglobulin proteins (BIP) and levels of other UPR proteins, including inositol‑requiring enzyme‑1 (IRE), activating transcription factor (ATF) 6 and PKR‑like eukaryotic initiation factor 2a kinase (PERK). These parameters were examined in HLECs exposed to calcimycin for 12, 24, 48 and 72 h. Fluorescent activated cell sorting analysis of the levels of ROS and apoptosis revealed an increase following 24 h calcimycin exposure. The reverse transcription quantitative polymerase chain reaction results demonstrated a gradual increase in the mRNA levels of BIP, IRE1, ATF6 and PERK between 12 and 72 h. A similar effect was observed in the protein levels, which also demonstrated a gradual increase in the levels of endoplasmic oxidoreductin‑1‑like (Ero1‑L)‑β and protein disulfide isomerase, but a lower level of Ero1‑Lα. Activation of the UPR involved the apoptotic pathway, revealed by increased levels of C/EBP homologous protein, ATF4 and caspase‑4. Additionally, the antioxidant protein levels were also suppressed. The investigation of aged human lenses revealed a similar increase in the protein expression of UPR. These results indicated that activation of the UPR‑induced ROS production suppressed the antioxidant status and triggered the apoptotic pathway, ultimately leading to the formation of age‑related cataracts.

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1	Kozutsumi Y, Segal M, Normington K, Gething MJ and Sambrook J: The presence of malfolded proteins in the endoplasmic reticulum signals the induction of glucose-regulated proteins. Nature. 332:462–464. 1988. View Article : Google Scholar : PubMed/NCBI
2	Brewer JW and Diehl JA: PERK mediates cell-cycle exit during the mammalian unfolded protein response. Proc Natl Acad Sci USA. 97:12625–12630. 2000. View Article : Google Scholar : PubMed/NCBI
3	Prostko CR, Brostrom MA, Malara EM and Brostrom CO: Phosphorylation of eukaryotic initiation factor (eIF) 2 alpha and inhibition of eIF-2B in GH3 pituitary cells by perturbants of early protein processing that induce GRP78. J Biol Chem. 267:16751–16754. 1992.PubMed/NCBI
4	Shi Y, Vattem KM, Sood R, An J, Liang J, Stramm L, et al: Identification and characterization of pancreatic eukaryotic initiation factor 2 alpha-subunit kinase, PEK, involved in translational control. Mol Cell Biol. 18:7499–7509. 1998.PubMed/NCBI
5	Tirasophon W, Welihinda AA and Kaufman RJ: A stress response pathway from the endoplasmic reticulum to the nucleus requires a novel bifunctional protein kinase/endoribonuclease (Ire1p) in mammalian cells. Genes Dev. 12:1812–1824. 1998. View Article : Google Scholar : PubMed/NCBI
6	Rao RV, Ellerby HM and Bredesen DE: Coupling endoplasmic reticulum stress to the cell death program. Cell Death Differ. 11:372–380. 2004. View Article : Google Scholar : PubMed/NCBI
7	Mandic A, Hansson J, Linder S and Shoshan MC: Cisplatin induces endoplasmic reticulum stress and nucleus-independent apoptotic signaling. J Biol Chem. 278:9100–9106. 2003. View Article : Google Scholar : PubMed/NCBI
8	Tinhofer I, Anether G, Senfter M, Pfaller K, Bernhard D, Hara M, et al: Stressful death of T-ALL tumor cells after treatment with the anti-tumor agent Tetrocarcin-A. FASEB J. 16:1295–1297. 2002.PubMed/NCBI
9	Xie Q, Khaoustov VI, Chung CC, Sohn J, Krishnan B, Lewis DE, et al: Effect of tauroursodeoxycholic acid on endoplasmic reticulum stress-induced caspase-12 activation. Hepatology. 36:592–601. 2002. View Article : Google Scholar : PubMed/NCBI
10	Kaufman RJ, Scheuner D, Schroder M, Shen X, Lee K, Liu CY, et al: The unfolded protein response in nutrient sensing and differentiation. Nat Rev Mol Cell Biol. 3:411–421. 2002. View Article : Google Scholar : PubMed/NCBI
11	Szegezdi E, Fitzgerald U and Samali A: Caspase-12 and ER stress-mediated apoptosis: the story so far. Ann N Y Acad Sci. 1010:186–194. 2003. View Article : Google Scholar
12	Ji C, Deng Q and Kaplowitz N: Role of TNF-alpha in ethanol-induced hyperhomocysteinemia and murine alcoholic liver injury. Hepatology. 40:442–451. 2004. View Article : Google Scholar : PubMed/NCBI
13	Haynes CM, Titus EA and Cooper AA: Degradation of misfolded proteins prevents ER-derived oxidative stress and cell death. Mol Cell. 15:767–776. 2004. View Article : Google Scholar : PubMed/NCBI
14	McCullough KD, Martindale JL, Klotz LO, Aw TY and Holbrook NJ: Gadd153 sensitizes cells to endoplasmic reticulum stress by down-regulating Bcl2 and perturbing the cellular redox state. Mol Cell Biol. 21:1249–1259. 2001. View Article : Google Scholar : PubMed/NCBI
15	Tu BP, Ho-Schleyer SC, Travers KJ and Weissman JS: Biochemical basis of oxidative protein folding in the endoplasmic reticulum. Science. 290:1571–1574. 2000. View Article : Google Scholar : PubMed/NCBI
16	Ikesugi K, Yamamoto R, Mulhern ML and Shinohara T: Role of the unfolded protein response (UPR) in cataract formation. Exp Eye Res. 83:508–516. 2006. View Article : Google Scholar : PubMed/NCBI
17	Elanchezhian R, Palsamy P, Madson CJ, et al: Low glucose under hypoxic conditions induces unfolded protein response and produces reactive oxygen species in lens epithelial cells. Cell Death Dis. 3:e3012012. View Article : Google Scholar : PubMed/NCBI
18	Elanchezhian R, Palsamy P, Madson CJ, Lynch DW and Shinohara T: Age-related cataracts: homocysteine coupled endoplasmic reticulum stress and suppression of Nrf2-dependent antioxidant protection. Chem Biol Interact. 200:1–10. 2012. View Article : Google Scholar : PubMed/NCBI
19	Michael R and Bron AJ: The ageing lens and cataract: a model of normal and pathological ageing. Philos Trans R Soc Lond B Biol Sci. 366:1278–1292. 2011. View Article : Google Scholar : PubMed/NCBI
20	Harding JJ: Free and protein-bound glutathione in normal and cataractous human lense. Biochem J. 117:957–960. 1970.PubMed/NCBI
21	Lou MF: Redox regulation in the lens. Prog Retin Eye Res. 22:657–682. 2003. View Article : Google Scholar : PubMed/NCBI
22	Ikesugi K, Mulhern ML, Madson CJ, et al: Induction of endoplasmic reticulum stress in retinal pericytes by glucose deprivation. Curr Eye Res. 31:947–953. 2006. View Article : Google Scholar : PubMed/NCBI
23	Mulhern ML, Madson CJ, Danford A, Ikesugi K, Kador PF and Shinohara T: The unfolded protein response in lens epithelial cells from galactosemic rat lenses. Invest Ophthalmol Vis Sci. 47:3951–3959. 2006. View Article : Google Scholar : PubMed/NCBI
24	Schmittgen TD and Livak KJ: Analyzing real-time PCR data by the comparative C(T) method. Nat Protoc. 3:1101–1108. 2008. View Article : Google Scholar : PubMed/NCBI
25	Shichi H: Cataract formation and prevention. Expert Opin Investig Drugs. 13:691–701. 2004. View Article : Google Scholar : PubMed/NCBI
26	Bloemendal H, de Jong W, Jaenicke R, Lubsen NH, Slingsby C and Tardieu A: Ageing and vision: structure, stability and function of lens crystallins. Prog Biophys Mol Biol. 86:407–485. 2004. View Article : Google Scholar : PubMed/NCBI
27	Huang L1, Tang D, Yappert MC and Borchman D: Oxidation-induced changes in human lens epithelial cells 2. Mitochondria and the generation of reactive oxygen species. Free Radic Biol Med. 41:926–936. 2006. View Article : Google Scholar : PubMed/NCBI
28	Ron D and Walter P: Signal integration in the endoplasmic reticulum unfolded protein response. Nat Rev Mol Cell Biol. 8:519–529. 2007. View Article : Google Scholar : PubMed/NCBI
29	Schröder M: The unfolded protein response. Mol Biotechnol. 34:279–290. 2006. View Article : Google Scholar : PubMed/NCBI
30	Puustjärvi T, Blomster H, Kontkanenv M, Punnonen K and Terasvirta M: Plasma and aqueous humour levels of homocysteine in exfoliation syndrome. Graefes Arch Clin Exp Ophthalmol. 242:749–754. 2004. View Article : Google Scholar : PubMed/NCBI
31	Arap MA, Lahdenranta J, Mintz PJ, Hajitou A, Sarkis AS, Arap W and Pasqualini R: Cell surface expression of the stress response chaperone GRP78 enables tumor targeting by circulating ligands. Cancer Cell. 6:275–284. 2004. View Article : Google Scholar : PubMed/NCBI
32	Huang HC, Nguyen T and Pickett CB: Phosphorylation of Nrf2 t Ser-40 by protein kinase C regulates antioxidant response element-mediated transcription. J Biol Chem. 277:42769–42774. 2002. View Article : Google Scholar : PubMed/NCBI