Abstract
Cadmium exposure is known to cause endoplasmic reticulum (ER) stress. In our current study, we examined the effects of salubrinal, a selective inhibitor of eukaryotic translation initiation factor 2 subunit α (eIF2α) dephosphorylation, on apoptotic cell death and ER stress-signaling events in HK-2 human renal proximal tubular cells exposed to cadmium chloride (CdCl2). Using phase-contrast microscopy and a cell viability assay, we observed that salubrinal suppressed CdCl2-induced cellular damage and cell death. Treatment with salubrinal reduced the number of TUNEL-positive cells and the cleavages of caspase-3 and poly(ADP-ribose) polymerase, but not the cleavage of light chain 3B, indicating protection from CdCl2-induced apoptosis but not autophagy. Although eIF2α remained phosphorylated after CdCl2 exposure to salubrinal-treated HK-2 cells, the expression of activating transcription factor 4 (ATF4) and the 78 kDa glucose-regulated protein (GRP78) was not increased. On the other hand, CdCl2-induced expression of C/EBP homologous protein (CHOP) was reduced by salubrinal treatment. Expression of ATF4, an upstream regulator of GRP78 and CHOP, appeared to be a prerequisite for full protection by salubrinal against cadmium cytotoxicity, because CdCl2-induced cellular damage was not fully suppressed in ATF4-deficient cells. Phosphorylated forms of mitogen-activated protein kinases (MAPKs), including c-Jun NH2-terminal kinase (JNK), p38, and extracellular signal-regulated protein kinase (ERK), increased after CdCl2 exposure, whereas salubrinal suppressed the phosphorylation of JNK and p38 but not ERK. These results suggest that salubrinal protects CdCl2-exposed HK-2 cells from apoptosis by suppressing cell death signal transduction pathways.
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References
Biagioli M, Pifferi S, Ragghianti M, Bucci S, Rizzuto R, Pinton P (2008) Endoplasmic reticulum stress and alteration in calcium homeostasis are involved in cadmium-induced apoptosis. Cell Calcium 43:184–195
Boyce M, Bryant KF, Jousse C, Long K, Harding HP, Scheuner D, Kaufman RJ, Ma D, Coen DM, Ron D, Yuan J (2005) A selective inhibitor of eIF2α dephosphorylation protects cells from ER stress. Science 307:935–939
Chipuk JE, Moldoveanu T, Llambi F, Parsons MJ, Green DR (2010) The BCL-2 family reunion. Mol Cell 37:299–310
Chou YH, Chao PL, Tsai MJ, Cheng HH, Chen KB, Yang DM, Yang CH, Lin AMY (2008) Arsenite-induced cytotoxicity in dorsal root ganglion explants. Free Radic Biol Med 44:1553–1561
Croute F, Beau B, Murat J-C, Vincent C, Komatsu H, Obata F, Soleilhavoup J-P (2005) Expression of stress-related genes in a cadmium-resistant A549 human cell line. J Toxicol Environ Health A 68:703–718
Gardarin A, Chédin S, Lagniel G, Aude J-C, Godat E, Catty P, Labarre J (2010) Endoplasmic reticulum is a major target of cadmium toxicity in yeast. Mol Microbiol 76:1034–1048
Harding HP, Novoa I, Zhang Y, Zeng H, Wek R, Schapira M, Ron D (2000) Regulated translation initiation controls stress-induced gene expression in mammalian cells. Mol Cell 6:1099–1108
He CH, Gong P, Hu B, Stewart D, Choi ME, Choi AMK, Alam J (2001) Identification of activating transcription factor 4 (ATF4) as an Nrf2-interacting protein: implication for heme oxygenase-1 gene regulation. J Biol Chem 276:20858–20865
Homma K, Katagiri K, Nishitoh H, Ichijo H (2009) Targeting ASK1 in ER stress-related neurodegenerative diseases. Expert Opin Ther Targets 13:653–664
Hotamisligil GS (2010) Endoplasmic reticulum stress and the inflammatory basis of metabolic disease. Cell 140:900–917
Ichijo H, Nishida E, Irie K, ten Dijke P, Saitoh M, Moriguchi T, Takagi M, Matsumoto K, Miyazono K, Gotoh Y (1997) Induction of apoptosis by ASK1, a mammalian MAPKKK that activates SAPK/JNK and p38 signaling pathways. Science 275:90–94
Inagi R (2010) Endoplasmic reticulum stress as a progression factor for kidney injury. Curr Opin Pharmacol 10:156–165
Iwatsuki M, Inageda K, Matsuoka M (2011) Cadmium induces phosphorylation and stabilization of c-Fos in HK-2 renal proximal tubular cells. Toxicol Appl Pharmacol 251:209–216
Lee AS (2001) The glucose-regulated proteins: stress induction and clinical applications. Trends Biochem Sci 26:504–510
Liu F, Inageda K, Nishitai G, Matsuoka M (2006) Cadmium induces the expression of Grp78, an endoplasmic reticulum molecular chaperone, in LLC-PK1 renal epithelial cells. Environ Health Perspect 114:859–864
Long K, Boyce M, Lin H, Yuan J, Ma D (2005) Structure-activity relationship studies of salubrinal lead to its active biotinylated derivative. Bioorg Med Chem Lett 15:3849–3852
Luo S, Baumeister P, Yang S, Abcouwer SF, Lee AS (2003) Induction of Grp78/BiP by translational block: activation of the Grp78 promoter by ATF4 through an upstream ATF/CRE site independent of the endoplasmic reticulum stress elements. J Biol Chem 278:37375–37385
Matsuzawa A, Ichijo H (2008) Redox control of cell fate by MAP kinase: physiological roles of ASK1-MAP kinase pathway in stress signaling. Biochim Biophys Acta 1780:1325–1336
Nordberg GF, Nogawa K, Nordberg M, Friberg LT (2007) Cadmium. In: Nordberg GF, Fowler BA, Nordberg M, Friberg LT (eds) Handbook on the toxicology of metals, 3rd edn. Academic Press, Burlington, pp 445–486
Oyadomari S, Mori M (2004) Roles of CHOP/GADD153 in endoplasmic reticulum stress. Cell Death Differ 11:381–389
Raman M, Chen W, Cobb MH (2007) Differential regulation and properties of MAPKs. Oncogene 26:3100–3112
Ron D, Walter P (2007) Signal integration in the endoplasmic reticulum unfolded protein response. Nat Rev Mol Cell Biol 8:519–529
Schröder M, Kaufman RJ (2005) ER stress and the unfolded protein response. Mutat Res 569:29–63
Sugisawa N, Matsuoka M, Okuno T, Igisu H (2004) Suppression of cadmium-induced JNK/p38 activation and HSP70 family gene expression by LL-Z1640–2 in NIH3T3 cells. Toxicol Appl Pharmacol 196:206–214
Templeton DM, Liu Y (2010) Multiple roles of cadmium in cell death and survival. Chem Biol Interact 188:267–275
Wada T, Penninger JM (2004) Mitogen-activated protein kinases in apoptosis regulation. Oncogene 23:2838–2849
Wang S-H, Shih Y-L, Lee C–C, Chen W-L, Lin C-J, Lin Y-S, Wu K-H, Shih C-M (2009) The role of endoplasmic reticulum in cadmium-induced mesangial cell apoptosis. Chem Biol Interact 181:45–51
Wang Q, Jiang H, Fan Y, Huang X, Shen J, Qi H, Li Q, Lu X, Shao J (2011) Phosphorylation of the α-subunit of the eukaryotic initiation factor-2 (eIF2α) alleviates benzo[a]pyrene-7, 8-diol-9, 10-epoxide induced cell cycle arrest and apoptosis in human cells. Environ Toxicol Pharmacol 31:18–24
Yang W, Tiffany-Castiglioni E, Koh HC, Son Il-H (2009) Paraquat activates the IRE1/ASK1/JNK cascade associated with apoptosis in human neuroblastoma SH-SY5Y cells. Toxicol Lett 191:203–210
Yokouchi M, Hiramatsu N, Hayakawa K, Kasai A, Takano Y, Yao J, Kitamura M (2007) Atypical, bidirectional regulation of cadmium-induced apoptosis via distinct signaling of unfolded protein response. Cell Death Differ 14:1467–1474
Acknowledgments
This work was supported in part by a Grant-in-Aid for Scientific Research (21510073) from the Japan Society for the Promotion of Science.
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Komoike, Y., Inamura, H. & Matsuoka, M. Effects of salubrinal on cadmium-induced apoptosis in HK-2 human renal proximal tubular cells. Arch Toxicol 86, 37–44 (2012). https://doi.org/10.1007/s00204-011-0742-x
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DOI: https://doi.org/10.1007/s00204-011-0742-x