Ryan Pauline M, Bedard Karen, Breining Tibor, Cribb Alastair E
Laboratory of Comparative Pharmacogenetics, Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
Toxicol Lett. 2005 Nov 15;159(2):154-63. doi: 10.1016/j.toxlet.2005.05.004.
Prior induction of an endoplasmic reticulum stress response results in protection against reactive cytotoxins in the LLC-PK1 cell line. The purpose of this investigation was to determine therefore if the endoplasmic reticulum was disrupted by iodoacetamide, tert-butylhydroperoxide or sulfamethoxazole hydroxylamine. Toxic concentrations of the three toxins caused a dramatic loss of GRP94 protein within 3-8h of exposure, while induction of GRP78 and calreticulin occurred at 8 and 24h following exposure. There was no evidence of cytosolic elevation of calcium and neither dantrolene nor xestospongin were able to block the cytotoxicity of IDAM and TBHP. Exposure to the toxins led to DNA degradation and cleavage of procaspase-12. There was only evidence of procaspase-3 cleavage after TBHP exposure. These results demonstrate that the ER is disrupted by the reactive cytotoxins examined in LLC-PK1cells and suggest that the cytoprotection against low to moderate concentrations of cytotoxins observed following endoplasmic reticulum stress protein induction is likely due to a mechanism other than maintenance of calcium homeostasis.
内质网应激反应的预先诱导可使LLC-PK1细胞系免受反应性细胞毒素的侵害。因此，本研究的目的是确定内质网是否会被碘乙酰胺、叔丁基过氧化氢或磺胺甲恶唑羟胺破坏。三种毒素的毒性浓度在暴露3-8小时内导致GRP94蛋白显著损失，而GRP78和钙网蛋白的诱导分别在暴露后8小时和24小时出现。没有证据表明细胞溶质钙升高，丹曲林和西司他汀均无法阻断碘乙酰胺和叔丁基过氧化氢的细胞毒性。毒素暴露导致DNA降解和procaspase-12的裂解。仅在叔丁基过氧化氢暴露后有procaspase-3裂解的证据。这些结果表明，内质网被LLC-PK1细胞中检测的反应性细胞毒素破坏，并表明内质网应激蛋白诱导后观察到的对低至中等浓度细胞毒素的细胞保护作用可能是由于维持钙稳态以外的机制。
