Disruption of the endoplasmic reticulum by cytotoxins in LLC-PK1 cells.
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.
Ryan
Pauline M
PM
Laboratory of Comparative Pharmacogenetics, Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
Bedard
Karen
K
Breining
Tibor
T
Cribb
Alastair E
AE
D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003603:Cytotoxins / Q000633:toxicity*; D053938:DNA Fragmentation; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005456:Fluorescent Dyes; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007460:Iodoacetamide / Q000633:toxicity*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018374:LLC-PK1 Cells; D008565:Membrane Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D013420:Sulfamethoxazole / Q000031:analogs & derivatives* / Q000633:toxicity; D013552:Swine; D020298:U937 Cells; D014966:Xanthenes; D020122:tert-Butylhydroperoxide / Q000633:toxicity*
D000814:Aniline Compounds; D003603:Cytotoxins; D000091342:Endoplasmic Reticulum Chaperone BiP; D005456:Fluorescent Dyes; D018840:HSP70 Heat-Shock Proteins; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D014966:Xanthenes; C018551:glucose-regulated proteins; C059873:sulfamethoxazole hydroxylamine; C059715:Fluo-3; D020122:tert-Butylhydroperoxide; D007770:L-Lactate Dehydrogenase; D013420:Sulfamethoxazole; D002118:Calcium; D007460:Iodoacetamide