Paraquat activates the IRE1/ASK1/JNK cascade associated with apoptosis in human neuroblastoma SH-SY5Y cells.
Epidemiologic and laboratory studies suggest that paraquat can be an environmental etiologic factor in Parkinson's disease (PD). One mechanism by which paraquat may mediate cell death of dopaminergic neurons is by inducing endoplasmic reticulum (ER) stress, as suggested in a recent report. In this study, we further investigated this linkage by examining ER stress cascades. To this aim, human neuroblastoma cells (SH-SY5Y cells) were treated with paraquat and the signaling cascades through which ER stress results in apoptosis were examined. Then, it was examined whether ER stress is produced by paraquat. Paraquat increased ER stress biomarker proteins, glucose-regulated protein 78 (GRP78), ER degradation-enhancing alpha-mannosidae-like protein (EDEM), and C/EBP homologous protein (CHOP). Then, it was investigated which ER stress cascades are affected by paraquat. Paraquat activated inositol-requiring enzyme 1 (IRE1), apoptosis signal regulating kinase 1 (ASK1), and c-jun kinase (JNK). Also, paraquat activated calpain and caspase 3, but did not affect the levels of intracellular calcium and the activity of caspase 12. Finally, apoptotic DNA damage by paraquat was investigated and this damage was attenuated by salubrinal (ER stress inhibitor), thioredoxin (ASK1 inhibitor) and SP600125 (JNK inhibitor). Therefore, current data indicate that paraquat activates the IRE1/ASK1/JNK cascade associated with apoptosis in SY5Y cells.
Yang
Wonsuk
W
Inam Neuroscience Research Center, College of Medicine, Wonkwang University, Sanbon, Republic of Korea.
Tiffany-Castiglioni
Evelyn
E
Koh
Hyun Chul
HC
Son
Il-Hong
IH
D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020013:Calcium Signaling / Q000502:physiology; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004396:Coloring Agents; D004249:DNA Damage; D000091342:Endoplasmic Reticulum Chaperone BiP; D004722:Endoribonucleases / Q000096:biosynthesis* / Q000235:genetics; D005562:Formazans / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D006540:Herbicides / Q000633:toxicity*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D048848:MAP Kinase Kinase Kinase 5 / Q000096:biosynthesis* / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D010269:Paraquat / Q000633:toxicity*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D051742:Transcription Factor CHOP / Q000096:biosynthesis; D014343:Trypan Blue
D004396:Coloring Agents; C497249:DDIT3 protein, human; C486654:EDEM1 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; D005562:Formazans; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D006540:Herbicides; D008565:Membrane Proteins; D051742:Transcription Factor CHOP; C403982:ERN2 protein, human; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human; D004722:Endoribonucleases; D020169:Caspases; D014343:Trypan Blue; D010269:Paraquat