GSK3beta and endoplasmic reticulum stress mediate rotenone-induced death of SK-N-MC neuroblastoma cells.
Rotenone, an environmental toxin that inhibits mitochondrial complex I, has been used to induce experimental Parkinsonism in animals and cell cultures. We investigated the mechanism underlying rotenone-induced death of SK-N-MC neuroblastoma cells. Rotenone-induced cell death preceded intracellular accumulation of reactive oxygen species, and antioxidants failed to protect cells, indicating that oxidative stress was minimally involved in rotenone-induced death of SK-N-MC cells. Glycogen synthase kinase 3beta (GSK3beta), a multifunctional serine/threonine kinase, has been implicated in the pathogenesis of neurodegeneration. We showed that rotenone activated GSK3beta by enhancing its phosphorylation at tyrosine 216 while inhibiting phosphorylation at serine 9. Inhibitors of GSK3beta and dominant negative (kinase deficient) GSK3beta partially protected SK-N-MC cells against rotenone cytotoxicity. Rotenone also induced endoplasmic reticulum (ER) stress which was evident by an increase in phosphorylation of PERK, PKR, and eIF2alpha as well as the expression of GRP78. Rotenone had a modest effect on the expression of CHOP. An eIF2alpha siRNA significantly reduced rotenone cytotoxicity. ER stress was experimentally induced by tunicamycin and thapsigargin, but tunicamycin/thapsigargin did not activate GSK3beta in SK-N-MC cells. Down-regulation of eIF2alpha also offered partial protection against rotenone cytotoxicity. Combined treatment of GSK3beta inhibitors and eIF2alpha siRNA provided much greater protection than either treatment alone. Taken together, the results suggest that GSK3beta activation and ER stress contribute separately to rotenone cytotoxicity.
Chen
Yuan-Yuan
YY
Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai 200031, PR China.
Chen
Gang
G
Fan
Zhiqin
Z
Luo
Jia
J
Ke
Zun-Ji
ZJ
D016923:Cell Death / Q000187:drug effects*; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D018384:Oxidative Stress; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology*
D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D012402:Rotenone; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3