Bibenzyl compound 20c protects against endoplasmic reticulum stress in tunicamycin-treated PC12 cells in vitro.
OBJECTIVE
Accumulation of α-synuclein (α-syn) in the brain is a characteristic of Parkinson's disease (PD). In this study, we investigated whether treatment with tunicamycin, an endoplasmic reticulum (ER) stress inducer, led to the accumulation of α-syn in PC12 cells, and where α-syn protein was accumulated, and finally, whether bibenzyl compound 20c, a novel compound isolated from Gastrodia elata (Tian ma), could alleviate the accumulation of α-syn and ER stress activation in tunicamycin-treated PC12 cells.


METHODS
PC12 cells were treated with tunicamycin for different time (6 h, 12 h, 24 h, 48 h). Cell viability was determined by a MTT assay. Subcellular fractions of ER and mitochondria were extracted with the Tissue Endoplasmic reticulum Isolation Kit. The levels of α-syn protein and ER-stress-associated downstream chaperones were detected using Western blots and immunofluorescence.


RESULTS
Treatment of PC12 cells with tunicamycin (0.5-10 μg/mL) dose-dependently increased the accumulation of α-syn monomer (19 kDa) and oligomer (55 kDa), and decreased the cell viability. Accumulation of the two forms of α-syn was observed in both the ER and mitochondria with increasing treatment time. Co-treatment with 20c (10-5mol/L) significantly increased the viability of tunicamycin-treated cells, reduced the level of α-syn protein and suppressed ER stress activation in the cells, evidenced by the reductions in phosphorylation of eIF2α and expression of spliced ATF6 and XBP1.


CONCLUSIONS
Tunicamycin treatment caused accumulation of α-syn monomer and oligomer in PC12 cells. Bibenzyl compound 20c reduces the accumulation of α-syn and inhibits the activation of ER stress, which protected PC12 cells against the toxicity induced by tunicamycin.
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Zheng
Z
Mou
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Yu-He
YH
Yuan
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Yu-Xia
YX
Lou
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Yang
Y
Heng
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Ju-Yang
JY
Huang
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Cong-Yuan
CY
Xia
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Yan
Y
Gao
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Cheng-Gen
CG
Zhu
Hunan University of Chinese Medicine, Changsha 410208, China.
Shi-Feng
SF
Chu
Hunan University of Chinese Medicine, Changsha 410208, China.
Piao
P
Luo
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Jian-Gong
JG
Shi
State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.|Hunan University of Chinese Medicine, Changsha 410208, China.
Nai-Hong
NH
Chen
D000818:Animals; D001559:Benzhydryl Compounds / Q000494:pharmacology*; D001632:Bibenzyls / Q000494:pharmacology*; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D031668:Gastrodia / Q000737:chemistry*; D016716:PC12 Cells; D010636:Phenols / Q000494:pharmacology*; D020011:Protective Agents / Q000494:pharmacology*; D051381:Rats; D014415:Tunicamycin / Q000633:toxicity*; D051844:alpha-Synuclein / Q000378:metabolism
C000613700:2-(3-(4-hydroxybenzyl)-4-hydroxybenzyl)-4-(4-hydroxybenzyl)phenol; D001559:Benzhydryl Compounds; D001632:Bibenzyls; D010636:Phenols; D020011:Protective Agents; C497606:Snca protein, rat; D051844:alpha-Synuclein; D014415:Tunicamycin