title: Rifampicin protects PC12 cells from rotenone-induced cytotoxicity by activating GRP78 via PERK-eIF2α-ATF4 pathway.
abstract: Rifampicin has been proposed as a therapeutic candidate for Parkinson's disease (PD). We previously showed that rifampicin was neuroprotective in PD models in vivo and in vitro. However, the molecular mechanisms underlying are not fully elucidated. In this study, using the comprehensive proteomic analysis, we identified that the 78 kDa glucose-regulated protein (GRP78), a hallmark of the unfolded protein response (UPR), was upregulated in rifampicin-treated PC12 cells. Western blot analysis confirmed GRP78 activation. GRP78 functions cytoprotectively in stressed cells, therefore, we hypothesized that GRP78 mediated rifampicin-induced neuroprotection. Using RNA interference, we found that GRP78 gene knockdown significantly attenuated the neuroprotective effects of rifampicin. Next, we examined three UPR transducers, namely, protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol requiring kinase α (IREα) and activating transcription factor 6 (ATF 6), and how they regulated rifampicin-stimulated GRP78 expression. Our results showed that PERK, eukaryotic initiation factor 2α (eIF2α), and activating transcription factor 4 (ATF4) were activated in rifampicin-treated PC12 cells. Silencing the ATF4 gene using RNAi inhibited GRP78 stimulation. Interestingly, we did not detect significant IREα activation, X-box binding protein 1 mRNA splicing, or ATF6 cleavage up to 24 h after rifampicin treatment. Taken together, our data suggested that rifampicin induced GRP78 via the PERK-eIF2α-ATF4 pathway to protect neurons against rotenone-induced cell damage. Targeting molecules in this pathway could be a novel therapeutic approach for PD treatment.
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Xiuna
authors.initials: X
authors.lastname: Jing
authors.affiliation: Department of Radiology, School of Medicine, Stanford University, Stanford, California, United States of America.
authors.forename: Qiaoyun
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China; Department of Neurology, the First Affiliated Hospital of Jinan University, Guangzhou, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Bi
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Zhifen
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Yanran
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Xia
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Songhua
authors.initials: S
authors.lastname: Xiao
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Lianhong
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Neurology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Enxiang
authors.initials: E
authors.lastname: Tao
mesh_terms: D051701:Activating Transcription Factor 4 / Q000378:metabolism*; D051702:Activating Transcription Factor 6 / Q000378:metabolism; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D000091342:Endoplasmic Reticulum Chaperone BiP; D004722:Endoribonucleases / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016716:PC12 Cells; D051381:Rats; D000071701:Regulatory Factor X Transcription Factors; D012293:Rifampin / Q000494:pharmacology*; D012402:Rotenone / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D051701:Activating Transcription Factor 4; D051702:Activating Transcription Factor 6; D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D004722:Endoribonucleases; D015852:Eukaryotic Initiation Factor-2; D006360:Heat-Shock Proteins; D018696:Neuroprotective Agents; D000071701:Regulatory Factor X Transcription Factors; D012293:Rifampin; D012402:Rotenone; D014157:Transcription Factors; D019892:eIF-2 Kinase