Rifampicin protects PC12 cells from rotenone-induced cytotoxicity by activating GRP78 via PERK-eIF2α-ATF4 pathway

PLoS One. 2014 Mar 17;9(3):e92110. doi: 10.1371/journal.pone.0092110. eCollection 2014.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activating Transcription Factor 4 / metabolism*
  • Activating Transcription Factor 6 / metabolism
  • Animals
  • Cell Death / drug effects
  • DNA-Binding Proteins / metabolism
  • Electrophoresis, Gel, Two-Dimensional
  • Endoplasmic Reticulum Chaperone BiP
  • Endoribonucleases / metabolism
  • Eukaryotic Initiation Factor-2 / metabolism*
  • Heat-Shock Proteins / metabolism*
  • Neuroprotective Agents / pharmacology*
  • PC12 Cells
  • Rats
  • Regulatory Factor X Transcription Factors
  • Rifampin / pharmacology*
  • Rotenone / pharmacology*
  • Signal Transduction / drug effects
  • Time Factors
  • Transcription Factors / metabolism
  • eIF-2 Kinase / metabolism*

Substances

  • Activating Transcription Factor 6
  • DNA-Binding Proteins
  • Endoplasmic Reticulum Chaperone BiP
  • Eukaryotic Initiation Factor-2
  • Heat-Shock Proteins
  • Neuroprotective Agents
  • Regulatory Factor X Transcription Factors
  • Transcription Factors
  • Rotenone
  • Activating Transcription Factor 4
  • PERK kinase
  • eIF-2 Kinase
  • Endoribonucleases
  • Rifampin

Grants and funding

This work was funded by the the National Natural Science Foundation of China (NSFC, 81371391), and the Guangdong Provincial Department of Science and Technology (7001599; S2012010010731) and the Ph.D. Programs Foundation of Ministry of Education of China (No. 20070558257). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.