Endoplasmic Reticulum Stress Plays a Key Role in Rotenone-Induced Apoptotic Death of Neurons
Authors: Neeraj Joshi
Supriya Swarnkar
Poonam Goswami
Chandishwar Nath
Sarika Singh
Joyshree Biswas
Sonam Gupta
Journal: Molecular Neurobiology (2016)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Apoptosis; DNA damage; Endoplasmic reticulum stress; Reactive oxygen species; Rotenone
Affiliations: Toxicology Division, CSIR- Central Drug Research Institute, Lucknow, 226031, Uttar Pradesh, India., Academy of Scientific & Innovative Research (AcSIR), New Delhi, India., Center for Gene Regulation in Health and Disease, Department of Biological Sciences, Cleveland State University, Cleveland, OH, USA., Department of Genetics, Harvard Medical School, Boston, MA, USA., Scripps Research Institute, Jupiter, FL, USA., Toxicology Division, CSIR- Central Drug Research Institute, Lucknow, 226031, Uttar Pradesh, India. ., Academy of Scientific & Innovative Research (AcSIR), New Delhi, India. .

Abstract:  Rotenone, a pesticide, causes neurotoxicity via the mitochondrial complex-I inhibition. The present study was conducted to evaluate the role of endoplasmic reticulum (ER) stress in rotenone-induced neuronal death. Cell viability, cytotoxicity, reactive oxygen species (ROS) generation, nitrite level, mitochondrial membrane potential (MMP), and DNA damage were assessed in rotenone-treated neuro-2A cells. Protein levels of ER stress markers glucose regulated protein 78 (GRP78), growth arrest- and DNA damage-inducible gene 153 (GADD153), and phosphorylation of eukaryotic translation initiation factor 2 subunit Œ± (eIF2-Œ±) were estimated to assess the ER stress. To confirm the apoptotic death of neurons, mRNA levels of caspase-9, caspase-12 and caspase-3 were estimated. Further, to confirm the involvement of ER stress, neuro-2A cells were pretreated with ER stress inhibitor salubrinal. Co-treatment of antioxidant melatonin was also given to assess the role of oxidative stress in rotenone-induced apoptosis. Rotenone (0.1, 0.5, and 1 ŒºM) treatment to neurons caused significantly decreased cell viability, increased cytotoxicity, increased ROS generation, increased expression of GRP78 and GADD, DNA damage and activation of caspase-12 and caspase-3 which were significantly attenuated by pretreatment of salubrinal (25 ŒºM). Rotenone-induced dephosphorylation of eIF2Œ± was also inhibited with salubrinal treatment. However, pretreatment of salubrinal did not affect the rotenone-induced increased nitrite levels, decreased MMP and caspase-9 activation. Co-treatment of antioxidant melatonin (1 mM) did not offer attenuation against rotenone-induced increased expression of caspase-9, caspase-12 and caspase-3. In conclusion, results indicated that ER stress plays a key role in rotenone-induced neuronal death, rather than oxidative stress. Graphical Abstract Pictorial presentation showed the involvement of endoplasmic reticulum (ER) stress, increased reactive oxygen species (ROS), nitrite level, decreased mitochondrial membrane potential (MMP), caspase activation and DNA damage in neuronal cells after rotenone treatment. ER stress inhibitor-salubrinal showed significant attenuation against most of the rotenone-induced adverse effects reflecting its key involvement in rotenone-induced neuronal death. 

Retracted: No

PubPeer comments:
 There are similarities in images in different panel of fig4c, as per mentioned below Yellow-yellow and blu-blue are similar  , 
 Thanks for pointing out the mistake. In Fig4 c the images of control+Sal and Rot0.1u00b5M+Sal. are wrongly pasted. However as evident in graphical presentation (Fig4b), the salubrinal treatment did not offer any alteration in mitochondrial membrane potential neither in control cells nor in rotenone treated cells. Therefore, the mistake in image does not affect the conclusion made from this study. Readers may please find the amended image.  , 
 Thanks for pointing out the mistake. In Fig4 c the images of control+Sal and Rot0.1u00b5M+Sal. are wrongly pasted. However as evident in graphical presentation (Fig4b), the salubrinal treatment did not offer any alteration in mitochondrial membrane potential neither in control cells nor in rotenone treated cells. Therefore, the mistake in image does not affect the conclusion made from this study.  ,