title: Activation of Autophagic Flux against Xenoestrogen Bisphenol-A-induced Hippocampal Neurodegeneration via AMP kinase (AMPK)/Mammalian Target of Rapamycin (mTOR) Pathways.
abstract: The human health hazards related to persisting use of bisphenol-A (BPA) are well documented. BPA-induced neurotoxicity occurs with the generation of oxidative stress, neurodegeneration, and cognitive dysfunctions. However, the cellular and molecular mechanism(s) of the effects of BPA on autophagy and association with oxidative stress and apoptosis are still elusive. We observed that BPA exposure during the early postnatal period enhanced the expression and the levels of autophagy genes/proteins. BPA treatment in the presence of bafilomycin A1 increased the levels of LC3-II and SQSTM1 and also potentiated GFP-LC3 puncta index in GFP-LC3-transfected hippocampal neural stem cell-derived neurons. BPA-induced generation of reactive oxygen species and apoptosis were mitigated by a pharmacological activator of autophagy (rapamycin). Pharmacological (wortmannin and bafilomycin A1) and genetic (beclin siRNA) inhibition of autophagy aggravated BPA neurotoxicity. Activation of autophagy against BPA resulted in intracellular energy sensor AMP kinase (AMPK) activation, increased phosphorylation of raptor and acetyl-CoA carboxylase, and decreased phosphorylation of ULK1 (Ser-757), and silencing of AMPK exacerbated BPA neurotoxicity. Conversely, BPA exposure down-regulated the mammalian target of rapamycin (mTOR) pathway by phosphorylation of raptor as a transient cell's compensatory mechanism to preserve cellular energy pool. Moreover, silencing of mTOR enhanced autophagy, which further alleviated BPA-induced reactive oxygen species generation and apoptosis. BPA-mediated neurotoxicity also resulted in mitochondrial loss, bioenergetic deficits, and increased PARKIN mitochondrial translocation, suggesting enhanced mitophagy. These results suggest implication of autophagy against BPA-mediated neurodegeneration through involvement of AMPK and mTOR pathways. Hence, autophagy, which arbitrates cell survival and demise during stress conditions, requires further assessment to be established as a biomarker of xenoestrogen exposure.
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Swati
authors.initials: S
authors.lastname: Agarwal
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Shashi Kant
authors.initials: SK
authors.lastname: Tiwari
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Brashket
authors.initials: B
authors.lastname: Seth
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Yadav
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India.
authors.forename: Anshuman
authors.initials: A
authors.lastname: Singh
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Anubha
authors.initials: A
authors.lastname: Mudawal
authors.affiliation: Central Instrumentation Facility, CSIR-IITR, Lucknow 226001, India.
authors.forename: Lalit Kumar Singh
authors.initials: LKS
authors.lastname: Chauhan
authors.affiliation: Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India; Systems Toxicology and Health Risk Assessment Group, CSIR-IITR, Lucknow 226001, India.
authors.forename: Shailendra Kumar
authors.initials: SK
authors.lastname: Gupta
authors.affiliation: Department of Pharmacology, Centre of Excellence for Translational Medicine, University of Tartu, Tartu, 50050 Estonia.
authors.forename: Vinay
authors.initials: V
authors.lastname: Choubey
authors.affiliation: Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India; Food Drug and Chemical Toxicology Group, CSIR-IITR, Lucknow 226001, India.
authors.forename: Anurag
authors.initials: A
authors.lastname: Tripathi
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India; Systems Toxicology and Health Risk Assessment Group, CSIR-IITR, Lucknow 226001, India.
authors.forename: Ratan Singh
authors.initials: RS
authors.lastname: Ray
authors.affiliation: Department of Pharmacology, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Lucknow 226031, India.
authors.forename: Shubha
authors.initials: S
authors.lastname: Shukla
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India.
authors.forename: Devendra
authors.initials: D
authors.lastname: Parmar
authors.affiliation: Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow 226001, India; Academy of Scientific and Innovative Research, CSIR-IITR Lucknow Campus, Lucknow 226001, India. Electronic address: rajnish@iitr.res.in.
authors.forename: Rajnish Kumar
authors.initials: RK
authors.lastname: Chaturvedi
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D000071186:Beclin-1; D001559:Benzhydryl Compounds / Q000037:antagonists & inhibitors / Q000633:toxicity*; D004785:Environmental Pollutants / Q000037:antagonists & inhibitors / Q000633:toxicity*; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress; D010636:Phenols / Q000037:antagonists & inhibitors / Q000633:toxicity*; D061251:Primary Cell Culture; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D000071456:Sequestosome-1 Protein; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D000077191:Wortmannin; D000098826:Bisphenol A Compounds
chemical_list: D000091162:AMP-Activated Protein Kinase Kinases; D000730:Androstadienes; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D001559:Benzhydryl Compounds; D004785:Environmental Pollutants; D006360:Heat-Shock Proteins; D018942:Macrolides; D008869:Microtubule-Associated Proteins; D010636:Phenols; D011494:Protein Kinases; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D000071456:Sequestosome-1 Protein; D020123:Sirolimus; D058570:TOR Serine-Threonine Kinases; D000077191:Wortmannin; C512829:Becn1 protein, rat; C526109:Anxa3 protein, rat; C491079:Sqstm1 protein, rat; C040929:bafilomycin A1; C546845:mTOR protein, rat; C006780:bisphenol A; D000098826:Bisphenol A Compounds
keywords: hippocampus; neural stem cell (NSC); neurodegeneration; toxicology; xenobiotic