title: Cocaine-Mediated Autophagy in Astrocytes Involves Sigma 1 Receptor, PI3K, mTOR, Atg5/7, Beclin-1 and Induces Type II Programed Cell Death.
abstract: Cocaine, a commonly used drug of abuse, has been shown to cause neuropathological dysfunction and damage in the human brain. However, the role of autophagy in this process is not defined. Autophagy, generally protective in nature, can also be destructive leading to autophagic cell death. This study was designed to investigate whether cocaine induces autophagy in the cells of CNS origin. We employed astrocyte, the most abundant cell in the CNS, to define the effects of cocaine on autophagy. We measured levels of the autophagic marker protein LC3II in SVGA astrocytes after exposure with cocaine. The results showed that cocaine caused an increase in LC3II level in a dose- and time-dependent manner, with the peak observed at 1 mM cocaine after 6-h exposure. This result was also confirmed by detecting LC3II in SVGA astrocytes using confocal microscopy and transmission electron microscopy. Next, we sought to explore the mechanism by which cocaine induces the autophagic response. We found that cocaine-induced autophagy was mediated by sigma 1 receptor, and autophagy signaling proteins p-mTOR, Atg5, Atg7, and p-Bcl-2/Beclin-1 were also involved, and this was confirmed by using selective inhibitors and small interfering RNAs (siRNAs). In addition, we found that chronic treatment with cocaine resulted in cell death, which is caspase-3 independent and can be ameliorated by autophagy inhibitor. Therefore, this study demonstrated that cocaine induces autophagy in astrocytes and is associated with autophagic cell death.
authors.affiliation: Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Cao
authors.affiliation: Department of Oral and Craniofacial Sciences, School of Dentistry Center of Excellence in Musculoskeletal and Dental Tissues, University of Missouri-Kansas City, Kansas City, MO, 64108, USA.
authors.forename: Mary P
authors.initials: MP
authors.lastname: Walker
authors.affiliation: Department of Mathematics and Statistics, University of Missouri, Kansas City, MO, 64110, USA.
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Vaidya
authors.affiliation: Department of Basic Medical Science, School of Medicine, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, 64108, USA.
authors.forename: Mingui
authors.initials: M
authors.lastname: Fu
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
authors.forename: Santosh
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO, 64108, USA. kumaran@umkc.edu.
authors.forename: Anil
authors.identifier: 0000-0003-2110-7731
authors.initials: A
authors.lastname: Kumar
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D001343:Autophagy / Q000187:drug effects*; D000071183:Autophagy-Related Proteins / Q000378:metabolism; D000071186:Beclin-1 / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D003042:Cocaine / Q000494:pharmacology*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008954:Models, Biological; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017480:Receptors, sigma / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D013997:Time Factors; D000097605:Sigma-1 Receptor
chemical_list: D000071183:Autophagy-Related Proteins; D000071186:Beclin-1; D053148:Caspase 3; D003042:Cocaine; D008869:Microtubule-Associated Proteins; D019869:Phosphatidylinositol 3-Kinases; D017480:Receptors, sigma; D058570:TOR Serine-Threonine Kinases; D000097605:Sigma-1 Receptor; C477012:MAP1LC3A protein, human
keywords: Astrocytes; Autophagy; Cocaine; mTOR; siRNAs