title: Chronic nicotine exposure augments renal oxidative stress and injury through transcriptional activation of p66shc.
abstract: BACKGROUND
  Chronic nicotine (Ch-NIC) exposure exacerbates ischemia/reperfusion (I/R)-induced oxidative stress and acute kidney injury (AKI), and mitochondrial production of reactive oxygen species (ROS) in cultured renal proximal tubule cells (RPTCs). Because Ser36-phosphorylated p66shc modulates mitochondrial ROS production and injury of RPTCs, we hypothesized that Ch-NIC exacerbates AKI by increasing stress-induced phosphorylation of p66shc.
  
  
  METHODS
  We first tested whether Ch-NIC augments I/R-AKI-induced expression and phosphorylation of p66shc in vivo. We then examined whether knocking down p66shc, or impairing its Ser36 phosphorylation or binding to cytochrome c, alters the effects of Ch-NIC on oxidative stress (H₂O₂)-induced production of ROS, mitochondrial depolarization and injury in RPTCs in vitro.
  
  
  RESULTS
  We found that Ch-NIC increased the expression of p66shc in the control and ischemic kidneys, but only increased its Ser36 phosphorylation after renal I/R. Knocking down p66shc or impairing phosphorylation of its Ser36 residue, via the S36A mutation (but not the phosphomimetic S36D mutation), blunted Ch-NIC + H2O2-dependent ROS production, mitochondrial depolarization and injury in RPTCs. Additionally, Ch-NIC + H2O2-dependent binding of p66shc to mitochondrial cytochrome c was attenuated by S36A mutation of p66shc, and impairing cytochrome c binding (via W134F mutation) abolished ROS production, mitochondrial depolarization and injury, while ectopic overexpression of p66shc (which mimics Ch-NIC treatment) augmented oxidant injury. We determined that Ch-NIC stimulates the p66shc promoter through p53- and epigenetic modification (promoter hypomethylation).
  
  
  CONCLUSIONS
  Ch-NIC worsens oxidative stress-dependent acute renal injury by increasing expression and consequent oxidative stress-dependent Ser36 phosphorylation of p66shc. Thus, targeting this pathway may have therapeutic relevance in preventing/ameliorating tobacco-related kidney injury.
authors: Division of Pediatric Nephrology, Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS, USA. iarany@umc.edu
authors: Istvan
authors: I
authors: Arany
authors: Jeb
authors: J
authors: Clark
authors: Dustin K
authors: DK
authors: Reed
authors: Luis A
authors: LA
authors: Juncos
mesh_terms: D058186:Acute Kidney Injury / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D047468:Immunoprecipitation; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008156:Luciferases / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009538:Nicotine / Q000633:toxicity*; D018722:Nicotinic Agonists / Q000633:toxicity; D010085:Oxidative Phosphorylation; D018384:Oxidative Stress / Q000187:drug effects*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015427:Reperfusion Injury / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D012694:Serine / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins / Q000235:genetics / Q000378:metabolism*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D015533:Transcriptional Activation
chemical_list: D018722:Nicotinic Agonists; D017382:Reactive Oxygen Species; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D012694:Serine; D009538:Nicotine; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D008156:Luciferases
keywords: ROS; cytochrome c; mitochondria; nicotine; p66shc