Chronic nicotine exposure augments renal oxidative stress and injury through transcriptional activation of p66shc

• Published in: Nephrology, dialysis, transplantation dialysis, transplantation, 2013-06, Vol.28 (6), p.1417-1425
• Main Authors: Arany, Istvan, Clark, Jeb, Reed, Dustin K, Juncos, Luis A
• Format: Article
• Language: English
• Subjects: Acute Kidney Injury - chemically induced; Acute Kidney Injury - metabolism; Acute Kidney Injury - pathology; Animals; Blotting, Western; Cells, Cultured; Cytochromes c - metabolism; Hydrogen Peroxide - metabolism; Immunoprecipitation; Kidney Tubules, Proximal - drug effects; Kidney Tubules, Proximal - metabolism; Kidney Tubules, Proximal - pathology; Luciferases - metabolism; Male; Mice; Mice, Inbred C57BL; Mitochondria - drug effects; Mitochondria - metabolism; Nicotine - toxicity; Nicotinic Agonists - toxicity; Original; Oxidative Phosphorylation; Oxidative Stress - drug effects; Phosphorylation; Promoter Regions, Genetic - genetics; Reactive Oxygen Species - metabolism; Reperfusion Injury - chemically induced; Reperfusion Injury - metabolism; Reperfusion Injury - pathology; Serine - metabolism; Shc Signaling Adaptor Proteins - genetics; Shc Signaling Adaptor Proteins - metabolism; Src Homology 2 Domain-Containing, Transforming Protein 1; Transcriptional Activation
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfs596

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. 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. 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). 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.