L-carnitine protects against carboplatin-mediated renal injury: AMPK- and PPARα-dependent inactivation of NFAT3

• Published in: PloS one 2014-08, Vol.9 (8), p.e104079
• Main Authors: Sue, Yuh-Mou, Chou, Hsiu-Chu, Chang, Chih-Cheng, Yang, Nian-Jie, Chou, Ying, Juan, Shu-Hui
• Format: Article
• Language: English
• Subjects: Activation; Acute Kidney Injury - chemically induced; Acute Kidney Injury - drug therapy; Acute Kidney Injury - genetics; Acute Kidney Injury - pathology; AMP-Activated Protein Kinases - genetics; Animals; Antioxidants; Apoptosis; Apoptosis - drug effects; Atherosclerosis; Biology and Life Sciences; Carboplatin; Carboplatin - adverse effects; Carnitine; Carnitine - administration & dosage; Cell activation; Cell adhesion & migration; Coronary vessels; Cyclooxygenase 2 - biosynthesis; Cyclooxygenase-2; Cytokines; Deactivation; DNA nucleotidylexotransferase; Drug dosages; Fatty acids; Feedback loops; Gene expression; Gene Expression Regulation - drug effects; Gene Knockdown Techniques; Growth factors; Heme; Heme oxygenase (decyclizing); Humans; In vivo methods and tests; Inactivation; Inflammation; Inflammation - chemically induced; Inflammation - genetics; Inflammation - pathology; Injury prevention; Ischemia; Kidney - drug effects; Kidney - injuries; Kidney - pathology; Kidneys; Kinases; L-Carnitine; Ligands; Lymphocytes; Medicine; Medicine and Health Sciences; Mice; Molecular modelling; NF-AT protein; NF-κB protein; NFATC Transcription Factors - biosynthesis; NFATC Transcription Factors - genetics; Nitric oxide; Nuclear transport; Oxygen; Oxygenase; Phosphorylation; Physiology; Positive feedback; PPAR alpha - biosynthesis; PPAR alpha - genetics; Prostacyclin; Protective Agents - administration & dosage; Proteins; Rats; Reactive oxygen species; Reactive Oxygen Species - metabolism; Regulatory sequences; Rodents; Signal Transduction - drug effects; Smooth muscle; Transcription factors; Translocation; Tumor necrosis factor-TNF
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0104079

We have previously shown that carboplatin induces inflammation and apoptosis in renal tubular cells (RTCs) through the activation of the nuclear factor of activated T cells-3 (NFAT3) protein by reactive oxygen species (ROS), and that the ROS-mediated activation of NFAT3 is prevented by N-acetyl cysteine and heme oxygenase-1 treatment. In the current study, we investigated the underlying molecular mechanisms of the protective effect of L-carnitine on carboplatin-mediated renal injury. Balb/c mice and RTCs were used as model systems. Carboplatin-induced apoptosis in RTCs was examined using terminal-deoxynucleotidyl-transferase-mediated dUTP nick end labeling. We evaluated the effects of the overexpression of the peroxisome-proliferator-activated receptor alpha (PPARα) protein, the knockdown of PPARα gene, and the blockade of AMPK activation and PPARα to investigate the underlying mechanisms of the protective effect of L-carnitine on carboplatin-mediated renal injury. Carboplatin reduced the nuclear translocation, phosphorylation, and peroxisome proliferator responsive element transactivational activity of PPARα. These carboplatin-mediated effects were prevented by L-carnitine through a mechanism dependent on AMPK phosphorylation and subsequent PPARα activation. The activation of PPARα induced cyclooxygenase 2 (COX-2) and prostacyclin (PGI2) synthase expression that formed a positive feedback loop to further activate PPARα. The coimmunoprecipitation of the nuclear factor (NF) κB proteins increased following the induction of PPARα by L-carnitine, which reduced NFκB transactivational activity and cytokine expression. The in vivo study showed that the inactivation of AMPK suppressed the protective effect of L-carnitine in carboplatin-treated mice, indicating that AMPK phosphorylation is required for PPARα activation in the L-carnitine-mediated protection of RTC apoptosis caused by carboplatin. The results of our study provide molecular evidence that L-carnitine prevents carboplatin-mediated apoptosis through AMPK-mediated PPARα activation.