Adiponectin-Mediated Heme Oxygenase-1 Induction Protects Against Iron-Induced Liver Injury via a PPAR alpha-Dependent Mechanism

作者:Lin Heng; Yu Chun Hsien; Jen Chih Yu; Cheng Ching Feng; Chou Ying; Chang Chih Cheng; Juan Shu Hui*
来源:American Journal Of Pathology, 2010, 177(4): 1697-1709.
DOI:10.2353/ajpath.2010.090789

摘要

Protective effects of adiponectin (APN; an adipocytokine) were shown against various oxidative challenges; however, its therapeutic implications and the mechanisms underlying hepatic iron overload remain unclear. Herein, we show that the deleterious effects of iron dextran on liver function and iron deposition were significantly reversed by adiponectin gene therapy, which was accompanied by AMP-activated protein kinase (AMPK) phosphorylation and heme oxygenase (HO)-1 induction. Furthermore, AMPK-mediated peroxisome proliferator-activated receptor-alpha (PPAR alpha) activation by APN was ascribable to HO-1 induction. Additionally, we revealed direct transcriptional regulation of HO-1 by the binding of PPAR alpha to a PPAR-responsive element (PPRE) by various experimental assessments. Interestingly, overexpression of HO-1 in hepatocytes mimicked the protective effect of APN in attenuating iron-mediated injury, whereas it was abolished by SnPP and small interfering HO-1. Furthermore, bilirubin, the end-product of the HO-1 reaction, but not CO, protected hepatocytes from iron dextran-mediated caspase activation. Herein, we demonstrate a novel functional PPRE in the promoter regions of HO-1, and APN-mediated HO-1 induction elicited an antiapoptotic effect and a decrease in iron deposition in hepatocytes subjected to iron challenge. (Am J Pathol 2010, 177:1697-1709. DOI: 10.2353/ajpath.2010.090789)