title: Small heterodimer partner attenuates hydrogen peroxide-induced expression of cyclooxygenase-2 and inducible nitric oxide synthase by suppression of activator protein-1 and nuclear factor-κB in renal proximal tubule epithelial cells.
abstract: The orphan nuclear receptor, small heterodimer partner (SHP), plays a negative regulatory role in innate immune responses and is involved in various inflammatory signaling pathways. In the present study, we aimed to ascertain whether SHP is effective in preventing hydrogen peroxide (H2O2)-induced kidney tubular inflammation and explored the molecular mechanisms underlying the protective effects of SHP. Renal ischemia/reperfusion (I/R) injury was induced in mice by clamping both renal pedicles for 30 min. The effects of H2O2 on cell viability in human renal proximal tubule (HK-2) cells were determined using MTT assays. 2',7'-DCF-DA was used to determine intracellular reactive oxygen species (ROS). SHP, cyclooxygenase-2 (COX-2) levels, and inducible nitric oxide synthase (iNOS) expression levels were determined by semi-quantitative immunoblotting and real-time polymerase chain reaction. In addition, SHP, nuclear factor-κB (NF-κB), and activator protein-1 (AP-1) promoter activities were determined by luciferase assays. SHP mRNA and protein expression levels were reduced, whereas COX-2 and iNOS levels were increased in mice subjected to renal I/R. H2O2 treatment in HK-2 cells decreased cell viability, increased ROS production, and induced COX-2 and iNOS expression. These changes were counteracted by transient transfection with SHP. H2O2 treatment decreased SHP luciferase activity, which was recovered by treatment with the NF-κB inhibitor Bay11-7082, transfection with dominant-negative c-Jun or treatment with N-acetyl cysteine (NAC). AP-1 and NF-κB promoter activities were increased by H2O2 and this increase was blocked by SHP transfection. To conclude, SHP protected HK-2 cells from H2O2-induced tubular injury by inhibition of COX-2 and iNOS through suppression of AP-1 and NF-κB promoter activities.
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju 501-757, Republic of Korea.
authors.forename: Jung Sun
authors.initials: JS
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju 501-757, Republic of Korea.
authors.forename: Hoon In
authors.initials: HI
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju 501-757, Republic of Korea.
authors.forename: Eun Hui
authors.initials: EH
authors.lastname: Bae
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju 501-757, Republic of Korea.
authors.forename: Seong Kwon
authors.initials: SK
authors.lastname: Ma
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju 501-757, Republic of Korea.
authors.forename: Soo Wan
authors.initials: SW
authors.lastname: Kim
mesh_terms: D000818:Animals; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007674:Kidney Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D015427:Reperfusion Injury / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D016328:NF-kappa B; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D018160:Receptors, Cytoplasmic and Nuclear; D018808:Transcription Factor AP-1; C099713:nuclear receptor subfamily 0, group B, member 2; D006861:Hydrogen Peroxide; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2