title: TNF-α down-regulates sarcoplasmic reticulum Ca²⁺ ATPase expression and leads to left ventricular diastolic dysfunction through binding of NF-κB to promoter response element.
abstract: OBJECTIVE
  TNF-alpha (TNF-α) causes left ventricular diastolic dysfunction. Down-regulation of sarcoplasmic reticulum Ca(2+)-ATPase 2a protein (SERCA2a) expression is one of the major mechanisms underlying diastolic dysfunction. We investigated whether TNF-α modulates SERCA2a expression and alters cardiac diastolic function, and its detailed signalling pathway.
  
  
  RESULTS
  We used both in vitro cellular cardiomyocyte model and in vivo rat model to address this issue. We found that TNF-α decreased the levels of both SERCA2a mRNA and protein in the cardiomyocytes, with corresponding impairment of diastolic calcium reuptake, a cellular phenotype of cardiac diastolic function. An ∼2 kb promoter of the SERCA2a gene (atp2a2) along with its serial deletions was cloned into the luciferase reporter system. TNF-α significantly decreased the promoter activity, and truncation of the SERCA2a gene promoter with the putative nuclear factor kappa-B (NF-κB) response element abolished TNF-α-induced SERCA2a gene suppression. Chromatin immunoprecipitation and gel retardation also confirmed the binding of NF-κB to this putative-binding site. TNF-α increased the phosphorylation of IKK and the degradation of IκB, resulted in NF-κB nuclear translocation, and decreased SERCA2a gene promoter activity. This process was attenuated by NF-κB blockers and simvastatin. In the in vivo rat model, lipopolysaccharide treatment significantly elevated the serum TNF-α level, as well as phosphorylation of IKK, resulting in a decrease in myocardial SERCA2a expression, diastolic calcium reuptake, and diastolic dysfunction. Oral treatment with simvastatin led to an increase in SERCA2a expression, alleviation, and prevention of the diastolic dysfunction.
  
  
  CONCLUSIONS
  TNF-α suppresses SERCA2a gene expression via the IKK/IκB/NF-κB pathway and binding of NF-κB to the SERCA2a gene promoter, and its effect is blocked by simvastatin, demonstrating the potential therapeutic effect of statins in treating inflammation-related diastolic dysfunction.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital Yun-Lin, No.579, Sec. 2, Yunlin Rd., Douliou City, Yunlin County 640, Taiwan Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan cttsai@ntuh.gov.tw cttsai1999@gmail.com.
authors.forename: Chia-Ti
authors.initials: CT
authors.lastname: Tsai
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Cho-Kai
authors.initials: CK
authors.lastname: Wu
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan.
authors.forename: Jen-Kuang
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital Yun-Lin, No.579, Sec. 2, Yunlin Rd., Douliou City, Yunlin County 640, Taiwan Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Sheng-Nan
authors.initials: SN
authors.lastname: Chang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Yu-Min
authors.initials: YM
authors.lastname: Kuo
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan.
authors.forename: Yi-Chih
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan.
authors.forename: Ling-Ping
authors.initials: LP
authors.lastname: Lai
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Fu-Tien
authors.initials: FT
authors.lastname: Chiang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan.
authors.forename: Juey-Jen
authors.initials: JJ
authors.lastname: Hwang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan.
authors.forename: Jiunn-Lee
authors.initials: JL
authors.lastname: Lin
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001665:Binding Sites; D002460:Cell Line; D003971:Diastole; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D015971:Gene Expression Regulation, Enzymologic; D007249:Inflammation / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology / Q000517:prevention & control; D008070:Lipopolysaccharides; D008297:Male; D051379:Mice; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017208:Rats, Wistar; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D018487:Ventricular Dysfunction, Left / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology / Q000517:prevention & control; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D000893:Anti-Inflammatory Agents; C506948:Atp2a2 protein, rat; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
keywords: Diastolic dysfunction; SERCA2a; Simvastatin; TNF-α; Transcription; atp2a2