title: Opposing actions of heat shock protein 90 and 70 regulate nicotinamide adenine dinucleotide phosphate oxidase stability and reactive oxygen species production.
abstract: OBJECTIVE
  Excessive reactive oxygen species contribute to vascular dysfunction. We have previously shown that heat shock protein (Hsp90) inhibitors potently suppress Nox 1 to 3 and 5, and the goals of this study were to identify how molecular chaperones regulate Nox function.
  
  
  RESULTS
  In vitro, protein expression of Nox 1 to 2, 5 was decreased by Hsp90 inhibitors in multiple cell types (human pulmonary artery endothelial cells, neutrophils, macrophages, and human saphenous vein). In mice treated with Hsp90 inhibitors, Nox1 expression was reduced in lung along with reduced reactive oxygen species from leukocytes. Elevated reactive oxygen species production in obese (db/db) aorta was suppressed by Hsp90 inhibition. Hsp90 inhibitors did not alter Nox5 micro RNA levels, and proteasome inhibition prevented Nox2 and 5 protein degradation and increased ubiquitin incorporation. Inhibition of Hsp90 upregulated the expression of Hsp70 and Hsp70-bound Nox2, 5 and promoted degradation. Silencing Hsp70 prevented Hsp90 inhibitor-mediated degradation of Nox5. The Hsp70-regulated ubiquitin ligase, carboxyl terminus of Hsp70-interacting protein (CHIP), also bound Nox5 and promoted increased Nox5 ubiquitination and degradation. The chaperone binding and ubiquitination domains of CHIP were required, and the silencing of CHIP blunted Hsp90 inhibitor-mediated degradation of Nox2 and 5.
  
  
  CONCLUSIONS
  We conclude that Hsp90 binds to and regulates Nox protein stability. These actions are opposed by Hsp70 and CHIP, which promote the ubiquitination and degradation of Nox proteins and reduce reactive oxygen species production.
authors.affiliation: Vascular Biology Center, Georgia Health Sciences University, Augusta, Georgia 30912, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Yu
authors.forename: Jin
authors.initials: J
authors.lastname: Qian
authors.forename: Yusi
authors.initials: Y
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Cheng
authors.forename: Christiana
authors.initials: C
authors.lastname: Dimitropoulou
authors.forename: Vijay
authors.initials: V
authors.lastname: Patel
authors.forename: Ahmed
authors.initials: A
authors.lastname: Chadli
authors.forename: R Dan
authors.initials: RD
authors.lastname: Rudic
authors.forename: David W
authors.initials: DW
authors.lastname: Stepp
authors.forename: John D
authors.initials: JD
authors.lastname: Catravas
authors.forename: David J R
authors.initials: DJ
authors.lastname: Fulton
mesh_terms: D000818:Animals; D019556:COS Cells; D057809:HEK293 Cells; D018922:HL-60 Cells; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D018841:HSP90 Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019255:NADPH Oxidases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics
chemical_list: D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D013481:Superoxides; D019255:NADPH Oxidases; C467728:STUB1 protein, human; D044767:Ubiquitin-Protein Ligases