title: Overexpression of steroidogenic acute regulatory protein in rat aortic endothelial cells attenuates palmitic acid-induced inflammation and reduction in nitric oxide bioavailability.
abstract: BACKGROUND
  Endothelial dysfunction is a well documented evidence for the onset of atherosclerosis and other cardiovascular diseases. Lipids disorder is among the main risk factors for endothelial dysfunction in these diseases. Steroidogenic acute regulatory protein (StAR), one of the cholesterol transporters, plays an important role in the maintenance of intracellular lipid homeostasis. However, the effect of StAR on endothelial dysfunction is not well understood. Palmitic acid (PA) has been shown to decrease eNOS activity and induce inflammation, both are the causes of endothelial dysfunction, in an endothelial cell culture model.
  
  
  METHODS
  StAR gene was introduced into primary rat aortic endothelial cells by adenovirus infection. Real-time PCR and Western blotting were performed to determine the relative genes and proteins expression level to elucidate the underlying mechanism. The free fatty acid and cholesterol quantification kits were used to detect total cellular free fatty acid and cholesterol. The levels of inflammatory factors and nitric oxide were determined by ELISA and classic Griess reagent methods respectively.
  
  
  RESULTS
  We successfully overexpressed StAR in primary rat aortic endothelial cells. Following StAR overexpression, mRNA levels of IL-1β, TNFα, IL6 and VCAM-1 and protein levels of IL-1β, , TNFα and IL-6 in culture supernatant were significantly decreased, which duing to blocke NFκB nuclear translocation and activation. Moreover, StAR overexpression attenuated the PA-induced reduction of nitric oxide bioavailability by protecting the bioactivity of pAkt/peNOS/NO pathway. Furthermore, the key genes involved in lipid metabolism were greatly reduced following StAR overexpression. In order to investigate the underlying mechanism, cerulenin and lovastatin, the inhibitor of fatty acid and cholesterol synthase, were added prior to PA treatment. The results showed that both cerulenin and lovastatin had a similar effect as StAR overexpression. On the other hand, the role of StAR was inhibited when siRNA was introduced to reduce StAR expression.
  
  
  CONCLUSIONS
  Our results showed that StAR attenuated lipid synthesis and uptake as well as PA-induced inflammation and reduction in NO bioavailability in aortic endothelial cells. StAR can ameliorate endothelial dysfunction induced by PA via reducing the intracellular lipid levels.
authors.affiliation: Department of Physiology & Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, 200032, PR China.
authors.forename: Dai
authors.initials: D
authors.lastname: Tian
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Qiu
authors.forename: Yongkun
authors.initials: Y
authors.lastname: Zhan
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Li
authors.forename: Xiuling
authors.initials: X
authors.lastname: Zhi
authors.forename: Xinhong
authors.initials: X
authors.lastname: Wang
authors.forename: Lianhua
authors.initials: L
authors.lastname: Yin
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Ning
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001013:Aorta, Thoracic / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D001682:Biological Availability; D015153:Blotting, Western; D002478:Cells, Cultured; D002569:Cerulenin / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D054872:Fatty Acid Synthesis Inhibitors / Q000494:pharmacology; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000517:prevention & control; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008148:Lovastatin / Q000494:pharmacology; D008297:Male; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D000893:Anti-Inflammatory Agents; D054872:Fatty Acid Synthesis Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D016328:NF-kappa B; D010750:Phosphoproteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D000098682:Steroidogenic Acute Regulatory Protein; D002569:Cerulenin; D019308:Palmitic Acid; D009569:Nitric Oxide; D002784:Cholesterol; D008148:Lovastatin