title: Plasma proprotein convertase subtilisin/kexin type 9: a marker of LDL apolipoprotein B-100 catabolism?
abstract: BACKGROUND
  Experimental studies suggest that proprotein convertase subtilisin/kexin type 9 (PCSK9) is an important regulator of LDL metabolism because of its ability to facilitate degradation of the LDL receptor. We investigated the association between plasma PCSK9 concentration and LDL apolipoprotein B-100 (apo B-100) metabolism in men with a wide range of body mass index values.
  
  
  METHODS
  We used GC-MS to study the kinetics of LDL apo B-100 after intravenous administration of deuterated leucine and analyzed the data by compartmental modeling. The plasma PCSK9 concentration was measured by ELISA.
  
  
  RESULTS
  Univariate regression analysis revealed the plasma PCSK9 concentration to be significantly and positively correlated with cholesterol (r = 0.543; P = 0.011), LDL cholesterol (r = 0.543; P = 0.011), apo B-100 (r = 0.548; P = 0.010), and LDL apo B-100 concentrations (r = 0.514; P = 0.023), and inversely correlated with the LDL apo B-100 fractional catabolic rate (FCR) (r = -0.456; P = 0.038). The association between plasma PCSK9 concentration and the LDL apo B-100 FCR remained statistically significant after adjusting for age, obesity, plasma insulin, homeostasis model assessment score, and dietary energy; however, this association had borderline significance after adjusting for plasma lathosterol.
  
  
  CONCLUSIONS
  In men, variation in plasma PCSK9 concentration influences the catabolism of LDL apo B-100. This finding appears to be independent of obesity, insulin resistance, energy intake, and age.
authors.affiliation: Metabolic Research Centre, School of Medicine and Pharmacology, University of Western Australia, Perth, WA6847, Australia.
authors.forename: Dick C
authors.initials: DC
authors.lastname: Chan
authors.forename: Gilles
authors.initials: G
authors.lastname: Lambert
authors.forename: P Hugh R
authors.initials: PH
authors.lastname: Barrett
authors.forename: Kerry-Anne
authors.initials: KA
authors.lastname: Rye
authors.forename: Esther M M
authors.initials: EM
authors.lastname: Ooi
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Watts
mesh_terms: D000328:Adult; D000368:Aged; D053299:Apolipoprotein B-100 / Q000097:blood / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases / Q000097:blood*
chemical_list: D053299:Apolipoprotein B-100; D015415:Biomarkers; D008078:Cholesterol, LDL; D007328:Insulin; C001521:lathosterol; D002784:Cholesterol; C472125:PCSK9 protein, human; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases