title: Fasting reduces plasma proprotein convertase, subtilisin/kexin type 9 and cholesterol biosynthesis in humans.
abstract: Proprotein convertase, subtilisin/kexin type 9 (PCSK9), a key regulator of plasma LDL-cholesterol (LDL-c) and cardiovascular risk, is produced in liver and secreted into plasma where it binds hepatic LDL receptors (LDLR), leading to their degradation. PCSK9 is transcriptionally activated by sterol response element-binding protein (SREBP)-2, a transcription factor that also activates all genes for cholesterol synthesis as well as the LDLR. Here we investigated the relationship between plasma PCSK9 levels and the lathosterol-to-cholesterol ratio, a marker of cholesterol biosynthesis, in 18 healthy subjects during a 48 h fast. In all individuals, plasma PCSK9 levels declined steadily during the fasting period, reaching a nadir at 36 h that was ∼58% lower than levels measured in the fed state (P < 0.001). Similarly, the lathosterol-to-cholesterol ratio declined in parallel with plasma PCSK9 concentrations during the fast, reaching a nadir at 36 h that was ∼28% lower than that measured in the fed state (P = 0.024). In summary, fasting has a marked effect on plasma PCSK9 concentrations, which is mirrored by measures of cholesterol synthesis in humans. Inasmuch as cholesterol synthesis and PCSK9 are both regulated by SREBP-2, these results suggest that plasma PCSK9 levels may serve as a surrogate marker of hepatic SREBP-2 activity in humans.
authors: Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA. jeffrey.browning@utsouthwestern.edu
authors: Jeffrey D
authors: JD
authors: Browning
authors: Jay D
authors: JD
authors: Horton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002784:Cholesterol / Q000096:biosynthesis*; D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases / Q000097:blood* / Q000378:metabolism; D055815:Young Adult
chemical_list: D002784:Cholesterol; C472125:PCSK9 protein, human; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases