PCSK9 Activity Is Potentiated Through HDL Binding

Circ Res. 2021 Nov 12;129(11):1039-1053. doi: 10.1161/CIRCRESAHA.121.319272. Epub 2021 Oct 4.


Rationale: Proprotein convertase subtilisin/kexin type 9 (PCSK9) circulates in a free and lipoprotein-bound form, yet the functional consequence of the association between PCSK9 and high-density lipoprotein (HDL) remains unexplored.

Objective: This study sought to interrogate the novel relationship between PCSK9 and HDL in humans.

Methods and results: Comparing lipoprotein and apolipoprotein profiles by nuclear magnetic resonance and targeted mass spectrometry measurements with PCSK9 levels in the community-based Bruneck (n=656) study revealed a positive association of plasma PCSK9 with small HDL, alongside a highly significant positive correlation between plasma levels of PCSK9 and apolipoprotein-C3, an inhibitor of lipoprotein lipase. The latter association was replicated in an independent cohort, the SAPHIR study (n=270). Thus, PCSK9-HDL association was determined during the postprandial response in two dietary studies (n=20 participants each, 8 times points). Peak triglyceride levels coincided with an attenuation of the PCSK9-HDL association, a loss of apolipoprotein-C3 from HDL and lower levels of small HDL as measured by nuclear magnetic resonance. Crosslinking mass spectrometry (XLMS) upon isolated HDL identified PCSK9 as a potential HDL-binding partner. PCSK9 association with HDL was confirmed through size-exclusion chromatography and immuno-isolation. Quantitative proteomics upon HDL isolated from patients with coronary artery disease (n=172) returned PCSK9 as a core member of the HDL proteome. Combined interrogation of the HDL proteome and lipidome revealed a distinct cluster of PCSK9, phospholipid transfer protein, clusterin and apolipoprotein-E within the HDL proteome, that was altered by sex and positively correlated with sphingomyelin content. Mechanistically, HDL facilitated PCSK9-mediated low-density lipoprotein receptor degradation and reduced low-density lipoprotein uptake through the modulation of PCSK9 internalisation and multimerisation.

Conclusions: This study reports HDL as a binder of PCSK9 and regulator of its function. The combination of -omic technologies revealed postprandial lipaemia as a driver of PCSK9 and apolipoprotein-C3 release from HDL.

Trial registration: ClinicalTrials.gov NCT03191513.

Keywords: apolipoproteins; cardiovascular diseases; coronary artery disease; lipoproteins; mass spectrometry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apolipoprotein C-III / blood
  • Biomarkers / blood
  • Coronary Artery Disease / blood*
  • Female
  • Hep G2 Cells
  • Humans
  • Lipoproteins, HDL / blood
  • Lipoproteins, HDL / metabolism*
  • Male
  • Middle Aged
  • Postprandial Period
  • Proprotein Convertase 9 / blood
  • Proprotein Convertase 9 / metabolism*
  • Protein Binding
  • Proteome / metabolism


  • APOC3 protein, human
  • Apolipoprotein C-III
  • Biomarkers
  • Lipoproteins, HDL
  • Proteome
  • PCSK9 protein, human
  • Proprotein Convertase 9

Associated data

  • ClinicalTrials.gov/NCT03191513