Secreted PCSK9 decreases the number of LDL receptors in hepatocytes and in livers of parabiotic mice

Thomas A. Lagace, David E. Curtis, Rita Garuti, Markey C. McNutt, Wook Park Sahng, Heidi B. Prather, Norma N. Anderson, Y. K. Ho, Robert E Hammer, Jay D Horton

Research output: Contribution to journalArticle

422 Scopus citations

Abstract

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a member of the proteinase K subfamily of subtilases that reduces the number of LDL receptors (LDLRs) in liver through an undefined posttranscriptional mechanism. We show that purified PCSK9 added to the medium of HepG2 cells reduces the number of cell-surface LDLRs in a dose- and time-dependent manner. This activity was approximately 10-fold greater for a gain-of-function mutant, PCSK9(D374Y), that causes hypercholesterolemia. Binding and uptake of PCSK9 were largely dependent on the presence of LDLRs. Coimmunoprecipitation and ligand blotting studies indicated that PCSK9 and LDLR directly associate; both proteins colocalized to late endocytic compartments. Purified PCSK9 had no effect on cell-surface LDLRs in hepatocytes lacking autosomal recessive hypercholesterolemia (ARH), an adaptor protein required for endocytosis of the receptor. Transgenic mice overexpressing human PCSK9 in liver secreted large amounts of the protein into plasma, which increased plasma LDL cholesterol concentrations to levels similar to those of LDLR-knockout mice. To determine whether PCSK9 was active in plasma, transgenic PCSK9 mice were parabiosed with wild-type littermates. After parabiosis, secreted PCSK9 was transferred to the circulation of wild-type mice and reduced the number of hepatic LDLRs to nearly undetectable levels. We conclude that secreted PCSK9 associates with the LDLR and reduces hepatic LDLR protein levels.

Original languageEnglish (US)
Pages (from-to)2995-3005
Number of pages11
JournalJournal of Clinical Investigation
Volume116
Issue number11
DOIs
StatePublished - Nov 1 2006

ASJC Scopus subject areas

  • Medicine(all)

Fingerprint Dive into the research topics of 'Secreted PCSK9 decreases the number of LDL receptors in hepatocytes and in livers of parabiotic mice'. Together they form a unique fingerprint.

  • Cite this

    Lagace, T. A., Curtis, D. E., Garuti, R., McNutt, M. C., Sahng, W. P., Prather, H. B., Anderson, N. N., Ho, Y. K., Hammer, R. E., & Horton, J. D. (2006). Secreted PCSK9 decreases the number of LDL receptors in hepatocytes and in livers of parabiotic mice. Journal of Clinical Investigation, 116(11), 2995-3005. https://doi.org/10.1172/JCI29383