Cell cholesterol modulates metalloproteinase-dependent shedding of low-density lipoprotein receptor-related protein-1 (LRP-1) and clearance function

FASEB J. 2011 Aug;25(8):2770-81. doi: 10.1096/fj.10-169508. Epub 2011 Apr 25.

Abstract

Low-density lipoprotein receptor-related protein-1 (LRP-1) is a plasma membrane scavenger and signaling receptor, composed of a large ligand-binding subunit (515-kDa α-chain) linked to a shorter transmembrane subunit (85-kDa β-chain). LRP-1 cell-surface level and function are controlled by proteolytic shedding of its ectodomain. Here, we identified ectodomain sheddases in human HT1080 cells and demonstrated regulation of the cleavage by cholesterol by comparing the classical fibroblastoid type with a spontaneous epithelioid variant, enriched ∼ 2-fold in cholesterol. Two membrane-associated metalloproteinases were involved in LRP-1 shedding: a disintegrin and metalloproteinase-12 (ADAM-12) and membrane-type 1 matrix metalloproteinase (MT1-MMP). Although both variants expressed similar levels of LRP-1, ADAM-12, MT1-MMP, and specific tissue inhibitor of metalloproteinases-2 (TIMP-2), LRP-1 shedding from epithelioid cells was ∼4-fold lower than from fibroblastoid cells. Release of the ectodomain was triggered by cholesterol depletion in epithelioid cells and impaired by cholesterol overload in fibroblastoid cells. Modulation of LRP-1 shedding on clearance was reflected by accumulation of gelatinases (MMP-2 and MMP-9) in the medium. We conclude that cholesterol exerts an important control on LRP-1 levels and function at the plasma membrane by modulating shedding of its ectodomain, and therefore represents a novel regulator of extracellular proteolytic activities.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAM Proteins / antagonists & inhibitors
  • ADAM Proteins / genetics
  • ADAM Proteins / metabolism
  • ADAM12 Protein
  • Antigens, CD / chemistry
  • Antigens, CD / metabolism*
  • Base Sequence
  • Cell Line, Tumor
  • Cell Membrane / metabolism
  • Cholesterol / metabolism*
  • Epithelioid Cells / metabolism
  • Fibroblasts / metabolism
  • Humans
  • Low Density Lipoprotein Receptor-Related Protein-1 / chemistry
  • Low Density Lipoprotein Receptor-Related Protein-1 / metabolism*
  • Matrix Metalloproteinase 14 / metabolism
  • Matrix Metalloproteinase 2 / metabolism
  • Matrix Metalloproteinase 9 / metabolism
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Metalloproteases / metabolism*
  • Protein Structure, Tertiary
  • RNA, Small Interfering / genetics
  • Signal Transduction

Substances

  • Antigens, CD
  • LRP1 protein, human
  • Low Density Lipoprotein Receptor-Related Protein-1
  • Membrane Proteins
  • RNA, Small Interfering
  • Cholesterol
  • Metalloproteases
  • ADAM Proteins
  • ADAM12 Protein
  • ADAM12 protein, human
  • MMP2 protein, human
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9
  • MMP14 protein, human
  • Matrix Metalloproteinase 14