uPARAP/endo180 directs lysosomal delivery and degradation of collagen IV

Exp Cell Res. 2004 Feb 1;293(1):106-16. doi: 10.1016/j.yexcr.2003.10.008.

Abstract

Collagen turnover is crucial for tissue homeostasis and remodeling and pathological processes such as cancer invasion, but the underlying molecular mechanisms are poorly understood. A major pathway appears to be internalization and degradation by fibroblasts. We now show that the endocytic transmembrane glycoprotein urokinase plasminogen activator receptor-associated protein (uPARAP/endo180) directs collagen IV for lysosomal delivery and degradation. In wild-type fibroblasts, fluorescently labeled collagen IV was first internalized into vesicular structures with diffuse fluorescence eventually appearing uniformly within the wild-type cells after longer incubation times. In these cells, some collagen-containing vesicles were identified as lysosomes by staining for LAMP-1. In contrast, collagen IV remained extracellular and associated with fiber-like structures on uPARAP/endo180-deficient fibroblasts. Blocking lysosomal cysteine proteases with the inhibitor E64d resulted in strong accumulation of collagen IV in lysosomes in wild-type cells, but only very weak intracellular fluorescence accumulation in uPARAP/endo180-deficient fibroblasts. We conclude that uPARAP/endo180 is critical for targeted delivery of collagen IV to lysosomes for degradation implicating the receptor in normal and malignant extracellular matrix degradation. A similar localization pattern was observed for collagen V, suggesting that uPARAP/endo180 might be generally involved in collagen degradation.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Antibodies, Monoclonal / metabolism
  • Antigens, CD / metabolism
  • Cells, Cultured
  • Collagen Type IV / metabolism*
  • Collagen Type IV / pharmacokinetics
  • Cysteine Endopeptidases / drug effects
  • Cysteine Endopeptidases / metabolism
  • Enzyme Inhibitors / pharmacology
  • Fibroblasts / cytology
  • Fibroblasts / metabolism*
  • Kinetics
  • Leucine / analogs & derivatives*
  • Leucine / pharmacology
  • Lysosome-Associated Membrane Glycoproteins
  • Lysosomes / metabolism*
  • Membrane Glycoproteins / deficiency
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Mice, Knockout
  • Rats
  • Receptors, Cell Surface / deficiency
  • Receptors, Cell Surface / metabolism*
  • Skin / cytology
  • Subcellular Fractions

Substances

  • Antibodies, Monoclonal
  • Antigens, CD
  • Collagen Type IV
  • Enzyme Inhibitors
  • Lysosome-Associated Membrane Glycoproteins
  • Membrane Glycoproteins
  • Mrc2 protein, mouse
  • Receptors, Cell Surface
  • Cysteine Endopeptidases
  • Leucine
  • aloxistatin