title: uPARAP/endo180 directs lysosomal delivery and degradation of collagen IV.
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.
authors.affiliation: Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark. lkjoller@finsenlab.dk
authors.forename: Lars
authors.initials: L
authors.lastname: Kjøller
authors.forename: Lars H
authors.initials: LH
authors.lastname: Engelholm
authors.forename: Maria
authors.initials: M
authors.lastname: Høyer-Hansen
authors.forename: Keld
authors.initials: K
authors.lastname: Danø
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Bugge
authors.forename: Niels
authors.initials: N
authors.lastname: Behrendt
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000911:Antibodies, Monoclonal / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D002478:Cells, Cultured; D024141:Collagen Type IV / Q000378:metabolism* / Q000493:pharmacokinetics; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D007700:Kinetics; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D051381:Rats; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000378:metabolism*; D012867:Skin / Q000166:cytology; D013347:Subcellular Fractions
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D024141:Collagen Type IV; D004791:Enzyme Inhibitors; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; C474081:Mrc2 protein, mouse; D011956:Receptors, Cell Surface; D003546:Cysteine Endopeptidases; D007930:Leucine; C108192:aloxistatin