Abstract
The uPAR-associated protein (uPARAP/Endo180), a type-1 membrane protein belonging to the mannose receptor family, is an endocytic receptor for collagen. Through this endocytic function, the protein takes part in a previously unrecognized mechanism of collagen turnover. uPARAP/Endo180 can bind and internalize both intact and partially degraded collagens. In some turnover pathways, the function of the receptor probably involves an interplay with certain matrix-degrading proteases whereas, in other physiological processes, redundant mechanisms involving both endocytic and pericellular collagenolysis seem to operate in parallel. On certain cell types, uPARAP/Endo180 occurs in a complex with the urokinase plasminogen activator receptor (uPAR) where it seems to fulfill other functions in addition to collagenolysis. uPARAP/Endo180 is expressed on various mesenchymal cells, including subpopulations of fibroblasts, osteoblasts and chondrocytes, generally in conjunction with matrix turnover and collagenolysis. A striking expression is found in developing bone where the collagenolytic function of uPARAP/Endo180 is one of the rate-limiting steps in growth. In murine breast tumors, the endocytic function of the receptor in collagen breakdown seems to be involved in invasive tumor growth.
| Original language | English |
|---|---|
| Journal | Frontiers in Bioscience |
| Volume | 14 |
| Pages (from-to) | 2103-14 |
| Number of pages | 12 |
| ISSN | 1093-9946 |
| Publication status | Published - 1 Jan 2009 |
Keywords
- Humans
- Mannose-Binding Lectins
- Membrane Glycoproteins
- Protein Conformation
- Receptors, Cell Surface
- Receptors, Mitogen
- Journal Article
- Research Support, Non-U.S. Gov't
- Review