Open Access
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The collagen receptor uPARAP/Endo180
Lars H Engelholm1,Signe Ingvarsen1,Henrik J Jürgensen1,Thore Hillig1,Daniel H Madsen1,Boye S Nielsen1,Niels Behrendt1
1
The Finsen Laboratory, Rigshospitalet section 3735, Copenhagen Biocenter, Ole Maaloes Vej 5, DK-2200 Copenhagen N, Denmark. lars@engelholm.dk
DOI: 10.2741/3365 Volume 14 Issue 6, pp.2103-2114
Published: 01 January 2009
(This article belongs to the Special Issue Urokinase-mediated plasminogen activation system)
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.

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Lars H Engelholm, Signe Ingvarsen, Henrik J Jürgensen, Thore Hillig, Daniel H Madsen, Boye S Nielsen, Niels Behrendt. The collagen receptor uPARAP/Endo180. Frontiers in Bioscience-Landmark. 2009. 14(6); 2103-2114.