IMR Press / FBL / Volume 14 / Issue 6 / DOI: 10.2741/3365

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Article
The collagen receptor uPARAP/Endo180
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1 The Finsen Laboratory, Rigshospitalet section 3735, Copenhagen Biocenter, Ole Maaloes Vej 5, DK-2200 Copenhagen N, Denmark
2 The Bartholin Institute, Rigshospitalet section 3731, Copenhagen Biocenter room, Ole Maaloes Vej 5, DK-2200 Copenhagen N, Denmark
3 Exiqon, Bygstubben 9, 2950 Vedbaek, Denmark
Academic Editor:Pia Ragno
Front. Biosci. (Landmark Ed) 2009, 14(6), 2103–2114; https://doi.org/10.2741/3365
Published: 1 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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