Home Life Sciences Plasminogen-dependent internalization of soluble melanotransferrin involves the low-density lipoprotein receptor-related protein and annexin II
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Plasminogen-dependent internalization of soluble melanotransferrin involves the low-density lipoprotein receptor-related protein and annexin II

  • Jonathan Michaud-Levesque , Michel Demeule and Richard Béliveau
Published/Copyright: July 1, 2007
Biological Chemistry
From the journal Volume 388 Issue 7

Abstract

We investigated the effect of plasminogen (Plg) on the internalization of recombinant soluble melanotransferrin (sMTf) using U87 human glioblastoma cells and murine embryonic fibroblasts (MEF) deficient in the low-density lipoprotein receptor-related protein (LRP). Using biospecific interaction analysis, both Glu- and Lys-Plg were shown to interact with immobilized sMTf. The binding of sMTf at the cell surface increased in the presence of both forms of Plg in control and in LRP-deficient MEF cells, whereas the uptake was strongly stimulated only by Lys-Plg in control MEF and U87 cells. In addition, in the presence of Lys-Plg, the internalization of sMTf was a saturable process, sensitive to temperature and dependent on the integrity of lysine residues. The addition of the receptor-associated protein, lactoferrin and aprotinin, as well as a monoclonal antibody (mAb) directed against LRP, inhibited the Lys-Plg-dependent uptake of sMTf. These results suggest an important role for LRP in this process. In addition, using binding and uptake assays in the presence of anti-annexin II mAb, we showed that annexin II might be responsible for the initial binding of sMTf in the presence of Plg. Our results suggest a Plg-mediated internalization mechanism for the clearance of sMTf via annexin II and LRP.


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Received: 2006-11-23
Accepted: 2007-4-3
Published Online: 2007-07-01

©2007 by Walter de Gruyter Berlin New York

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