Thromb Haemost 1995; 74(05): 1298-1304
DOI: 10.1055/s-0038-1649930
Original Article
Fibrinolysis
Schattauer GmbH Stuttgart

Characterization of the Interaction of a Complex of Tissue-type Plasminogen Activator and Plasminogen Activator Inhibitor Type 1 with Rat Liver Cells

Authors

  • J Kuiper

    1   The Division of Biopharmaceutics, Leiden Amsterdam Center for Drug Research, University of Leiden, Leiden, The Netherlands
  • M Otter

    2   The Gaubius Laboratory, TNO Prevention and Health, Leiden, The Netherlands
  • A H Voorschuur

    1   The Division of Biopharmaceutics, Leiden Amsterdam Center for Drug Research, University of Leiden, Leiden, The Netherlands
  • A J van Zonneveld

    3   The Department of Biochemistry, Amsterdam Medical Center, Amsterdam, The Netherlands
  • D C Rijken

    2   The Gaubius Laboratory, TNO Prevention and Health, Leiden, The Netherlands
  • Th J C van Berkel

    1   The Division of Biopharmaceutics, Leiden Amsterdam Center for Drug Research, University of Leiden, Leiden, The Netherlands
Further Information

Publication History

Received 30 December 1994

Accepted after revision 02 August 1995

Publication Date:
10 July 2018 (online)

Preview

Summary

The present study was undertaken in order to determine the recognition site for tissue-type plasminogen activator-plasminogen activator inhibitor type 1 [t-PA-PAI-1] complexes in rat liver in vivo and in vitro. After intravenous injection into rats t-PA-PAI-1 complexes were rapidly removed from the plasma and the liver took up 80% of the injected dose. Within the liver parenchymal and endothelial liver cells contributed mainly to the uptake of t-PA-PAI-1, and were responsible for 62% and 24% of the liver uptake, respectively. The interaction of t-PA- PAI-1 with isolated rat parenchymal liver cells was of high affinity (Kd 17 nM). A well-known antagonist of the α2-macroglobulin receptor (α2MR/low-density lipoprotein receptor-related protein (LRP), GST-39kDa protein (GST-39kDaP) efficiently inhibited the binding (IC50 0.7 nM) of t-PA-PAI-1 to rat parenchymal liver cells. The interaction of t-PA-PAI-1 with LRP on rat parenchymal liver cells was not Ca2+-dependent and is most probably mediated by a specific determinant on PAI-1, since an anti-PAI-1 monoclonal antibody inhibited the binding of t-PA-PAI-1, where as free t-PA did not. The binding of t-PA-PAI-1 to rat hepatocytes could not be inhibited by a complex of plasmin and α2-antiplasmin nor by various other ligands of LRP like β-VLDL and lactoferrin. Binding of t-PA-PAI-1 to rat parenchymal liver cells was followed by internalization and subsequent degradation in the lysosomal compartment.

It is concluded that parenchymal and endothelial liver cells mediate the removal of t-PA-PAI-1 complexes from the circulation. LRP on rat parenchymal liver cells is responsible for the uptake and degradation of t-PA-PAI-1 and may therefore be important for the regulation of the t-PA levels in the circulation.