Title
The role of the low-density lipoprotein receptor-related protein (LRP) in the plasma clearance and liver uptake of recombinant single-chain urokinase-type plasminogen activator in rats
Author
van der Kaaden, M.E.
Rijken, D.C.
Kruijt, J.K.
van Berkel, T.J.C.
Kuiper, J.
TNO Preventie en Gezondheid
Publication year
1997
Abstract
Urokinase-type plasminogen activator (u-PA) is used as a thrombolytic agent in the treatment of acute myocardial infarction. In vitro, recombinant single-chain u-PA (rscu-PA) expressed in E. coli is recognized by the Low-Density Lipoprotein Receptor-related Protein (LRP) on rat parenchymal liver cells. In this study we investigated the role of LRP in the liver uptake and plasma clearance of rscu-PA in rats. A preinjection of the LRP inhibitor GST-RAP reduced the maximal liver uptake of 125I-rscu-PA at 5 min after injection from 50 to 30% of the injected dose and decreased the clearance of rscu-PA from 2.37 ml/min to 1.58 ml/min. Parenchymal, Kupffer and endothelial cells were responsible for 40, 50 and 10% of the liver uptake, respectively. The reduction in liver uptake of rscu-PA by the preinjection of GST-RAP was caused by a 91% and 62% reduction in the uptake by parenchymal and Kupffer cells, respectively. In order to investigate the part of rscu-PA that accounted for the interaction with LRP, experiments were performed with a mutant of rscu-PA lacking residues 11-135 (= delta125-rscu-PA). Deletion of residues 11-135 resulted in a 80% reduction in liver uptake and a 2.4 times slower clearance (0.97 ml/min). The parenchymal, Kupffer and endothelial cells were responsible for respectively 60, 33 and 7% of the liver uptake of 125I-delta125-rscu-PA. Preinjection of GST-RAP completely reduced the liver uptake of delta125-rscu-PA and reduced its clearance to 0.79 ml/min. Treatment of isolated Kupffer cells with PI-PLC reduced the binding of rscu-PA by 40%, suggesting the involvement of the urokinase-type Plasminogen Activator Receptor (u-PAR) in the recognition of rscu-PA. Our results demonstrate that in vivo LRP is responsible for more than 90% of the parenchymal liver cell mediated uptake of rscu-PA and for 60% of the Kupffer cell interaction. It is also suggested that u-PAR is involved in the Kupffer cell recognition of rscu-PA. Copyright © 1997 Schattauer Verlag
Subject
Animals
Drug Evaluation, Preclinical
Iodine Radioisotopes
Kupffer Cells
LDL-Receptor Related Protein 1
Liver
Male
Metabolic Clearance Rate
Plasminogen Activators
Rats
Rats, Wistar
Receptors, Immunologic
Receptors, LDL
Recombinant Proteins
Tissue Distribution
Urinary Plasminogen Activator
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DOI
https://doi.org/10.1055/s-0038-1656039
TNO identifier
233873
ISSN
0340-6245
Source
Thrombosis and Haemostasis, 77 (4), 710-717
Document type
article