Very Low Density Lipoprotein Receptor Binds and Mediates Endocytosis of Urokinase-type Plasminogen Activator-Type-1 Plasminogen Activator Inhibitor Complex (*)
- Christian W. Heegaard(1),
- Anna Carina Wiborg Simonsen(1),
- Kazuhiro Oka(2),
- Lars Kj(1),
- Anni Christensen(1),
- Bente Madsen(1),
- Lars Ellgaard(3),
- Lawrence Chan(2) and
- Peter A. Andreasen(1)(§)
- From the (1) Department of Molecular Biology, University of Aarhus, DK-8000C, Aarhus, Denmark, the
- (2) Departments of Cell Biology and Medicine, Baylor College of Medicine, Houston, Texas 77030 and the
- (3) Laboratory of Gene Expression, University of Aarhus, DK-8000 C Aarhus, Denmark
- § To whom correspondence should be addressed: Dept. of Molecular Biology, University of Aarhus, 130 C. F. M's Allé, DK-8000 C Aarhus, Denmark. Tel.: 45-89422680; Fax: 45-86196500.
Abstract
Very low density lipoprotein receptor (VLDL-R) was found to be expressed in bovine mammary gland and the human breast carcinoma
cell line MCF-7 as an M
105,000 variant, and in Chinese hamster ovary (CHO) cells transfected with human VLDL-R cDNA as an M
130,000 variant. The receptor was purified by ligand affinity chromatography with immobilized M
40,000 receptor-associated protein (RAP). The purified receptor was found to bind urokinase-type plasminogen activator-type-1
plasminogen activator inhibitor complex (u-PA•PAI-1), while there was no or very weak binding of active site blocked u-PA
(DFP-u-PA), PAI-1 or u-PA-type-2 plasminogen activator inhibitor complex. The binding of u-PA•PAI-1 was blocked by RAP. The
transfected CHO cells had an efficient, RAP-sensitive endocytosis of u-PA•PAI-1, severalfold higher than non-transfected parental
CHO cells. u-PA•PAI-1 endocytosis was partially inhibited by DFP-u-PA, which blocks binding of the complex to the u-PA receptor.
RAP and DFP-u-PA sensitive u-PA•PAI-1 endocytosis was also observed in MCF-7 cells, which were without detectable levels of
other RAP-binding endocytosis receptors. These results show that VLDL-R represents a novel endocytosis mechanism for u-PA
receptor-bound u-PA•PAI-1.
Footnotes
-
↵* This work was supported by the Danish Cancer Society, the Danish Medical Research Council, and the Danish Biotechnology Programme (grants to P. A. A.) and by National Institutes of Health Grants HL16512 and HL27341 (to L. C.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵1 The abbreviations used are:
- u-PA
-
urokinase-type plasminogen activator
- α1I3
-
α1-inhibitor-3
- α1I3•CT
-
α1I3-chymotrypsin complex
- α2M
-
α2-macroglobulin
- α2M*
-
α2M-methylamine
- α2MR/LRP
-
α2-macroglobulin receptor/low density lipoprotein receptor-related protein
- CHAPS
-
3-[(3-cholamido-propyl)dimethyl- ammonio]-1-propanesulfonate
- DFP-u-PA
-
diisopropyl fluorophosphate-inhibited urokinase-type plasminogen activator
- gp330
-
glycoprotein 330
- LDL-R
-
low density lipoprotein receptor
- PAI-1
-
type-1 plasminogen activator inhibitor
- PAI-2
-
type-2 plasminogen activator inhibitor
- PBS
-
phosphate-buffered saline
- PMA
-
phorbol 12-myristate 13-acetate
- RAP
-
M
40,000 receptor-associated protein
- PAGE
-
polyacrylamide gel electrophoresis
- t-PA
-
tissue-type plasminogen activator
- t-PA•PAI-1
-
t-PA•PAI-1 complex
- u-PA•PAI-1
-
u-PA•PAI-1 complex
- u-PA•PAI-2
-
u-PA•PAI-2 complex
- u-PAR
-
urokinase-type plasminogen activator receptor
- VLDL-R
-
very low density lipoprotein receptor.
-
- Received December 8, 1994.
- Revision received May 24, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
