Thromb Haemost 2008; 100(02): 319-329
DOI: 10.1160/TH08-02-0119
Cellular Proteolysis and Oncology
Schattauer GmbH

Plasminogen activator inhibitor type 2 inhibits cell surface associated tissue plasminogen activator in vitro

Potential receptor interactions
Sergei Lobov
1   School of Biological Sciences, University of Wollongong, New South Wales, Australia
,
David R. Croucher*
1   School of Biological Sciences, University of Wollongong, New South Wales, Australia
,
Darren N. Saunders
2   Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
3   Department of Pathology and Laboratory Medicine, University of British Columbia and Department Molecular Oncology, BC Cancer Research Centre, Vancouver, British Columbia, Canada
,
Marie Ranson
1   School of Biological Sciences, University of Wollongong, New South Wales, Australia
› Author Affiliations
Further Information

Publication History

Received 27 February 2008

Accepted after major revision 16 June 2008

Publication Date:
25 November 2017 (online)

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Summary

Regulation of cellular plasminogen activation is necessary for maintenance of tissue homeostasis. Despite increasing evidence for co-expression of tissue type plasminogen activator (tPA) and plasminogen activator inhibitor type-2 (PAI-2;SERPINB2) under patho/physiological conditions, the inhibition of cell-bound tPAmediated plasminogen activation by PAI-2 has not been addressed. Here we show that PAI-2 can inhibit cell-bound tPA activity in vitro and thus prevent plasmin formation. We also examined the potential involvement in this inhibition of the annexin II heterotetramer (AIIt), one of the many well characterized cell-surface co/receptors for tPA and plasminogen that efficiently promotes plasminogen activation. This receptor was of interest because AIIt has also been shown to directly bind PAI-2. Characterization of these potential interactions using purified protein systems revealed that PAI-2 directly bound AIIt via the p11 (S100A10) subunit. However, PAI-2 prevented AIIt/tPA-mediated plasminogen activation by its classic serpin inhibitory activity rather than through competition with tPA/plasminogen for binding. Further analysis showed that PAI-2 inhibited cell bound tPA-induced plasmin activity in both an AIIt-dependent and -independent manner. These data open new possibilities for further investigations regarding the regulation of cellular plasmin generation in vivo, especially in tissues where PAI-2 and tPA may be co-expressed.

* Current address: Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, 2010 NSW, Australia.