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Journal of Biomedicine and Biotechnology
Volume 2012 (2012), Article ID 721657, 13 pages
http://dx.doi.org/10.1155/2012/721657
Review Article

The Plasminogen Activation System and the Regulation of Catecholaminergic Function

1Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
2Veterans Administration San Diego Healthcare System, San Diego, CA 92161, USA

Received 20 March 2012; Accepted 17 May 2012

Academic Editor: David M. Waisman

Copyright © 2012 Hongdong Bai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The local environment of neurosecretory cells contains the major components of the plasminogen activation system, including the plasminogen activators, tissue plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), as well as binding sites for t-PA, the receptor for u-PA (uPAR), and also the plasminogen activator inhibitor, PAI-1. Furthermore, these cells express specific binding sites for plasminogen, which is available in the circulation and in interstitial fluid. Colocalization of plasminogen and its activators on cell surfaces provides a mechanism for promoting local plasminogen activation. Plasmin is retained on the cell surface where it is protected from its inhibitor, š¯›¼ 2 -antiplasmin. In neurosecretory cells, localized plasmin activity provides a mechanism for extracellular processing of secreted hormones. Neurotransmitter release from catecholaminergic cells is negatively regulated by cleavage products formed by plasmin-mediated proteolysis. Recently, we have identified a major plasminogen receptor, Plg- R K T . We have found that Plg- R K T is highly expressed in chromaffin cells of the adrenal medulla as well as in other catecholaminergic cells and tissues. Plg- R K T -dependent plasminogen activation plays a key role in regulating catecholaminergic neurosecretory cell function.