Thromb Haemost 1999; 81(03): 428-435
DOI: 10.1055/s-0037-1614490
Review Article
Schattauer GmbH

Comparison of the Effects of Apo(a) Kringle IV-10 and Plasminogen Kringles on the Interactions of Lipoprotein(a) with Regulatory Molecules

Song Xue
1   From The Scripps Research Institute, Department of Vascular Biology, USA
,
Michael A. Green
1   From The Scripps Research Institute, Department of Vascular Biology, USA
,
Philip V. LoGrasso*
2   Novartis Pharmaceuticals Corporation, Summit, USA
,
Brian R. Boettcher
3   The Scripps Research Institute, Department of Vascular Biology La Jolla, CA, USA
,
Edwin L. Madison
1   From The Scripps Research Institute, Department of Vascular Biology, USA
,
Linda K. Curtiss
1   From The Scripps Research Institute, Department of Vascular Biology, USA
,
Lindsey A. Miles*
1   From The Scripps Research Institute, Department of Vascular Biology, USA
› Author Affiliations

Blood drawing was performed in the General Clinical Research Center of Scripps Clinic, supported by NIH grant MOI RROO833. This is publication number 11071-VB from the Scripps Research Institute.
Further Information

Publication History

Publication Date:
09 December 2017 (online)

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Summary

Lipoprotein(a) [Lp(a)] is associated with atherosclerosis and with disease processes involving thrombosis. Lp(a) contains apoprotein (a) [apo(a)], which has a sequence highly homologous to plasminogen. Hence, Lp(a) binds directly to extracellular matrix, cellular plasminogen receptors and fibrin(ogen) and competes for the binding of plasminogen to these regulatory surfaces. These interactions may contribute to the proatherothrombogenic consequences of high Lp(a) levels. These interactions are mediated by lysine binding sites (LBS). Therefore, we examined the role of apo(a) kringle IV-10 [the only apo(a) kringle demonstrated to exhibit lysine binding activity in the intact lipoprotein] in the interaction of Lp(a) with these regulatory molecules. We have compared directly apo(a) KIV-10 with plasminogen K4 to examine whether these highly structurally homologous kringle modules are also functionally homologous. Futhermore, because the plasminogen K5-protease domain (K5-PD) binds directly to fibrin, we have also examined the ability of this plasminogen fragment to inhibit the interaction of Lp(a) with these regulatory molecules and with extracellular matrix. Apo(a) KIV-10 competed effectively for the binding of 125I-Lp(a) to these surfaces but was less effective than either intact Lp(a), plasminogen K4 or plasminogen. Plasminogen K5-PD was a better competitor than apo(a) KIV-10 for 125I-Lp(a) binding to the representative extra-cellular matrix, Matrigel, and to plasmin-treated fibrinogen. In contrast, plasminogen K5-PD did not compete for the interaction of Lp(a) with cells, although it effectively competed for plasminogen binding. These results suggest that Lp(a) recognizes sites in all of the regulatory molecules that are also recognized by apo(a) KIV-10 and that Lp(a) recognizes sites in extracellular matrix and in plasmin-modified fibrinogen that also are recognized by plasminogen K5-PD. Thus, the interaction of Lp(a) with cells is clearly distinct from that with extracellular matrix and with plasmin-treated fibrinogen and the recognition sites within Lp(a) and plasminogen for these regulatory molecules are not identical.

Portions of this manuscript were presented at the 69th Meeting of the American Heart Association, New Orleans, LA 1996.

* Present address: Dr. LoGrasso, Department of Molecular Design and Diversity, Merck Research Laboratories, Rahway, NJ 07065, USA


* This work was supported in part by The National Institute of Health, Grant #’s HL38272, HL45934 and HL31950 and by the American Heart Grant-In-Aid #9650636N. Dr. Xue is the recipient of an Individual National Research Service Award grant #HL09721.