title: Apolipoprotein(a), through its strong lysine-binding site in KIV(10'), mediates increased endothelial cell contraction and permeability via a Rho/Rho kinase/MYPT1-dependent pathway.
abstract: Substantial evidence indicates that endothelial dysfunction plays a critical role in atherogenesis. We previously demonstrated that apolipoprotein(a) (apo(a); the distinguishing protein component of the atherothrombotic risk factor lipoprotein(a)) elicits rearrangement of the actin cytoskeleton in human umbilical vein endothelial cells, characterized by increased myosin light chain (MLC) phosphorylation via a Rho/Rho kinase-dependent signaling pathway. Apo(a) contains kringle (K)IV and KV domains similar to those in plasminogen: apo(a) contains 10 types of plasminogen KIV-like sequences, followed by sequences homologous to the plasminogen KV and protease domains. Several of the apo(a) kringles contain lysine-binding sites (LBS) that have been proposed to contribute to the pathogenicity of Lp(a). Here we demonstrate that apo(a)-induced endothelial barrier dysfunction is mediated via a Rho/Rho kinase-dependent signaling pathway that results in increased MYPT1 phosphorylation and hence decreased MLC phosphatase activity, thus leading to an increase in MLC phosphorylation, stress fiber formation, cell contraction, and permeability. In addition, studies using recombinant apo(a) variants indicated that these effects of apo(a) are dependent on sequences within the C-terminal half of the apo(a) molecule, specifically, the strong LBS in KIV(10). In parallel experiments, the apo(a)-induced effects were completely abolished by treatment of the cells with the lysine analogue epsilon-aminocaproic acid and the Rho kinase inhibitor Y27632. Taken together, our findings indicate that the strong LBS in apo(a) KIV(10) mediates all of our observed effects of apo(a) on human umbilical vein endothelial cell barrier dysfunction. Studies are ongoing to further dissect the molecular basis of these findings.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Taewoo
authors.initials: T
authors.lastname: Cho
authors.forename: Yoojin
authors.initials: Y
authors.lastname: Jung
authors.forename: Marlys L
authors.initials: ML
authors.lastname: Koschinsky
mesh_terms: D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D015119:Aminocaproic Acid / Q000494:pharmacology; D000933:Antifibrinolytic Agents / Q000494:pharmacology; D001054:Apolipoproteins A / Q000378:metabolism / Q000494:pharmacology*; D050197:Atherosclerosis / Q000378:metabolism; D001665:Binding Sites / Q000502:physiology; D002199:Capillary Permeability / Q000187:drug effects*; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008239:Lysine / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010958:Plasminogen; D017434:Protein Structure, Tertiary; D011725:Pyridines / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000187:drug effects*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D000199:Actins; D000577:Amides; D000933:Antifibrinolytic Agents; D001054:Apolipoproteins A; D004791:Enzyme Inhibitors; D018994:Myosin Light Chains; D011725:Pyridines; C108830:Y 27632; D010958:Plasminogen; D054460:rho-Associated Kinases; D043263:Myosin-Light-Chain Phosphatase; C490372:PPP1R12A protein, human; D020741:rho GTP-Binding Proteins; D008239:Lysine; D015119:Aminocaproic Acid
references.citation: J Cell Biol. 1999 Nov 29;147(5):1023-38
references.pmid: 10579722
references.citation: Biochemistry. 2004 Aug 10;43(31):9978-88
references.pmid: 15287725
references.citation: J Biol Chem. 1998 Aug 21;273(34):21867-74
references.pmid: 9705325
references.citation: Biochem Cell Biol. 2000;78(4):519-25
references.pmid: 11012092
references.citation: Science. 2004 Feb 6;303(5659):773-4
references.pmid: 14764856
references.citation: Clin Chem. 2003 Nov;49(11):1785-96
references.pmid: 14578310
references.citation: Am J Pathol. 2007 Mar;170(3):951-66
references.pmid: 17322380
references.citation: Nature. 1987 Nov 12-18;330(6144):132-7
references.pmid: 3670400
references.citation: J Biol Chem. 2003 Jun 27;278(26):23260-9
references.pmid: 12697748
references.citation: Curr Opin Lipidol. 1997 Dec;8(6):337-41
references.pmid: 9412773
references.citation: Hum Mol Genet. 1993 Jul;2(7):933-40
references.pmid: 8395942
references.citation: Am J Physiol. 1992 Aug;263(2 Pt 1):L219-25
references.pmid: 1514647
references.citation: Front Biosci. 2005 Jan 01;10:300-25
references.pmid: 15574370
references.citation: J Physiol. 1990 Dec;431:379-401
references.pmid: 2100310
references.citation: Science. 2004 Feb 6;303(5659):836-9
references.pmid: 14764879
references.citation: Physiol Rev. 1999 Jul;79(3):703-61
references.pmid: 10390517
references.citation: Clin Lab Med. 2006 Dec;26(4):751-72
references.pmid: 17110238
references.citation: J Biol Chem. 1999 Oct 22;274(43):30361-4
references.pmid: 10521411
references.citation: Circ Res. 1998 Nov 30;83(11):1115-23
references.pmid: 9831706
references.citation: J Clin Invest. 1994 Jan;93(1):50-5
references.pmid: 8282821
references.citation: Science. 1996 Jul 12;273(5272):245-8
references.pmid: 8662509
references.citation: J Biol Chem. 1993 Sep 15;268(26):19819-25
references.pmid: 8366120
references.citation: Cardiovasc Res. 2003 Aug 1;59(2):470-8
references.pmid: 12909330
references.citation: J Cell Physiol. 1998 Jul;176(1):150-65
references.pmid: 9618155
references.citation: J Am Coll Cardiol. 1995 Nov 1;26(5):1242-50
references.pmid: 7594038
references.citation: Biochemistry. 1991 May 21;30(20):5044-51
references.pmid: 2036372
references.citation: Circulation. 2000 Aug 15;102(7):786-92
references.pmid: 10942748
references.citation: Cardiovasc Hematol Disord Drug Targets. 2006 Dec;6(4):267-78
references.pmid: 17378772
references.citation: Baillieres Clin Haematol. 1995 Jun;8(2):313-27
references.pmid: 7549065
references.citation: J Physiol. 2000 Jan 15;522 Pt 2:177-85
references.pmid: 10639096
references.citation: J Cell Physiol. 1995 Jun;163(3):510-22
references.pmid: 7775594
references.citation: Science. 2004 Feb 6;303(5659):839-42
references.pmid: 14764880
references.citation: Biochemistry. 1997 Aug 26;36(34):10353-63
references.pmid: 9265615
references.citation: Biochemistry. 2005 Jan 18;44(2):555-64
references.pmid: 15641780
references.citation: Circulation. 1998 Mar 3;97(8):721-8
references.pmid: 9498534
references.citation: Thromb Res. 2000 Dec 15;100(6):501-10
references.pmid: 11152930
references.citation: J Clin Invest. 1997 Aug 1;100(3):558-64
references.pmid: 9239402
references.citation: Biochemistry. 1995 Dec 5;34(48):15777-84
references.pmid: 7495809
references.citation: J Cell Biol. 1995 Aug;130(3):613-27
references.pmid: 7622562
references.citation: J Am Coll Cardiol. 1997 Oct;30(4):927-34
references.pmid: 9316520
references.citation: Hum Mol Genet. 1993 Apr;2(4):361-6
references.pmid: 8389224
references.citation: FASEB J. 1998 Dec;12(15):1765-76
references.pmid: 9837867
references.citation: J Biol Chem. 2004 Feb 20;279(8):6526-33
references.pmid: 14660654
references.citation: Microvasc Res. 1997 May;53(3):261-71
references.pmid: 9211404
references.citation: J Biol Chem. 2001 Sep 28;276(39):36155-62
references.pmid: 11473115
references.citation: J Clin Invest. 1997 Sep 15;100(6):1493-500
references.pmid: 9294116