Apolipoprotein A-I mimetic peptide 4F blocks sphingomyelinase-induced LDL aggregation

Lipolytic modification of LDL particles by SMase generates LDL aggregates with a strong affinity for human arterial proteoglycans and may so enhance LDL retention in the arterial wall. Here, we evaluated the effects of apoA-I mimetic peptide 4F on structural and functional properties of the SMase-modified LDL particles. LDL particles with and without 4F were incubated with SMase, after which their aggregation, structure, and proteoglycan binding were analyzed. At a molar ratio of L-4F to apoB-100 of 2.5 to 20:1, 4F dose-dependently inhibited SMase-induced LDL aggregation. At a molar ratio of 20:1, SMase-induced aggregation was fully blocked. Binding of 4F to LDL particles inhibited SMase-induced hydrolysis of LDL by 10% and prevented SMase-induced LDL aggregation. In addition, the binding of the SMase-modified LDL particles to human aortic proteoglycans was dose-dependently inhibited by pretreating LDL with 4F. The 4F stabilized apoB-100 conformation and inhibited SMase-induced conformational changes of apoB-100. Molecular dynamic simulations showed that upon binding to protein-free LDL surface, 4F locally alters membrane order and fluidity and induces structural changes to the lipid layer. Collectively, 4F stabilizes LDL particles by preventing the SMase-induced conformational changes in apoB-100 and so blocks SMase-induced LDL aggregation and the resulting increase in LDL retention. Lipolytic modification of LDL particles by SMase generates LDL aggregates with a strong affinity for human arterial proteoglycans and may so enhance LDL retention in the arterial wall. Here, we evaluated the effects of apoA-I mimetic peptide 4F on structural and functional properties of the SMase-modified LDL particles. LDL particles with and without 4F were incubated with SMase, after which their aggregation, structure, and proteoglycan binding were analyzed. At a molar ratio of L-4F to apoB-100 of 2.5 to 20:1, 4F dose-dependently inhibited SMase-induced LDL aggregation. At a molar ratio of 20:1, SMase-induced aggregation was fully blocked. Binding of 4F to LDL particles inhibited SMase-induced hydrolysis of LDL by 10% and prevented SMase-induced LDL aggregation. In addition, the binding of the SMase-modified LDL particles to human aortic proteoglycans was dose-dependently inhibited by pretreating LDL with 4F. The 4F stabilized apoB-100 conformation and inhibited SMase-induced conformational changes of apoB-100. Molecular dynamic simulations showed that upon binding to protein-free LDL surface, 4F locally alters membrane order and fluidity and induces structural changes to the lipid layer. Collectively, 4F stabilizes LDL particles by preventing the SMase-induced conformational changes in apoB-100 and so blocks SMase-induced LDL aggregation and the resulting increase in LDL retention. Subendothelial retention of LDL by the proteoglycans of the extracellular matrix is the key initiating event in the development of atherosclerosis (1.Skålén K. Gustafsson M. Rydberg E.K. Hulten L.M. Wiklund O. Innerarity T.L. Boren J. Subendothelial retention of atherogenic lipoproteins in early atherosclerosis.Nature. 2002; 417: 750-754Crossref PubMed Scopus (728) Google Scholar, 2.Tabas I. Williams K.J. Boren J. Subendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implications.Circulation. 2007; 116: 1832-1844Crossref PubMed Scopus (977) Google Scholar). Modification of the retained LDL by lipolytic and proteolytic enzymes present in the arterial intima induces aggregation and/or fusion of the modified LDL particles (3.Oörni K. Pentikainen M.O. Ala-Korpela M. Kovanen P.T. Aggregation, fusion, and vesicle formation of modified low density lipoprotein particles: molecular mechanisms and effects on matrix interactions.J. PubMed Google Scholar). of LDL particles their binding to the the extracellular retention of LDL in the arterial intima (3.Oörni K. Pentikainen M.O. Ala-Korpela M. Kovanen P.T. Aggregation, fusion, and vesicle formation of modified low density lipoprotein particles: molecular mechanisms and effects on matrix interactions.J. PubMed Google Scholar, K. Ala-Korpela M. M. Kovanen P.T. induces aggregation and fusion of lipoprotein and lipoprotein particles and their retention to human arterial PubMed Scopus Google Scholar). SMase, locally by and in the Williams K.J. I. a and of for early and PubMed Scopus Google Scholar, Williams K.J. I. is by and is a of the PubMed Scopus Google to of the enzymes for LDL aggregation (3.Oörni K. Pentikainen M.O. Ala-Korpela M. Kovanen P.T. Aggregation, fusion, and vesicle formation of modified low density lipoprotein particles: molecular mechanisms and effects on matrix interactions.J. PubMed Google Scholar). LDL particles LDL aggregates by of LDL with SMase in J. Williams K.J. I. and human the of retained for in retention and aggregation of atherogenic PubMed Scopus Google Scholar). of SMase with a of lipoprotein retention and in for a for SMase in the development of in Williams K.J. I. lipoprotein retention early and PubMed Scopus Google Scholar). to atherosclerosis apoA-I mimetic peptide of PubMed Scopus Google Scholar). to the as apoA-I M. mimetic PubMed Scopus Google Scholar, M. mimetic and their in atherosclerosis PubMed Scopus Google Scholar, and mimetic a in PubMed Scopus Google Scholar, M. M. for and properties of mimetic 2007; PubMed Scopus Google Scholar). of apoA-I the peptide 4F is of with the of M. mimetic PubMed Scopus Google Scholar, and mimetic a in PubMed Scopus Google Scholar). The 4F peptide of the properties of and is and M. mimetic PubMed Scopus Google Scholar, M. mimetic and their in atherosclerosis PubMed Scopus Google Scholar, and mimetic a in PubMed Scopus Google Scholar, M. M. for and properties of mimetic 2007; PubMed Scopus Google Scholar). In of 4F the development of early M. formation of lipoprotein and and in PubMed Scopus Google Scholar, J. effects of peptide on and atherosclerosis in PubMed Scopus Google Scholar). mechanisms by which 4F properties The 4F peptide induces which formation of with and in of and of M. formation of lipoprotein and and in PubMed Scopus Google Scholar). The properties of 4F binding and which a in atherosclerosis The of in PubMed Scopus Google Scholar). 4F to and with affinity to of apoA-I M. with affinity human PubMed Scopus Google Scholar). the affinity of 4F for which present in in lipoproteins M. M. density lipoprotein in the formation of low density PubMed Google Scholar, M. and the by PubMed Scopus Google is to that apoA-I mimetic peptide to LDL particles. 4F was to to LDL LDL was with M. by LDL of of L-4F and to in and human PubMed Scopus Google Scholar). that LDL aggregation of low density lipoprotein aggregation by density lipoprotein PubMed Google Scholar, of aggregation of low density lipoprotein by PubMed Scopus Google Scholar). on the we that 4F the of LDL to SMase-induced aggregation. that 4F with LDL particles and stabilizes by preventing SMase-induced conformational changes in apoB-100 and SMase-induced LDL aggregation and the resulting increase in LDL retention. The of L-4F is The peptide L-4F the as L-4F in a that formation 4F were by the peptide M. 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K. changes of apoB-100 in SMase-modified LDL formation of aggregates PubMed Scopus Google Scholar). the which 4F LDL SMase-induced LDL aggregation. the of of L-4F LDL particles were with L-4F molar ratio of 4F to apoB-100 for by to with LDL particles the of LDL a increase in that 4F the of apoB-100 The showed a and and which of the of LDL showed a increase in which changes in the upon with 4F the L-4F was in and without to and were Collectively, that of 4F with LDL particles to conformational in apoB-100. changes in LDL the of LDL to to LDL of human that molar ratio of L-4F to apoB-100 20:1, LDL LDL binding to a of 4F molar ratio of 4F to binding to LDL the LDL and LDL were to with SMase conformational changes in apoB-100 as by the in the and changes in as a of with SMase M. Kovanen P.T. 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K. changes of apoB-100 in SMase-modified LDL formation of aggregates PubMed Scopus Google Scholar). to the effects of 4F on the of LDL particles. that with the and of apoB-100 in LDL particles was the conformational changes in LDL a 4F the of LDL particles to SMase-induced of apoB-100 structural changes of apoB-100 the of the to to and/or on the of LDL particles M. with affinity human PubMed Scopus Google Scholar, M. by LDL of of L-4F and to in and human PubMed Scopus Google lipid in LDL that apoB-100 lipid to the protein-free that 4F and LDL and changes in lipid in the is the in the of and and the of 4F to the membrane a strong to by the The binding is the to SMase strong after the The binding of 4F to the the LDL the conformational order of the that in the of the peptide the order the 4F binding the membrane The of in LDL particles upon with 4F by that LDL particles to SMase, to to lipid and membrane 2002; PubMed Scopus Google Scholar). the conformational of apoB-100 4F is with the of conformational of apoB-100 is a a for lipoprotein PubMed Scopus Google and with the structural changes in of apoB-100 for structural changes in of PubMed Scopus Google Scholar). to a we the that the structural changes in apoB-100 to of 4F to to of apoB-100 on the LDL to conformational properties of apoB-100 by binding to LDL particles and preventing LDL aggregation in the of LDL M. 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M. of with with of PubMed Scopus Google Scholar). 4F SMase-induced LDL aggregation of 4F was to 4F was present 4F SMase modification of 4F SMase-induced LDL aggregation and that 4F and LDL particles were of with PubMed Scopus Google Scholar). SMase-induced aggregation of LDL to on the and of of apoB-100 that in LDL particles M. Kovanen P.T. K. changes of apoB-100 in SMase-modified LDL formation of aggregates PubMed Scopus Google Scholar). we that present of LDL with SMase after aggregation of LDL particles blocks SMase-induced aggregation by with the the of SMase-modified LDL particles that for their aggregation. 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The of the present by that LDL was to SMase-induced aggregation. SMase modification the of LDL and generates modified particles with affinity to proteoglycans K. Ala-Korpela M. Kovanen P.T. induces aggregation and fusion, aggregation, of low density lipoprotein particles. mechanisms to binding of LDL to human aortic PubMed Scopus Google Scholar). SMase to a in the retention of LDL particles and so to the development of (3.Oörni K. Pentikainen M.O. Ala-Korpela M. Kovanen P.T. Aggregation, fusion, and vesicle formation of modified low density lipoprotein particles: molecular mechanisms and effects on matrix interactions.J. PubMed Google Scholar, J. Williams K.J. I. and human the of retained for in retention and aggregation of atherogenic PubMed Scopus Google Scholar, Williams K.J. I. lipoprotein retention early and PubMed Scopus Google Scholar). In the that with LDL 4F alters lipid in LDL which induces a conformational in LDL particles with the to SMase-induced LDL aggregation and so the binding of SMase-modified to The of the were in their that was in the of the LDL to to peptide of the and the of and of the for and the that was as with on the changes that to the the The and for and for and in SMase dynamic human SMase