Aggregated Electronegative Low Density Lipoprotein in Human Plasma Shows a High Tendency toward Phospholipolysis and Particle Fusion

Bancells, Cristina; Villegas, Sandra; Blanco, Francisco J.; Benı́tez, Sònia; Gállego, Isaac; Beloki, Lorea; Pérez-Cuellar, Montserrat; Ordóñez-Llanos, Jordi; Sánchez-Quesada, José Luís

doi:10.1074/jbc.m110.139691

Cited by 49 publications

(54 citation statements)

References 46 publications

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“…LDL(Ϫ) or oxidized LDL (oxLDL) were subjected to gel-filtration chromatography to separate aggregated (agLDL) and nonaggregated (nagLDL) fractions. Gel-filtration chromatography was performed using two on-line connected Superose 6 columns in an AKTA-FPLC system (GE Healthcare), as described previously (21). One ml of LDL(ϩ), LDL(Ϫ), or oxLDL at 1 g protein/liter was loaded into the columns and was eluted with buffer 10 mM Tris, 150 mM NaCl, 1 mM EDTA, 2 M BHT, pH 7.4, at a flow of 1 ml/min.…”

Section: Isolation Of Ldl Subfractionsmentioning

confidence: 99%

Immunochemical Analysis of the Electronegative LDL Subfraction Shows That Abnormal N-terminal Apolipoprotein B Conformation Is Involved in Increased Binding to Proteoglycans

Bancells

Benı́tez

Ordóñez-Llanos

et al. 2011

Journal of Biological Chemistry

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Electronegative LDL (LDL(؊)) is a minor subfraction of modified LDL present in plasma. Among its atherogenic characteristics, low affinity to the LDL receptor and high binding to arterial proteoglycans (PGs) could be related to abnormalities in the conformation of its main protein, apolipoprotein B-100 (apoB-100). In the current study, we have performed an immunochemical analysis using monoclonal antibody (mAb) probes to analyze the conformation of apoB-100 in LDL(؊). The study, performed with 28 anti-apoB-100 mAbs, showed that major differences of apoB-100 immunoreactivity between native LDL and LDL(؊) concentrate in both terminal extremes. The mAbs Bsol 10, Bsol 14 (which recognize the amino-terminal region), Bsol 2, and Bsol 7 (carboxyl-terminal region) showed increased immunoreactivity in LDL(؊), suggesting that both terminal extremes are more accessible in LDL(؊) than in native LDL. The analysis of in vitro-modified LDLs, including LDL lipolyzed with sphingomyelinase (SMase-LDL) or phospholipase A 2 (PLA 2 -LDL) and oxidized LDL (oxLDL), suggested that increased amino-terminal immunoreactivity was related to altered conformation due to aggregation. This was confirmed when the aggregated subfractions of LDL(؊) (agLDL(؊)) and oxLDL (ag-oxLDL) were isolated and analyzed. Thus, Bsol 10 and Bsol 14 immunoreactivity was high in SMase-LDL, ag-oxLDL, and agLDL(؊). The altered amino-terminal apoB-100 conformation was involved in the increased PG binding affinity of agLDL(؊) because Bsol 10 and Bsol 14 blocked its high PG-binding. These observations suggest that an abnormal conformation of the amino-terminal region of apoB-100 is responsible for the increased PG binding affinity of agLDL(؊).

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Section: Isolation Of Ldl Subfractionsmentioning

confidence: 99%

Immunochemical Analysis of the Electronegative LDL Subfraction Shows That Abnormal N-terminal Apolipoprotein B Conformation Is Involved in Increased Binding to Proteoglycans

Bancells

Benı́tez

Ordóñez-Llanos

et al. 2011

Journal of Biological Chemistry

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“…On the other hand, PAF-AH, which has a 5-10-fold higher activity in LDL(-) than in native LDL, could also play a role in increasing the content of LPC and NEFA and in the generation of LDL(-) Sanchez-Quesada, 2005). Some type of SMase activity could also be involved in LDL(-) generation since a minor subfraction of LDL(-) is aggregated (Bancells, 2010b). It has been reported that LDL(-) has an intrinsic phospholipase C-like (PLC-like) activity that degrades with high affinity both SM and LPC (Bancells, 2008).…”

Section: Lipolysismentioning

confidence: 99%

“…Some characteristics in LDL(-) are involved in this higher affinity. Aggregation of lipoproteins favors PG binding, and LDL(-) has a high tendency to aggregate (Bancells, 2010b). In fact, a subfraction of aggregated LDL(-) is responsible for the binding to PG (Bancells, 2009).…”

Section: Binding To Proteoglycansmentioning

confidence: 99%

“…LDL(-) is reported to promote aggregation of non-aggregated LDL particles in a process that fits an amyloidogenic model (Parasassi, 2008). It has been reported that the capacity to induce aggregation could be mediated by the PLC-like activity (Bancells, 2010b), although other authors have suggested that plasma sPLA 2 could be involved in apoB misfolding (Greco, 2009). Regarding secondary structure of apoB, some authors have reported loss of secondary -helix structures whereas others did not find differences with native LDL (Asatryan, 2005;Bancells, 2009;Benitez, 2004b;Parasassi, 2001).…”

Section: Physico-chemical Characteristics Of Ldl(-) 431 Structurementioning

confidence: 99%

“…The role of PAF-AH in LDL(-) would be to deactivate oxidized phospholipids, but its undesirable effect would be the formation of LPC and short-chain NEFA. It has been suggested that the PLC-like activity present in LDL(-) could act in cooperation with PAF-AH degrading LPC (Bancells, 2010b). Therefore, this would be a mechanism to limit the deleterious effects exerted by minimal LDL oxidation on vascular cells.…”

Section: Proteinsmentioning

confidence: 99%

See 2 more Smart Citations

Modified Forms of LDL in Plasma

Sánchez-Quesada¹,

Villegas²

2012

Atherogenesis

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Amyloid-Forming Properties of Human Apolipoproteins: Sequence Analyses and Structural Insights

Das

Gursky

2015

Advances in Experimental Medicine and Biology

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Apolipoproteins are protein constituents of lipoproteins that transport cholesterol and fat in circulation and are central to cardiovascular health and disease. Soluble apolipoproteins can transiently dissociate from the lipoprotein surface in a labile free form that can misfold, potentially leading to amyloid disease. Misfolding of apoA-I, apoA-II, and serum amyloid A (SAA) causes systemic amyloidoses, apoE4 is a critical risk factor in Alzheimer's disease, and apolipoprotein misfolding is also implicated in cardiovascular disease. To explain why apolipoproteins are overrepresented in amyloidoses, it was proposed that the amphipathic α-helices, which form the lipid surface-binding motif in this protein family, have high amyloid-forming propensity. Here, we use 12 sequence-based bioinformatics approaches to assess amyloid-forming potential of human apolipoproteins and to identify segments that are likely to initiate β-aggregation. Mapping such segments on the available atomic structures of apolipoproteins helps explain why some of them readily form amyloid while others do not. Our analysis shows that nearly all amyloidogenic segments: (i) are largely hydrophobic, (ii) are located in the lipid-binding amphipathic α-helices in the native structures of soluble apolipoproteins, (iii) are predicted in both native α-helices and β-sheets in the insoluble apoB, and (iv) are predicted to form parallel in-register β-sheet in amyloid. Most of these predictions have been verified experimentally for apoC-II, apoA-I, apoA-II and SAA. Surprisingly, the rank order of the amino acid sequence propensity to form amyloid (apoB > apoA-II > apoC-II ≥ apoA-I, apoC-III, SAA, apoC-I > apoA-IV, apoA-V, apoE) does not correlate with the proteins' involvement in amyloidosis. Rather, it correlates directly with the strength of the protein-lipid association, which increases with increasing protein hydrophobicity. Therefore, the lipid surface-binding function and the amyloid-forming propensity are both rooted in apolipoproteins' hydrophobicity, suggesting that functional constraints make it difficult to completely eliminate pathogenic apolipoprotein misfolding. We propose that apolipoproteins have evolved protective mechanisms against misfolding, such as the sequestration of the amyloidogenic segments via the native protein-lipid and protein-protein interactions involving amphipathic α-helices and, in case of apoB, β-sheets. KeywordsLipid transport; Systemic amyloidosis; Atherosclerosis and Alzheimer's disease; Atomic protein structure; Sequence-based prediction algorithms Correspondence to: Olga Gursky. HHS Public AccessAuthor manuscript Adv Exp Med Biol. Author manuscript; available in PMC 2017 September 24.Published in final edited form as:Adv Exp Med Biol. 2015 ; 855: 175-211. doi:10.1007/978-3-319-17344-3_8. Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript Lipoproteins and Apolipoproteins in Lipid Transport and MetabolismLipids in plasma, lymph and cerebrospinal fluid are transported via lipoproteins that are...

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Aggregated Electronegative Low Density Lipoprotein in Human Plasma Shows a High Tendency toward Phospholipolysis and Particle Fusion

Cited by 49 publications

References 46 publications

Immunochemical Analysis of the Electronegative LDL Subfraction Shows That Abnormal N-terminal Apolipoprotein B Conformation Is Involved in Increased Binding to Proteoglycans

Immunochemical Analysis of the Electronegative LDL Subfraction Shows That Abnormal N-terminal Apolipoprotein B Conformation Is Involved in Increased Binding to Proteoglycans

Modified Forms of LDL in Plasma

Amyloid-Forming Properties of Human Apolipoproteins: Sequence Analyses and Structural Insights

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