Immunochemical evidence that human apoB differs when expressed in rodent versus human cells

Wang, Xingyu; Chauhan, Vinita; Nguyen, Anh Thu; Schultz, Joshua R.; Davignon, Jean; Young, Stephen G.; Borén, Jan; Innerarity, Thomas L.; Hui, Rutai; Milne, Ross W.

doi:10.1194/jlr.m200413-jlr200

Cited by 8 publications

(6 citation statements)

References 34 publications

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“…However, there are some limitations to the present model that should be considered. There is evidence that human apo B expressed by rodent hepatocytes adopt a different conformation or undergoes different post‐translational modifications than apo B expressed by human hepatocytes [27]. Moreover, although these mice express LDL particles with human apo B‐100 it is not known whether the modifications taking place in the mouse arterial tissue are identical to those taking place in man.…”

Section: Discussionmentioning

confidence: 99%

Treatment with apo B peptide vaccines inhibits atherosclerosis in human apo B‐100 transgenic mice without inducing an increase in peptide‐specific antibodies

Fredrikson

Björkbacka

Söderberg

et al. 2008

Journal of Internal Medicine

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Objectives. Autoantibodies to apolipoprotein (apo) B-100 peptides are present in human plasma and have been shown to be associated with decreased cardiovascular risk. The present study aimed to determine if apo B-100 peptide vaccines are atheroprotective in mice expressing human apo B-100 and if the effectiveness of the vaccines is influenced by the level of pre-existing peptide-specific autoantibodies.Design. LDL receptor ) ⁄ ) ⁄ human apo B-100 transgenic mice were immunized with native human apo B-100 peptides p45 or p210 at 6, 9 and 11 weeks and the extent of atherosclerosis determined by en face Oil Red O staining of the aorta at 25 weeks. Autoantibody levels were determined by enzyme-linked immunosorbent assay, and RNA expression in the spleen was assessed by real time PCR.Results. Control mice had high levels of autoantibodies against p210 but only low levels against p45. Immunization with native p45 and p210 reduced atherosclerosis by 66% (P < 0.02) and 59% (P = 0.06), respectively. The atheroprotective effect of apo B peptide immunization occurred in the absence of an increase in peptide-specific IgG, but was associated with an increase in IgM recognizing native and copper-oxidized LDL.Conclusions. Immunization with apo B peptide-based vaccines inhibits atherosclerosis in mice expressing human apo B-100 suggesting that they can interact with their target as expressed in humans. The protective effect is independent of the pre-existing level of apo B peptide autoantibodies and can occur without activating an increase in peptide-specific antibodies suggesting that atheroprotection can be mediated by cellular immune responses.

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Section: Discussionmentioning

confidence: 99%

Treatment with apo B peptide vaccines inhibits atherosclerosis in human apo B‐100 transgenic mice without inducing an increase in peptide‐specific antibodies

Fredrikson

Björkbacka

Söderberg

et al. 2008

Journal of Internal Medicine

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“…Moreover, as certain of the antibodies can inhibit the binding of LDL to the LDLr, they should be valuable reagents for determining the contribution of the LDLr to lipoprotein binding. Finally, this study is another example (33,34) of the utility of genetically modified mice for the production of monoclonal antibodies.…”

Section: Discussionmentioning

confidence: 99%

Binding characteristics of a panel of monoclonal antibodies against the ligand binding domain of the human LDLr

Nguyen

Hirama

Chauhan

et al. 2006

Journal of Lipid Research

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To obtain a panel of monoclonal antibodies (MAbs) to study the folding and conformation of the low density lipoprotein receptor (LDLr), we have generated hybridomas from LDLr-deficient mice that had been immunized with the extracellular domain of the human LDLr. The 12 MAbs were specific for the ligand binding domain of the LDLr, with individual MAbs recognizing epitopes in ligand binding repeats 1, 2, 3, 5, and 7. A subset of the MAbs failed to react with the LDLr when disulfide bonds were reduced, and one MAb, specific for an epitope that spans ligand binding repeats 1 and 2, recognized two conformational forms of the LDLr with different affinities. Antibodies specific for ligand binding repeats 3, 5, and 7 completely blocked the binding of LDL particles to the LDLr on cultured human fibroblasts, whereas MAbs with epitopes in ligand binding repeats 1 and 2 partially blocked the binding of LDL to the LDLr. These anti-LDLr MAbs will serve as useful probes for further analysis of LDLr conformation and LDLr-mediated lipoprotein binding. The low density lipoprotein receptor (LDLr) is located in clathrin-coated pits on the cell surface and can bind and mediate the endocytosis of plasma lipoproteins that contain either apolipoprotein E (apoE) or apoB-100. It has an important role in regulating cholesterol homeostasis, and mutations in the LDLr gene can lead to familial hypercholesterolemia. The 839 amino acid human LDLr is organized into five structural domains (1, 2). The amino terminal 292 residues constitute the ligand binding domain (LBD) that is composed of seven imperfect 40 residue repeats (R1-R7) with a short linker between R4 and R5.The LBD is followed by the 400 residue epidermal growth factor (EGF) precursor homology domain (EGFPHD) that contains three EGF-like repeats, EGF-A, EGF-B, and EGF-C, and a b-propeller subdomain inserted between EGF-B and EGF-C (3, 4). The EGFPHD is necessary for the pHdependent dissociation of receptor and lipoprotein in the endosome (1). The third domain (O-linked sugar domain) is rich in threonine and serine residues that become O-glycosylated during the intracellular maturation of the receptor. A short transmembrane domain is followed by a 50 residue cytoplasmic tail that is required to localize the LDLr in clathrin-coated pits on the cell surface and for the endocytosis of ligands.Each of the LBD repeats contains a site for the coordination of a calcium ion and six cysteine residues that form three intrarepeat disulfide bonds (5-8). Folding of newly synthesized LDLr occurs posttranslationally and is nonvectorial with the formation of transient, nonnative, longrange disulfide bonds that are subsequently isomerized into the native intrarepeat disulfide bonds that characterize the LDLr LBD (9). Binding of lipoproteins to the LDLr appears to be mediated by an interaction between acidic residues in the LDLr LBD and basic residues of apoE and apoB-100. By systematic deletion of individual ligand binding repeats of the LDLr, it has been shown that the repeats contribute di...

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“…Each TRL particle contains one molecule of apolipoprotein B (apoB). [23][24][25] ApoB exists in two forms, apoB100 and apoB48, which are coded by the same gene. ApoB48, which is formed in the intestine, is present on chylomicrons and chylomicron remnants, whereas apoB100 exists on VLDL, intermediate-density lipoprotein (IDL) and LDL.…”

Section: Distribution Of Trl Speciesmentioning

confidence: 99%

New insights into the pathophysiology of dyslipidemia in type 2 diabetes

2015

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Immunochemical evidence that human apoB differs when expressed in rodent versus human cells

Cited by 8 publications

References 34 publications

Treatment with apo B peptide vaccines inhibits atherosclerosis in human apo B‐100 transgenic mice without inducing an increase in peptide‐specific antibodies

Treatment with apo B peptide vaccines inhibits atherosclerosis in human apo B‐100 transgenic mice without inducing an increase in peptide‐specific antibodies

Binding characteristics of a panel of monoclonal antibodies against the ligand binding domain of the human LDLr

New insights into the pathophysiology of dyslipidemia in type 2 diabetes

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