Early-glycation of apolipoprotein E: effect on its binding to LDL receptor, scavenger receptor A and heparan sulfates.
Glycation is responsible for disruption of lipoprotein functions leading to the development of atherosclerosis in diabetes. The effects of apolipoprotein E (apoE) glycation were investigated with respect to its interaction with receptors. The interaction of apoE with the low density lipoprotein receptor (LDL-R) and scavenger receptor A (SR-A) was measured by competition experiments performed using, respectively, on a human fibroblast cell line 125I-LDL, and on a murine macrophage cell line (J774) 125I-acetylated LDL, and unlabeled apoE/phospholipid complexes. Glycated apoE binding to heparin and heparan sulfates (HS) was assessed by surface plasmon resonance (SPR) technology. Site-directed mutagenesis was then performed on Lys-75, the major glycation site of the protein. The prepared mutant protein proved to be useful as a tool to study the role of Lys-75 in apoE glycation. The findings showed that, although glycation has no effect on apoE binding either to the LDL-R or to SR-A, it impairs its binding to immobilized heparin and HS. The glycation of Lys-75 was found to be proceed rapidly and contributed significantly to total protein glycation. We propose that, in the case of diabetes, glycation may lead to the atherogenicity of apoE-containing lipoproteins disturbing their uptake via the HS proteoglycan pathway.
Laffont
Isabelle
I
INSERM U525 (Equipe 4), Centre du Médicament, Université Henri Poincaré Nancy 1, 30, rue Lionnois, France.
Shuvaev
Vladimir V
VV
Briand
Olivier
O
Lestavel
Sophie
S
Barbier
Anne
A
Taniguchi
Naoyuki
N
Fruchart
Jean-Charles
JC
Clavey
Véronique
V
Siest
Gérard
G
D001057:Apolipoproteins E / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D005947:Glucose / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011971:Receptors, Immunologic / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism*; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins / Q000378:metabolism; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B
D001057:Apolipoproteins E; D017931:DNA Primers; D005947:Glucose; D006497:Heparan Sulfate; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D011973:Receptors, LDL; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; C454739:Scarb1 protein, mouse