title: Differential binding of vascular cell-derived proteoglycans (perlecan, biglycan, decorin, and versican) to the beta-amyloid protein of Alzheimer's disease.
abstract: Previous studies have demonstrated the immunolocalization of perlecan, a specific heparan sulfate proteoglycan, to the beta-amyloid protein (A beta)-containing amyloid deposits within the walls of blood vessels (i.e., congophilic angiopathy) in Alzheimer's disease (AD) brain. In the present investigation, the differential binding of previously characterized endothelial cell (EC)- and smooth muscle cell (SMC)-derived PGs to A beta was examined to determine whether the accumulation of A beta in cerebrovascular amyloid deposits may be due to its interactions with perlecan. Pretreatment of AA amyloidotic splenic and liver tissue sections with synthetic A beta (1-28) produced strong immunoreactivity with A beta antibodies at tissue sites enriched in perlecan which was partially removed by pretreatment with heparitinase, but not by chondroitin ABC lyase. [35S]-Sulfate labeled proteoglycans (PGs) derived from cultured ECs and SMCs bound to affinity columns containing A beta (1-28) or (1-40), with virtually no binding to A beta (40-1) (reverse peptide), beta-amyloid precursor protein (410-429), or bovine serum albumin. Characterization of EC and SMC PGs bound to A beta (1-28) revealed strong binding by perlecan, weak binding by decorin and biglycan, two dermatan sulfate proteoglycans, and lack of binding by versican/PG-M, a large chondroitin sulfate proteoglycan. Binding of 125I-labeled perlecan to A beta (1-28) was strongly inhibited by isolated perlecan and to a lesser extent by heparin, but not by chondroitin-6-sulfate or unsulfated dextran sulfate. Heparitinase treatment decreased, but did not eliminate the binding of 125I-labeled perlecan to A beta (1-28). Scatchard analysis of the interaction of A beta (1-28)- and EC-derived perlecan in solid-phase assays indicated high-affinity (Kd = 8.3 x 10(-11) M) and lower-affinity (Kd = 4.2 x 10(-8) M) binding sites, with approximately 1 mol of perlecan binding 1.8 mol of A beta. A significant decrease in binding of EC-derived perlecan to A beta (1-28) was observed when a sequence within the putative heparin-binding motif of A beta (His13His14Gln15Lys16) was replaced by the uncharged peptide sequence, Gly13Gly14Gln15Gly16, indicating a perlecan binding site on A beta near the postulated alpha-secretase site (at Lys-16). Overall, the results indicate that specific vascular cell-derived PGs differentially interact with A beta, and that the interactions of highest affinity occur between A beta and binding sites on both the core protein and glycosaminoglycan chains of perlecan.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Pathology, University of Washington, Seattle 98195-6480, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Snow
authors.forename: M G
authors.initials: MG
authors.lastname: Kinsella
authors.forename: E
authors.initials: E
authors.lastname: Parks
authors.forename: R T
authors.initials: RT
authors.lastname: Sekiguchi
authors.forename: J D
authors.initials: JD
authors.lastname: Miller
authors.forename: K
authors.initials: K
authors.lastname: Kimata
authors.forename: T N
authors.initials: TN
authors.lastname: Wight
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism*; D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D000818:Animals; D058578:Biglycan; D001665:Binding Sites; D001808:Blood Vessels / Q000378:metabolism*; D002417:Cattle; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism; D058575:Decorin; D016326:Extracellular Matrix Proteins; D005260:Female; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D037181:Lectins, C-Type; D051379:Mice; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism*; D053675:Versicans
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D058578:Biglycan; D011508:Chondroitin Sulfate Proteoglycans; D058575:Decorin; D016326:Extracellular Matrix Proteins; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D037181:Lectins, C-Type; D010446:Peptide Fragments; D011509:Proteoglycans; D053675:Versicans; C546884:BGN protein, human; C546885:Bgn protein, mouse; C546878:DCN protein, human; C546879:Dcn protein, mouse; C508322:VCAN protein, human; C508323:Vcan protein, mouse; C084358:amyloid beta-protein (1-28); C078592:amyloid beta-protein (1-40); C071927:perlecan