Human blood-brain barrier receptors for Alzheimer's amyloid-beta 1- 40. Asymmetrical binding, endocytosis, and transcytosis at the apical side of brain microvascular endothelial cell monolayer.
A soluble monomeric form of Alzheimer's amyloid-beta (1-40) peptide (sAbeta1-40) is present in the circulation and could contribute to neurotoxicity if it crosses the brain capillary endothelium, which comprises the blood-brain barrier (BBB) in vivo. This study characterizes endothelial binding and transcytosis of a synthetic peptide homologous to human sAbeta1-40 using an in vitro model of human BBB. 125I-sAbeta1-40 binding to the brain microvascular endothelial cell monolayer was time dependent, polarized to the apical side, and saturable with high- and low-affinity dissociation constants of 7.8+/-1.2 and 52.8+/-6.2 nM, respectively. Binding of 125I-sAbeta1-40 was inhibited by anti-RAGE (receptor for advanced glycation end products) antibody (63%) and by acetylated low density lipoproteins (33%). Consistent with these data, transfected cultured cells overexpressing RAGE or macrophage scavenger receptor (SR), type A, displayed binding and internalization of 125I-sAbeta1-40. The internalized peptide remains intact > 94%. Transcytosis of 125I-sAbeta1-40 was time and temperature dependent, asymmetrical from the apical to basolateral side, saturable with a Michaelis constant of 45+/-9 nM, and partially sensitive to RAGE blockade (36%) but not to SR blockade. We conclude that RAGE and SR mediate binding of sAbeta1-40 at the apical side of human BBB, and that RAGE is also involved in sAbeta1-40 transcytosis.
Mackic
J B
JB
Department of Neurological Surgery, USC School of Medicine, Los Angeles, California 90033, USA.
Stins
M
M
McComb
J G
JG
Calero
M
M
Ghiso
J
J
Kim
K S
KS
Yan
S D
SD
Stern
D
D
Schmidt
A M
AM
Frangione
B
B
Zlokovic
B V
BV
D000544:Alzheimer Disease / Q000378:metabolism*; D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001692:Biological Transport; D001812:Blood-Brain Barrier / Q000502:physiology*; D016764:Cell Polarity; D004705:Endocytosis; D004730:Endothelium, Vascular; D006801:Humans; D008565:Membrane Proteins; D008833:Microcirculation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism*; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins / Q000378:metabolism; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B
D016229:Amyloid beta-Peptides; D008565:Membrane Proteins; D010446:Peptide Fragments; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins; C454739:Scarb1 protein, mouse; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; C078592:amyloid beta-protein (1-40)