Amyloid-beta-induced occludin down-regulation and increased permeability in human brain endothelial cells is mediated by MAPK activation.
Vascular dysfunction is emerging as a key pathological hallmark in Alzheimer's disease (AD). A leaky blood-brain barrier (BBB) has been described in AD patient tissue and in vivo AD mouse models. Brain endothelial cells (BECs) are linked together by tight junctional (TJ) proteins, which are a key determinant in restricting the permeability of the BBB. The amyloid beta (Abeta) peptides of 1-40 and 1-42 amino acids are believed to be pivotal in AD pathogenesis. We therefore decided to investigate the effect of Abeta 1-40, the Abeta variant found at the highest concentration in human plasma, on the permeability of an immortalized human BEC line, hCMEC/D3. Abeta 1-40 induced a marked increase in hCMEC/D3 cell permeability to the paracellular tracer 70 kD FITC-dextran when compared with cells incubated with the scrambled Abeta 1-40 peptide. Increased permeability was associated with a specific decrease, both at the protein and mRNA level, in the TJ protein occludin, whereas claudin-5 and ZO-1 were unaffected. JNK and p38MAPK inhibition prevented both Abeta 1-40-mediated down-regulation of occludin and the increase in paracellular permeability in hCMEC/D3 cells. Our findings suggest that the JNK and p38MAPK pathways might represent attractive therapeutic targets for preventing BBB dysfunction in AD.
Tai
L M
LM
Department of Life Sciences, The Open University, Milton Keynes, UK.
Holloway
K A
KA
Male
D K
DK
Loughlin
A J
AJ
Romero
I A
IA
D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D001921:Brain / Q000166:cytology*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects*; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D062793:Occludin; D010455:Peptides / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors
D016229:Amyloid beta-Peptides; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; C568986:Ocln protein, mouse; D010455:Peptides; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases