VEGF-mediated disruption of endothelial CLN-5 promotes blood-brain barrier breakdown.
Breakdown of the blood-brain barrier (BBB) is an early and significant event in CNS inflammation. Astrocyte-derived VEGF-A has been implicated in this response, but the underlying mechanisms remain unresolved. Here, we identify the endothelial transmembrane tight junction proteins claudin-5 (CLN-5) and occludin (OCLN) as targets of VEGF-A action. Down-regulation of CLN-5 and OCLN accompanied up-regulation of VEGF-A and correlated with BBB breakdown in experimental autoimmune encephalomyelitis, an animal model of CNS inflammatory disease. In cultures of brain microvascular endothelial cells, VEGF-A specifically down-regulated CLN-5 and OCLN protein and mRNA. In mouse cerebral cortex, microinjection of VEGF-A disrupted CLN-5 and OCLN and induced loss of barrier function. Importantly, functional studies revealed that expression of recombinant CLN-5 protected brain microvascular endothelial cell cultures from a VEGF-induced increase in paracellular permeability, whereas recombinant OCLN expressed under the same promoter was not protective. Previous studies have shown CLN-5 to be a key determinant of trans-endothelial resistance at the BBB. Our findings suggest that its down-regulation by VEGF-A constitutes a significant mechanism in BBB breakdown.
Argaw
Azeb Tadesse
AT
Corinne Goldsmith Dickinson Center for Multiple Sclerosis and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA.
Gurfein
Blake T
BT
Zhang
Yueting
Y
Zameer
Andleeb
A
John
Gareth R
GR
D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism* / Q000473:pathology; D002417:Cattle; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D002490:Central Nervous System / Q000473:pathology; D002540:Cerebral Cortex; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000235:genetics; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000473:pathology; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D007249:Inflammation; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology; D051379:Mice; D062793:Occludin; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
C113332:CLN5 protein, human; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; C568986:Ocln protein, mouse; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A