Premium
N‐cadherin signaling stabilizes occludin tight junction via PI3K p110β signaling
Author(s) -
Lee Quinn,
Kruse Kevin,
Zhao Shuangping,
Tai Leon,
Komarova Yulia
Publication year - 2022
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2022.36.s1.r5589
Subject(s) - occludin , tight junction , microbiology and biotechnology , claudin , cadherin , chemistry , blood–brain barrier , pericyte , adherens junction , biology , biochemistry , neuroscience , endothelial stem cell , in vitro , central nervous system , cell
The blood‐brain barrier (BBB) is a specialized microvasculature integral for brain tissue‐fluid homeostasis that is comprised of brain endothelial cells (BECs) and pericytes. Disruption of the BBB and subsequent vascular leakage of protein‐rich fluids is toxic to surrounding neurons and is an underlying risk factor in neurodegenerative disorders. BECs and pericytes form adhesions through the transmembrane protein Neural (N)‐cadherin. Although BEC‐pericyte interactions are critical for maintaining the BBB, the role of N‐cadherin adhesions in regulating the BBB remain unclear. Our previous work demonstrated that mutant mice lacking Cdh2 (N‐cadherin) in ECs or pericytes exhibited a size‐dependent increase in BBB permeability without affecting vessel or pericyte coverage. These findings raise the possibility that N‐cadherin junctions activate outside‐in signaling to strengthen the BBB. Analysis of tight junction (TJ) proteins occludin and claudins 1 and 5 in microvascular BECs of the cortex demonstrated a significant reduction in the accumulation of occludin, but not claudins, at TJs of KO mice. To delineate the signaling mechanism by which N‐cadherin adhesion‐mediated signaling regulates occludin TJs, we utilize biomimetic surfaces (Ncdh‐BioS) bearing covalently linked N‐cadherin extracellular domain to induce N‐cadherin adhesion in BEC monolayers in vitro . Consistent with our observations in mice, assembly of N‐cadherin junctions induced the accumulation of occludin and ZO1 at TJs in BEC monolayers. Depletion of N‐cadherin reversed these events, suggesting that N‐cadherin adhesion‐induced signaling assembles or stabilizes occludin TJs. Analysis of occludin‐Dendra 2 kinetics revealed decreased internalization rates of occludin from TJs in BECs grown on Ncdh‐BioS as compared to collagen, suggesting that N‐cadherin signaling stabilized occludin TJs. Furthermore, formation of N‐cadherin adhesion complexes led to activation of phosphoinositide 3‐kinase (PI3K) signaling as evidenced by the spatial redistribution of Akt to the plasma membrane as well as Akt phosphorylation. Pharmacological inhibition of class I PI3K with Copanlisib or depletion of PI3K p110β, but not of other PI3K catalytic isoforms, abolished Akt activation and increased the rate of occludin internalization from TJs in BECs grown on Ncdh‐BioS. Cumulatively, these data demonstrates that N‐cadherin outside‐in signaling strengthens the BBB by stabilizing occludin TJs through PI3K p110β signaling.