Hyperosmotic mannitol induces Src kinase-dependent phosphorylation of beta-catenin in cerebral endothelial cells.
Mannitol, which is a cell-impermeable and nontoxic polyalcohol, has been shown to be a useful tool for reversible opening of the blood-brain barrier (BBB). Despite successful clinical trials, the molecular mechanism of the mannitol-induced changes in cerebral endothelial cells (CECs) are poorly understood. For our experiments, we used CECs in culture, which were treated with different, clinically relevant concentrations of mannitol. We found that mannitol induced a rapid, concentration-dependent, and reversible tyrosine phosphorylation of a broad range of proteins between 50 and 190 kDa. One of the targets of tyrosine phosphorylation turned out to be the adherens junction protein beta-catenin. Phosphorylation of beta-catenin on tyrosine residues caused its subcellular redistribution and its dissociation from cadherin and alpha-catenin as shown by coimmunoprecipitation studies. All these effects could be inhibited by the Src kinase inhibitor PP-1 but not by the Erk inhibitor U0126, the Rho kinase inhibitor Y27632, or the calcium channel blocker verapamil. Because beta-catenin is a key component of the junctional complex, its Src-mediated phpsphorylation may play an important role in the mannitol induced reversible opening of the BBB.
Farkas
Attila
A
Institute of Biophysics, Biological Research Center, Szeged, Hungary.
Szatmári
Erzsébet
E
Orbók
Anna
A
Wilhelm
Imola
I
Wejksza
Katarzyna
K
Nagyoszi
Péter
P
Hutamekalin
Pilaiwanwadee
P
Bauer
Hannelore
H
Bauer
Hans-Christian
HC
Traweger
Andreas
A
Krizbai
István A
IA
D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000187:drug effects* / Q000378:metabolism; D004234:Diuretics, Osmotic / Q000494:pharmacology*; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D047468:Immunoprecipitation; D008353:Mannitol / Q000494:pharmacology*; D009997:Osmotic Pressure; D010766:Phosphorylation; D051381:Rats; D015534:Trans-Activators / Q000187:drug effects* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology; D051176:beta Catenin; D019061:src-Family Kinases / Q000187:drug effects* / Q000378:metabolism
D002121:Calcium Channel Blockers; C495268:Ctnnb1 protein, rat; D003598:Cytoskeletal Proteins; D004234:Diuretics, Osmotic; D004791:Enzyme Inhibitors; D015534:Trans-Activators; D051176:beta Catenin; D008353:Mannitol; D014443:Tyrosine; D014700:Verapamil; D019061:src-Family Kinases