Expression of endothelial phosphorylated caveolin-1 is increased in brain injury.
OBJECTIVE
Increased endothelial caveolae leading to transcytosis of plasma proteins is associated with blood-brain barrier (BBB) breakdown and cerebral oedema in brain injury. Increased expression of caveolin-1alpha (Cav-1), an integral caveolar membrane protein, was reported in endothelium of arterioles and veins with BBB breakdown to fibronectin post injury. In this study the phosphorylation state of Cav-1 and its association with BBB breakdown was determined in the rat cortical cold injury model over a period of days 0.5-6 post lesion.


METHODS
Expression of phosphorylated Cav-1 was determined by immunoblotting and dual labelling immunofluorescence for phosphorylated caveolin-1 and fibronectin, a marker of BBB breakdown. A phospho-specific monoclonal antibody that selectively recognizes only tyrosine 14-phosphorylated Cav-1 (PY14Cav-1) was used.


RESULTS
Immunoblots showed constitutive expression of PY14Cav-1 in cortex of control rats and a significant increase in PY14Cav-1 expression at the lesion site up to day 4 post lesion. PY14Cav-1 immunostaining was observed in the endothelium of lesion vessels at days 0.5-4 post lesion, in neutrophils at days 0.5 and 2 and in macrophages at day 6 post lesion. Dual labelling showed that 100% of vessels with BBB breakdown to fibronectin showed endothelial PY14Cav-1 on day 0.5, the percentage decreasing to 62% on day 4. On day 6, none of the vessels showed endothelial phosphorylated Cav-1.


CONCLUSIONS
The presence of phosphorylated Cav-1 in endothelium of vessels showing BBB breakdown suggests that phosphorylated Cav-1 signalling may be one of the factors associated with early BBB breakdown and brain oedema in brain injury.
Nag
S
S
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, and.
Manias
J L
JL
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, and.
Stewart
D J
DJ
Ottawa Health Research Institute, University of Ottawa, Ottawa, ON, Canada.
D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism*; D015153:Blotting, Western; D001930:Brain Injuries / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D008264:Macrophages / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D009504:Neutrophils / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D051242:Caveolin 1; D005353:Fibronectins