Liver sinusoidal endothelial fenestrations in caveolin-1 knockout mice.
OBJECTIVE
Fenestrations are pores in the liver sinusoidal endothelium that facilitate the transfer of particulate substrates between the sinusoidal lumen and hepatocytes. Fenestrations express caveolin-1 and have structural similarities to caveolae, therefore might be a form of caveolae and caveolin-1 may be integral to fenestration structure and function. Therefore, fenestrations were studied in the livers of caveolin-1 knockout mice.


METHODS
Scanning, transmission and immunogold electron microscopic techniques were used to study the liver sinusoidal endothelium and other tissues in caveolin-1 knockout and wild-type mice.


RESULTS
Comparison of fenestrations in wild-type and knockout mice did not reveal any differences on either scanning or transmission electron microscopy. The diameter of the fenestrations was not significantly different (74 +/- 13 nm knockout mice vs 78 +/- 12 nm wild-type mice) nor was the fenestration porosity (6.5 +/- 2.1 knockout vs 7.3 +/- 2.4% wild-type mice). In contrast, adipocytes and blood vessels in other tissues lacked caveolae in the knockout mice. Caveolin-1 immunogold of livers of wild-type mice indicated sparse expression in sinusoidal endothelial cells.


CONCLUSIONS
The normal structure of fenestrations in the liver sinusoidal endothelium is not dependent upon caveolin-1 and fenestrations are not a form of caveolae.
Centre for Education and Research on Ageing and ANZAC Research Institute, University of Sydney and Concord RG Hospital, Sydney, Australia.
Alessandra
A
Warren
Victoria C
VC
Cogger
Irwin M
IM
Arias
Robert S
RS
McCuskey
David G
DG
Le Couteur
D000818:Animals; D021941:Caveolae / Q000378:metabolism / Q000648:ultrastructure; D051242:Caveolin 1 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D008099:Liver / Q000098:blood supply* / Q000378:metabolism / Q000648:ultrastructure*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D016253:Microscopy, Immunoelectron
D051242:Caveolin 1