Submitted on February 13, 2008
Accepted on May 14, 2008
The response of fenestrations, actin and caveolin-1 to vascular endothelial growth factor in SK Hep1 cells (a liver endothelial cell line)
Victoria C Cogger1, Irwin M Arias2, Alessandra Warren1, Aisling C McMahon3, Debra L Kiss4, Vicky M Avery4, and David G Le Couteur5*
1 Centre for Education and Research on Ageing, University of Sydney, Sydney, New South Wales, Australia
2 National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States
3 Centre for Education and Research on Ageing, University of Sydney, 2139, New South Wales, Australia
4 Eskitis Institute, Griffith University, Brisbane, Queensland, Australia
5 Centre for Education and Research on Ageing, University of Sydney, Concord, New South Wales, Australia
* To whom correspondence should be addressed. E-mail: dlecouteur{at}med.usyd.edu.au.
To study the regulation of fenestrations by vascular endothelial growth factor in liver sinusoidal endothelial cells, SK Hep1 cells were transfected with GFP-actin and GFP-caveolin-1. SK Hep1 cells had pores some of which appeared to be fenestrations (diameter 55 ± 28 nm, porosity 2.0 ± 1.4%), rudimentary sieve plates, bristle-coated micropinocytotic vesicles and expressed caveolin-1, von Willebrand factor, vascular endothelial growth factor receptor-2, endothelial nitric oxide synthase and clathrin, but not CD31. There was avid uptake of formaldehyde serum albumin, consistent with endocytosis. Vascular endothelial growth factor caused an increase in porosity to 4.8 ± 2.6% (P<0.01) and pore diameter to 104 ± 59 nm (P<0.001). GFP-actin was expressed throughout the cells whereas GFP-caveolin-1 had a punctate appearance and both responded to vascular endothelial growth factor by contraction towards the nucleus over hours in parallel with the formation of fenestrations. SK Hep1 cells resemble liver sinusoidal endothelial cells and the VEGF-induced formation of fenestration-like pores is preceded by contraction of actin cytoskeleton and attached caveolin-1 towards the nucleus.
