VEGF induces nuclear translocation of Flk-1/KDR, endothelial nitric oxide synthase, and caveolin-1 in vascular endothelial cells

VEGF increases endothelial cell permeability and growth by a process requir ing NOS activity. Because eNOS activity is regulated by its interaction wit h the caveolar structural protein caveolin-1, we analyzed VEGF effects on s tructural interactions between eNOS, caveolin-1 and the VEGF receptor Flk-1 /KDR. Confocal immunolocalization analysis of the subcellular distribution of Flk-1/KDR, caveolin-1 and eNOS showed that VEGF stimulated the transloca tion of all three proteins into the nucleus. This result was confirmed by c ell fractionation and immunoblotting studies showing that levels of all thr ee proteins within the caveolar compartment declined progressively after 30 and 60 min of VEGF treatment. The pattern was reversed for nuclear fractio ns. Protein levels were lowest in the control cultures, but increased progr essively after 30 and 60 min of treatment. Nuclear translocation of eNOS an d Flk-1/KDR within caveolae may represent a mechanism for targeting NO prod uction to the nuclear compartment where it could influence transcription fa ctor activation. (C) 1999 Academic Press.