NITRIC-OXIDE IS NECESSARY FOR A SWITCH FROM STATIONARY TO LOCOMOTING PHENOTYPE IN EPITHELIAL-CELLS

The restitution of epithelial integrity is accomplished in part by cel l migration. Studying this process, we have found that nitric oxide (N O) release from migrating epithelial BSC-1 cells displayed a biphasic response to the inflicted wounds; an initial transient release of NO i s followed by a delayed sustained elevation. Whereas the constitutive endothelial NO synthase (NOS) did not show any spatial or temporal cha nges associated with wounding, the inducible NOS became expressed 3 h after wounding and showed higher abundance at the edges of epithelial wounds. L-Arginine (L-Arg) or NO-donor, S-nitroso-N-acetyl-DL-penicill amine, exerted motogenic effect in epithelial and endothelial cells. I nhibition of NOS with N-G-nitro-L-arginine methyl ester (L-NAME) or a selective knockout of inducible NOS with antisense oligodeoxynucleotid es reduced the rate of spontaneous or epidermal growth factor (EGF)-in duced BSC-1 cell migration. Migrating cells showed the polarized expre ssion of NOS, suggesting a head-to-rear NO gradient. Several growth fa ctors (EGF, insulin-like growth factor I, hepatocyte growth factor, an d fibroblast growth factor) were motogenic for BSC-1 cells, but this e ffect was abrogated by pretreatment with L-NAME. We conclude that endo genous NO production is a prerequisite for BSC-1 cell migration. A vec torial NO release may be essential for the spatially and temporally co ordinated reciprocal phenomena that occur at the leading and trailing edge of locomoting epithelial cells. Although the exact mode of NO act ion remains uncertain, it is conceivable that the production of NO ser ves as a cellular switch from the stationary to the locomoting epithel ial phenotype.