It has been suggested that a cGMP independent mechanism(s) may be mediating NO's inhibitory effect on mitogenesis Since Octl is a ubiquitous DNA binding protein that stimulates DNA replication, we studied whether NO directly regulates the DNA binding activity of Octl in A7R5 VSMC line Two NO donors, sodium nitroprusside (SNP) or S-nitroso-acetylpenicillamine (SNAP) were directly added to the reaction mixture, and following 30 minutes incubation, DNA binding of Octl was assessed by gel shift assays. Both NO donors dose-dependently (0.01-1mM) inhibited the DNA binding activity of Oct 1. This inhibitory effect was not attenuated by dithiothreitol (DTT) (ImM) Diamide, a sulfhydryl oxidizing agent, abolished the Oct 1 binding activity, an effect that was antagonized by DTT. The in vitro inhibitory effect of NO was also reproduced in vivo in A7R5 cells without affecting the cli viability. Our findings provide the first evidence that NO inhibits the DNA binding activity of Octl both in vitro and in vivo, probably through an oxidation-independent mechanism suggesting that NO may inhibit mitogenesis in part through a direct, cGMP-independent effect on Oct 1 binding protein in VSMCs.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology