Nitric oxide decreases activity and levels of the 11S proteasome activator PA28 in the vasculature

► PA28 binds to the 20S proteasome and increases its ability to degrade small peptides. ► Expression of PA28 subunits (α, β, γ) is induced by interferon-γ stimulation. ► We show that NO inhibits a PA28-mediated increase in 26S proteasome activity in VSMC. ► NO decreased levels of PA28 subunits in balloon-injured arteries. ► Decreasing PA28 is a possible mechanism by which NO inhibits neointimal hyperplasia.