FIGURE 5.

Reduced BH4 levels lead to down-regulated eNOS expression in an Nrf2-dependent manner. A, BH4 levels were reduced by treatment of HUVEC with either MTX (10 μmol/liter) or aminopterin (APT; 100 μmol/liter). Total cell lysates were subjected to Western blot analysis for eNOS and tubulin. B, HUVEC were transfected either with scrambled siRNA (scr) or siRNA targeted against Nrf2 and then treated with MTX as indicated. Total cell lysates were subjected to Western blot analysis for eNOS, Nrf2, and tubulin. Representative blots out of three independent experiments with consistent results are shown. The numbers below the blots depict mean densitometric arbitrary units (ratio protein/tubulin as -fold DMSO control) of all performed experiments (* p < 0.05, ANOVA, Dunnett's post test versus control).