Figure 6.

CRIF1 deficiency decreased BH4 bioavailability in vivo. (A,B) Fluorescent signals of total biopterin and BH₂ + B in WT and CRIF1 KO mice lung endothelial cells. Arrows indicated the signal of total biopterin and BH₂ + B. Quantification of total biopterin, BH₂ + B and BH₄ signal in endothelial cells were shown. (C) BH4 synthesis enzymes (GCH-1, PTS, SPR, and DHFR) expression in lung endothelial cells of WT and endothelial specific CRIF1 knockout mice. (D) DHFR protein expression in aorta of mice transfected with p16 siRNA. (E) DHFR protein expression in aorta of mice inhibited with p21 inhibitor (UC2288). Densitometric analysis of western blot was used for quantifying expression level of each protein (n = 3 per group; ^*P < 0.05 vs WT).