Endothelium-targeted transgenic GTP-cyclohydrolase I overexpression inhibits neointima formation in mouse carotid artery.
1. Tetrahydrobiopterin (BH(4)) is an essential cofactor that maintains the normal function of endothelial nitric oxide (NO) synthase. Restenosis is a key complication after transluminal angioplasty. Guanosine 5'-triphosphate-cyclohydrolase I (GTPCH) is the first rate-limiting enzyme for de novo BH(4) synthesis. However, the role of GTPCH in restenosis is not fully understood. The present study tested the hypothesis that endothelial-targeted GTPCH overexpression retards neointimal formation, a hallmark of restenosis, in mouse carotid artery. 2. Transluminal wire injury was induced in the left carotid arteries of adult male wild-type C57BL/6 (WT) and endothelial GTPCH transgenic (Tg-GCH) mice. Re-endothelialization was confirmed with in vivo Evans blue staining. Endothelium-dependent and -independent relaxations were measured using isometric tension recording. Morphological analysis was performed 2 and 4 weeks after carotid injury to assess neointimal formation. Fluorescence-based high-performance liquid chromatography (HPLC) was used to determine GTPCH activity and BH(4) levels. Basal NO release following carotid injury was assessed by N(G)-nitro-L-arginine methyl ester-induced vascular contraction. 3. The endothelium was completely removed upon transluminal wire injury and full re-endothelialization was achieved at Day 10. Endothelium-dependent relaxation was impaired 10 days and 4 weeks after carotid injury, whereas endothelium-independent relaxation remained unaffected. Morphological analysis revealed that the endothelial-specific overexpression of GTPCH reduced neointimal formation and medial hypertrophy 2 and 4 weeks after carotid injury. Both arterial GTPCH enzyme activity and BH(4) levels were significantly elevated in Tg-GCH mice compared with WT mice and basal NO release of the injured carotid artery tended to increase in Tg-GCH mice. 4. These findings suggest that the endothelial overexpression of GTPCH increased endothelial BH(4) synthesis and played a preventive role in neointimal formation induced by endothelium denudation.
Liao
Song-Jie
SJ
Department of Pharmacology and Neurology, Neuroscience Program and Molecular Biology Program, Michigan State University, East Lansing, MI 48824-1317, USA.
Lin
Li
L
Zeng
Jin-Sheng
JS
Huang
Ru-Xun
RX
Channon
Keith M
KM
Chen
Alex F
AF
D000818:Animals; D001011:Aorta / Q000502:physiology; D001708:Biopterins / Q000031:analogs & derivatives* / Q000378:metabolism; D002339:Carotid Arteries / Q000473:pathology / Q000503:physiopathology*; D023903:Coronary Restenosis / Q000503:physiopathology; D006136:GTP Cyclohydrolase / Q000502:physiology*; D006984:Hypertrophy; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009569:Nitric Oxide / Q000378:metabolism; D017539:Tunica Intima / Q000473:pathology / Q000503:physiopathology*
D001708:Biopterins; D009569:Nitric Oxide; D006136:GTP Cyclohydrolase; C003402:sapropterin