title: GTP cyclohydrolase I prevents diabetic-impaired endothelial progenitor cells and wound healing by suppressing oxidative stress/thrombospondin-1.
abstract: Endothelial progenitor cell (EPC) dysfunction is a key contributor to diabetic refractory wounds. Endothelial nitric oxide synthase (eNOS), which critically regulates the mobilization and function of EPCs, is uncoupled in diabetes due to decreased cofactor tetrahydrobiopterin (BH4). We tested whether GTP cyclohydrolase I (GTPCH I), the rate-limiting enzyme of BH4 synthesis, preserves EPC function in type 1 diabetic mice. Type 1 diabetes was induced in wild-type (WT) and GTPCH I transgenic (Tg-GCH) mice by intraperitoneal injection of streptozotocin (STZ). EPCs were isolated from the peripheral blood and bone marrow of WT, Tg-GCH, and GTPCH I-deficient hph-1 mice. The number of EPCs was significantly lower in STZ-WT mice and hph-1 mice and was rescued in STZ Tg-GCH mice. Furthermore, GTPCH I overexpression improved impaired diabetic EPC migration and tube formation. EPCs from WT, Tg-GCH, and STZ-Tg-GCH mice were administered to diabetic excisional wounds and accelerated wound healing significantly, with a concomitant augmentation of angiogenesis. Flow cytometry measurements showed that intracellular nitric oxide (NO) levels were reduced significantly in STZ-WT and hph-1 mice, paralleled by increased superoxide anion levels; both were rescued in STZ-Tg-GCH mice. Western blot analysis revealed that thrombospondin-1 (TSP-1) was significantly upregulated in the EPCs of STZ-WT mice and hph-1 mice and suppressed in STZ-treated Tg-GCH mice. Our results demonstrate that the GTPCH I/BH4 pathway is critical to preserve EPC quantity, function, and regenerative capacity during wound healing in type 1 diabetic mice at least partly through the attenuation of superoxide and TSP-1 levels and augmentation of NO level.
authors.affiliation: Department of Pharmacology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China;
authors.forename: Lu
authors.initials: L
authors.lastname: Tie
authors.affiliation: Department of Cardiology, Guangdong General Hospital, Guangzhou, China; and.
authors.forename: Lu-Yuan
authors.initials: LY
authors.lastname: Chen
authors.affiliation: Center of Clinical Pharmacology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China;
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Chen
authors.affiliation: Center of Clinical Pharmacology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China;
authors.forename: He-Hui
authors.initials: HH
authors.lastname: Xie
authors.affiliation: Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: Center of Clinical Pharmacology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China; afychen@yahoo.com.
authors.forename: Alex F
authors.initials: AF
authors.lastname: Chen
mesh_terms: D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism; D049109:Cell Proliferation; D003921:Diabetes Mellitus, Experimental / Q000473:pathology*; D003922:Diabetes Mellitus, Type 1 / Q000473:pathology*; D015536:Down-Regulation / Q000235:genetics; D042783:Endothelial Cells / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D006136:GTP Cyclohydrolase / Q000235:genetics / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018384:Oxidative Stress / Q000235:genetics*; D019700:Thrombospondin 1 / Q000378:metabolism*; D014945:Wound Healing / Q000187:drug effects / Q000235:genetics*
chemical_list: D019700:Thrombospondin 1; D001708:Biopterins; D006136:GTP Cyclohydrolase; C003402:sapropterin
keywords: diabetes; endothelial progenitor cells; guanosine triphosphate cyclohydrolase I; oxidative stress; wound healing