Tetrahydrobiopterin biosynthesis enhanced by lipopolysaccharide stimulation in murine neuroblastoma cell line N1E-115.
We investigated for the first time the effect of lipopolysaccharide and the signal transduction pathway on the biosynthesis of tetrahydrobiopterin [(6R-L-erythro-1',2'-dihydroxypropyl) -2-amino-4-hydroxy-5,6,7,8-tetrahydropteridine], the cofactor for the enzymatic hydroxylation of the aromatic amino acids, in the murine neuroblastoma cell line N1E-115, which synthesizes tetrahydrobiopterin constitutively. Activation of N1E-115 cells with 1 microgram/ml lipopolysaccharide resulted in statistically significant increases in both intracellular tetrahydrobiopterin contents and the activity (Vmax) of GTP cyclohydrolase I, a rate-limiting enzyme in tetrahydrobiopterin de novo biosynthesis. Following simultaneous addition of the inhibitors of protein tyrosine kinases and GTP-binding proteins into serum-free culture media with lipopolysaccharide, we analyzed the transduction pathway of lipopolysaccharide signal toward the tetrahydrobiopterin biosynthetic system in N1E-115 cells. Our data indicate the following conclusions: (a) Protein tyrosine kinase systems are involved in mediating lipopoly-saccharide signal to tetrahydrobiopterin production, and (b) there may be a cross-talk between GTP-binding protein and the protein tyrosine kinase system in mediating lipopolysaccharide signal. These observations suggest that a neuronal cell such as N1E-115, which barely expresses CD14 on its cell surface, responds to lipopolysaccharide like macrophages and monocytes in the absence of soluble CD14.
Ota
A
A
Joint Research Division for Therapies Against Intractable Diseases, School of Medicine, Fujita Health University, Aich, Japan.
Yoshida
S
S
Nomura
T
T
Matsui
S
S
Hagino
Y
Y
Umezawa
K
K
Katoh
S
S
Nagatsu
T
T
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism*; D016227:Benzoquinones; D001708:Biopterins / Q000031:analogs & derivatives* / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006136:GTP Cyclohydrolase / Q000378:metabolism; D006873:Hydroquinones / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D009447:Neuroblastoma; D011809:Quinones / Q000494:pharmacology; D012263:Ribonucleosides / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000975:Antioxidants; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides; D011809:Quinones; D012263:Ribonucleosides; D017828:Rifabutin; D001708:Biopterins; C020754:herbimycin; C032886:oxanosine; D006136:GTP Cyclohydrolase; C003402:sapropterin; C048212:erbstatin