title: Nerve growth factor-induced expression of the GTP cyclohydrolase I gene via Ras/MEK pathway in PC12D cells.
abstract: Neurotrophins are essential for the development and survival of the catecholaminergic neurons. GTP cyclohydrolase I (GCH) is the first and rate-limiting enzyme in the biosynthesis of 5,6,7,8-tertahydrobiopterin (BH4), the required cofactor for tyrosine hydroxylase. Previously, we reported that TH requires the Ras/mitogen-activated protein kinase kinase (MEK) pathway for its induction by nerve growth factor (NGF). Here, we examined intracellular signals required for NGF-induced expression of the GCH gene in PC12D cells. The activity of GCH was increased up to 5-fold after the NGF treatment, and the increase was repressed by pretreatment with U0126, an MEK1/2 inhibitor, but not with protein kinase A (PKA), phosphoinositide 3-kinase (PI3K), p38 mitogen-activated protein kinase (MAPK), and c-Jun NH2-terminal kinase (JNK) inhibitors. Induction of GCH mRNA by NGF was also abolished by pretreatment with U0126. The human GCH promoter activity was significantly enhanced by NGF treatment. Deletion analysis showed that the 465-bp 5'-flanking region is responsible for NGF-enhanced promoter activity. These data suggest that the Ras-MEK pathway is required for coordinate expression of the GCH and TH genes induced by neurotrophins.
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: Takehito
authors.initials: T
authors.lastname: Ito
authors.forename: Takahiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ichinose
mesh_terms: D024506:5' Flanking Region / Q000235:genetics; D000818:Animals; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006136:GTP Cyclohydrolase / Q000096:biosynthesis* / Q000235:genetics; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D008156:Luciferases / Q000235:genetics; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics*; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009570:Nitriles / Q000494:pharmacology; D016716:PC12 Cells; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; D012333:RNA, Messenger; C113580:U 0126; D004247:DNA; D020932:Nerve Growth Factor; D008156:Luciferases; D020929:Mitogen-Activated Protein Kinase Kinases; D006136:GTP Cyclohydrolase