title: Enhanced expression of GTP cyclohydrolase I in V-1-overexpressing PC12D cells.
abstract: Three of the catecholamine-synthesizing enzymes, i.e., tyrosine hydroxylase (TH), aromatic l-amino acid decarboxylase, and dopamine beta-hydroxylase, were earlier shown to be up-regulated in cloned PC12D cells overexpressing V-1, a cdc10/SWI6 motif-containing protein. GTP cyclohydrolase I (GCH) is the rate-limiting enzyme for the biosynthesis of tetrahydrobiopterin (BH(4)), known as an essential cofactor for TH; and here we found the increased expression of GCH in V-1-overexpressing clones. Both GCH activity and total biopterin content were highly increased in the V-1 clones; whereas the activity of sepiapterin reductase, enzyme in the final step of the BH(4) biosynthesis, was not altered. Biochemical analyses revealed increased levels of GCH protein, mRNA, and transcription in the V-1 clones. Promoter analysis showed increased reporter activity in the construct with 150 bp of the promoter region of the human GCH gene, suggesting the involvement of cAMP-responsive element-mediated transcriptional regulation.
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hidehito
authors.initials: H
authors.lastname: Inagaki
authors.forename: Tohru
authors.initials: T
authors.lastname: Yamakuni
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Nagatsu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ichinose
mesh_terms: D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000096:biosynthesis; D002999:Clone Cells; D006136:GTP Cyclohydrolase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D016716:PC12 Cells; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D015533:Transcriptional Activation; D014162:Transfection; D015854:Up-Regulation
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C065700:myotrophin; D001708:Biopterins; D006136:GTP Cyclohydrolase; C003402:sapropterin