title: Regulation of GTP cyclohydrolase I gene expression and tetrahydrobiopterin content in cultured sympathetic neurons by leukemia inhibitory factor and ciliary neurotrophic factor.
abstract: Cultures of neonatal rat superior cervical ganglia (SCG) were used to test the hypothesis that the cytokines leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) control GTP cyclohydrolase I (GTPCH) gene expression and 5,6,7,8-tetrahydrobiopterin (BH4) content as traits of the noradrenergic phenotype. Treatment for 7 days with 1 ng/ml of LIF was found to produce the characteristic switch in the SCG neurotransmitter phenotype reported by others, as evidenced by a 60% decline in tyrosine hydroxylase. (TH) activity and a 75% increase in choline acetyltransferase activity. This LIF treatment paradigm decreased BH4 levels in a concentration-dependent manner, with a maximal decline of 60% observed at 1 ng/ml. Analysis of the time course of this response indicated that LIF decreased BH4 levels by 60% following 3-7 days of treatment. Treatment of cultures with CNTF (2 ng/ml) resulted in a decline in BH4 levels that was of equal magnitude and followed the same time course as that produced by LIF. The LIF-dependent decline in BH4 levels resulted from a reduction in GTPCH enzyme activity, which decreased by 75% following 7 days of treatment. Nuclease protection assays of RNA extracted from cells treated for 7 days with 2 ng/ml of LIF or CNTF detected a 78-96% reduction in GTPCH mRNA content relative to beta-actin mRNA content. Concomitant decreases in TH and GTPCH gene expression in response to LIF or CNTF demonstrate a coordinated regulation of gene expression for this BH4-dependent enzyme and the rate-limiting enzyme in the synthesis of its essential cofactor, BH4. Moreover, these results indicate that GTPCH gene expression in SCG neurons should be regarded as a trait of the noradrenergic phenotype.
authors.affiliation: Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Stegenga
authors.forename: K
authors.initials: K
authors.lastname: Hirayama
authors.forename: G
authors.initials: G
authors.lastname: Kapatos
mesh_terms: D000320:Adrenergic Fibers / Q000737:chemistry / Q000201:enzymology; D000818:Animals; D000975:Antioxidants / Q000032:analysis*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000032:analysis; D002478:Cells, Cultured / Q000737:chemistry / Q000201:enzymology; D020934:Ciliary Neurotrophic Factor; D004305:Dose-Response Relationship, Drug; D006136:GTP Cyclohydrolase / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006131:Growth Inhibitors / Q000494:pharmacology*; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000494:pharmacology*; D009414:Nerve Growth Factors / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009474:Neurons / Q000737:chemistry / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017783:Superior Cervical Ganglion / Q000166:cytology; D013997:Time Factors
chemical_list: D000975:Antioxidants; D020934:Ciliary Neurotrophic Factor; D006131:Growth Inhibitors; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D001708:Biopterins; D006136:GTP Cyclohydrolase; C003402:sapropterin