title: Dopamine or biopterin deficiency potentiates phosphorylation at (40)Ser and ubiquitination of tyrosine hydroxylase to be degraded by the ubiquitin proteasome system.
abstract: The protein amount of tyrosine hydroxylase (TH), that is the rate-limiting enzyme for the biosynthesis of dopamine (DA), should be tightly regulated, whereas its degradation pathway is largely unknown. In this study, we analyzed how the TH protein is chemically modified and subsequently degraded under deficiencies of DA and tetrahydrobiopterin (BH4), a cofactor for TH, by using pharmacological agents in PC12D cells and cultured mesencephalic neurons. When inhibition of DA- or BH4-synthesizing enzymes greatly reduced the DA contents in PC12D cells, a marked and persistent increase in phosphorylated TH at (40)Ser (p40-TH) was concomitantly observed. This phosphorylation was mediated by D2 dopamine auto-receptor and cAMP-dependent protein kinase (PKA). Our immunoprecipitation experiments showed that the increase in the p40-TH level was accompanied with its poly-ubiquitination. Treatment of PC12D cells with cycloheximide showed that total-TH protein level was reduced by the DA- or BH4-depletion. Notably, this reduction in the total-TH protein level was sensitive not only to a 26S proteasomal inhibitor, MG-132, but also to a PKA inhibitor, H-89. These data demonstrated that DA deficiency should induce compensatory activation of TH via phosphorylation at (40)Ser through D2-autoreceptor and PKA-mediated pathways, which in turn give a rise to its degradation through an ubiquitin-proteasome pathway, resulting in a negative spiral of DA production when DA deficiency persists.
authors.affiliation: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan; Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawahata
authors.affiliation: Department of Oncology, Pharmacy Practice and Sciences, School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Shiori
authors.initials: S
authors.lastname: Ohtaku
authors.affiliation: Department of Oncology, Pharmacy Practice and Sciences, School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Tomioka
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan. Electronic address: hichinos@bio.titech.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ichinose
authors.affiliation: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Yamakuni
mesh_terms: D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000172:deficiency; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004298:Dopamine / Q000172:deficiency*; D005786:Gene Expression Regulation; D007546:Isoquinolines / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008636:Mesencephalon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D061251:Primary Cell Culture; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism*; D059748:Proteolysis / Q000187:drug effects; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007546:Isoquinolines; D007976:Leupeptins; D017448:Receptors, Dopamine D2; D013449:Sulfonamides; D025801:Ubiquitin; D001708:Biopterins; D012694:Serine; D003513:Cycloheximide; D014446:Tyrosine 3-Monooxygenase; D017868:Cyclic AMP-Dependent Protein Kinases; D046988:Proteasome Endopeptidase Complex; C003402:sapropterin; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D004298:Dopamine
keywords: Dopa-responsive dystonia; Dopamine; Parkinson's disease; Proteasome; Tyrosine hydroxylase; Ubiquitin