Hirayama K, Kapatos G
Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Neurochem Int. 1995 Jun;26(6):601-6. doi: 10.1016/0197-0186(94)00175-t.
6-Pyruvoyl tetrahydropterin synthase catalyzes the second step in the biosynthesis of tetrahydrobiopterin. In the present study, the reverse transcription-polymerase chain reaction technique was used to clone a portion of 6-pyruvoyl tetrahydropterin synthase cDNA from rat pineal gland RNA. The sequence of this cDNA was found to be essentially identical to that previously reported for the rat liver. 6-Pyruvoyl tetrahydropterin synthase mRNA levels in various rat tissues, including the brain, were then analyzed by Northern blot and nuclease protection assay. A single 1.35 kb transcript of 6-pyruvoyl tetrahydropterin synthase mRNA was detected by Northern blot analysis in the rat adrenal gland, brain-stem, and liver. Quantitation by nuclease protection assay demonstrated that 6-pyruvoyl tetrahydropterin synthase mRNA was most abundant in the adrenal gland, kidney, and pineal gland (19.5-25.5 amol/microgram RNA). Relatively homogeneous levels of 6-pyruvoyl tetrahydropterin synthase mRNA were found in various brain regions including the cerebellum, substantia nigra and locus coeruleus (4.12-12 amol/microgram RNA). In the adrenal gland, 6-pyruvoyl tetrahydropterin synthase and tyrosine hydroxylase mRNAs were elevated between 3 and 4-fold 24 h after a single dose of reserpine (10 mg/kg), a treatment known to increase tetrahydrobiopterin levels in this tissue. This result suggests that although 6-pyruvoyl tetrahydropterin synthase is not believed to be rate-limiting in the tetrahydrobiopterin biosynthetic pathway, control of gene expression for this enzyme may play an essential role in regulating the synthesis of this important cofactor.
6-丙酮酰四氢蝶呤合酶催化四氢生物蝶呤生物合成的第二步。在本研究中，采用逆转录-聚合酶链反应技术从大鼠松果体RNA中克隆了6-丙酮酰四氢蝶呤合酶cDNA的一部分。发现该cDNA的序列与先前报道的大鼠肝脏的序列基本相同。然后通过Northern印迹和核酸酶保护试验分析了包括脑在内的各种大鼠组织中6-丙酮酰四氢蝶呤合酶mRNA的水平。通过Northern印迹分析在大鼠肾上腺、脑干和肝脏中检测到一条单一的1.35 kb的6-丙酮酰四氢蝶呤合酶mRNA转录本。通过核酸酶保护试验定量显示，6-丙酮酰四氢蝶呤合酶mRNA在肾上腺、肾脏和松果体中最为丰富（19.5 - 25.5 amol/微克RNA）。在包括小脑、黑质和蓝斑在内的各种脑区中发现6-丙酮酰四氢蝶呤合酶mRNA水平相对均匀（4.12 - 12 amol/微克RNA）。在肾上腺中，单次给予利血平（10 mg/kg）24小时后，6-丙酮酰四氢蝶呤合酶和酪氨酸羟化酶mRNA升高了3至4倍，已知这种处理会增加该组织中四氢生物蝶呤的水平。该结果表明，尽管6-丙酮酰四氢蝶呤合酶在四氢生物蝶呤生物合成途径中不被认为是限速酶，但该酶基因表达的调控可能在调节这种重要辅因子的合成中起重要作用。
