Tryptophan Hydroxylase Gene Structure and Regulation

色氨酸羟化酶(TPH)是循环色氨酸转化为5-羟色胺的限速酶，5-羟色胺是中枢神经系统中的一种单胺类神经递质。色氨酸羟化酶是通过蛋白激酶介导的磷酸化来调节的，而这一关键酶也可能在基因表达水平上受到调节。基于克隆的松果体cDNA序列，合成了大鼠色氨酸羟基酶基因的寡核苷酸探针。该探针将通过杂交检测基因序列，并通过敏感的引物延伸技术检测mRNA水平。初步结果表明，与克隆的松果体cDNA相比，色氨酸羟基酶基因的CNS形式在5‘端发生了变化。改变5-羟色胺水平的药物对中缝核团--中枢神经系统中5-羟色胺能细胞高度集中的区域--的稳态TPH mRNA水平有影响。含有TPH基因的大鼠基因组克隆将被用来确定导致组织特异性mRNAs的表达模式。这些研究将提供有关TPH结构的必要信息，从而促进调节性研究的发展。

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the conversion of circulating tryptophan to serotonin, a monoamine neurotransmitter in the central nervous system. While tryptophan hydroxylase is known to be regulated through a protein kinase- mediated phosphorylation, this key enzyme may also be regulated at the level of gene expression. Synthesis of an oligonucleotide probe for rat tryptophan hydroxylase mRNA based on the sequence of cloned, pineal cDNAs has been achieved. This probe will detect gene sequences by hybridization and mRNA levels by the sensitive technique of primer extension. Initial results demonstrate the CNS form of tryptophan hydroxylase mRNA is altered at the 5'end when compared with the cloned, pineal cDNAs. Pharmacological agents which alter serotonin levels have an effect on steady-state TPH mRNA levels in the raphe nuclei--a region of high concentration of serotonergic cells in the CNS. Rat genomic clones containing the TPH gene will be used to determine the patterns of expression that lead to tissue-specific mRNAs. These studies will provide necessary information about TPH structures leading to the development of regulatory studies.