Human monoamine oxidase A gene determines levels of enzyme activity.
Human monoamine oxidase A gene determines levels of enzyme activity.
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DOI：
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发表时间：
1991-08
影响因子：
9.8
通讯作者：
G. Hotamisligil;X. Breakefield
中科院分区：
文献类型：
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作者：
G. Hotamisligil;X. Breakefield
单胺氧化酶（Monoamine oxidase，MAO）是生物胺降解脱氨的关键酶。这种酶的两种生物化学上不同的形式，A和B，由人类X染色体上不同的基因编码。在这些研究中，我们研究了MAO-A的结构基因在确定人类活性水平中的作用，如在培养的皮肤成纤维细胞中测量的。通过第一链cDNA合成、PCR扩增和直接双脱氧测序确定MAO-A mRNA的编码序列。两个单碱基对的取代，观察到从细胞的cDNA与30倍的活性水平的差异。这两个取代是在三联体密码子的第三个碱基，因此不影响推导的氨基酸序列，但确实影响EcoRV和Fnu 4 HI的限制酶位点的存在或不存在，这可以在来自基因组DNA或cDNA的PCR片段上阐明。第三个多态性MspI在非编码区的MAOA基因也进行了评估，使用基因组DNA的Southern印迹分析。在人类男性成纤维细胞系中，观察到MAOA等位基因与MAO活性水平之间存在统计学显著相关性。这种关联表明，MAOA基因本身是一个主要的决定因素的活动水平，显然，部分，通过非编码，调节元件。
Monoamine oxidase (MAO) is a critical enzyme in the degradative deamination of biogenic amines throughout the body. Two biochemically distinct forms of the enzyme, A and B, are encoded in separate genes on the human X chromosome. In these studies we investigated the role of the structural gene for MAO-A in determining levels of activity in humans, as measured in cultured skin fibroblasts. The coding sequence of the mRNA for MAO-A was determined by first-strand cDNA synthesis, PCR amplification, and direct dideoxy sequencing. Two single-basepair substitutions were observed in cDNAs from cells with a 30-fold difference in activity levels. These two substitutions were in the third base of a triplet codon and hence did not affect the deduced amino acid sequence but did affect the presence or absence of restriction-enzyme sites for EcoRV and Fnu4HI, which could be elucidated on PCR fragments derived from genomic DNA or cDNAs. A third polymorphism for MspI in the noncoding region of the MAOA gene was also evaluated by Southern blot analysis using genomic DNA. Statistically significant associations were observed between the alleles for MAOA and levels of MAO activity in human male fibroblast lines. This association indicates that the MAOA gene itself is a major determinant of activity levels, apparently, in part, through noncoding, regulatory elements.