Abstract
單胺氧化脢(monoamine oxidase, MAO) 為粒腺體外酵素，其主要在用於將生物體內的生物性胺類進行氧化去胺的作用。單胺氧化脢在人體內存在有兩型, 即 A 型及 B，簡稱為 MAOA 及 MAOB。此兩型在其作用受質及抑制劑種類上有顯著的不同。MAOA及MAOB基因位在人體Ｘ染色體p11.23 至 p22.1 的區域中反向相鄰，均有15個表現序列，cDNA也已成功被選殖並表現。 在單胺氧化脢啟動區域具有兩個90bp的重複序列，為-89至-268，並具有 Sp1 的鍵結區域，故有研究結果指出MAOA啟動區域的調控限制因子極可能為Sp1，但卻也有其他研究結果認為其調控方師應由起始子(initiator element)之作用。此外，MAOA很可能為一個雙向的啟動子(bidirectional promoter)，除了直接調控 MAOA 的表現之外，可能還涉及其他基因表現的調控。 本篇研究中，主要想了解在MAOA啟動區域是否存有一些變異性，且這些變異性是否會與一些疾病或生物性指標存有相關性。首先將MAOA啟動區域約 1kb(-1~-1036) 的片段細分為四個區域進行單股構型多形性分析(SSCP)，在實驗結果可以找到少數特定的變異性存在，但並無法確定變異點之所在。而針對在MAOA更上游啟動區域，在-1143到-1262的位置，發現的四個重複相似性為百分之百的30bp 縱向重複，在研究中發現其具有序列變異性存在，其以 30bp 唯一個重複單位，其重複次數從 2到5 次不等，並依族群不同會有不同重複數目區間。以台南教養院學生為樣本，做此區域的序列變異性與其代謝物MHPG 在血液中的含量的相關性分析，將結果再利用變異數的區域做轉錄活性分析，也完成將該區植入含有螢光素脢表現的質體中。Monoamine aoxidase (MAO) A and B are localized in the outermitochondrialmembrane, where they oxidize catecholamine andindoleamine neurotransmittersand other biogenic amine。此兩型在其作用受質erotinin, and is inactivated irreversibly by theacetylenic inhibitorclorgyline. MAO-B preferentially oxidizesphenylethylamine and benzylamine. Itis inactivated by theirreversible inhibitor pargyline and deprenyl. Dopamine,tyramineand tryptamine are common substrates for both forms.It has beenproposed that Sp1 is a major transcription factor interactingwithMAO-A core promoter and the concentration of Sp1 in cellappears to acontrolling factor for MAO-A expression. It also hasbeen propose that themajor transcription inhibition site of thehuman MAOA gene is defined by an Inrelement between -42 and -35upstream from the ATG initiation codon and that itprobably bindsmost TFII-I or related factors.We try to find out sequencevariations in the 5'-noncoding region of MAOA.Single strandconformational analysis of the 1 kb (+1 ~ -1036) MAOA upstreamofthe ATG start site for MAOA revealed possible sequencevariations in thisregion. A systematic search for lengthvariations in the region upstram from-1143 showed variations inthe number of repetitive sequences made of 30 bpunits. Thevariations range from two to five repeats between MAOArepeatsvariations and plasma MHPG levels. A 1.4 kb 5'-noncodingregion of MAOA wasfused with luciferase reporter gene (pGL2vector) for future analysis of thepromoter of MAOA and possibleeffect of sequence variations that we havediscoverd.