芳基胺N-乙酰基转移酶在人体肠道中的表达。
Expression of arylamine N-acetyltransferase in human intestine.
作者信息
Hickman D, Pope J, Patil S D, Fakis G, Smelt V, Stanley L A, Payton M, Unadkat J D, Sim E
机构信息
Department of Pharmaceutics, University of Washington, Seattle, USA.
出版信息
Gut. 1998 Mar;42(3):402-9. doi: 10.1136/gut.42.3.402.
BACKGROUND
Arylamine N-acetyltransferases in humans (NAT1 and NAT2) catalyse the acetylation of arylamines including food derived heterocyclic arylamine carcinogens. Other substrates include the sulphonamide 5-aminosalicylic acid (5-ASA), which is an NAT1 specific substrate; N-acetylation of 5-ASA is a major route of metabolism. NAT1 and NAT2 are both polymorphic.
AIMS
To investigate NAT expression in apparently healthy human intestines in order to understand the possible role of NAT in colorectal cancer and in the therapeutic response to 5-ASA.
METHODS
The intestines of four organ donors were divided into eight sections. DNA was prepared for genotyping NAT1 and NAT2 and enzymic activities of NAT1 and NAT2 were determined in cytosols prepared from each section. Tissue was fixed for immunohistochemistry with specific NAT antibodies. Western blotting was carried out on all samples of cytosol and on homogenates of separated muscle and villi after microdissection.
RESULTS
NAT1 activity of all cytosols was greater than NAT2 activity. NAT1 and NAT2 activities correlated with the genotypes of NAT1 and NAT2 and with the levels of NAT1 staining determined by western blotting. The ratio of NAT1:NAT2 activities showed interindividual variations from 2 to 70. NAT1 antigenic activity was greater in villi than in muscle. NAT1 was detected along the length of the villi in the small intestine. In colon samples there was less NAT1 at the base of the crypts with intense staining at the tips.
CONCLUSIONS
The interindividual variation in NAT1 and NAT2 in the colon could affect how individuals respond to exposure to specific NAT substrates including carcinogens and 5-ASA.
背景
人类芳胺N - 乙酰基转移酶（NAT1和NAT2）催化芳胺的乙酰化反应，其中包括食物来源的杂环芳胺致癌物。其他底物包括磺胺类药物5 - 氨基水杨酸（5 - ASA），它是NAT1的特异性底物；5 - ASA的N - 乙酰化是主要的代谢途径。NAT1和NAT2均具有多态性。
目的
研究NAT在表面健康的人体肠道中的表达，以了解NAT在结直肠癌及对5 - ASA治疗反应中的可能作用。
方法
将4名器官捐献者的肠道分成8个部分。制备DNA用于NAT1和NAT2基因分型，并在每个部分制备的胞质溶胶中测定NAT1和NAT2的酶活性。组织固定后用特异性NAT抗体进行免疫组织化学检测。对所有胞质溶胶样品以及显微切割后分离的肌肉和绒毛匀浆进行蛋白质免疫印迹分析。
结果
所有胞质溶胶的NAT1活性均高于NAT2活性。NAT1和NAT2活性与NAT1和NAT2的基因型以及蛋白质免疫印迹法测定的NAT1染色水平相关。NAT1:NAT2活性比值在个体间从2到70不等。绒毛中的NAT1抗原活性高于肌肉。在小肠绒毛全长均检测到NAT1。在结肠样本中，隐窝底部的NAT1较少，尖端染色强烈。
结论
结肠中NAT1和NAT2的个体间差异可能影响个体对包括致癌物和5 - ASA在内的特定NAT底物暴露的反应方式。
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