Identification of histaminergic fiber in human lung

通过对编码功能性HDC的人类HDC cDNA克隆（p-TN2）的核苷酸序列进行分析，确定了KU-812F中HDC的一级结构。人类HDC有662个氨基酸（Mr为74,178），与大鼠和小鼠的HDC序列有85%的同源性。通过对HDC mRNA的体外翻译，证实了人类HDC的74kDa过早形成，表明人类HDC是在翻译后加工的。KU-817F分别表达2.4 kb和3.4 kb的HDC mRNA，由HDC基因交替拼接而成。在这些mRNA中，只有2.4 kb的mRNA编码功能性HDC。在肺、脑等人体组织中，检测2.4 kb HDC mRNA的表达。正常人肺中HDC基因表达较低，IPF患者肺中未检测到HDC基因表达，而支气管哮喘患者肺中HDC mRNA水平明显升高，提示组胺分泌过多可能参与支气管哮喘的发病机制。

The primary structure of HDC from KU-812F was determined by the analysis of the amino acid sequence deduced from the nucleotide sequence of the human HDC cDNA clone(p-TN2)encoding functional HDC. Human HDC has 662 amino acids(Mr 74,178)and shows 85% homology in amino acid sequence to the rat and mouse HDC sequences. 74kDa premature form of human HDC was demonstrated by in vitro translation from HDC mRNA,suggesting that human HDC is processed post-translationally. KU-817F expresses 2.4-kb and 3.4-kb HDC mRNA's which are alternatively spliced from the HDC gene. Among these mRNA's,only 2.4-kb mRNA encodes functional HDC.In human tissues including the lung and brain,the expression of 2.4-kb HDC mRNA was evaluated. While HDC gene expression was low in the lungs of normal individual,or not detected in the lungs from the patients with IPF,the HDC mRNA level was markedly increased in the lungs from the patients with bronchial asthma,suggesting that hyperproduction of histamine may be involved in the pathogenesis of bronchial asthma.