T 細胞接受器(α/δ)基因座上高度保留DNA片段與核蛋白間的作用研究

Abstract

位於T細胞接受器α/δ基因座上有幾處具有高度保留性，且位於插入子的DNA序列，最初發現的被稱之為 conserved sequence block (CSB)。CSB長125 bp且其在人類與老鼠之間的相似性高達95%。本實驗室之前的研究指出CSB在胸腺細胞核萃取液中，會有具特異性的蛋白質與其結合。同時CSB具有調控T細胞接受器加強子的功能。本論文是針對位於T細胞接受器基因Jα52及Jα53之間長107 bp的conserved sequence block，我們稱之為CSB-3的 DNA片段作研究。CSB-3在人類與老鼠之間的相似性高達97％。本論文利用EMSA、geloverlay及 chromatin immunoprecipitation的方式，試著分析在各個器官中是否有與其結合的蛋白質。結果顯示在胸腺及肝臟中都具有特異性的蛋白質與其結合。而且在in vivo的狀態下，CSB-3會與具淋巴特異性的轉錄因數有交互作用。這些結果初步的證實CSB-3會在淋巴組織中與某些蛋白質有交互作用，而其在Jα locus上的功用仍需進一步的實驗證明。

A DNA block located between the J α 3 and J α 4 of T cell receptor J α locus, named conserved sequence block (CSB),has 95% sequence similarity between human and mouse. We previous showed that CSB can bind specific nuclear factors from mouse thymus and enhance TCR α enhancer activity. We thus proposed that CSB may regulate the chromatin structure at the region flanking CSB. In this study, we investigated another conserved seqnence block, located at the 5' end of the TCR J α locus, to verify the proposed functional role of the CSB. This block of DNA, we named it CSB-3, was found to bind proteins defferentially expressed in liver and thymus in vitro and associate with transcriptional factors, such as GATA-3, Oct-1 and Oct-2, in vivo. Thus, these results suggest that CSB-3 may function similarly to the CSB in regulating the local chromatin structure to control the accessibility of the regional J α s to the recombinase.