Biochemical Studies of Human Cell Surface Markers

T淋巴细胞在胸腺中成熟，在胸腺环境的影响下经历一系列的分化、扩增和选择活动。这项建议的主要目的是研究CD3Gamma、Delta和epsilon基因的表达调控。CD3基因参与了胸腺内的分化，从TCR前阶段开始，甚至更早。因此，CD3Gamma、Delta和epsilon在正选择和负选择过程中起着至关重要的作用。在T淋巴细胞发育的后期，CD3蛋白控制TCR/CD3复合体的表面表达，对于抗原/MHC驱动的信号转导是不可或缺的。此前，我们已经证明CD3Gamma、Delta和epsilon基因紧密地映射在人类染色体11q23(小鼠9号染色体)上的一个小簇中。CD3Gamma和Delta的转录差异很大，它们的转录起始点相距1.2~1.4kb。CD3epsilon基因位于CD3Delta基因下游26kb，其转录方向为CD3Gamma基因。虽然CD3Gamma、Delta和epsilon基因主要在胸腺来源的淋巴细胞中表达，但在人和小鼠激活的自然杀伤细胞中也发现了CD3epsilon。尽管这三个基因在组织分布和聚集性上有相似之处，但我们的研究清楚地表明，它们各自的调控元件是不同的。因此，我们对CD3Gamma、Delta、epsilon基因簇的兴趣不仅在于其基因产物的重要功能，还在于其表达的独特发育调节。我们的第一个假设是，CD3Gamma、Delta和epsilon的表达除了共同的元素外，还受到独特的T细胞特异性机制的控制。第二个假设是，在前体T细胞中诱导CD3Gamma、Delta或epsilon使用不同的途径。我们特别建议：1研究CD3Delta基因的T细胞特异性转录调控；2研究CD3epsilon基因在T细胞和NK细胞中表达的分子机制；3鉴定T细胞特异性表达CD3Gamma基因的转录元件；4研究CD3Gamma、Delta和epsilon基因在淋巴细胞发育早期的调控。

T lymphocytes mature in the thymus, where they undergo a series of differentiation, expansion and selection events under the influence of the thymic environment. The main objective of this proposal is to study regulation of expression of the CD3gamma, delta and epsilon genes. The CD3 genes are involved in intrathymic differentiation from the pre-TCR phase on and perhaps earlier. Thus, CD3gamma, delta and epsilon are of paramount importance in positive and negative selection processes. At later stages of T lymphocyte development, the CD3 proteins control surface expression of the TCR/CD3 complex and are indispensable for antigen/MHC driven signal transduction. Previously, we had shown that the CD3gamma, delta and epsilon genes map closely together in a small cluster on human chromosome 11q23 (mouse chromosome 9). CD3 gamma and delta are transcribed divergently, their transcription start sites being 1.2 to 1.4 kb apart. The CD3epsilon gene is located 26 kb downstream from the CD3delta gene and is transcribed in the direction of the CD3gamma gene. Although the CD3gamma, delta and epsilon genes are primarily expressed in thymus derived lymphocytes, CD3epsilon has been found in human and murine activated natural killer cells. In spite of the similarities in tissue distribution and the clustering of these three genes, our studies have clearly demonstrated that their respective regulatory elements are distinct. Our interest in the CD3gamma, delta, epsilon genes cluster lies therefore not only in the important functions of their gene products, but also in the unique developmental regulation of their expression. Our first hypothesis is that expression of CD3gamma, delta and epsilon is governed by unique T cell specific mechanisms in addition to common elements. A second hypothesis is that induction of CD3gamma, delta or epsilon in the precursor T cell utilizes distinct pathways. We specifically propose to: 1 Study T cell specific transcriptional regulation of the CD3delta gene; 2 Investigate the molecular mechanisms that govern expression of the CD3epsilon gene in T and NK cell; 3 Characterize transcriptional elements involved in T cell specific expression of the CD3gamma gene; 4 Examine the regulation of the CD3gamma, delta and epsilon genes during early lymphocyte development.