Kastrup J, Lauritsen J P, Menné C, Dietrich J, Geisler C
Institute of Medical Microbiology and Immunology, University of Copenhagen, The Panum Institute, Copenhagen, Denmark.
Scand J Immunol. 2000 May;51(5):491-6. doi: 10.1046/j.1365-3083.2000.00716.x.
Down-regulation of the T-cell receptor (TCR) plays an important role in modulating T-cell responses, both during T-cell development and in mature T cells. At least two distinct pathways exist for TCR down-regulation: down-regulation following TCR ligation; and down-regulation following activation of protein kinase C (PKC). Ligand-induced TCR down-regulation is dependent on protein tyrosine kinase (PTK) activity and seems to be closely related to T-cell activation. In addition, previous studies have indicated that ligand-induced TCR down-regulation is dependent on the expression of CD45, a transmembrane protein tyrosine phosphatase. The role of the different domains of CD45 in TCR down-regulation was investigated in this study. We found that the phosphatase domains of CD45 are required for efficient ligand-induced TCR down-regulation. In contrast, the extracellular domain of CD45 is dispensable for ligand-mediated TCR down-regulation. Finally, PKC-mediated TCR down-regulation was found to be independent of both the extra-and intracellular domains of CD45.
T细胞受体（TCR）的下调在调节T细胞反应中起着重要作用，这一过程发生在T细胞发育期间以及成熟T细胞中。TCR下调至少存在两条不同的途径：TCR连接后的下调；以及蛋白激酶C（PKC）激活后的下调。配体诱导的TCR下调依赖于蛋白酪氨酸激酶（PTK）活性，并且似乎与T细胞激活密切相关。此外，先前的研究表明，配体诱导的TCR下调依赖于跨膜蛋白酪氨酸磷酸酶CD45的表达。本研究调查了CD45不同结构域在TCR下调中的作用。我们发现，CD45的磷酸酶结构域是有效配体诱导TCR下调所必需的。相反，CD45的胞外结构域对于配体介导的TCR下调是可有可无的。最后，发现PKC介导的TCR下调与CD45的胞外和胞内结构域均无关。
