INHIBITION OF T-CELL SIGNALING BY IMMUNOPHILIN LIGAND COMPLEXES CORRELATES WITH LOSS OF CALCINEURIN PHOSPHATASE-ACTIVITY
INHIBITION OF T-CELL SIGNALING BY IMMUNOPHILIN LIGAND COMPLEXES CORRELATES WITH LOSS OF CALCINEURIN PHOSPHATASE-ACTIVITY
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DOI：
10.1021/bi00131a002
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发表时间：
1992-04-28
期刊：
影响因子：
2.9
通讯作者：
SCHREIBER, SL
中科院分区：
文献类型：
--
作者：
LIU, J;ALBERS, MW;SCHREIBER, SL
钙调磷酸酶是一种钙调素依赖性蛋白磷酸酶，最近发现它与两种不同的免疫抑制剂结合蛋白（亲免疫蛋白）具有高亲和力，并且绝对依赖于免疫抑制剂FK506或环孢素a （CsA）的存在[Liu et al. (1991) Cell 66, 807-815]。现在已经确定了亲免疫药物复合物对钙调神经磷酸酶的结合亲和力以及由此产生的多聚物复合物的化学计量学，并且已经确定了FK506、CsA和钙调神经磷酸酶的结构元件，这些元件对介导它们的相互作用至关重要。FK506的类似物（FK520, FK523, 15-O-demethyl-FK520）和CsA （mebm2_1 -CsA和MeAla6-CsA）的亲缘性与其免疫抑制活性不相关，已经制备并在生化和细胞分析中进行了评估。我们证明，当这些类似物与它们的亲免疫蛋白结合时，它们抑制钙调磷酸酶活性的能力与它们抑制NF-AT（一种调节人类T细胞中IL-2基因合成的T细胞特异性转录因子）转录激活的能力之间存在很强的相关性。此外，FKBP-FK506和CyP-CsA不抑制PP1、PP2A和PP2C类丝氨酸/苏氨酸磷酸酶的成员。这些数据表明，钙调磷酸酶是这些免疫抑制剂的相关细胞靶点，并参与Ca2+依赖性信号转导通路，其中包括T细胞和肥大细胞。
Calcineurin, a Ca2+, calmodulin-dependent protein phosphatase, was recently found to bind with high affinity to two different immunosuppressant binding proteins (immunophilins) with absolute dependence on the presence of the immunosuppressants FK506 or cyclosporin A (CsA) [Liu et al. (1991) Cell 66, 807-815]. The binding affinities of the immunophilin-drug complexes toward calcineurin and the stoichiometry of the resultant multimeric complexes have now been determined, and structural elements of FK506, CsA, and calcineurin that are critical for mediating their interactions have been identified. Analogues of FK506 (FK520, FK523, 15-O-demethyl-FK520) and CsA (MeBm2t1-CsA and MeAla6-CsA) whose affinities for their cognate immunophilins do not correlate with their immunosuppressive activities have been prepared and evaluated in biochemical and cellular assays. We demonstrate a strong correlation between the ability of these analogues, when bound to their immunophilins, to inhibit the phosphatase activity of calcineurin and their ability to inhibit transcriptional activation by NF-AT, a T cell specific transcription factor that regulates IL-2 gene synthesis in human T cells. In addition, FKBP-FK506 and CyP-CsA do not inhibit members of the PP1, PP2A, and PP2C classes of serine/threonine phosphatases. These data suggest that calcineurin is the relevant cellular target of these immunosuppressive agents and is involved in Ca2+-dependent signal transduction pathways in, among others, T cells and mast cells.