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Abstract：
Activation of resting T cells relies on sustained Ca2+ influx across the plasma membrane, which in turn depends on the functional expression of potassium channels, whose activity repolarizes the membrane potential. Depending on the T-cells subset, upon activation the expression of Ca2+- or voltage-activated K+ channels, KCa or Kv, is up-regulated. In this study, by means of patch-clamp technique in the whole cell mode, we have studied in detail the characteristics of Kv and KCa currents in resting and activated human T cells, the only well explored human T-leukemic cell line Jurkat, and two additional human leukemic T cell lines, CEM and MOLT-3. Voltage dependence of activation and inactivation of Kv1.3 current were shifted up to by 15 mV to more negative potentials upon a prolonged incubation in the whole cell mode and displayed little difference at a stable state in all cell lines but CEM, where the activation curve was biphasic, with a high and low potential components. In Jurkat, KCa currents were dominated by apamine-sensitive KCa2.2 channels, whereas only KCa3.1 current was detected in healthy T and leukemic CEM and MOLT-3 cells. Despite a high proliferation potential of Jurkat cells, Kv and KCa currents were unexpectedly small, more than 10-fold lesser as compared to activated healthy human T cells, CEM and MOLT-3, which displayed characteristic Kv1.3high:KCa3.1high phenotype. Our results suggest that Jurkat cells represent perhaps a singular case and call for more extensive studies on primary leukemic T cell lines as well as a verification of the therapeutic potential of specific KCa3.1 blockers to combat acute lymphoblastic T leukemias.
摘要：
静息T细胞的激活依赖于持续的Ca2+跨质膜流入,这又取决于钾通道的功能表达，其活性使膜电位重新极化。取决于T细胞亚群,激活后，Ca2-或电压激活的K通道的表达，KCa或Kv,是上调的。在这项研究中,通过全细胞模式的膜片钳技术，我们详细研究了静息和活化的人类T细胞中Kv和KCa电流的特征，人类T白血病细胞系Jurkat,和另外两个人类白血病T细胞系，CEM和MOLT-3。在全细胞模式下长时间孵育后，Kv1.3电流的激活和失活的电压依赖性向上移动15mV至更大的负电位，并且在所有细胞系中，除CEM外，在稳定状态下几乎没有差异。激活曲线是双相的，具有高和低电位成分。在Jurkat,KCa电流以阿帕明敏感的KCa2.2通道为主，而在健康T和白血病CEM和MOLT-3细胞中仅检测到KCa3.1电流。尽管Jurkat细胞具有很高的增殖潜力,Kv和KCa电流出乎意料的小，与激活的健康人类T细胞相比，少了10倍以上，CEM和MOLT-3，表现出特征性Kv1.3high：KCa3.1high表型。我们的结果表明，Jurkat细胞可能代表了一个单一的病例，需要对原发性白血病T细胞系进行更广泛的研究，并验证特定KCa3.1阻断剂对抗急性淋巴细胞性T白血病的治疗潜力。
