Hosseinzadeh Zohreh, Warsi Jamshed, Elvira Bernat, Almilaji Ahmad, Shumilina Ekaterina, Lang Florian
Department of Physiology, Institute of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany.
J Membr Biol. 2015 Apr;248(2):309-17. doi: 10.1007/s00232-015-9772-2. Epub 2015 Feb 3.
The janus-activated kinase 2 JAK2 participates in the signalling of several hormones including interferon, a powerful regulator of lymphocyte function. Lymphocyte activity and survival depend on the activity of the voltage-gated K(+) channel KCNA3 (Kv1.3). The present study thus explored whether JAK2 modifies the activity of voltage-gated K(+) channel KCNA3. To this end, cRNA encoding KCNA3 was injected in Xenopus oocytes with or without additional injection of cRNA encoding wild-type human JAK2, human inactive (K882E)JAK2 mutant, or human gain-of-function (V617F)JAK2 mutant. KCNA3-dependent depolarization-induced current was determined utilizing dual-electrode voltage clamp, and protein KCNA3 abundance in the cell membrane was quantified by chemiluminescence. Moreover, the effect of interferon-γ on voltage-gated K(+) current was determined by patch clamp in mainly KCNA3-expressing Jurkat T cells with or without prior treatment with JAK2 inhibitor AG490 (40 µM). As a result, KCNA3 channel activity and protein abundance were up-regulated by coexpression of JAK2 or (V617F)JAK2 but not (K882E)JAK2. The effect of JAK2 coexpression was reversed by AG490 treatment. In human Jurkat T lymphoma cells, voltage-gated K(+) current was up-regulated by interferon-γ and down-regulated by AG490 (40 µM). In conclusion, JAK2 participates in the signalling, regulating the voltage-gated K(+) channel KCNA3.
Janus激酶2（JAK2）参与包括干扰素在内的多种激素的信号传导，干扰素是淋巴细胞功能的强大调节剂。淋巴细胞的活性和存活取决于电压门控钾通道KCNA3（Kv1.3）的活性。因此，本研究探讨了JAK2是否会改变电压门控钾通道KCNA3的活性。为此，将编码KCNA3的cRNA注射到非洲爪蟾卵母细胞中，同时或不额外注射编码野生型人JAK2、人无活性（K882E）JAK2突变体或人功能获得性（V617F）JAK2突变体的cRNA。利用双电极电压钳测定KCNA3依赖性去极化诱导电流，并通过化学发光法定量细胞膜中蛋白质KCNA3的丰度。此外，在主要表达KCNA3的Jurkat T细胞中，通过膜片钳测定干扰素-γ对电压门控钾电流的影响，这些细胞在有或没有用JAK2抑制剂AG490（40μM）预处理的情况下。结果，JAK2或（V617F）JAK2共表达上调了KCNA3通道活性和蛋白质丰度，但（K882E）JAK2则没有。AG490处理可逆转JAK2共表达的作用。在人Jurkat T淋巴瘤细胞中，电压门控钾电流被干扰素-γ上调，被AG490（40μM）下调。总之，JAK2参与信号传导，调节电压门控钾通道KCNA3。
