Differential roles of PKC-θ in the regulation of intracellular calcium concentration in primary T cells
Differential roles of PKC-θ in the regulation of intracellular calcium concentration in primary T cells
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DOI：
10.1016/j.jmb.2005.10.043
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发表时间：
2006-01-20
影响因子：
5.6
通讯作者：
Sun, ZM
中科院分区：
文献类型：
--
作者：
Manicassamy, S;Sadim, M;Sun, ZM
T淋巴细胞的激活需要蛋白激酶C theta(PKC-theta)和适当升高的细胞内游离钙离子浓度([Ca2+]i)。在这里，我们发现佛波酯(PMA)抑制野生型T细胞的钙内流，但不抑制PKC-theta(-/-)T细胞的钙内流，这表明PKC-theta在PMA介导的抑制钙内流中起作用。相反，在相同的PKC-theta(-/-)T细胞中，T细胞受体(TCR)的交联确实导致了PKC-theta在TCR介导的钙动员中的积极作用。在PKC-theta(-/-)小鼠中，外周成熟T细胞，而不是发育中的胸腺细胞，在TCR次优交联时，显示出显著减少TCR诱导的钙内流和活化T细胞核因子(NFAT)的移位。细胞内游离钙离子的减少是由于钙离子内流的改变，而不是细胞外和细胞内钙动员研究中观察到的外流的变化。然而，随着TCR交联度的增加，这些钙离子内流和活化T细胞核因子(NFAT)易位的差异消失。PKC-theta对Ca~(2+)内流的促进作用不仅依赖于TCR的交联强度，而且与T细胞的发育阶段有关。其潜在机制涉及磷脂酶C-γ1的激活和三磷酸肌醇的产生。此外，抑制Jurkat细胞内源性PKC-theta的表达可显著抑制TCR诱导的NFAT激活，NFAT报告研究证实。在PKCA-theta(-/-)Jurkat细胞中强制表达具有结构性活性的钙调神经磷酸酶可以很容易地克服上述抑制。因此，PKC-theta可以正向和负向地调节对NFAT活性至关重要的钙离子内流。(C)2005爱思唯尔有限公司。保留所有权利。
Activation of T lymphocytes requires protein kinase C theta (PKC-theta) and an appropriately elevated free intracellular Ca2+ concentration ([Ca2+]i). Here, we show that phorbol 12 myristate 13-acetate (PMA) inhibited Ca2+ influx in wild-type but not PKC-theta(-/-) T cells, suggesting that PKC-theta plays a role in PMA-mediated inhibition of Ca2+ influx. In contrast, T cell receptor (TCR) crosslinking in the same PKC-theta(-/-) T cells did result a positive role for PKC-theta in TCR-mediated Ca2+ mobilization. In PKC-theta(-/-) mice, peripheral mature T cells, but not developing thymocytes, displayed significantly decreased TCR-induced Ca2+ influx and nuclear factor of activated T cells (NFAT) translocation upon sub-optimal TCR crosslinking. The decreased intracellular free Ca2+ was due to changes in Ca2+ influx but not efflux, as observed in extracellular and intracellular Ca2+ mobilization studies. However, these differences in Ca2+ influx and nuclear factor of activated T cells (NFAT) translocation disappeared with increasing intensity of TCR crosslinking. The enhancing effect of PKC-theta on Ca2+ influx is not only dependent on the strength of TCR crosslinking but also on the developmental stage of T cells. The underlying mechanism involved phospholipase C gamma 1 activation and inositol triphosphate production. Furthermore, knockdown of endogenous PKC-theta expression in Jurkat cells resulted in significant inhibition of TCR-induced activation of NFAT, as evidenced from NFAT reporter studies. Forced expression of a constitutively active form of calcineurin in PKCA-theta(-/-) Jurkat cells could readily overcome the above inhibition. Thus, PKC-theta can both positively and negatively regulate the Ca2+ influx that is critical for NFAT activity. (c) 2005 Elsevier Ltd. All rights reserved.