Essential role for Ca2+ in regulation of IL-1β secretion by P2X7 nucleotide receptor in monocytes, macrophages, and HEK-293 cells
Essential role for Ca2+ in regulation of IL-1β secretion by P2X7 nucleotide receptor in monocytes, macrophages, and HEK-293 cells
复制标题
DOI：
10.1152/ajpcell.00070.2003
复制
发表时间：
2003-08-01
影响因子：
5.5
通讯作者：
Dubyak, GR
中科院分区：
文献类型：
--
作者：
Gudipaty, L;Munetz, J;Dubyak, GR
白细胞介素(IL)-1 β是一种促炎细胞因子，其大部分生物活性在细胞外产生，但缺乏分泌信号序列阻碍了其通过经典分泌途径输出。il -1 β在巨噬细胞和单核细胞中的有效外化可以通过细胞外ATP刺激P2X(7)核苷酸受体来实现。然而，激活这些非选择性阳离子通道促进il -1 β分泌的确切机制尚不清楚。在这里，我们证明了细胞质Ca2+的持续增加对通过P2X(7)受体增强il -1 β分泌的关键作用。利用HEK-293细胞工程共表达P2X(7)受体与成熟的il -1 β (mil -1 β)，我们发现P2X(7)受体的激活导致mil -1 β的快速分泌，这一过程依赖于细胞外Ca2+的内流和细胞质Ca2+的持续上升。此外，细胞外Ca2+的减少减少了P2X(7)受体介导的il -1 β分泌的90%，但对caspase-1将前体il -1 β (proil -1 β)转化为mil -1 β的酶处理没有影响。在THP-1人单核细胞和Bac1.2F5小鼠巨噬细胞中进行的类似实验证实了Ca2+在P2X(7)受体介导的il -1 β分泌中的独特作用。此外，我们报道P2X(7)受体的细胞表面表达在缺乏外界刺激的情况下也会导致il -1 β的释放增强，而这可以被P2X(7)受体抑制剂抑制。我们阐明了Ca2+在atp诱导的il -1 β分泌中的重要作用，并指出P2X(7)受体作为il -1 β释放的分泌器官的增强剂的额外作用。
Interleukin (IL)-1beta is a proinflammatory cytokine that elicits the majority of its biological activity extracellularly, but the lack of a secretory signal sequence prevents its export via classic secretory pathways. Efficient externalization of IL-1beta in macrophages and monocytes can occur via stimulation of P2X(7) nucleotide receptors with extracellular ATP. However, the exact mechanisms by which the activation of these nonselective cation channels facilitates secretion of IL-1beta remain unclear. Here we demonstrate a pivotal role for a sustained increase in cytosolic Ca2+ to potentiate secretion of IL-1beta via the P2X(7) receptors. Using HEK-293 cells engineered to coexpress P2X(7) receptors with mature IL-1beta ( mIL-1beta), we show that activation of P2X(7) receptors results in a rapid secretion of mIL-1beta by a process(es) that is dependent on influx of extracellular Ca2+ and a sustained rise in cytosolic Ca2+. Moreover, reduction in extracellular Ca2+ attenuates similar to90% of P2X(7) receptor-ediated IL-1beta secretion but has no effect on enzymatic processing of precursor IL-1beta ( proIL-1beta) to mIL-1beta by caspase-1. Similar experiments with THP-1 human monocytes and Bac1.2F5 murine macrophages confirm the unique role of Ca2+ in P2X(7) receptor-mediated secretion of IL-1beta. In addition, we report that cell surface expression of P2X(7) receptors in the absence of external stimulation also results in enhanced release of IL-1beta and that this can be repressed by inhibitors of P2X(7) receptors. We clarify an essential role for Ca2+ in ATP-induced IL-1beta secretion and indicate an additional role of P2X(7) receptors as enhancers of the secretory apparatus by which IL-1beta is released.