The p21-activated protein kinase-related kinase Cla4 is a coincidence detector of signaling by Cdc42 and phosphatidylinositol 4-phosphate
The p21-activated protein kinase-related kinase Cla4 is a coincidence detector of signaling by Cdc42 and phosphatidylinositol 4-phosphate
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DOI：
10.1074/jbc.m314035200
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发表时间：
2004-04-23
影响因子：
4.8
通讯作者：
Blumer, KJ
中科院分区：
文献类型：
--
作者：
Wild, AC;Yu, JW;Blumer, KJ
共同调节给定生物过程的信号转导途径通常由充当巧合检测器的分子组织成网络。磷酸肌醇和 Rho 型 GTP 酶 Cdc42 调节所有真核细胞中的重叠过程。然而，将这些路径连接到网络中的重合检测器仍然未知。在这里，我们证明酵母的 p21 激活蛋白激酶相关激酶 Cla4 整合了 Cdc42 和磷脂酰肌醇 4-磷酸 (PI4P) 的信号传导。我们发现 Cla4 pleckstrin 同源 (PH) 结构域在体外与多种磷酸肌醇结合。为了确定哪些磷酸肌醇在体内调节 Cla4，我们分析了磷脂酰肌醇激酶突变体（stt4、mss4 和 pik1）。这表明，Cla4 定位到极化生长位点需要 PI4P 质膜库，而不是磷脂酰肌醇 4,5-二磷酸或 PI4P 高尔基体库。 Cdc42 结合域和 Cla4 的 PH 域的组合对于定位到极化生长位点来说是必要且充分的。影响任一结构域的点突变都会损害 Cla4 调节细胞形态发生和有丝分裂出口网络（Lte1 的定位）的能力。因此，Cla4 必须保留结合 Cdc42 和磷酸肌醇的能力，这是符合检测器的标志。 PI4P 可能会将 Cla4 招募到质膜，在质膜上 Cdc42 激活其激酶活性，并将其定位到极化生长的皮质位点。在哺乳动物细胞中，强直性营养不良相关的 Cdc42 结合激酶具有 p21 结合和 PH 结构域，表明该激酶可能是 Cdc42 和磷酸肌醇信号传导的重合检测器。
Signal transduction pathways that co-regulate a given biological process often are organized into networks by molecules that act as coincidence detectors. Phosphoinositides and the Rho-type GTPase Cdc42 regulate overlapping processes in all eukaryotic cells. However, the coincidence detectors that link these pathways into networks remain unknown. Here we show that the p21-activated protein kinase-related kinase Cla4 of yeast integrates signaling by Cdc42 and phosphatidylinositol 4-phosphate (PI4P). We found that the Cla4 pleckstrin homology (PH) domain binds in vitro to several phosphoinositide species. To determine which phosphoinositides regulate Cla4 in vivo, we analyzed phosphatidylinositol kinase mutants (stt4, mss4, and pik1). This indicated that the plasma membrane pool of PI4P, but not phosphatidylinositol 4,5-bisphosphate or the Golgi pool of PI4P, is required for localization of Cla4 to sites of polarized growth. A combination of the Cdc42-binding and PH domains of Cla4 was necessary and sufficient for localization to sites of polarized growth. Point mutations affecting either domain impaired the ability of Cla4 to regulate cell morphogenesis and the mitotic exit network ( localization of Lte1). Therefore, Cla4 must retain the ability to bind both Cdc42 and phosphoinositides, the hallmark of a coincidence detector. PI4P may recruit Cla4 to the plasma membrane where Cdc42 activates its kinase activity and refines its localization to cortical sites of polarized growth. In mammalian cells, the myotonic dystrophy-related Cdc42-binding kinase possesses p21-binding and PH domains, suggesting that this kinase may be a coincidence detector of signaling by Cdc42 and phosphoinositides.