Novel functions of the phospholipase D2-phox homology domain in protein kinase Cζ activation
Novel functions of the phospholipase D2-phox homology domain in protein kinase Cζ activation
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DOI：
10.1128/mcb.25.8.3194-3208.2005
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发表时间：
2005-04-01
影响因子：
5.3
通讯作者：
Ryu, SH
中科院分区：
文献类型：
--
作者：
Kim, JH;Kim, JH;Ryu, SH
蛋白激酶C zeta （PKC zeta）在多种细胞中参与多种信号通路和细胞功能，表现出与细胞存活和增殖相关的特性。目前，PKC zeta的调控机制尚不明确。在这里，我们首次确定磷脂酶D2 （PLD2）通过与脂肪酶活性无关的方式直接相互作用增强PKC zeta活性。PLD2-Phox同源（PX）结构域与PKC zeta激酶结构域的相互作用也诱导PKC zeta的激活环磷酸化和下游信号刺激，通过p70 S6激酶磷酸化来测量。此外，在体外实验中，只有PLD2-PX结构域直接刺激PKC zeta活性，并且它是与磷酸肌苷依赖性激酶I和PKC zeta形成三元配合物所必需的。用丙氨酸替代PLD2-PX结构域中的三赖氨酸残基(Lys（101), Lys（102）和LYS103）的突变体消除了与PKC zeta激酶结构域的相互作用和PKC zeta的激活。此外，PLD2沉默显著影响乳腺癌细胞活力。综上所述，这些结果表明pld2介导的PKC zeta激活是由其PX结构域诱导的，它既直接激活PKC zeta，又辅助激活环磷酸化。此外，我们发现它是乳腺癌细胞存活的重要因素。
It has been established that protein kinase C zeta (PKC zeta) participates in diverse signaling pathways and cellular functions in a wide variety of cells, exhibiting properties relevant to cellular survival and proliferation. Currently, however, the regulation mechanism of PKC zeta remains elusive. Here, for the first time, we determine that phospholipase D2 (PLD2) enhances PKC zeta activity through direct interaction in a lipase activity-independent manner. This interaction of the PLD2-Phox homology (PX) domain with the PKC zeta-kinase domain also induces the activation loop phosphorylation of PKC zeta and downstream signal stimulation, as measured by p70 S6 kinase phosphorylation. Furthermore, only the PLD2-PX domain directly stimulates PKC zeta activity in vitro, and it is necessary for the formation of the ternary complex with phosphoinositide-dependent kinase I and PKC zeta. The mutant that substitutes the triple lysine residues (Lys(101), Lys(102), and LYS103) within the PLD2-PX domain with alanine abolishes interaction with the PKC zeta-kinase domain and activation of PKC zeta. Moreover, breast cancer cell viability is significantly affected by PLD2 silencing. Taken together, these results suggest that the PLD2-mediated PKC zeta activation is induced by its PX domain performing both direct activation of PKC zeta and assistance of activation loop phosphorylation. Furthermore, we find it is an important factor in the survival of breast cancer cells.