Early phosphoinositide 3-kinase activity is required for late activation of protein kinase Cε in platelet-derived-growth-factor-stimulated cells:: evidence for signalling across a large temporal gap
Early phosphoinositide 3-kinase activity is required for late activation of protein kinase Cε in platelet-derived-growth-factor-stimulated cells:: evidence for signalling across a large temporal gap
复制标题
DOI：
10.1042/0264-6021:3580281
复制
发表时间：
2001-09-01
影响因子：
4.1
通讯作者：
Kazlauskas, A
中科院分区：
文献类型：
--
作者：
Balciunaite, E;Kazlauskas, A
至少有两种信号系统有可能促进蛋白激酶C （PKC）家族成员的激活，如PKC epsilon。其中之一是磷酸肌苷3-激酶（PI 3-激酶），其脂质产物在体外和活细胞中激活PKC epsilon。最近的观察发现，在G(0)- s期间隔内存在多波PI 3-激酶和PKC epsilon活性，这为研究这两种信号酶在体内的关系提供了新的机会。我们已经评估了PI 3-激酶活性的早期和晚期波对PKC epsilon活性的相应波的相对重要性。阻断PI 3-激酶第一阶段活性可抑制PKC epsilon的早期和晚期激活。相比之下，第二波PI 3激酶活性对于PKC epsilon的后期激活是必不可少的。这些发现表明，早期PI 3激酶激活诱导PKC epsilon的稳定变化，这使其易于随后被脂质辅助因子激活。事实上，PKC epsilon的部分蛋白水解表明，PI 3激酶的早期激活导致PKC epsilon的构象改变，这种改变随着PKC epsilon活性的循环而持续。我们提出了PKC epsilon在体内激活的两步假设。一个步骤是稳定的，依赖于PI 3-激酶，而另一个是短暂的，可能取决于脂质辅助因子的可用性。最后，这些研究揭示了PI 3-激酶和PKC epsilon能够在相对较长的时间间隔内进行通信，并开始阐明其机制。
At least two signalling systems have the potential to contribute to the activation of protein kinase C (PKC) family members such as PKC epsilon. One of these is phosphoinositide 3-kinase (PI 3-kinase), whose lipid products activate PKC epsilon in vitro and in living cells. The recent observation that there are multiple waves of PI 3-kinase and PKC epsilon activity within the G(0)-to-S phase interval provides a new opportunity to investigate the relationship between these two signalling enzymes in vivo. We have assessed the relative importance of the early and late waves of PI 3-kinase activity for the corresponding waves of PKC epsilon activity. Blocking the first phase of PI 3-kinase activity inhibited both early and late activation of PKC epsilon. In contrast, the second wave of PI 3-kinase activity was dispensable for late activation of PKC epsilon. These findings suggested that early PI 3-kinase activation induced a stable change in PKC epsilon, which predisposed it to subsequent activation by lipid cofactors. Indeed, partial proteolysis of PKC epsilon indicated that early activation of PI 3-kinase led to a conformation change in PKC epsilon that persisted as the activity of PKC epsilon cycled. We propose a two-step hypothesis for the activation of PKC epsilon in vivo. One step is stable and depends on PI 3-kinase, whereas the other is transient and may depend on the availability of lipid cofactors. Finally, these studies reveal that PI 3-kinase and PKC epsilon are capable of communicating over a relatively long time interval and begin to elucidate the mechanism.