Mapping of atypical protein kinase C within the nerve growth factor signaling cascade: Relationship to differentiation and survival of PC12 cells
Mapping of atypical protein kinase C within the nerve growth factor signaling cascade: Relationship to differentiation and survival of PC12 cells
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DOI：
10.1128/mcb.20.13.4494-4504.2000
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发表时间：
2000-07-01
影响因子：
5.3
通讯作者：
Vandenplas, ML
中科院分区：
文献类型：
--
作者：
Wooten, MW;Seibenhener, ML;Vandenplas, ML
非典型蛋白激酶C （aPKC）参与神经生长因子（NGF）信号传导的途径尚不清楚。我们之前报道过，在PC12细胞中，ngf诱导的丝裂原活化蛋白激酶（MAPK）的激活独立于经典和非经典PKC亚型发生，而aPKC亚型被证明是ngf诱导分化所必需的。我们观察到ngf诱导的PKC-L的激活依赖于磷脂酰肌醇3-激酶（PI3K），并导致PKC-L与Ras和Src的联合。Src （DN2）或Ras （Asn-17）显性阴性突变体的表达会破坏NGF对PKC-L的激活。在Raf-1水平上，PKC-L和PI3激酶都不需要激活；PKC-L可以弱激活MEK。PKC-L活性和PI3K抑制剂对ngf诱导的MAPK或p38激活没有影响，但会降低ngf刺激的c-Jun n末端激酶活性。Src、PI3K和PKC-L同样是ngf诱导的NF-kappa B激活和细胞存活所必需的，而Ras既不是存活所必需的，也不是NF-kappa B激活所必需的，但却是分化所必需的。IKK以PKC-L、Src和I kappa B复合物的形式存在。与Src在调节NF-kappa B活化中的作用一致，缺乏Src活性会损害PKC-L进入IKK复合物的募集，并显著损害ngf诱导的p65/NF-kappa B向细胞核的易位。这些发现表明，在PC12细胞中，aPKCs包含一个分子开关来调节下游NF-kappa B的分化和生存反应。基于这些发现，Src成为PKC-L和NF-kappa B途径的关键上游调节因子。
The pathway by which atypical protein kinase C (aPKC) contributes to nerve growth factor (NGF) signaling is poorly understood. We previously reported that in PC12 cells NGF-induced activation of mitogen-activated protein kinase (MAPK) occurs independently of classical and nonclassical PKC isoforms, whereas aPKC isoforms were shown to be required for NGF-induced differentiation. NGF-induced activation of PKC-L was observed to be dependent on phosphatidylinositol 3-kinase (PI3K) and led to coassociation of PKC-L with Ras and Src. Expression of dominant negative mutants of either Src (DN2) or Ras (Asn-17) impaired activation of PKC-L by NGF. At the level of Raf-1, neither PKC-L nor PI3 kinase was required for activation; however, PKC-L could weakly activate MEK. Inhibitors of PKC-L activity and PI3K had no effect on NGF-induced MAPK or p38 activation but reduced NGF-stimulated c-Jun N-terminal kinase activity. Src, PI3K, and PKC-L were likewise required for NGF-induced NF-kappa B activation and cell survival, whereas Ras was not required for either survival or NF-kappa B activation but was required for differentiation. IKK existed as a complex with PKC-L, Src and I kappa B. Consistent with a role for Src in regulating NF-kappa B activation, an absence of Src activity impaired recruitment of PKC-L into an IKK complex and markedly impaired NGF-induced translocation of p65/NF-kappa B to the nucleus. These findings reveal that in PC12 cells, aPKCs comprise a molecular switch to regulate differentiation and survival responses coupled downstream to NF-kappa B. On the basis of these findings, Src emerges as a critical upstream regulator of both PKC-L and the NF-kappa B pathway.