Involvement of protein kinase Cepsilon (PKCepsilon) in thyroid cell death. A truncated chimeric PKCepsilon cloned from a thyroid cancer cell line protects thyroid cells from apoptosis.
Involvement of protein kinase Cepsilon (PKCepsilon) in thyroid cell death. A truncated chimeric PKCepsilon cloned from a thyroid cancer cell line protects thyroid cells from apoptosis.
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DOI：
10.1074/jbc.274.33.23414
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发表时间：
1999-08
期刊：
影响因子：
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通讯作者：
J. Knauf;R. Elisei;D. Mochly‐Rosen;T. Liron;Xiao Ning Chen;R. Gonsky;J. Korenberg;J. Fagin
中科院分区：
文献类型：
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作者：
J. Knauf;R. Elisei;D. Mochly‐Rosen;T. Liron;Xiao Ning Chen;R. Gonsky;J. Korenberg;J. Fagin
蛋白激酶C（PKC）家族参与细胞凋亡的调节。然而，单个PKC同工酶对这一过程的贡献还不清楚。我们报道了28%的甲状腺肿瘤和WRO甲状腺癌细胞系中染色体2 p21位点的扩增。通过定位克隆，我们确定了一个重排和扩增的PKC 3基因，映射到2 p21，在WRO细胞。这导致嵌合/截短的PKC β（Tr-PKC β）mRNA的过表达，其编码与不相关序列融合的同工酶的N-末端氨基酸1-116。在PCCL 3细胞中表达的Tr-PKC 3蛋白抑制激活诱导的内源性PKC 3易位，但其激酶活性不受影响，与突变蛋白对激活诱导的野生型PKC 3易位和/或同工酶移位到异常亚细胞位置的显性负效应一致。表达Tr-PKC β的细胞系生长至比对照更高的饱和密度。此外，表达Tr-PKC β的细胞对凋亡具有抗性，这与较高的Bcl-2水平、p53稳定性的显著损害和Bax表达的抑制有关。这些发现指出了PKC β在甲状腺细胞凋亡信号通路中的作用，并表明天然存在的PKC β突变体作为显性阴性可以阻断由各种刺激引发的细胞死亡。
The protein kinase C (PKC) family has been implicated in the regulation of apoptosis. However, the contribution of individual PKC isozymes to this process is not well understood. We reported amplification of the chromosome 2p21 locus in 28% of thyroid neoplasms, and in the WRO thyroid carcinoma cell line. By positional cloning we identified a rearrangement and amplification of the PKCepsilon gene, that maps to 2p21, in WRO cells. This resulted in the overexpression of a chimeric/truncated PKCepsilon (Tr-PKCepsilon) mRNA, coding for N-terminal amino acids 1-116 of the isozyme fused to an unrelated sequence. Expression of the Tr-PKCepsilon protein in PCCL3 cells inhibited activation-induced translocation of endogenous PKCepsilon, but its kinase activity was unaffected, consistent with a dominant negative effect of the mutant protein on activation-induced translocation of wild-type PKCepsilon and/or displacement of the isozyme to an aberrant subcellular location. Cell lines expressing Tr-PKCepsilon grew to a higher saturation density than controls. Moreover, cells expressing Tr-PKCepsilon were resistant to apoptosis, which was associated with higher Bcl-2 levels, a marked impairment in p53 stabilization, and dampened expression of Bax. These findings point to a role for PKCepsilon in apoptosis-signaling pathways in thyroid cells, and indicate that a naturally occurring PKCepsilon mutant that functions as a dominant negative can block cell death triggered by a variety of stimuli.