Isolation and characterization of a novel, transforming allele of the c-Cbl proto-oncogene from a murine macrophage cell line
Isolation and characterization of a novel, transforming allele of the c-Cbl proto-oncogene from a murine macrophage cell line
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DOI：
10.1038/sj.onc.1205510
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发表时间：
2002-05-23
期刊：
影响因子：
8
通讯作者：
Robbins, SM
中科院分区：
文献类型：
--
作者：
Bisson, SA;Ujack, EE;Robbins, SM
c-Cbl原癌基因作为E3泛素连接酶通过其RING指结构域负调节激活的细胞信号转导途径。我们从鼠网状肉瘤细胞系J-774中鉴定出一种约95 kDa的异常Cbl蛋白，我们称之为p95 Cbl。p95 Cbl cDNA的克隆显示，它含有一个缺失，导致111个氨基酸的损失，消除了两个关键的酪氨酸残基的连接区，以及整个环指结构域。p95 Cbl显示出与Src家族激酶Hck相互作用的倾向，超过在相同细胞中表达的细胞Cbl。与其野生型对应物一样，p95 Cbl响应于造血细胞上的Fc γ受体接合而被诱导性酪氨酸磷酸化，然而这种磷酸化持续超过细胞Cbl的磷酸化。稳定表达p95 Cbl的NIH 3 T3成纤维细胞获得与细胞转化相关的典型可触变形态，并在焦点形成测定中形成集落。外源表达的突变蛋白在成纤维细胞中组成性磷酸化并分配到细胞的颗粒部分中，而细胞Cbl仅在细胞质中。p95 Cbl是c-Cbl原癌基因的一种新的致癌突变体，其可能以显性负性方式通过干扰通过c-Cbl的活化信号复合物的下调来延长正常细胞信号应答。
The c-Cbl proto-oncogene acts as an E3 ubiquitin ligase via its RING finger domain to negatively regulate activated cellular signal transduction pathways. We have identified an aberrant Cbl-protein of approximately 95 kDa, which we have called p95Cbl, from the murine reticulum sarcoma cell-line, J-774. Cloning of the p95Cbl cDNA revealed that it contains a deletion resulting in the loss of 111 amino acids, eliminating two critical tyrosine residues in the linker region as well as the entire RING finger domain. p95Cbl displays a propensity for its interaction with the Src-family kinase Hck over cellular Cbl expressed in the same cells. Like its wildtype counterpart, p95Cbl is inducibly tyrosine phosphorylated in response to Fcgamma receptor engagement on hematopoietic cells, however this phosphorylation is sustained beyond that of cellular Cbl. NIH3T3 fibroblasts stably expressing p95Cbl acquire the typical refractile morphology associated with cellular transformation and form colonies in a focus-formation assay. The exogenously expressed mutant protein is constitutively phosphorylated in fibroblasts and partitions into the particulate fraction of cells, while cellular Cbl is exclusively cytoplasmic. p95Cbl is a novel, oncogenic mutant of the c-Cbl proto-oncogene, which might act in a dominant negative fashion to prolong normal cellular signaling responses by interfering with the down-regulation of activated signaling complexes through c-Cbl.