Tcl1 enhances Akt kinase activity and mediates its nuclear translocation.
Tcl1 enhances Akt kinase activity and mediates its nuclear translocation.
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DOI：
10.1073/pnas.97.7.3028
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发表时间：
2000
影响因子：
11.1
通讯作者：
Y. Pekarsky;A. Koval;C. Hallas;R. Bichi;M. Tresini;S. Malstrom;G. Russo;P. Tsichlis;C. Croce
中科院分区：
文献类型：
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作者：
Y. Pekarsky;A. Koval;C. Hallas;R. Bichi;M. Tresini;S. Malstrom;G. Russo;P. Tsichlis;C. Croce
位于14q32.1的TCL 1癌基因参与人类成熟T细胞白血病的发展。Tcl 1的作用机制尚不清楚。由于含有v-akt癌基因的病毒导致小鼠T细胞淋巴瘤，Akt是T细胞中抗凋亡和增殖信号转导的关键参与者，我们研究了Akt和Tcl 1是否在相同的通路中起作用。免疫共沉淀实验表明，内源性Akt 1和Tcl 1物理相互作用的T细胞白血病细胞系SupT 11，这两种蛋白质也相互作用时，共转染到293细胞。在共转染实验中使用几种AKT 1构建体，我们确定这种相互作用是通过Akt 1蛋白的pleckstrin同源结构域发生的。我们进一步证明，在用Tcl 1转染的293细胞中，与Tcl 1结合的内源性Akt 1的活性是不与Tcl 1结合的Akt 1的5-10倍。采用免疫荧光法研究了Tcl 1和Akt 1在小鼠成纤维细胞中的细胞内定位。当单独转染时，Akt 1仅存在于细胞质中，而Tcl 1定位于细胞质和细胞核中。有趣的是，当AKT 1与TCL 1共转染时，Akt 1也在细胞核中被发现，这表明TCL 1促进Akt 1向细胞核的转运。当Tcl 1或Akt 1分别局限于特定的细胞室时，Akt 1或Tcl 1的细胞内定位支持这些发现。因此，我们证明，Tcl 1是Akt 1的辅助因子，增强Akt 1激酶活性，促进其核转运。
The TCL1 oncogene at 14q32.1 is involved in the development of human mature T-cell leukemia. The mechanism of action of Tcl1 is unknown. Because the virus containing the v-akt oncogene causes T-cell lymphoma in mice and Akt is a key player in transduction of antiapoptotic and proliferative signals in T-cells, we investigated whether Akt and Tcl1 function in the same pathway. Coimmunoprecipitation experiments showed that endogenous Akt1 and Tcl1 physically interact in the T-cell leukemia cell line SupT11; both proteins also interact when cotransfected into 293 cells. Using several AKT1 constructs in cotransfection experiments, we determined that this interaction occurs through the pleckstrin homology domain of the Akt1 protein. We further demonstrated that, in 293 cells transfected with TCL1, the endogenous Akt1 bound to Tcl1 is 5-10 times more active compared with Akt1 not bound to Tcl1. The intracellular localization of Tcl1 and Akt1 in mouse fibroblasts was investigated by immunofluorescence. When transfected alone, Akt1 was found only in cytoplasm whereas Tcl1 was localized in the cytoplasm and in the nucleus. Interestingly, Akt1 was also found in the nucleus when AKT1 was cotransfected with TCL1, suggesting that Tcl1 promotes the transport of Akt1 to the nucleus. These findings were supported by the intracellular localization of Akt1 or Tcl1 when Tcl1 or Akt1, respectively, were confined to the specific cellular compartments. Thus, we demonstrate that Tcl1 is a cofactor of Akt1 that enhances Akt1 kinase activity and promotes its nuclear transport.