Sattler M, Salgia R, Okuda K, Uemura N, Durstin M A, Pisick E, Xu G, Li J L, Prasad K V, Griffin J D
Division of Hematologic Malignancies, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
Oncogene. 1996 Feb 15;12(4):839-46.
Chronic myelogenous leukemia (CML) and some acute lymphoblastic leukemias (ALL) are caused by the t(9;22) chromosome translocation, which produces the constitutively activated BCR/ABL tyrosine kinase. When introduced into factor dependent hematopoietic cell lines, BCR/ABL induces the tyrosine phosphorylation of many cellular proteins. One prominent BCR/ABL substrate is p120CBL, the cellular homolog of the v-Cbl oncoprotein. In an effort to understand the possible contribution of p120CBL to transformation by BCR/ABL, we looked for cellular proteins which associate with p120CBL in hematopoietic cell lines transformed by BCR/ABL. In addition to p210BCR/ABL and c-ABL, p120CBL coprecipitated with an 85 kDa phosphoprotein, which was identified as the p85 subunit of PI3K. Anti-p120CBL immunoprecipitates from BCR/ABL-transformed, but not from untransformed, cell lines contained PI3K lipid kinase activity. Interestingly, the adaptor proteins CRKL and c-CRK were also found in these complexes. In vitro binding studies indicated that the SH2 domains of CRKL and c-CRK bound directly to p120CBL, while the SH3 domains of c-CRK and CRKL bound to BCR/ABL and c-ABL. The N-terminal and the C-terminal SH2 and the SH3 domain of p85PI3K bound directly in vitro to p120CBL. The ABL-SH2, but not ABL-SH3, could also bind to p120CBL. These data suggest that BCR/ABL may induce the formation of multimeric complexes of signaling proteins which include p120CBL, PI3K, c-CRK or CRKL, c-ABL and BCR/ABL itself.
慢性粒细胞白血病（CML）和一些急性淋巴细胞白血病（ALL）是由t(9;22)染色体易位引起的，该易位产生组成型激活的BCR/ABL酪氨酸激酶。当将其导入依赖因子的造血细胞系时，BCR/ABL会诱导许多细胞蛋白的酪氨酸磷酸化。一个突出的BCR/ABL底物是p120CBL，它是v-Cbl癌蛋白的细胞同源物。为了了解p120CBL对BCR/ABL转化的可能作用，我们在BCR/ABL转化的造血细胞系中寻找与p120CBL相关的细胞蛋白。除了p210BCR/ABL和c-ABL外，p120CBL还与一种85 kDa的磷蛋白共沉淀，该磷蛋白被鉴定为PI3K的p85亚基。来自BCR/ABL转化细胞系而非未转化细胞系的抗p120CBL免疫沉淀物含有PI3K脂质激酶活性。有趣的是，接头蛋白CRKL和c-CRK也存在于这些复合物中。体外结合研究表明，CRKL和c-CRK的SH2结构域直接与p120CBL结合，而c-CRK和CRKL的SH3结构域与BCR/ABL和c-ABL结合。p85PI3K的N端和C端SH2以及SH3结构域在体外直接与p120CBL结合。ABL-SH2而非ABL-SH3也能与p120CBL结合。这些数据表明，BCR/ABL可能诱导信号蛋白多聚体复合物的形成，这些复合物包括p120CBL、PI3K、c-CRK或CRKL、c-ABL以及BCR/ABL自身。
