de Jong R, van Wijk A, Haataja L, Heisterkamp N, Groffen J
Section of Molecular Carcinogenesis, Department of Pathology, Childrens Hospital of Los Angeles, Los Angeles, California 90027, USA.
J Biol Chem. 1997 Dec 19;272(51):32649-55. doi: 10.1074/jbc.272.51.32649.
BCR/ABL is considered responsible for the development of Philadelphia chromosome-positive leukemia. Experimental animal models, such as transgenic mice, have demonstrated unambiguously that Bcr/Abl is capable of inducing leukemogenesis. The adaptor molecule Crkl is a major in vivo substrate of the deregulated Bcr/Abl tyrosine kinase and functions as a molecular link with other signaling proteins. While associated in vivo with Bcr/Abl through its SH3 domain, Crkl can interact simultaneously via its SH2 domain with other tyrosine-phosphorylated proteins. Here we report the identification of prominently tyrosine-phosphorylated proteins with a molecular mass of approximately 110 kDa, which bind specifically to the Crkl SH2 domain in leukemic tissues of P190BCR/ABL transgenic mice. We demonstrate that these proteins are identical to Hef1/Cas-L, which is related to p130(Cas). The proto-oncoprotein p120(Cbl) and Hef1, but not p130(Cas), were detectably phosphorylated on tyrosine in P190Bcr/Abl-expressing leukemic cells and were found in complex with Crkl, showing the existence of protein complexes in P190Bcr/Abl leukemic cells, consisting of P190Bcr/Abl, Crkl, and Hef1 or p120(Cbl). This supports a model in which Crkl acts as mediator between Bcr/Abl and downstream effectors. Since Hef1 is involved in the beta1-integrin signaling pathway, our study demonstrates that Bcr/Abl could specifically interfere with normal beta1-integrin signaling.
BCR/ABL被认为与费城染色体阳性白血病的发生有关。实验动物模型，如转基因小鼠，已明确证明Bcr/Abl能够诱导白血病发生。衔接分子Crkl是失调的Bcr/Abl酪氨酸激酶的主要体内底物，并且作为与其他信号蛋白的分子连接起作用。虽然Crkl在体内通过其SH3结构域与Bcr/Abl相关联，但它可以通过其SH2结构域同时与其他酪氨酸磷酸化蛋白相互作用。在这里，我们报告鉴定出分子量约为110 kDa的显著酪氨酸磷酸化蛋白，它们在P190BCR/ABL转基因小鼠的白血病组织中特异性结合Crkl SH2结构域。我们证明这些蛋白与Hef1/Cas-L相同，Hef1/Cas-L与p130(Cas)相关。原癌蛋白p120(Cbl)和Hef1，但不是p130(Cas)，在表达P190Bcr/Abl的白血病细胞中酪氨酸可检测到磷酸化，并发现与Crkl形成复合物，表明在P190Bcr/Abl白血病细胞中存在由P190Bcr/Abl、Crkl和Hef1或p120(Cbl)组成的蛋白复合物。这支持了一种模型，其中Crkl作为Bcr/Abl和下游效应器之间的介质。由于Hef1参与β1整合素信号通路，我们的研究表明Bcr/Abl可能特异性干扰正常的β1整合素信号。
