Cbl-mediated ubiquitinylation and negative regulation of Vav
Cbl-mediated ubiquitinylation and negative regulation of Vav
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DOI：
10.1074/jbc.m305656200
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发表时间：
2003-10-03
影响因子：
4.8
通讯作者：
Band, H
中科院分区：
文献类型：
--
作者：
Miura-Shimura, Y;Duan, L;Band, H
Cbl泛素连接酶已成为受体和非受体酪氨酸激酶的负调节因子。已知Cbl与原癌基因产物Vav相关，Vav是一种造血限制性Rac鸟嘌呤核苷酸交换因子，但这种相互作用的后果仍有待阐明。利用Cbl（+/+）和Cbl（-/-）小鼠的永生化T细胞系，以及对293T细胞的转染分析，我们证明了在促进Cbl和Vav磷酸化的条件下，Vav发生了Cbl依赖的泛素化。与Cbl的相互作用也诱导磷酸化Vav的丢失。此外，我们发现激活的Vav突变体（Vav- y174f）对ccl依赖性泛素化更敏感。我们证明了Cbl依赖的Vav泛素化需要Cbl/Vav通过磷酸化Cbl上的Tyr-700结合，并且还需要一个完整的Cbl环指结构域。最后，通过对Jurkat T细胞系的转染分析，我们发现Cbl，而不是其泛素连接酶突变体，可以抑制vav依赖的信号传导。因此，我们的研究结果强烈支持Cbl通过其泛素连接酶活性作为活化Vav的负调节因子的作用。
The Cbl ubiquitin ligase has emerged as a negative regulator of receptor and non-receptor tyrosine kinases. Cbl is known to associate with the proto-oncogene product Vav, a hematopoietic-restricted Rac guanine nucleotide exchange factor, but the consequences of this interaction remain to be elucidated. Using immortalized T cell lines from Cbl(+/+) and Cbl(-/-) mice, and transfection analyses in 293T cells, we demonstrate that Vav undergoes Cbl-dependent ubiquitinylation under conditions that promote Cbl and Vav phosphorylation. Interaction with Cbl also induced the loss of phosphorylated Vav. In addition, we show that an activated Vav mutant (Vav-Y174F) is more sensitive to Cbl-dependent ubiquitinylation. We demonstrate that the Cbl-dependent ubiquitinylation of Vav requires Cbl/Vav association through phosphorylated Tyr-700 on Cbl, and also requires an intact Cbl RING finger domain. Finally, using transfection analyses in the Jurkat T cell line, we show that Cbl, but not its ubiquitin ligase mutant, can inhibit Vav-dependent signaling. Thus, our findings strongly support the role of Cbl, via its ubiquitin ligase activity, as a negative regulator of activated Vav.