Depletion of Csk preferentially reduces the protein level of LynA in a Cbl-dependent manner in cancer cells
Depletion of Csk preferentially reduces the protein level of LynA in a Cbl-dependent manner in cancer cells
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DOI：
10.1038/s41598-020-64624-x
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发表时间：
2020-05-06
影响因子：
4.6
通讯作者：
Yamagishi, Nobuyuki
中科院分区：
文献类型：
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作者：
Kuga, Takahisa;Yamane, Yuka;Yamagishi, Nobuyuki
人类 Src 家族酪氨酸激酶 (SFK) 有八种。 SFK 成员 c-Src、c-Yes、Fyn 和 Lyn 在多种癌细胞中表达。 SFK 激酶活性受 Csk 酪氨酸激酶负调节。 Csk 活性降低会导致 SFK 异常激活，而 SFK 可以通过依赖于 Cbl 家族泛素连接酶的补偿机制来降解。我们在此研究了在缺乏 Csk 活性的癌细胞中，所有 SFK 成员是否同样受到 Cbl 家族泛素连接酶的下调。我们对敲除 Csk 的多个癌细胞进行了蛋白质印迹，发现 Lyn 的 56kDa 同工型 (LynA)、Lyn 的 53kDa 同工型 (LynB)、c-Src 和 Fyn 的蛋白水平因 Csk 耗竭而降低，但 c-Yes 的蛋白水平没有降低。在 Csk 耗尽的细胞中也观察到 c-Cbl 蛋白水平的诱导。伴随 Csk 消耗的 LynA 减少可通过 Cbls 的敲低显着逆转，而没有观察到 LynB、c-Src 和 Fyn 的如此显着恢复。这些结果表明，在缺乏 Csk 活性的癌细胞中，LynA 被 Cbls 选择性下调。
There are eight human Src-family tyrosine kinases (SFKs). SFK members c-Src, c-Yes, Fyn, and Lyn are expressed in various cancer cells. SFK kinase activity is negatively regulated by Csk tyrosine kinase. Reduced activity of Csk causes aberrant activation of SFKs, which can be degraded by a compensatory mechanism depending on Cbl-family ubiquitin ligases. We herein investigated whether all SFK members are similarly downregulated by Cbl-family ubiquitin ligases in cancer cells lacking Csk activity. We performed Western blotting of multiple cancer cells knocked down for Csk and found that the protein levels of the 56kDa isoform of Lyn (LynA), 53kDa isoform of Lyn (LynB), c-Src, and Fyn, but not of c-Yes, were reduced by Csk depletion. Induction of c-Cbl protein levels was also observed in Csk-depleted cells. The reduction of LynA accompanying the depletion of Csk was significantly reversed by the knockdown for Cbls, whereas such significant recovery of LynB, c-Src, and Fyn was not observed. These results suggested that LynA is selectively downregulated by Cbls in cancer cells lacking Csk activity.