Regulation of Ly49D/DAP12 signal transduction by Src-family kinases and CD451,2
Regulation of Ly49D/DAP12 signal transduction by Src-family kinases and CD451,2
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DOI：
10.4049/jimmunol.176.11.6615
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发表时间：
2006-06-01
影响因子：
4.4
通讯作者：
McVicar, Daniel W.
中科院分区：
文献类型：
--
作者：
Mason, Llewellyn H.;Willette-Brown, Jami;McVicar, Daniel W.
活化的，DAP 12偶联的NK细胞受体Ly-49家族成员有助于控制小鼠的病毒感染。然而，激酶和/或磷酸酶介导的Ly-49 D相关的DAP 12的酪氨酸磷酸化尚未阐明。在这项研究中，我们首次表明，Src家族酪氨酸激酶的物理和功能与小鼠NK细胞中的Ly-49 D/DAP 12信号。具体而言，我们证明了以下内容：1）Src家族激酶的抑制抑制DAP 12磷酸化和下游DAP 12信号; 2）Fyn和Lck都能够磷酸化DAP 12;以及3）两种激酶都与NK细胞中的Ly-49 D/DAP 12复合物免疫共沉淀。尽管我们检测到NK细胞中Ly-49 D交联后Fyn的磷酸化增强，但Fyn（-/-）和Fyn/Lck（-/-）小鼠中的Ly-49 D介导的事件似乎是正常的，加强了Src家族激酶启动激活事件的能力冗余的主题。与特定Src家族酶的破坏相反，Ly-49 D/DAP 12介导的CD 45无效NK细胞的钙动员和细胞因子产生是有缺陷的。虽然其他人认为CD 45突变的作用仅仅是对Src家族活性的抑制，但我们在本研究中证明，在CD 45缺失的NK细胞中，DAP 12过度磷酸化，导致Ly-49 D连接后酪氨酸介导的信号传导不协调。因此，尽管我们的数据与DAP 12信号传导中的Src激酶活性接近一致，但DAP 12似乎也是CD 45的底物，表明这种磷酸酶的作用比以前报道的更复杂。
Activating, DAP12-coupled members of the Ly-49 family of NK cell receptors help control viral infections in mice. However, the kinases and/or phosphatases mediating tyrosine phosphorylation of Ly-49D-associated DAP12 have not been elucidated. In this study, we show for the first time that Src family tyrosine kinases are physically and functionally associated with Ly-49D/DAP12 signaling in murine NK cells. Specifically, we demonstrate the following: 1) inhibition of Src family kinases suppresses DAP12 phosphorylation and downstream DAP12 signals; 2) both Fyn and Lck are capable of phosphorylating DAP12; and 3) both kinases coimmunoprecipitate with the Ly-49D/DAP12 complex in NK cells. Although we detect enhanced phosphorylation of Fyn upon Ly-49D cross-linking in NK cells, Ly-49D-mediated events in both Fyn(-/-) and Fyn/Lck(-/-) mice appear normal, reinforcing the theme of redundancy in the ability of Src family kinases to initiate activation events. In contrast to disruption of specific Src family enzymes, Ly-49D/DAP12-mediated calcium mobilization and cytokine production by CD45 null NK cells are defective. Although others have ascribed the effects of CD45 mutation solely on the suppression of Src family activity, we demonstrate in this study that DAP12 is hyperphosphorylated in CD45 null NK cells, resulting in uncoordinated tyrosine-mediated signaling upon Ly-49D ligation. Therefore, although our data are consistent with a Src kinase activity proximally within DAP12 signaling, DAP12 also appears to be a substrate of CD45, suggesting a more complex role for this phosphatase than has been reported previously.