The TGFβ Receptor-interacting Protein km23-1/DYNLRB1 Plays an Adaptor Role in TGFβ1 Autoinduction via Its Association with Ras
The TGFβ Receptor-interacting Protein km23-1/DYNLRB1 Plays an Adaptor Role in TGFβ1 Autoinduction via Its Association with Ras
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DOI：
10.1074/jbc.m112.344887
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发表时间：
2012-07-27
影响因子：
4.8
通讯作者：
Mulder, Kathleen M.
中科院分区：
文献类型：
--
作者：
Jin, Qunyan;Ding, Wei;Mulder, Kathleen M.
我们先前已经阐明了TGF β 1自身诱导所需的信号传导事件（Yue，J.，Mulder，K. M.（2000）J. Biol. Chem. 275，30765-30773）。此外，我们已经报道了TGF β受体（T β R）相互作用蛋白km 23 -1在TGF β信号转导中起重要作用（Jin，Q.，丁伟，Mulder，K. M.（2007）J.Biol.Chem.282，19122-19132）。在这里，我们研究了km 23 -1在TGF β敏感上皮细胞中TGF β 1自身诱导中的作用。km 23 -1的siRNA阻断降低了TGF β 1 mRNA表达，以及人TGF β 1启动子中相关激活蛋白-1位点的DNA结合和转录激活。此外，km 23 -1的敲低抑制了TGF β介导的ERK和JNK的活化、c-Jun的磷酸化和c-Jun启动子的反式激活。蔗糖梯度分析表明，TGF β处理后，km 23 -1与Ras和T β RII一起存在于脂筏中。免疫沉淀/印迹分析显示，在加入TGF β的几分钟内，在体内Ras和km 23 -1之间形成TGF β诱导复合物。此外，我们第一次证明了km 23 -1是TGF β激活Ras所必需的。我们的研究结果表明，km 23 -1是通过Smad 2非依赖性Ras/ERK/JNK途径进行TGF β 1自身诱导所必需的。更重要的是，我们的研究结果表明，km 23 -1的功能作为一个关键的适配器耦合T β R激活Ras效应通路下游的激活。
We have previously elucidated the signaling events that are required for TGF beta 1 autoinduction (Yue, J., and Mulder, K. M. (2000) J. Biol. Chem. 275, 30765-30773). Further, we have reported that the TGF beta receptor (T beta R)-interacting protein km23-1 plays an important role in TGF beta signal transduction (Jin, Q., Ding, W., and Mulder, K. M. (2007) J. Biol. Chem. 282, 19122-19132). Here we examined the role of km23-1 in TGF beta 1 autoinduction in TGF beta-sensitive epithelial cells. siRNA blockade of km23-1 reduced TGF beta 1 mRNA expression, as well as DNA binding and transcriptional activation of the relevant activator protein-1 site in the human TGF beta 1 promoter. Further, knockdown of km23-1 inhibited TGF beta-mediated activation of ERK and JNK, phosphorylation of c-Jun, and transactivation of the c-Jun promoter. Sucrose gradient analyses indicate that km23-1 was present in lipid rafts together with Ras and T beta RII after TGF beta treatment. Immunoprecipitation/blot analyses revealed the formation of a TGF beta-inducible complex between Ras and km23-1 in vivo within minutes of TGF beta addition. Moreover, we demonstrate for the first time that km23-1 is required for Ras activation by TGF beta. Our results indicate that km23-1 is required for TGF beta 1 autoinduction through Smad2-independent Ras/ERK/JNK pathways. More importantly, our findings demonstrate that km23-1 functions as a critical adaptor coupling T beta R activation to activation of Ras effector pathways downstream.