Identification of Transmembrane Protein 88 (TMEM88) as a Dishevelled-binding Protein
Identification of Transmembrane Protein 88 (TMEM88) as a Dishevelled-binding Protein
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DOI：
10.1074/jbc.m110.193383
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发表时间：
2010-12-31
影响因子：
4.8
通讯作者：
Zheng, Jie J.
中科院分区：
文献类型：
--
作者：
Lee, Ho-Jin;Finkelstein, David;Zheng, Jie J.
WNT信号通路参与胚胎发育和成人组织的维持，并与肿瘤的发生有关。脱发蛋白(Dvl/Dsh)是Wnt信号通路中的关键成分之一，通过蛋白质之间的相互作用在调节这些信号通路中发挥着重要作用。鉴定和鉴定DVL结合蛋白是了解生物学功能的关键步骤。由于三肽VWV(Val-Trp-Val)与DVL的PDZ结构域结合，我们搜索了公共数据库，以确定在C末端含有VWV基序的蛋白质可能是新的DVL结合伙伴。根据候选蛋白的细胞定位和表达模式，我们选择了两种跨膜型蛋白TMEM88(靶蛋白跨膜88)进行进一步研究。用核磁共振和荧光光谱证实了DVL的PDZ结构域与TMEM88的C末端相互作用。此外，在HEK293细胞中，TMEM88以剂量依赖的方式减弱Wnt-1配体诱导的Wnt/β-catenin信号转导，而RNAi敲除TMEM88可增强Wnt的活性。在非洲爪哇，TMEM88蛋白被亚阻化在细胞膜上，并抑制Xdsh诱导的Wnt信号，但不能抑制β-catenin。此外，TMEM88蛋白抑制Xdsh正常诱导的次生轴的形成。研究结果提示，TMEM88在调节Wnt信号转导中起作用。事实上，对微阵列数据的分析表明，Tmen88基因在小鼠胚胎肠道中的表达与Wnt信号相关基因的表达密切相关。总之，我们认为TMEM88与DVL蛋白结合，并以上下文相关的方式调节Wnt信号。
Wnt signaling pathways are involved in embryonic development and adult tissue maintenance and have been implicated in tumorigenesis. Dishevelled (Dvl/Dsh) protein is one of key components in Wnt signaling and plays essential roles in regulating these pathways through protein-protein interactions. Identifying and characterizing Dvl-binding proteins are key steps toward understanding biological functions. Given that the tripeptide VWV (Val-Trp-Val) binds to the PDZ domain of Dvl, we searched publically available databases to identify proteins containing the VWV motif at the C terminus that could be novel Dvl-binding partners. On the basis of the cellular localization and expression patterns of the candidates, we selected for further study the TMEM88 (target protein transmembrane 88), a two-transmembrane-type protein. The interaction between the PDZ domain of Dvl and the C-terminal tail of TMEM88 was confirmed by using NMR and fluorescence spectroscopy. Furthermore, in HEK293 cells, TMEM88 attenuated the Wnt/beta-catenin signaling induced by Wnt-1 ligand in a dose-dependent manner, and TMEM88 knockdown by RNAi increased Wnt activity. In Xenopus, TMEM88 protein is sublocalized at the cell membrane and inhibits Wnt signaling induced by Xdsh but not beta-catenin. In addition, TMEM88 protein inhibits the formation of a secondary axis normally induced by Xdsh. The findings suggest that TMEM88 plays a role in regulating Wnt signaling. Indeed, analysis of microarray data revealed that the expression of the Tmem88 gene was strongly correlated with that of Wnt signaling-related genes in embryonic mouse intestines. Together, we propose that TMEM88 associates with Dvl proteins and regulates Wnt signaling in a context-dependent manner.