Identifying a Neuromedin U Receptor 2 Splice Variant and Determining Its Roles in the Regulation of Signaling and Tumorigenesis In Vitro.
Identifying a Neuromedin U Receptor 2 Splice Variant and Determining Its Roles in the Regulation of Signaling and Tumorigenesis In Vitro.
复制标题
DOI：
10.1371/journal.pone.0136836
复制
发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Luo CW
中科院分区：
文献类型：
--
作者：
Lin TY;Huang WL;Lee WY;Luo CW
神经素U （NMU）激活两个G蛋白偶联受体NMUR1和NMUR2；这种信号不仅控制许多生理反应，而且还促进多种组织的肿瘤发生。我们最近从人类卵巢癌cDNA中鉴定出一种通过选择性剪接衍生的新型截断的NMUR2，即NMUR2S。序列分析、细胞表面ELISA和293T细胞免疫细胞化学染色表明，NMUR2S可以作为六跨膜蛋白在细胞表面良好表达。受体下拉和荧光共振能量转移实验表明，NMUR1、NMUR2和新发现的NMUR2S不仅可以形成同型络合物，还可以形成异质络合物。虽然NMUR2S不被NMU本身激活，但结合受体定量和放射性配体结合在293T细胞中的功能分析表明，NMUR2S不会改变NMUR1或NMUR2的易位和稳定性，而是通过受体异二聚化阻断它们的NMU结合能力，有效地抑制它们的信号传导。我们进一步证明，NMU信号在人卵巢癌中显著上调，而NMUR2S的表达可以阻断内源性NMU信号，进而抑制SKOV-3卵巢癌细胞的增殖。相比之下，在表达NMUR1和NMUR2S水平相当的单核THP-1细胞中，NMUR2S的缺失恢复了NMU的信号传导和作用。因此，这些结果不仅揭示了NMU受体之间存在以前未被表征的异质关系，而且还提供了NMUR2S作为未来治疗NMU信号介导的癌症的潜在治疗靶点。
Neuromedin U (NMU) activates two G protein-coupled receptors, NMUR1 and NMUR2; this signaling not only controls many physiological responses but also promotes tumorigenesis in diverse tissues. We recently identified a novel truncated NMUR2 derived by alternative splicing, namely NMUR2S, from human ovarian cancer cDNA. Sequence analysis, cell surface ELISA and immunocytochemical staining using 293T cells indicated that NMUR2S can be expressed well on the cell surface as a six-transmembrane protein. Receptor pull-down and fluorescent resonance energy transfer assays demonstrated that NMUR1, NMUR2 and this newly discovered NMUR2S can not only form homomeric complexes but also heteromeric complexes with each other. Although not activated by NMU itself, functional assay in combination with receptor quantification and radio-ligand binding in 293T cells indicated that NMUR2S does not alter the translocation and stability of NMUR1 or NMUR2, but rather effectively dampens their signaling by blocking their NMU binding capability through receptor heterodimerization. We further demonstrated that NMU signaling is significantly up-regulated in human ovarian cancers, whereas expression of NMUR2S can block endogenous NMU signaling and further lead to suppression of proliferation in SKOV-3 ovarian cancer cells. In contrast, in monocytic THP-1 cells that express comparable levels of NMUR1 and NMUR2S, depletion of NMUR2S restored both the signaling and effect of NMU. Thus, these results not only reveal the presence of previously uncharacterized heteromeric relationships among NMU receptors but also provide NMUR2S as a potential therapeutic target for the future treatment of NMU signaling-mediated cancers.