The sphingosine 1-phosphate receptor 2 is shed in exosomes from breast cancer cells and is N-terminally processed to a short constitutively active form that promotes extracellular signal regulated kinase activation and DNA synthesis in fibroblasts.
The sphingosine 1-phosphate receptor 2 is shed in exosomes from breast cancer cells and is N-terminally processed to a short constitutively active form that promotes extracellular signal regulated kinase activation and DNA synthesis in fibroblasts.
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DOI：
10.18632/oncotarget.25658
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发表时间：
2018-06-29
期刊：
影响因子：
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通讯作者：
Pyne NJ
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文献类型：
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作者：
El Buri A;Adams DR;Smith D;Tate RJ;Mullin M;Pyne S;Pyne NJ
我们在此证明，G 蛋白偶联受体 (GPCR)、鞘氨醇 1-磷酸受体 2 (S1P2，Mr = 40 kDa) 在来自 MDA-MB-231 乳腺癌细胞的含有 hsp70+ 和 CD63+ 的外泌体中脱落。该受体被成纤维细胞摄取，在 N 端加工成较短的形式 (Mr = 36 kDa)，该形式似乎具有组成型活性，能够刺激细胞外信号调节激酶 1/2 (ERK-1/2) 途径和 DNA 合成。 S1P2 N 端截短的构建体可能对应于成纤维细胞中产生的受体的加工形式，当在 HEK293 细胞中过表达时，它被发现具有组成型活性。基于同源S1P1受体的现有晶体结构的分析表明，在非活性状态下，S1P2的N末端可能会拉紧TM1，从而维持对TM7的压缩作用。这反过来又可以稳定 TM7 和 TM6 细胞内末端之间的封闭基础状态界面。推测 S1P2 N 端肽的裂解和去除有利于 TM1 的松弛以及伴随的 TM6 和 TM7 的分离。后一转变是 G 蛋白结合的关键要素之一，需要打开 GPCR 螺旋束下方的细胞内偶联界面。因此，去除 S1P2 N 端可能会增强 G 蛋白偶联。这些发现提供了第一个证据，证明 S1P2 从外泌体中的乳腺癌细胞中释放出来，并由成纤维细胞处理以促进 ERK 信号传导和这些细胞的增殖。
We demonstrate here that the G protein-coupled receptor (GPCR), sphingosine 1-phosphate receptor 2 (S1P2, Mr = 40 kDa) is shed in hsp70+ and CD63+ containing exosomes from MDA-MB-231 breast cancer cells. The receptor is taken up by fibroblasts, where it is N-terminally processed to a shorter form (Mr = 36 kDa) that appears to be constitutively active and able to stimulate the extracellular signal regulated kinase-1/2 (ERK-1/2) pathway and DNA synthesis. An N-terminally truncated construct of S1P2, which may correspond to the processed form of the receptor generated in fibroblasts, was found to be constitutively active when over-expressed in HEK293 cells. Analysis based on the available crystal structure of the homologous S1P1 receptor suggests that, in the inactive-state, the N-terminus of S1P2 may tension TM1 so as to maintain a compressive action on TM7. This in turn may stabilise a closed basal state interface between the intracellular ends of TM7 and TM6. Cleavage and removal of the S1P2 N-terminal peptide is postulated to facilitate relaxation of TM1 and accompanying separation of TM6 and TM7. The latter transition is one of the key elements of G protein engagement and is required to open the intracellular coupling interface beneath the GPCR helix bundle. Therefore, removal at the N-terminus of S1P2 is likely to enhance G protein coupling. These findings provide the first evidence that S1P2 is released from breast cancer cells in exosomes and is processed by fibroblasts to promote ERK signaling and proliferation of these cells.