The luminal domain participates in the endosomal trafficking of the cation-independent mannose 6-phosphate receptor.
The luminal domain participates in the endosomal trafficking of the cation-independent mannose 6-phosphate receptor.
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DOI：
10.1016/j.yexcr.2006.09.024
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发表时间：
2006-12
影响因子：
3.7
通讯作者：
S. Waguri;Yuji Tomiyama;H. Ikeda;T. Hida;N. Sakai;M. Taniike;S. Ebisu;Y. Uchiyama
中科院分区：
文献类型：
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作者：
S. Waguri;Yuji Tomiyama;H. Ikeda;T. Hida;N. Sakai;M. Taniike;S. Ebisu;Y. Uchiyama
尽管阳离子非依赖性甘露糖6-磷酸受体(CIMPR)的细胞质尾部在受体转运中的作用已经得到了很好的证实，但管腔结构域的作用仍然存在争议。我们注意到，与CIMPR跨膜区和胞浆区融合的GFP(G-CIMPR-Tail)与内源性CIMPR或与全长CIMPR融合的GFP(G-CIMPR-Full)的周边分布不同。通过活细胞成像，含有G-CIMPR-Full的跨高尔基网络(TGN)来源的转运载体比含有G-CIMPR-Tail的转运载体更频繁地在外周区域停止并与含有转铁蛋白的内体重叠。与G-CIMPR-Tail相比，G-CIMPR-Full回到核周TGN的速度较慢，光漂白分析后的荧光恢复证明了这一点。此外，内源性CIMPR和G-CIMPR-Full，而不是GFP-CIMPR-Tail，显著改变了氯喹处理后的特征分布。突变受体G-CIMPR-Full R/A不能识别甘露糖6-磷酸(M6P)信号，其行为与G-CIMPR-Full相似，表明这些差异不是M6P配体结合情况所致。有趣的是，我们还发现U18666A处理能够区分M6P配体结合依赖的CIMPR转运。基于这些发现，我们认为CIMPR管腔结构域是与内细胞室紧密相互作用所必需的，并被它们保留，并且还有额外的运输步骤，其中涉及与M6P-配体的结合。
Although the role of the cytoplasmic tail of the cation-independent mannose 6-phosphate receptor (CIMPR) has been well established in the receptor trafficking, that of the luminal domain is still controversial. We noticed that the peripheral distribution of GFP, fused to the transmembrane and cytoplasmic domains of CIMPR (G-CIMPR-tail), was distinct from that of endogenous CIMPR or of GFP fused to the full-length CIMPR (G-CIMPR-full). By live-cell imaging, trans-Golgi-network (TGN)-derived transport carriers containing G-CIMPR-full more frequently stopped and overlapped with transferrin-containing endosomes in the peripheral region than those containing G-CIMPR-tail. G-CIMPR-full was recycled back to the perinuclear TGN more slowly than that for G-CIMPR-tail, evidenced by fluorescence recovery after photobleaching analysis. Moreover, endogenous CIMPR and G-CIMPR-full, but not GFP-CIMPR-tail, drastically altered the characteristic distribution after treatment with chloroquine. A mutant receptor, G-CIMPR-full R/A, that cannot recognize the mannose 6-phosphate (M6P)-signal, behaved similarly to G-CIMPR-full, indicating that these differences are not attributable to the M6P-ligands binding situation. Interestingly, we also found that U18666A treatment was able to discriminate the M6P-ligand binding-dependent trafficking of CIMPR. Based on these findings, we propose that the CIMPR luminal domain is required for tight interaction with endocytic compartments, and retention by them, and that there are additional transport steps, in which the binding to M6P-ligands is involved.