Retromer-mediated direct sorting is required for proper endosomal recycling of the mammalian iron transporter DMT1
Retromer-mediated direct sorting is required for proper endosomal recycling of the mammalian iron transporter DMT1
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DOI：
10.1242/jcs.060574
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发表时间：
2010-03-01
影响因子：
4
通讯作者：
Kishi, Fumio
中科院分区：
文献类型：
--
作者：
Tabuchi, Mitsuaki;Yanatori, Izumi;Kishi, Fumio
哺乳动物铁转运蛋白DMT 1的内体再循环被认为对于铁在转铁蛋白循环中穿过内体膜的有效和快速摄取是重要的。在这里，我们表明，retromer，一个复杂的，介导逆行转运的跨膜货物从内涵体的trans-Golgi网络，是必需的内涵体回收的DMT 1-II，选择性剪接异构体的DMT 1。细菌表达的Vps 26-Vsp 29-Vsp 35三聚体，一种逆转录物货物识别复合物，在体外特异性结合DMT 1-II的胞质尾区。特别是，这种结合依赖于DMT 1-II的特定疏水基序，这是其内体再循环所需的。DMT 1-II与TfR阳性内体中的逆转录聚合物的Vps 35亚基共定位。通过针对Vps 35的siRNA消耗逆转录聚合物导致DMT 1-II错误分选为LAMP 2阳性结构，并且siRNA抗性Vps 35的表达可以挽救这种效果。这些发现表明，retromer识别DMT 1-II的再循环信号，并确保其适当的内体再循环。
Endosomal recycling of the mammalian iron transporter DMT1 is assumed to be important for efficient and rapid uptake of iron across the endosomal membrane in the transferrin cycle. Here, we show that the retromer, a complex that mediates retrograde transport of transmembrane cargoes from endosomes to the trans-Golgi network, is required for endosomal recycling of DMT1-II, an alternative splicing isoform of DMT1. Bacterially expressed Vps26-Vsp29-Vsp35 trimer, a retromer cargo recognition complex, specifically binds to the cytoplasmic tail domain of DMT1-II in vitro. In particular, this binding is dependent on a specific hydrophobic motif of DMT1-II, which is required for its endosomal recycling. DMT1-II colocalizes with the Vps35 subunit of the retromer in TfR-positive endosomes. Depletion of the retromer by siRNA against Vps35 leads to mis-sorting of DMT1-II to LAMP2-positive structures, and expression of siRNA-resistant Vps35 can rescue this effect. These findings demonstrate that the retromer recognizes the recycling signal of DMT1-II and ensures its proper endosomal recycling.