Mutant Huntingtin Impairs Vesicle Formation from Recycling Endosomes by Interfering with Rab11 Activity
Mutant Huntingtin Impairs Vesicle Formation from Recycling Endosomes by Interfering with Rab11 Activity
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DOI：
10.1128/mcb.00420-09
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发表时间：
2009-11-15
影响因子：
5.3
通讯作者：
DiFiglia, Marian
中科院分区：
文献类型：
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作者：
Li, Xueyi;Standley, Clive;DiFiglia, Marian
亨廷顿蛋白（Htt）定位于内体，但其在内吞途径中的作用尚未确定。最近，我们发现Htt对于Rab 11的激活是重要的，Rab 11是一种参与内体再循环的GTT。在这里，我们研究了健康个体和患有亨廷顿病（HD）的患者的成纤维细胞，亨廷顿病是一种由Htt中的多聚谷氨酰胺扩增引起的运动障碍。含有转铁蛋白的胞吞囊泡在质膜上的形成在对照组和HD患者成纤维细胞中是相同的。然而，HD成纤维细胞在回收生物素转铁蛋白回到质膜延迟。HD成纤维细胞的膜支持Rab 11上的核苷酸交换比对照膜少。Rab 11阳性囊泡和管状结构在HD成纤维细胞异常大，这表明他们在形成囊泡受损。我们使用活的成纤维细胞的全内反射荧光成像来监测从再循环内体中出现的荧光标记的携带转铁蛋白的运输中间体。HD成纤维细胞有较少的小泡和更多的大泡和长小管比对照成纤维细胞。显性活性Rab 11在HD成纤维细胞中表达使生物素-转铁蛋白的再循环正常化。我们提出了一种新的机制，细胞功能障碍的HD突变所产生的Rab 11活性的抑制和缺陷的囊泡形成在回收内体。
Huntingtin (Htt) localizes to endosomes, but its role in the endocytic pathway is not established. Recently, we found that Htt is important for the activation of Rab11, a GTPase involved in endosomal recycling. Here we studied fibroblasts of healthy individuals and patients with Huntington's disease (HD), which is a movement disorder caused by polyglutamine expansion in Htt. The formation of endocytic vesicles containing transferrin at plasma membranes was the same in control and HD patient fibroblasts. However, HD fibroblasts were delayed in recycling biotin-transferrin back to the plasma membrane. Membranes of HD fibroblasts supported less nucleotide exchange on Rab11 than did control membranes. Rab11-positive vesicular and tubular structures in HD fibroblasts were abnormally large, suggesting that they were impaired in forming vesicles. We used total internal reflection fluorescence imaging of living fibroblasts to monitor fluorescence-labeled transferrin-carrying transport intermediates that emerged from recycling endosomes. HD fibroblasts had fewer small vesicles and more large vesicles and long tubules than did control fibroblasts. Dominant active Rab11 expressed in HD fibroblasts normalized the recycling of biotin-transferrin. We propose a novel mechanism for cellular dysfunction by the HD mutation arising from the inhibition of Rab11 activity and a deficit in vesicle formation at recycling endosomes.