Primary cilia membrane assembly is initiated by Rab11 and transport protein particle II (TRAPPII) complex-dependent trafficking of Rabin8 to the centrosome
Primary cilia membrane assembly is initiated by Rab11 and transport protein particle II (TRAPPII) complex-dependent trafficking of Rabin8 to the centrosome
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DOI：
10.1073/pnas.1018823108
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发表时间：
2011-02-15
影响因子：
11.1
通讯作者：
Jackson, Peter K.
中科院分区：
文献类型：
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作者：
Westlake, Christopher J.;Baye, Lisa M.;Jackson, Peter K.
感觉和信号通路在初级纤毛中组织得很巧妙。Bardet-Biedl综合征(BBS)患者纤毛和信号受损。BBS蛋白形成BBSome，与Rabin8结合，Rabin8是一种鸟嘌呤核苷酸交换因子(Genf)，激活Rab8 GTP酶，是纤毛组装所必需的。我们现在描述了血清调节的上游囊泡运输事件导致中心体Rab8的激活和睫状膜的形成。利用活体显微成像技术，我们发现在撤除血清后，可以观察到Rab8在大约100分钟内组装好睫状膜。依赖Rab8的纤毛组装是由Rabin8到Rab11阳性小泡的重新定位启动的，这些小泡被运输到中心体。纤毛发生后，Rab8纤毛运输明显减少，这种减少似乎与Rabin8中心体聚集减少有关。Rab11-GTP与Rabin8 COOH末端区域结合，是Rabin8纤毛膜运输到中心体和纤毛发生所必需的。以斑马鱼为模型生物，我们发现Rabin8和Rab11与BBS途径相关。最后，通过串联亲和纯化和质谱分析，我们确定运输蛋白颗粒(TRapp)II复合体与Rabin8氨基末端结构域结合，并表明TRapp II亚单位与中心体Rabin8共定位，是Rabin8纤毛靶向和纤毛发生所必需的。
Sensory and signaling pathways are exquisitely organized in primary cilia. Bardet-Biedl syndrome (BBS) patients have compromised cilia and signaling. BBS proteins form the BBSome, which binds Rabin8, a guanine nucleotide exchange factor (GEF) activating the Rab8 GTPase, required for ciliary assembly. We now describe serum-regulated upstream vesicular transport events leading to centrosomal Rab8 activation and ciliary membrane formation. Using live microscopy-imaging, we show that upon serum withdrawal Rab8 is observed to assemble the ciliary membrane in similar to 100 min. Rab8-dependent ciliary assembly is initiated by the relocalization of Rabin8 to Rab11-positive vesicles that are transported to the centrosome. After ciliogenesis, Rab8 ciliary transport is strongly reduced, and this reduction appears to be associated with decreased Rabin8 centrosomal accumulation. Rab11-GTP associates with the Rabin8 COOH-terminal region and is required for Rabin8 preciliary membrane trafficking to the centrosome and for ciliogenesis. Using zebrafish as a model organism, we show that Rabin8 and Rab11 are associated with the BBS pathway. Finally, using tandem affinity purification and mass spectrometry, we determined that the transport protein particle (TRAPP) II complex associates with the Rabin8 NH2-terminal domain and show that TRAPP II subunits colocalize with centrosomal Rabin8 and are required for Rabin8 preciliary targeting and ciliogenesis.