Arf-like Protein 3 (ARL3) Regulates Protein Trafficking and Ciliogenesis in Mouse Photoreceptors
Arf-like Protein 3 (ARL3) Regulates Protein Trafficking and Ciliogenesis in Mouse Photoreceptors
复制标题
DOI：
10.1074/jbc.m115.710954
复制
发表时间：
2016-03-25
影响因子：
4.8
通讯作者：
Baehr, Wolfgang
中科院分区：
文献类型：
--
作者：
Hanke-Gogokhia, Christin;Wu, Zhijian;Baehr, Wolfgang
Arf样蛋白3（arf-like protein 3，ARL 3）是一种广泛存在于植物和动物纤毛细胞中的小G蛋白。小鼠中Arl 3的种系缺失引起多器官纤毛病变，使人联想到Bardet-Biedl或Joubert综合征。由于光感受器被优雅地划分并且具有纤毛，我们通过产生视杆光感受器特异性（前缀（rod））和视网膜特异性（前缀（ret））Arl 3缺失来探索ARL 3（ADP核糖基化因子（Arf）样3蛋白）的功能。在前退化（杆）Arl 3（-/-）小鼠，脂质化的光转导蛋白显示出运输缺陷，与ARL 3作为脂质结合蛋白的货物置换因子的作用一致。相反，在胚胎发育过程中表达Cre重组酶的（ret）Arl 3（-/-）视杆和视锥既不形成连接纤毛，也不形成外节，并迅速退化。纤毛的缺乏推断ARL 3参与纤毛发生和轴丝形成。通过视网膜下注射表达ARL 3-EGFP的腺相关病毒颗粒，纤毛发生被挽救，变性部分逆转。有条件的敲除表型允许识别两个ARL 3功能，都在GTP结合的形式如下：一个作为参与光感受器纤毛发生的鞭毛内运输的调节剂，另一个作为货物置换因子将脂化蛋白运输到外节。令人惊讶的是，法尼基化的肌醇多磷酸磷酸酶只从内质网运输到高尔基体，从而排除了它在感光纤毛生理学中的作用。
Arf-like protein 3 (ARL3) is a ubiquitous small GTPase expressed in ciliated cells of plants and animals. Germline deletion of Arl3 in mice causes multiorgan ciliopathy reminiscent of Bardet-Biedl or Joubert syndromes. As photoreceptors are elegantly compartmentalized and have cilia, we probed the function of ARL3 (ADP-ribosylation factor (Arf)-like 3 protein) by generating rod photoreceptor-specific (prefix (rod)) and retina-specific (prefix (ret)) Arl3 deletions. In predegenerate (rod)Arl3(-/-) mice, lipidated phototransduction proteins showed trafficking deficiencies, consistent with the role of ARL3 as a cargo displacement factor for lipid-binding proteins. By contrast, (ret)Arl3(-/-) rods and cones expressing Cre recombinase during embryonic development formed neither connecting cilia nor outer segments and degenerated rapidly. Absence of cilia infers participation of ARL3 in ciliogenesis and axoneme formation. Ciliogenesis was rescued, and degeneration was reversed in part by subretinal injection of adeno-associated virus particles expressing ARL3-EGFP. The conditional knock-out phenotypes permitted identification of two ARL3 functions, both in the GTP-bound form as follows: one as a regulator of intraflagellar transport participating in photoreceptor ciliogenesis and the other as a cargo displacement factor transporting lipidated protein to the outer segment. Surprisingly, a farnesylated inositol polyphosphate phosphatase only trafficked from the endoplasmic reticulum to the Golgi, thereby excluding it from a role in photoreceptor cilia physiology.