Lamb Christopher A, Nühlen Stefanie, Judith Delphine, Frith David, Snijders Ambrosius P, Behrends Christian, Tooze Sharon A
Molecular Cell Biology of Autophagy Group, Francis Crick Institute, London, UK.
Institute of Biochemistry II, Medical School Goethe University, Frankfurt, Germany.
EMBO J. 2016 Feb 1;35(3):281-301. doi: 10.15252/embj.201592695. Epub 2015 Dec 28.
Macroautophagy requires membrane trafficking and remodelling to form the autophagosome and deliver its contents to lysosomes for degradation. We have previously identified the TBC domain-containing protein, TBC1D14, as a negative regulator of autophagy that controls delivery of membranes from RAB11-positive recycling endosomes to forming autophagosomes. In this study, we identify the TRAPP complex, a multi-subunit tethering complex and GEF for RAB1, as an interactor of TBC1D14. TBC1D14 binds to the TRAPP complex via an N-terminal 103 amino acid region, and overexpression of this region inhibits both autophagy and secretory traffic. TRAPPC8, the mammalian orthologue of a yeast autophagy-specific TRAPP subunit, forms part of a mammalian TRAPPIII-like complex and both this complex and TBC1D14 are needed for RAB1 activation. TRAPPC8 modulates autophagy and secretory trafficking and is required for TBC1D14 to bind TRAPPIII. Importantly, TBC1D14 and TRAPPIII regulate ATG9 trafficking independently of ULK1. We propose a model whereby TBC1D14 and TRAPPIII regulate a constitutive trafficking step from peripheral recycling endosomes to the early Golgi, maintaining the cycling pool of ATG9 required for initiation of autophagy.
巨自噬需要膜运输和重塑以形成自噬体，并将其内容物输送到溶酶体进行降解。我们之前已确定含TBC结构域的蛋白TBC1D14是自噬的负调节因子，它控制从RAB11阳性再循环内体到形成中的自噬体的膜运输。在本研究中，我们确定TRAPP复合物（一种多亚基拴系复合物和RAB1的鸟苷酸交换因子）是TBC1D14的相互作用蛋白。TBC1D14通过N端103个氨基酸区域与TRAPP复合物结合，该区域的过表达会抑制自噬和分泌运输。TRAPPC8是酵母自噬特异性TRAPP亚基的哺乳动物同源物，它构成哺乳动物TRAPPIII样复合物的一部分，并且该复合物和TBC1D14都是RAB1激活所必需的。TRAPPC8调节自噬和分泌运输，并且是TBC1D14结合TRAPPIII所必需的。重要的是，TBC1D14和TRAPPIII独立于ULK1调节ATG9的运输。我们提出了一个模型，即TBC1D14和TRAPPIII调节从外周再循环内体到早期高尔基体的组成型运输步骤，维持自噬起始所需的ATG9循环池。
