Goodwin Jonathan M, Walkup Ward G, Hooper Kirsty, Li Taoyingnan, Kishi-Itakura Chieko, Ng Aylwin, Lehmberg Timothy, Jha Archana, Kommineni Sravya, Fletcher Katherine, Garcia-Fortanet Jorge, Fan Yaya, Tang Qing, Wei Menghao, Agrawal Asmita, Budhe Sagar R, Rouduri Sreekanth R, Baird Dan, Saunders Jeff, Kiselar Janna, Chance Mark R, Ballabio Andrea, Appleton Brent A, Brumell John H, Florey Oliver, Murphy Leon O
Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA.
Signalling Programme, Babraham Institute, Cambridge, UK.
Sci Adv. 2021 Oct;7(40):eabj2485. doi: 10.1126/sciadv.abj2485. Epub 2021 Oct 1.
Adaptive changes in lysosomal capacity are driven by the transcription factors TFEB and TFE3 in response to increased autophagic flux and endolysosomal stress, yet the molecular details of their activation are unclear. LC3 and GABARAP members of the ATG8 protein family are required for selective autophagy and sensing perturbation within the endolysosomal system. Here, we show that during the conjugation of ATG8 to single membranes (CASM), Parkin-dependent mitophagy, and -induced xenophagy, the membrane conjugation of GABARAP, but not LC3, is required for activation of TFEB/TFE3 to control lysosomal capacity. GABARAP directly binds to a previously unidentified LC3-interacting motif (LIR) in the FLCN/FNIP tumor suppressor complex and mediates sequestration to GABARAP-conjugated membrane compartments. This disrupts FLCN/FNIP GAP function toward RagC/D, resulting in impaired substrate-specific mTOR-dependent phosphorylation of TFEB. Thus, the GABARAP-FLCN/FNIP-TFEB axis serves as a molecular sensor that coordinates lysosomal homeostasis with perturbations and cargo flux within the autophagy-lysosomal network.
溶酶体容量的适应性变化由转录因子TFEB和TFE3驱动，以响应自噬通量增加和内溶酶体应激，但其激活的分子细节尚不清楚。ATG8蛋白家族的LC3和GABARAP成员对于内溶酶体系统内的选择性自噬和感知扰动是必需的。在这里，我们表明，在ATG8与单膜结合（CASM）、帕金依赖性线粒体自噬和诱导的异种自噬过程中，GABARAP而非LC3的膜结合对于激活TFEB/TFE3以控制溶酶体容量是必需的。GABARAP直接与FLCN/FNIP肿瘤抑制复合物中一个先前未鉴定的LC3相互作用基序（LIR）结合，并介导隔离至与GABARAP结合的膜区室。这破坏了FLCN/FNIP对RagC/D的GAP功能，导致TFEB的底物特异性mTOR依赖性磷酸化受损。因此，GABARAP-FLCN/FNIP-TFEB轴作为一种分子传感器，可协调溶酶体稳态与自噬-溶酶体网络内的扰动和货物通量。
