C9orf72-catalyzed GTP loading of Rab39A enables HOPS-mediated membrane tethering and fusion in mammalian autophagy

  • Nat Commun. 2023 Oct 11;14(1):6360. doi: 10.1038/s41467-023-42003-0.
Shen Zhang  #  1 ,  Mindan Tong  #  1 ,  Denghao Zheng  1 ,  Huiying Huang  1 ,  Linsen Li  1 ,  Christian Ungermann  2  3 ,  Yi Pan  1 ,  Hanyan Luo  1 ,  Ming Lei  4  5 ,  Zaiming Tang  1 ,  Wan Fu  1 ,  She Chen  6 ,  Xiaoxia Liu  7 ,  Qing Zhong  8
Affiliations
  • 1. Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
  • 2. Osnabrück University, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany.
  • 3. Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany.
  • 4. State Key Laboratory of Oncogenes and Related Genes, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China.
  • 5. Shanghai Institute of Precision Medicine, 200125, Shanghai, China.
  • 6. National Institute of Biological Sciences, 102206, Beijing, China.
  • 7. Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China. [email protected].
  • 8. Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China. [email protected].
  • # Contributed equally.
PMID: 37821429 DOI: 10.1038/s41467-023-42003-0
Abstract

The multi-subunit homotypic fusion and vacuole protein sorting (HOPS) membrane-tethering complex is required for autophagosome-lysosome fusion in mammals, yet reconstituting the mammalian HOPS complex remains a challenge. Here we propose a "hook-up" model for mammalian HOPS complex assembly, which requires two HOPS sub-complexes docking on membranes via membrane-associated Rabs. We identify Rab39A as a key small GTPase that recruits HOPS onto autophagic vesicles. Proper pairing with Rab2 and Rab39A enables HOPS complex assembly between proteoliposomes for its tethering function, facilitating efficient membrane fusion. GTP loading of Rab39A is important for the recruitment of HOPS to autophagic membranes. Activation of Rab39A is catalyzed by C9orf72, a Guanine exchange factor associated with Amyotrophic Lateral Sclerosis and familial frontotemporal dementia. Constitutive activation of Rab39A can rescue Autophagy defects caused by C9orf72 depletion. These results therefore reveal a crucial role for the C9orf72-Rab39A-HOPS axis in autophagosome-lysosome fusion.