Rab5 and Alsin regulate stress-activated cytoprotective signaling on mitochondria
Mitochondrial stress response is essential for cell survival, and damaged mitochondria are a hallmark of neurodegenerative diseases. Thus, it is fundamental to understand how mitochondria relay information within the cell. Here, by investigating mitochondrial-endosomal contact sites we made the surprising observation that the small GTPase Rab5 translocates from early endosomes to mitochondria upon oxidative stress. This process is reversible and accompanied by an increase in Rab5-positive endosomes in contact with mitochondria. Interestingly, activation of Rab5 on mitochondria depends on the Rab5-GEF ALS2/Alsin, encoded by a gene mutated in amyotrophic lateral sclerosis (ALS). Alsin-deficient human induced pluripotent stem cell-derived spinal motor neurons are defective in relocating Rab5 to mitochondria and display increased susceptibility to oxidative stress. These findings define a novel pathway whereby Alsin catalyzes the assembly of the Rab5 endocytic machinery on mitochondria. Defects in stress-sensing by endosomes could be crucial for mitochondrial quality control during the onset of ALS.
Article and author information
Human Frontier Science Program
- FoSheng Hsu
Max-Planck-Gesellschaft (Open-access funding)
- Marino Zerial
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Margaret S. Robinson, University of Cambridge, United Kingdom
- Received: September 25, 2017
- Accepted: February 20, 2018
- Accepted Manuscript published: February 22, 2018 (version 1)
- Version of Record published: March 12, 2018 (version 2)
- Version of Record updated: August 7, 2018 (version 3)
© 2018, Hsu et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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