Endophilin-A Deficiency Induces the Foxo3a-Fbxo32 Network in the Brain and Causes Dysregulation of Autophagy and the Ubiquitin-Proteasome System

Publication date: Available online 6 October 2016
Source:Cell Reports
Author(s): John D. Murdoch, Christine M. Rostosky, Sindhuja Gowrisankaran, Amandeep S. Arora, Sandra-Fausia Soukup, Ramon Vidal, Vincenzo Capece, Siona Freytag, Andre Fischer, Patrik Verstreken, Stefan Bonn, Nuno Raimundo, Ira Milosevic
Endophilin-A, a well-characterized endocytic adaptor essential for synaptic vesicle recycling, has recently been linked to neurodegeneration. We report here that endophilin-A deficiency results in impaired movement, age-dependent ataxia, and neurodegeneration in mice. Transcriptional analysis of endophilin-A mutant mice, complemented by proteomics, highlighted ataxia- and protein-homeostasis-related genes and revealed upregulation of the E3-ubiquitin ligase FBXO32/atrogin-1 and its transcription factor FOXO3A. FBXO32 overexpression triggers apoptosis in cultured cells and neurons but, remarkably, coexpression of endophilin-A rescues it. FBXO32 interacts with all three endophilin-A proteins. Similarly to endophilin-A, FBXO32 tubulates membranes and localizes on clathrin-coated structures. Additionally, FBXO32 and endophilin-A are necessary for autophagosome formation, and both colocalize transiently with autophagosomes. Our results point to a role for endophilin-A proteins in autophagy and protein degradation, processes that are impaired in their absence, potentially contributing to neurodegeneration and ataxia.

Graphical abstract

Teaser

Regulation of protein homeostasis and autophagy has become a promising line of research in the neurodegeneration field. Murdoch et al. now find that endophilin-A, a key factor in clathrin-mediated endocytosis, regulates protein homeostasis through the Foxo3a-Fbxo32 network.


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