ABSTRACT
Despite being an autosomal dominant disorder caused by a known coding mutation in the gene HTT, Huntington's disease (HD) patients with similar trinucleotide repeat mutations can have an age of onset that varies by decades. One likely contributing factor is the genetic heterogeneity of patients that might modify their vulnerability to disease. We report that although the heterozygous depletion of the autophagy adaptor protein Alfy/Wdfy3 has no consequence in control mice, it significantly accelerates age of onset and progression of HD pathogenesis. Alfy is required in the adult brain for the autophagy-dependent clearance of proteinaceous deposits, and its depletion in mice and neurons derived from patient fibroblasts accelerates the aberrant accumulation of this pathological hallmark shared across adult-onset neurodegenerative diseases. These findings indicate that selectively compromising the ability to eliminate aggregated proteins is a pathogenic driver, and the selective elimination of aggregates may confer disease resistance.
Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Autophagy-Related Proteins/genetics , Huntington Disease/genetics , Macroautophagy/genetics , Neurons/metabolism , Protein Aggregation, Pathological/genetics , Age of Onset , Animals , Cell Death/genetics , Disease Models, Animal , Female , Fibroblasts , Humans , Huntingtin Protein/genetics , Huntingtin Protein/metabolism , Huntington Disease/metabolism , Huntington Disease/physiopathology , Male , Mice , Mice, Knockout , Protein Aggregation, Pathological/metabolism , Protein Aggregation, Pathological/physiopathologyABSTRACT
The regulation of protein degradation is essential for maintaining the appropriate environment to coordinate complex cell signaling events and to promote cellular remodeling. The Autophagy linked FYVE protein (Alfy), previously identified as a molecular scaffold between the ubiquitinated cargo and the autophagic machinery, is highly expressed in the developing central nervous system, indicating that this pathway may have yet unexplored roles in neurodevelopment. To examine this possibility, we used mouse genetics to eliminate Alfy expression. We report that this evolutionarily conserved protein is required for the formation of axonal tracts throughout the brain and spinal cord, including the formation of the major forebrain commissures. Consistent with a phenotype reflecting a failure in axon guidance, the loss of Alfy in mice disrupts localization of glial guidepost cells, and attenuates axon outgrowth in response to Netrin-1. These findings further support the growing indication that macroautophagy plays a key role in the developing CNS.
