Motor Neuron-specific Disruption of Proteasomes, but not Autophagy, Replicates Amyotrophic Lateral Sclerosis.

Kyoto University Graduate School of Medicine, Japan
Journal of Biological Chemistry (Impact Factor: 4.6). 10/2012; DOI: 10.1074/jbc.M112.417600
Source: PubMed

ABSTRACT Evidence suggests that protein misfolding is crucially involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). However, controversy still exists regarding the involvement of proteasomes or autophagy in ALS due to previous conflicting results. Here, we show that impairment of the ubiquitin-proteasome system, but not the autophagy-lysosome system in motor neurons replicates ALS in mice. Conditional knockout mice of the proteasome subunit Rpt3 in a motor neuron-specific manner (Rpt3-CKO) showed locomotor dysfunction accompanied by progressive motor neuron loss and gliosis. Moreover, diverse ALS-linked proteins, including TAR DNA binding protein 43 kDa (TDP-43), fused in sarcoma (FUS), ubiquilin 2, and optineurin were mislocalized or accumulated in motor neurons, together with other typical ALS hallmarks such as basophilic inclusion bodies. On the other hand, motor neuron-specific knockout of Atg7, a crucial component for the induction of autophagy (Atg7-CKO), only resulted in cytosolic accumulation of ubiquitin and p62, and no TDP-43 or FUS pathologies or motor dysfunction was observed. These results strongly suggest that proteasomes, but not autophagy, fundamentally govern the development of ALS in which TDP-43 and FUS proteinopathy may play a crucial role. Enhancement of proteasome activity may be a promising strategy for the treatment of ALS.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Autophagy-linked FYVE (Alfy) is a protein implicated in the selective degradation of aggregated proteins. In our present study, we found that Alfy was recruited into the aggregated G93A-SOD1 in transgenic mice with amyotrophic lateral sclerosis (ALS). We demonstrated that Alfy overexpression could decrease the expression of mutant proteins via the autophagosome-lysosome pathway, and thereby, the toxicity of mutant proteins was reduced. The clearance of the mutant proteins in NSC34 cells was significantly inhibited in an Alfy knockdown cellular model. We therefore deduced that Alfy translocalization likely is involved in the pathogenesis of ALS. Alfy may be developed into a useful target for ALS therapy.
    In Vitro Cellular & Developmental Biology - Animal 11/2014; 51(3). DOI:10.1007/s11626-014-9832-4 · 1.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Many neurodegenerative disorders are linked to irreversible protein aggregation, a process that usually comes along with toxicity and serious cellular damage. However, it is emerging that protein aggregation can also serve for physiological purposes, as impressively shown for prions. While the aggregation of this protein family was initially considered exclusively toxic in mammalians organisms, it is now almost clear that many other proteins adopt prion-like attributes to rationally polymerize into higher order complexes with organized physiologic roles. This implies that cells can tolerate at least in some measure the accumulation of inherently dangerous protein aggregates for functional profit. This review summarizes currently known strategies that living organisms adopt to preserve beneficial aggregation, and to prevent the catastrophic accumulation of toxic aggregates that frequently accompany neurodegeneration.
    Frontiers in Cellular Neuroscience 02/2015; 9. DOI:10.3389/fncel.2015.00045 · 4.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Prion diseases are fatal neurodegenerative disorders. Pathology is closely linked to the misfolding of native cellular PrPC into the disease-associated form PrPSc that accumulates in the brain as disease progresses. Although treatments have yet to be developed, strategies aimed at stimulating the degradation of PrPSc have shown efficacy in experimental models of prion disease. Here, we describe the cellular pathways that mediate PrPSc degradation and review possible targets for therapeutic intervention. This article is part of a Special Issue entitled ‘Neuronal Protein’.
    Molecular and Cellular Neuroscience 01/2015; 66. DOI:10.1016/j.mcn.2014.12.009 · 3.73 Impact Factor