title: HspB8 mutation causing hereditary distal motor neuropathy impairs lysosomal delivery of autophagosomes.
abstract: HspB8, a small heat-shock protein implicated in autophagy, is mutated in patients with distal hereditary motor neuropathy type II (dHMNII). Autophagy is essential for maintaining protein homeostasis in the central nervous system, but its role has not been investigated in peripheral motor neurons. We used a novel, multispectral-imaging flow cytometry assay to measure autophagy in cells. This assay revealed that over-expression of wild-type HspB8 in motor neuron-like NSC34 cells led to an increased co-localisation of autophagosomes with the lysosomes. By contrast, over-expression of mutant HspB8 resulted in autophagosomes that co-localised with protein aggregates but failed to co-localise with the lysosomes. A similar impairment of autophagy could also be demonstrated in peripheral blood mononuclear cells from two dHMNII patients with the HspB8(K141E) mutation. We conclude that defects in HspB8-mediated autophagy are likely to contribute to dHMNII pathology and their detection in peripheral blood mononuclear cells could be a useful, accessible biomarker for the disease.
authors: MRC Functional Genomics Unit, Department of Anatomy Physiology and Genetics, University of Oxford, South Parks Road, Oxford, UK.
authors: Alice S
authors: AS
authors: Kwok
authors: Kanchan
authors: K
authors: Phadwal
authors: Bradley J
authors: BJ
authors: Turner
authors: Peter L
authors: PL
authors: Oliver
authors: Annie
authors: A
authors: Raw
authors: Anna Katharina
authors: AK
authors: Simon
authors: Kevin
authors: K
authors: Talbot
authors: Vishwas R
authors: VR
authors: Agashe
mesh_terms: D000704:Analysis of Variance; D001343:Autophagy / Q000235:genetics*; D002478:Cells, Cultured; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics* / Q000473:pathology*; D005434:Flow Cytometry; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D007963:Leukocytes, Mononuclear; D008247:Lysosomes / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D018832:Molecular Chaperones; D009154:Mutation / Q000235:genetics*; D009447:Neuroblastoma; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D014162:Transfection / Q000379:methods
chemical_list: C413214:HSPB8 protein, human; D006360:Heat-Shock Proteins; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D018832:Molecular Chaperones; C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D017346:Protein Serine-Threonine Kinases