Levy, J.R. et al. A motor neuron disease-associated mutation in p150Glued perturbs dynactin function and induces protein aggregation. J. Cell Biol. 172, 733-745

Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
The Journal of Cell Biology (Impact Factor: 9.83). 03/2006; 172(5):733-45. DOI: 10.1083/jcb.200511068
Source: PubMed


The microtubule motor cytoplasmic dynein and its activator dynactin drive vesicular transport and mitotic spindle organization. Dynactin is ubiquitously expressed in eukaryotes, but a G59S mutation in the p150Glued subunit of dynactin results in the specific degeneration of motor neurons. This mutation in the conserved cytoskeleton-associated protein, glycine-rich (CAP-Gly) domain lowers the affinity of p150Glued for microtubules and EB1. Cell lines from patients are morphologically normal but show delayed recovery after nocodazole treatment, consistent with a subtle disruption of dynein/dynactin function. The G59S mutation disrupts the folding of the CAP-Gly domain, resulting in aggregation of the p150Glued protein both in vitro and in vivo, which is accompanied by an increase in cell death in a motor neuron cell line. Overexpression of the chaperone Hsp70 inhibits aggregate formation and prevents cell death. These data support a model in which a point mutation in p150Glued causes both loss of dynein/dynactin function and gain of toxic function, which together lead to motor neuron cell death.

Download full-text


Available from: Jennifer R Levy,
  • Source
    • "Both aggregate formation and cell death are inhibited by overexpression of Hsp70, a molecular chaperone. These findings suggest that mutant p150glued aggregates play an important role in the mechanism of cell death in HMN7B [11]. We conclude that mutant p150glued aggregates cause apoptosis via activation of the intrinsic apoptotic pathway. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mutations in p150glued cause hereditary motor neuropathy with vocal cord paralysis (HMN7B) and Perry syndrome (PS). Here we show that both overexpression of p150glued mutants and knockdown of endogenous p150glued induce apoptosis. Overexpression of a p150glued plasmid containing either a HMN7B or PS mutation resulted in cytoplasmic p150glued-positive aggregates and was associated with cell death. Cells containing mutant p150glued aggregates underwent apoptosis that was characterized by an increase in cleaved caspase-3- or Annexin V-positive cells and was attenuated by both zVAD-fmk (a pan-caspase inhibitor) application and caspase-3 siRNA knockdown. In addition, overexpression of mutant p150glued decreased mitochondrial membrane potentials and increased levels of translocase of the mitochondrial outer membrane (Tom20) protein, indicating accumulation of damaged mitochondria. Importantly, siRNA knockdown of endogenous p150glued independently induced apoptosis via caspase-8 activation and was not associated with mitochondrial morphological changes. Simultaneous knockdown of endogenous p150glued and overexpression of mutant p150glued had additive apoptosis induction effects. These findings suggest that both p150glued gain-of-toxic-function and loss-of-physiological-function can cause apoptosis and may underlie the pathogenesis of p150glued-associated disorders.
    PLoS ONE 04/2014; 9(4):e94645. DOI:10.1371/journal.pone.0094645 · 3.23 Impact Factor
  • Source
    • "Moreover, mutations of DCTN1, the gene encoding dynactin 1, are linked to familial lower motor neuron disease [14]. Several mutant DCTN1 models exhibited motor dysfunction and pathological changes related to motor neuron disease [15], [16]. As seen in the motor neurons of SALS patients, mutant DCTN1 mice exhibited a massive accumulation of membrane vesicles, including autophagosomes, in spinal motor neurons [16]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. We previously showed that the expression of dynactin 1, an axon motor protein regulating retrograde transport, is markedly reduced in spinal motor neurons of sporadic ALS patients, although the mechanisms by which decreased dynactin 1 levels cause neurodegeneration have yet to be elucidated. The accumulation of autophagosomes in degenerated motor neurons is another key pathological feature of sporadic ALS. Since autophagosomes are cargo of dynein/dynactin complexes and play a crucial role in the turnover of several organelles and proteins, we hypothesized that the quantitative loss of dynactin 1 disrupts the transport of autophagosomes and induces the degeneration of motor neuron. In the present study, we generated a Caenorhabditis elegans model in which the expression of DNC-1, the homolog of dynactin 1, is specifically knocked down in motor neurons. This model exhibited severe motor defects together with axonal and neuronal degeneration. We also observed impaired movement and increased number of autophagosomes in the degenerated neurons. Furthermore, the combination of rapamycin, an activator of autophagy, and trichostatin which facilitates axonal transport dramatically ameliorated the motor phenotype and axonal degeneration of this model. Thus, our results suggest that decreased expression of dynactin 1 induces motor neuron degeneration and that the transport of autophagosomes is a novel and substantial therapeutic target for motor neuron degeneration.
    PLoS ONE 02/2013; 8(2):e54511. DOI:10.1371/journal.pone.0054511 · 3.23 Impact Factor
  • Source
    • "Indeed, the dynactin depletion model of Drosophila exhibited disrupted axonal transport [17]. The G59S substitution occurs in the highly conserved CAP-Gly motif of dynactin-1, a domain that binds directly to microtubules [8] and slows transport of organelles in vitro [18]. The G59S-mutated protein also has an enhanced propensity to misfold and forms aggregates in which trapped organelles, such as mitochondria, are found. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Motor neurons typically have very long axons, and fine-tuning axonal transport is crucial for their survival. The obstruction of axonal transport is gaining attention as a cause of neuronal dysfunction in a variety of neurodegenerative motor neuron diseases. Depletions in dynein and dynactin-1, motor molecules regulating axonal trafficking, disrupt axonal transport in flies, and mutations in their genes cause motor neuron degeneration in humans and rodents. Axonal transport defects are among the early molecular events leading to neurodegeneration in mouse models of amyotrophic lateral sclerosis (ALS). Gene expression profiles indicate that dynactin-1 mRNA is downregulated in degenerating spinal motor neurons of autopsied patients with sporadic ALS. Dynactin-1 mRNA is also reduced in the affected neurons of a mouse model of spinal and bulbar muscular atrophy, a motor neuron disease caused by triplet CAG repeat expansion in the gene encoding the androgen receptor. Pathogenic androgen receptor proteins also inhibit kinesin-1 microtubule-binding activity and disrupt anterograde axonal transport by activating c-Jun N-terminal kinase. Disruption of axonal transport also underlies the pathogenesis of spinal muscular atrophy and hereditary spastic paraplegias. These observations suggest that the impairment of axonal transport is a key event in the pathological processes of motor neuron degeneration and an important target of therapy development for motor neuron diseases.
    International Journal of Molecular Sciences 12/2012; 13(1):1225-38. DOI:10.3390/ijms13011225 · 2.86 Impact Factor
Show more