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Lookup NU author(s): Emily O'Connor, Dr Isabell Cordts, George Cairns, Daniel CoxORCiD, Professor Hanns Lochmuller, Dr Andreas Roos
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Congenital myasthenic syndromes (CMS) are a group of rare, inherited disorders characterized by compromised function of the neuromuscular junction, manifesting with fatigable muscle weakness. Mutations in MYO9A were previously identified as causative for CMS but the precise pathomechanism remained to be characterized. On the basis of the role of MYO9A as an actin-based molecular motor and as a negative regulator of RhoA, we hypothesized that loss of MYO9A may affect the neuronal cytoskeleton, leading to impaired intracellular transport. To investigate this, we used MYO9A-depleted NSC-34 cells (mouse motor neuron-derived cells), revealing altered expression of a number of cytoskeletal proteins important for neuron structure and intracellular transport. On the basis of these findings, the effect on protein transport was determined using a vesicular recycling assay which revealed impaired recycling of a neuronal growth factor receptor. In addition, an unbiased approach utilizing proteomic profiling of the secretome revealed a key role for defective intracellular transport affecting proper protein secretion in the pathophysiology of MYO9A-related CMS. This also led to the identification of agrin as being affected by the defective transport. Zebrafish with reduced MYO9A orthologue expression were treated with an artificial agrin compound, ameliorating defects in neurite extension and improving motility. In summary, loss of MYO9A affects the neuronal cytoskeleton and leads to impaired transport of proteins, including agrin, which may provide a new and unexpected treatment option.
Author(s): O'Connor E, Phan V, Cordts I, Cairns G, Hettwer S, Cox D, Lochmüller H, Roos A
Publication type: Article
Publication status: Published
Journal: Human Molecular Genetics
Year: 2018
Volume: 27
Issue: 8
Pages: 1434-1446
Print publication date: 15/04/2018
Online publication date: 16/02/2018
Acceptance date: 08/02/2018
Date deposited: 08/03/2018
ISSN (print): 0964-6906
ISSN (electronic): 1460-2083
Publisher: Oxford University Press
URL: https://doi.org/10.1093/hmg/ddy054
DOI: 10.1093/hmg/ddy054
PubMed id: 29462312
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