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La Fontaine, Sharon

Llanos, RM

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Takata, R

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Crossref

Journal of the Peripheral Nervous System

6<sup>th</sup>
 International Charcot-Marie-Tooth and Related Neuropathy Consortium (CMTR) Meeting

Green, R.

Simoes, F. A.

Reyes-Aldasoro, C. C.

Rossor, A. M.

Scoto, M.

Barri, M.

Greensmith, L.

Muntoni, F.

Reilly, M. M.

Hafezparast, M.

City Research Online

              City, University of London Institutional RepositoryCitation: Green, R., Simoes, F. A., Reyes-Aldasoro, C. C., Rossor, A. M., Scoto, M., Barri, M., Greensmith, L., Muntoni, F., Reilly, M. M. & Hafezparast, M. (2016). A DYNC1H1 mutation in autosomal dominant spinal muscular atrophy shows the potential of pharmacological inhibition of histone deacetylase 6 as a treatment for disease associated cellular phenotypes. Journal Of The Peripheral Nervous System, 21(3), pp. 261-262. doi: 10.1111/jns.12181 This is the accepted version of the paper. This version of the publication may differ from the final published version. Permanent repository link:  http://openaccess.city.ac.uk/15763/Link to published version: http://dx.doi.org/10.1111/jns.12181Copyright and reuse: City Research Online aims to make research outputs of City, University of London available to a wider audience. Copyright and Moral Rights remain with the author(s) and/or copyright holders. URLs from City Research Online may be freely distributed and linked to.City Research Online:            http://openaccess.city.ac.uk/            publications@city.ac.ukCity Research OnlineA DYNC1H1 MUTATION IN AUTOSOMAL DOMINANT SPINAL MUSCULAR ATROPHY SHOWS THE POTENTIAL OF PHARMACOLOGICAL INHIBITION OF HISTONE DEACETYLASE 6 AS A TREATMENT FOR DISEASE ASSOCIATED CELLULAR PHENOTYPES  Green RL1, Simoes FA1,2, Reyes-Aldasoro CC3, Rossor AM6, Scoto M5, Barri M1, Greensmith L4,6, Muntoni F5,6, Reilly MM6, Hafezparast M1. 1Neuroscience Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom; 2Medical Research Building, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom; 3Tait Building, City University London, Northampton Square, London, United Kingdom; 4Sobell Department of Motor Neuroscience and Movement Disorders, Queen Square, London, United Kingdom; 5Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, United Kingdom; 6MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, United Kingdom.    Spinal muscular atrophy with lower extremity predominance (SMA-LED) is an autosomal dominant congenital form of motor neuron disease. The most common cause of SMA-LED are mutations in dynein cytoplasmic 1 heavy chain 1 (DYNC1H1), which encodes the largest subunit of the retrograde motor cytoplasmic dynein 1.  As is typical in other cases of SMA-LED, patients harbouring the DYNC1H1 p.R399G mutation exhibit lower limb weakness as a consequence of muscle atrophy and also show a degree of cognitive impairment. However, the underlying molecular pathogenesis remains unknown. In addition to its characteristic function in retrograde trafficking, the dynein complex is increasingly understood to be involved in other cellular processes including growth cone dynamics and regulation of the Golgi apparatus. Here, we show that fibroblasts with the DYN1C1H1 p.R399G mutation exhibit a striking loss of Golgi apparatus integrity as measured by increased fragmentation, which correlates with increasing zygosity of the mutation. Importantly, we also see a decrease in the localisation of the dynein complex to the Golgi cisternae and a significant decrease in the acetylation of microtubules in the peri-nuclear region. Excitingly, the treatment of mutant fibroblasts with tubacin, an HDAC6 inhibitor, caused a striking amelioration of the Golgi apparatus integrity by increasing microtubule acetylation. This highlights for the first time a perturbed dynein-mediated regulation of microtubule acetylation and the fragmentation of the Golgi apparatus as a contributory factors in the pathogenesis of SMA-LED. Importantly, these data also illustrate that ameliorating the microtubule acetylation is sufficient to rescue the Golgi integrity, thereby providing a potential therapeutic target for this pathology.   

A DYNC1H1 mutation in autosomal dominant spinal muscular atrophy shows the potential of pharmacological inhibition of histone deacetylase 6 as a treatment for disease associated cellular phenotypes

Mice deficient of myelin protein zero (P0) are established models of demyelinating Charcot-Marie-Tooth (CMT) disease. Recent work form our laboratory indicated that in severely affected P0−/− as well as in P0+/− (modeling CMT1B), the neuropathy is aggravated by associated changes in voltage-gated Na + channel isoforms with ectopic expression of NaV1.8 on motor axons. This raised the hypothesis that treatments with NaV1.8 blockers could be used in treatment strategies to improve the motor function in these models. We investigated the effect of the NaV1.8 subtype selective blocker A-803467 and of the novel blocker Compound 31 (C31, Bioorg Med Chem Lett 2010, 20, 6812; AbbVie Inc.) which can be orally administered. Double P0 and NaV1.8 knockouts were used as controls. Multiple measures of tibial nerve excitability by “threshold-tracking” were used to monitor the acute changes in motor axon membrane function up to 2 hours after the blockers. Overall, the baseline excitability measures were much more abnormal in P0−/− at 4 months as compared to P0+/− at 20 months. Nevertheless, in both models, the NaV1.8 blockers produced similar deviations in excitability at a dose of 100 mg/Kg. Most notably, the deviations during both depolarizing and hyperpolarizing threshold electrotonus were increased. Optimizing the parameters of the “Bostock” nodal-internodal myelinated motor axon mathematical model indicated a hyperpolarizing change in resting membrane potential. Our data suggest that ectopic NaV1.8 expression causes a state of motor axon depolarization which can be reversed by pharmacologic NaV1.8 blockers. Measures of axonal excitability could be used to monitor the functional consequence of NaV1.8 blockers in future therapeutic studies

Moldovan, M.

Rosberg, M. R.

Alvarez Herrero, Susana

Krarup, C.

Copenhagen University Research Information System

NERVE EXCITABILITY CHANGES AFTER NA(V)1.8 CHANNEL BLOCKER TREATMENT IN MICE DEFICIENT OF MYELIN PROTEIN P-0

Background: Spinal muscular atrophy with lower extremity predominance (SMA-LED) is an autosomal dominant congenital motor neuron disease. The condition presents with distal limb weakness and muscle atrophy, further compounded with intellectual disability. The most common cause are mutations in dynein cytoplasmic 1 heavy chain 1 (DYNC1H1; OMIM:600112), which encodes the largest subunit of cytoplasmic dynein 1. Dynein is defined by its role as a retrogradely oriented molecular motor but it is also fundamental to other cellular processes including growth cone dynamics and regulation of the Golgi apparatus. Moreover, mutations in dynactin 1 (DCTN1; OMIM: 601143) encoding p150 (Glued) subunit of the dynactin complex, which regulates cytoplasmic dynein function, cause autosomal dominant distal hereditary motor neuronopathy.   Objective: To dissect common molecular mechanisms underlying motor neuron degeneration caused by R399G and D338N mutations in DYNC1H1.   Methods: Immunofluorescence was performed on patient fibroblasts harbouring the R399G or D338N DYNC1H1 mutation to assess the integrity of the Golgi apparatus and the localization of dynein to the organelle. Modifications of microtubules and the interaction of dynein with golgin-160 were investigated using biochemical analysis.   Results: Decreased a-tubulin acetylation was a common molecular phenotype in patient fibroblasts harbouring the R399G (p50.05, N=3) or D338N (p50.01, N=5) mutation in comparison to wild-type fibroblasts (N=3 and N=5, respectively). However, only the R399G mutant fibroblasts (N=20) exhibited a significant (p50.0001) decrease of dynein at the Golgi apparatus in comparison to wild-type cells (N=21). Uniquely, the R399G mutation also caused a significant and inherent fragmentation of the Golgi apparatus, which correlated with the zygosity of the mutation (+/R339G p50.01 N=4, R399G/R399G p50.0001 N=4). A consequent compensational response was measured as an increased interaction between the dynein intermediate chain and golgin-160 in the R399G mutant cells. Excitingly, the treatment of R399G mutant fibroblasts with tubacin (N=32), an HDAC6 inhibitor, caused a striking statistically significant (p50.0001) amelioration of the Golgi apparatus integrity by increasing microtubule acetylation in comparison to untreated R399G mutant fibroblasts (N=33).   Discussion and conclusions: Using DYNC1H1 mutations we illustrate a dynein-dependent acetylation of the microtubule network, which if aberrant and compounded by a decrease in the amount of dynein present on the Golgi membranes results in the fragmentation of the organelle. Intriguingly, a-tubulin acetylation, is significantly reduced in motor neurons harbouring ALS associated mutant TUBA4A (OMIM: 191110). These data suggest a tentative link between genetic variations in DYNC1H1 and the microtubule cytoskeleton, which could contribute to aberrant tubulin modification, Golgi integrity, and axonal transport and consequently susceptibility to ALS. Importantly, we show that ameliorating the microtubule acetylation is sufficient to rescue the Golgi integrity, thereby providing a potential therapeutic target for this pathology

A DYNC1H1 mutation in autosomal dominant spinal muscular atrophy shows the potential of pharmacological inhibition of histone deacetylase 6 as a treatment for disease associated cellular phenotypes

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