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Hum Mol Genet. 2017 Nov 1;26(21):4142-4152. doi: 10.1093/hmg/ddx301.

Dysregulation of chromatin remodelling complexes in amyotrophic lateral sclerosis.

Author information

1
Department of Neurology and Neurosurgery and the Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B3, Canada.
2
Tanz Centre for Research in Neurodegenerative Disease, University of Toronto, Toronto, ON M5T 2S8, Canada.
3
Inserm U1118, Faculté de Médecine, Université de Strasbourg, 67 085 Strasbourg Cedex, France.
4
Department of Laboratory Medicine and Pathobiology, Sunnybrook Health Sciences Center, University of Toronto, Toronto, ON M4N 3M5, Canada.

Abstract

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease with paralysis resulting from dysfunction and loss of motor neurons. A common neuropathological finding is attrition of motor neuron dendrites, which make central connections vital to motor control. The chromatin remodelling complex, neuronal Brahma-related gene 1 (Brg1)-associated factor complex (nBAF), is critical for neuronal differentiation, dendritic extension and synaptic function. We have identified loss of the crucial nBAF subunits Brg1, Brg1-associated factor 53b and calcium responsive transactivator in cultured motor neurons expressing FUS or TAR-DNA Binding Protein 43 (TDP-43) mutants linked to familial ALS. When plasmids encoding wild-type or mutant human FUS or TDP-43 were expressed in motor neurons of dissociated spinal cord cultures prepared from E13 mice, mutant proteins in particular accumulated in the cytoplasm. Immunolabelling of nBAF subunits was reduced in proportion to loss of nuclear FUS or TDP-43 and depletion of Brg1 was associated with nuclear retention of Brg1 mRNA. Dendritic attrition (loss of intermediate and terminal dendritic branches) occurred in motor neurons expressing mutant, but not wild-type, FUS or TDP-43. This attrition was delayed by ectopic over-expression of Brg1 and was reproduced by inhibiting Brg1 activity either through genetic manipulation or treatment with the chemical inhibitor, (E)-1-(2-Hydroxyphenyl)-3-((1R, 4R)-5-(pyridin-2-yl)-2, 5-diazabicyclo[2.2.1]heptan-2-yl)prop-2-en-1-one, demonstrating the importance of Brg1 to maintenance of dendritic architecture. Loss of nBAF subunits was also documented in spinal motor neurons in autopsy tissue from familial amyotrophic sclerosis (chromosome 9 open reading frame 72 with G4C2 nucleotide expansion) and from sporadic cases with no identified mutation, pointing to dysfunction of nBAF chromatin remodelling in multiple forms of ALS.

PMID:
28973294
DOI:
10.1093/hmg/ddx301
[Indexed for MEDLINE]

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