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SMN deficiency in spinal muscular atrophy causes widespread intron retention and DNA damage

ABSTRACT: Spinal muscular atrophy is the leading genetic cause of infant mortality and is caused by homozygous loss of the SMN1 gene. We investigated global transcriptome changes in the spinal cord of inducible SMA mice. SMN depletion caused widespread retention of introns with weak splice sites or belonging to the minor (U12) class. We further demonstrated accumulation of DNA double strand breaks in the spinal cord of SMA mice and in human SMA cell culture models. DNA damage was partially rescued by suppressing the formation of R-loops, which accumulated over retained introns. We propose that instead of single gene effects, pervasive splicing defects caused by SMN deficiency trigger a global DNA damage and stress response, thus compromising motor neuron survival.

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE87281 | GEO | 2017/03/21

SECONDARY ACCESSION(S): PRJNA343962

REPOSITORIES: GEO

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Mass spectrometry-based proteomic comparison of BirA-SMN, BirA-SMN-Y109C and BirA proxisomes.

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2022-10-19 | PXD030970 | Pride

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Project description:Spinal muscular atrophy (SMA) is the most common genetic cause of infant mortality, with an incidence of around 1 in 6,000-10,000 live births. SMA is caused by low levels of full-length survival of motor neuron protein (SMN). We demonstrate that SMN binds to ribosomes and that this interaction is tissue-dependent. We performed ribosome profiling analyses on lysates from P5 wild-type mouse brains exposed to RNase I, from which we isolated SMN-primed ribosomes by immunoprecipitation. SMN-primed ribosomes are preferentially positioned within the first five codons of a set of mRNAs which are enriched for translational enhancer sequences in the 5’UTR and rare codons at the beginning of their coding sequence. These SMN-specific mRNAs are associated with neurogenesis, lipid metabolism, ubiquitination, chromatin regulation and translation. Additionally, we analyzed the positioning of active ribosomes using the Active-RiboSeq method based on RiboLace and compared early symptomatic SMA mouse brains to age-matched controls. We found that loss of SMN induces ribosome depletion, especially at the beginning of the coding sequence of SMN-specific mRNAs, leading to impairment of proteins involved in motor neuron function and stability. Keywords: motor neuron disease, spinal muscular atrophy, SMA, SMN, SMN1, survival of motor neuron, SMN-primed ribosome profiling, translation, RiboLace, Ribo-Seq, active translation, ribosome heterogeneity

2020-08-11 | GSE154106 | GEO

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