title: C9ORF72 GGGGCC Expanded Repeats Produce Splicing Dysregulation which Correlates with Disease Severity in Amyotrophic Lateral Sclerosis.
abstract: OBJECTIVE
  An intronic GGGGCC-repeat expansion of C9ORF72 is the most common genetic variant of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. The mechanism of neurodegeneration is unknown, but a direct effect on RNA processing mediated by RNA foci transcribed from the repeat sequence has been proposed.
  
  
  METHODS
  Gene expression profiling utilised total RNA extracted from motor neurons and lymphoblastoid cell lines derived from human ALS patients, including those with an expansion of C9ORF72, and controls. In lymphoblastoid cell lines, expansion length and the frequency of sense and antisense RNA foci was also examined.
  
  
  RESULTS
  Gene level analysis revealed a number of differentially expressed networks and both cell types exhibited dysregulation of a network functionally enriched for genes encoding 'RNA splicing' proteins. There was a significant overlap of these genes with an independently generated list of GGGGCC-repeat protein binding partners. At the exon level, in lymphoblastoid cells derived from C9ORF72-ALS patients splicing consistency was lower than in lines derived from non-C9ORF72 ALS patients or controls; furthermore splicing consistency was lower in samples derived from patients with faster disease progression. Frequency of sense RNA foci showed a trend towards being higher in lymphoblastoid cells derived from patients with shorter survival, but there was no detectable correlation between disease severity and DNA expansion length.
  
  
  CONCLUSIONS
  Up-regulation of genes encoding predicted binding partners of the C9ORF72 expansion is consistent with an attempted compensation for sequestration of these proteins. A number of studies have analysed changes in the transcriptome caused by C9ORF72 expansion, but to date findings have been inconsistent. As a potential explanation we suggest that dynamic sequestration of RNA processing proteins by RNA foci might lead to a loss of splicing consistency; indeed in our samples measurement of splicing consistency correlates with disease severity.
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Johnathan
authors.initials: J
authors.lastname: Cooper-Knock
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Joanna J
authors.initials: JJ
authors.lastname: Bury
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Heath
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Wyles
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Adrian
authors.initials: A
authors.lastname: Higginbottom
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Catherine
authors.initials: C
authors.lastname: Gelsthorpe
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: J Robin
authors.initials: JR
authors.lastname: Highley
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Hautbergue
authors.affiliation: Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom.
authors.forename: Magnus
authors.initials: M
authors.lastname: Rattray
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Janine
authors.initials: J
authors.lastname: Kirby
authors.affiliation: Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ, United Kingdom.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Shaw
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics* / Q000473:pathology; D002460:Cell Line; D042622:DNA Repeat Expansion / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D063990:Gene Ontology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics*; D015203:Reproducibility of Results