title: Targeting RNA foci in iPSC-derived motor neurons from ALS patients with a C9ORF72 repeat expansion.
abstract: Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative condition characterized by loss of motor neurons in the brain and spinal cord. Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9ORF72 gene are the most common cause of the familial form of ALS (C9-ALS), as well as frontotemporal lobar degeneration and other neurological diseases. How the repeat expansion causes disease remains unclear, with both loss of function (haploinsufficiency) and gain of function (either toxic RNA or protein products) proposed. We report a cellular model of C9-ALS with motor neurons differentiated from induced pluripotent stem cells (iPSCs) derived from ALS patients carrying the C9ORF72 repeat expansion. No significant loss of C9ORF72 expression was observed, and knockdown of the transcript was not toxic to cultured human motor neurons. Transcription of the repeat was increased, leading to accumulation of GGGGCC repeat-containing RNA foci selectively in C9-ALS iPSC-derived motor neurons. Repeat-containing RNA foci colocalized with hnRNPA1 and Pur-α, suggesting that they may be able to alter RNA metabolism. C9-ALS motor neurons showed altered expression of genes involved in membrane excitability including DPP6, and demonstrated a diminished capacity to fire continuous spikes upon depolarization compared to control motor neurons. Antisense oligonucleotides targeting the C9ORF72 transcript suppressed RNA foci formation and reversed gene expression alterations in C9-ALS motor neurons. These data show that patient-derived motor neurons can be used to delineate pathogenic events in ALS.
authors.affiliation: Regenerative Medicine Institute, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
authors.forename: Dhruv
authors.initials: D
authors.lastname: Sareen
authors.forename: Jacqueline G
authors.initials: JG
authors.lastname: O'Rourke
authors.forename: Pratap
authors.initials: P
authors.lastname: Meera
authors.forename: A K M G
authors.initials: AK
authors.lastname: Muhammad
authors.forename: Sharday
authors.initials: S
authors.lastname: Grant
authors.forename: Megan
authors.initials: M
authors.lastname: Simpkinson
authors.forename: Shaughn
authors.initials: S
authors.lastname: Bell
authors.forename: Sharon
authors.initials: S
authors.lastname: Carmona
authors.forename: Loren
authors.initials: L
authors.lastname: Ornelas
authors.forename: Anais
authors.initials: A
authors.lastname: Sahabian
authors.forename: Tania
authors.initials: T
authors.lastname: Gendron
authors.forename: Leonard
authors.initials: L
authors.lastname: Petrucelli
authors.forename: Michael
authors.initials: M
authors.lastname: Baughn
authors.forename: John
authors.initials: J
authors.lastname: Ravits
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Harms
authors.forename: Frank
authors.initials: F
authors.lastname: Rigo
authors.forename: C Frank
authors.initials: CF
authors.lastname: Bennett
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Otis
authors.forename: Clive N
authors.initials: CN
authors.lastname: Svendsen
authors.forename: Robert H
authors.initials: RH
authors.lastname: Baloh
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics* / Q000473:pathology*; D000073885:C9orf72 Protein; D042622:DNA Repeat Expansion / Q000235:genetics*; D005091:Exons / Q000235:genetics; D055785:Gene Knockdown Techniques; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011506:Proteins / Q000235:genetics*; D012313:RNA / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000073885:C9orf72 Protein; C568651:C9orf72 protein, human; D016376:Oligonucleotides, Antisense; D011506:Proteins; D012313:RNA