TY - JOUR
T1 - Mechanisms of toxicity in C9FTLD/ALS
AU - Gendron, Tania F.
AU - Belzil, Veronique V.
AU - Zhang, Yong Jie
AU - Petrucelli, Leonard
N1 - Funding Information:
Acknowledgments This work was supported by Mayo Clinic Foundation; National Institutes of Health/National Institute on Aging [R01 AG026251 (LP)]; National Institutes of Health/National Institute of Neurological Disorders and Stroke [R21 NS074121 (TFG), R21 NS079807 (YZ), R01 NS063964 (LP); R01 NS077402 (LP), R21 NS084528 (LP)]; National Institute of Environmental Health Services [R01 ES20395 (LP)]; Amyotrophic Lateral Sclerosis Association (LP); the Canadian Institutes of Health Research (VVB), and the Sira-gusa Foundation (VVB).
PY - 2014/3
Y1 - 2014/3
N2 - A hexanucleotide repeat expansion within a non-coding region of the C9ORF72 gene is the most common mutation causative of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Elucidating how this bidirectionally transcribed G4C2·C 4G2 expanded repeat causes "C9FTLD/ALS" has since become an important goal of the field. Likely pathogenic mechanisms include toxicity induced by repeat-containing RNAs, and loss of C9orf72 function due to epigenetic changes resulting in decreased C9ORF72 mRNA expression. With regards to the former, sense and antisense transcripts of the expanded repeat aberrantly interact with various RNA-binding proteins and form discrete nuclear structures, termed RNA foci. These foci have the capacity to sequester select RNA-binding proteins, thereby impairing their function. (G4C 2)exp and (C4G2)exp transcripts also succumb to an alternative fate: repeat-associated non-ATG (RAN) translation. This unconventional mode of translation, which occurs in the absence of an initiating codon, results in the abnormal production of poly(GA), poly(GP), poly(GR), poly(PR) and poly(PA) peptides, collectively referred to as C9RAN proteins. C9RAN proteins form neuronal inclusions throughout the central nervous system of C9FTLD/ALS patients and may contribute to disease pathogenesis. This review aims to summarize the important findings from studies examining mechanisms of disease in C9FTLD/ALS, and will also highlight some of the many questions in need of further investigation.
AB - A hexanucleotide repeat expansion within a non-coding region of the C9ORF72 gene is the most common mutation causative of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Elucidating how this bidirectionally transcribed G4C2·C 4G2 expanded repeat causes "C9FTLD/ALS" has since become an important goal of the field. Likely pathogenic mechanisms include toxicity induced by repeat-containing RNAs, and loss of C9orf72 function due to epigenetic changes resulting in decreased C9ORF72 mRNA expression. With regards to the former, sense and antisense transcripts of the expanded repeat aberrantly interact with various RNA-binding proteins and form discrete nuclear structures, termed RNA foci. These foci have the capacity to sequester select RNA-binding proteins, thereby impairing their function. (G4C 2)exp and (C4G2)exp transcripts also succumb to an alternative fate: repeat-associated non-ATG (RAN) translation. This unconventional mode of translation, which occurs in the absence of an initiating codon, results in the abnormal production of poly(GA), poly(GP), poly(GR), poly(PR) and poly(PA) peptides, collectively referred to as C9RAN proteins. C9RAN proteins form neuronal inclusions throughout the central nervous system of C9FTLD/ALS patients and may contribute to disease pathogenesis. This review aims to summarize the important findings from studies examining mechanisms of disease in C9FTLD/ALS, and will also highlight some of the many questions in need of further investigation.
KW - Amyotrophic lateral sclerosis
KW - Bidirectional transcription
KW - C9ORF72
KW - Epigenetics
KW - Expanded repeat
KW - Frontotemporal lobar degeneration
KW - RNA foci
KW - Repeat-associated non-ATG translation
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U2 - 10.1007/s00401-013-1237-z
DO - 10.1007/s00401-013-1237-z
M3 - Review article
C2 - 24394885
AN - SCOPUS:84896699383
SN - 0001-6322
VL - 127
SP - 359
EP - 376
JO - Acta neuropathologica
JF - Acta neuropathologica
IS - 3
ER -