Insights into the pathogenic mechanisms of Chromosome 9 open reading frame 72 (C9orf72) repeat expansions

Tiffany W. Todd, Leonard Petrucelli

Research output: Contribution to journalReview article

34 Citations (Scopus)

Abstract

The identification of a hexanucleotide repeat expansion in a non-coding region of C9orf72 as a major cause of both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) drastically changed the field of research on both of these conditions. Yet, despite the vast amount of work aimed at elucidating the molecular mechanisms underlying the role of this repeat in disease, the exact pathomechanisms are still unclear. A reduction in the expression of the C9orf72 gene is observed in patients, but a gain-of-function model is now preferred. The hexanucleotide repeat expansion forms RNA foci in the central nervous system (CNS) of repeat-positive FTD and ALS patients, and these foci are believed to sequester RNA-binding proteins (RBPs) and impair their function in RNA processing. At the same time, the repeat undergoes repeat-associated non-ATG translation to produce dipeptide repeat proteins that also form inclusions in the patient CNS. Studies from cells and flies suggest that these proteins may also be an important factor in the disease. Finally, the hexanucleotide repeat also induces the mislocalization and aggregation of TAR DNA-binding protein 43 (TDP-43) through an as yet unknown mechanism. This review covers the different potential pathogenic factors that have been put forth for C9orf72-repeat-associated FTD and ALS (C9-FTD/ALS), while highlighting some remaining questions. (Figure presented.) A repeat expansion in C9orf72 is a common cause of both frontal temporal dementia and amyotrophic lateral sclerosis. Although there is a decrease in C9orf72 expression in patients, this repeat is believed to induce disease primarily through an unknown gain-of-function mechanism involving the RNA, repeat-associated non-AUG translation, or both. This review summarizes and discusses current knowledge on C9orf72 repeat-associated pathophysiology. This article is part of the Frontotemporal Dementia special issue.

Original languageEnglish (US)
Pages (from-to)145-162
Number of pages18
JournalJournal of Neurochemistry
DOIs
StatePublished - Aug 1 2016

Fingerprint

Chromosomes, Human, Pair 9
Chromosomes
Open Reading Frames
Neurology
RNA
Dementia
Central Nervous System
RNA-Binding Proteins
Dipeptides
Amyotrophic Lateral Sclerosis
DNA-Binding Proteins
Diptera
Proteins
Agglomeration
Genes
Processing
Research
Frontotemporal Dementia With Motor Neuron Disease

Keywords

  • ALS
  • C9orf72
  • FTD
  • RAN translation
  • RNA foci
  • TDP-43

ASJC Scopus subject areas

  • Biochemistry
  • Medicine(all)
  • Cellular and Molecular Neuroscience

Cite this

Insights into the pathogenic mechanisms of Chromosome 9 open reading frame 72 (C9orf72) repeat expansions. / Todd, Tiffany W.; Petrucelli, Leonard.

In: Journal of Neurochemistry, 01.08.2016, p. 145-162.

Research output: Contribution to journalReview article

@article{61b03cdcb48d443cb447393e368ca9ac,
title = "Insights into the pathogenic mechanisms of Chromosome 9 open reading frame 72 (C9orf72) repeat expansions",
abstract = "The identification of a hexanucleotide repeat expansion in a non-coding region of C9orf72 as a major cause of both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) drastically changed the field of research on both of these conditions. Yet, despite the vast amount of work aimed at elucidating the molecular mechanisms underlying the role of this repeat in disease, the exact pathomechanisms are still unclear. A reduction in the expression of the C9orf72 gene is observed in patients, but a gain-of-function model is now preferred. The hexanucleotide repeat expansion forms RNA foci in the central nervous system (CNS) of repeat-positive FTD and ALS patients, and these foci are believed to sequester RNA-binding proteins (RBPs) and impair their function in RNA processing. At the same time, the repeat undergoes repeat-associated non-ATG translation to produce dipeptide repeat proteins that also form inclusions in the patient CNS. Studies from cells and flies suggest that these proteins may also be an important factor in the disease. Finally, the hexanucleotide repeat also induces the mislocalization and aggregation of TAR DNA-binding protein 43 (TDP-43) through an as yet unknown mechanism. This review covers the different potential pathogenic factors that have been put forth for C9orf72-repeat-associated FTD and ALS (C9-FTD/ALS), while highlighting some remaining questions. (Figure presented.) A repeat expansion in C9orf72 is a common cause of both frontal temporal dementia and amyotrophic lateral sclerosis. Although there is a decrease in C9orf72 expression in patients, this repeat is believed to induce disease primarily through an unknown gain-of-function mechanism involving the RNA, repeat-associated non-AUG translation, or both. This review summarizes and discusses current knowledge on C9orf72 repeat-associated pathophysiology. This article is part of the Frontotemporal Dementia special issue.",
keywords = "ALS, C9orf72, FTD, RAN translation, RNA foci, TDP-43",
author = "Todd, {Tiffany W.} and Leonard Petrucelli",
year = "2016",
month = "8",
day = "1",
doi = "10.1111/jnc.13623",
language = "English (US)",
pages = "145--162",
journal = "Journal of Neurochemistry",
issn = "0022-3042",
publisher = "Wiley-Blackwell",

}

TY - JOUR

T1 - Insights into the pathogenic mechanisms of Chromosome 9 open reading frame 72 (C9orf72) repeat expansions

AU - Todd, Tiffany W.

AU - Petrucelli, Leonard

PY - 2016/8/1

Y1 - 2016/8/1

N2 - The identification of a hexanucleotide repeat expansion in a non-coding region of C9orf72 as a major cause of both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) drastically changed the field of research on both of these conditions. Yet, despite the vast amount of work aimed at elucidating the molecular mechanisms underlying the role of this repeat in disease, the exact pathomechanisms are still unclear. A reduction in the expression of the C9orf72 gene is observed in patients, but a gain-of-function model is now preferred. The hexanucleotide repeat expansion forms RNA foci in the central nervous system (CNS) of repeat-positive FTD and ALS patients, and these foci are believed to sequester RNA-binding proteins (RBPs) and impair their function in RNA processing. At the same time, the repeat undergoes repeat-associated non-ATG translation to produce dipeptide repeat proteins that also form inclusions in the patient CNS. Studies from cells and flies suggest that these proteins may also be an important factor in the disease. Finally, the hexanucleotide repeat also induces the mislocalization and aggregation of TAR DNA-binding protein 43 (TDP-43) through an as yet unknown mechanism. This review covers the different potential pathogenic factors that have been put forth for C9orf72-repeat-associated FTD and ALS (C9-FTD/ALS), while highlighting some remaining questions. (Figure presented.) A repeat expansion in C9orf72 is a common cause of both frontal temporal dementia and amyotrophic lateral sclerosis. Although there is a decrease in C9orf72 expression in patients, this repeat is believed to induce disease primarily through an unknown gain-of-function mechanism involving the RNA, repeat-associated non-AUG translation, or both. This review summarizes and discusses current knowledge on C9orf72 repeat-associated pathophysiology. This article is part of the Frontotemporal Dementia special issue.

AB - The identification of a hexanucleotide repeat expansion in a non-coding region of C9orf72 as a major cause of both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) drastically changed the field of research on both of these conditions. Yet, despite the vast amount of work aimed at elucidating the molecular mechanisms underlying the role of this repeat in disease, the exact pathomechanisms are still unclear. A reduction in the expression of the C9orf72 gene is observed in patients, but a gain-of-function model is now preferred. The hexanucleotide repeat expansion forms RNA foci in the central nervous system (CNS) of repeat-positive FTD and ALS patients, and these foci are believed to sequester RNA-binding proteins (RBPs) and impair their function in RNA processing. At the same time, the repeat undergoes repeat-associated non-ATG translation to produce dipeptide repeat proteins that also form inclusions in the patient CNS. Studies from cells and flies suggest that these proteins may also be an important factor in the disease. Finally, the hexanucleotide repeat also induces the mislocalization and aggregation of TAR DNA-binding protein 43 (TDP-43) through an as yet unknown mechanism. This review covers the different potential pathogenic factors that have been put forth for C9orf72-repeat-associated FTD and ALS (C9-FTD/ALS), while highlighting some remaining questions. (Figure presented.) A repeat expansion in C9orf72 is a common cause of both frontal temporal dementia and amyotrophic lateral sclerosis. Although there is a decrease in C9orf72 expression in patients, this repeat is believed to induce disease primarily through an unknown gain-of-function mechanism involving the RNA, repeat-associated non-AUG translation, or both. This review summarizes and discusses current knowledge on C9orf72 repeat-associated pathophysiology. This article is part of the Frontotemporal Dementia special issue.

KW - ALS

KW - C9orf72

KW - FTD

KW - RAN translation

KW - RNA foci

KW - TDP-43

UR - http://www.scopus.com/inward/record.url?scp=84981276961&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84981276961&partnerID=8YFLogxK

U2 - 10.1111/jnc.13623

DO - 10.1111/jnc.13623

M3 - Review article

C2 - 27016280

AN - SCOPUS:84981276961

SP - 145

EP - 162

JO - Journal of Neurochemistry

JF - Journal of Neurochemistry

SN - 0022-3042

ER -