TY - JOUR
T1 - Translation of dipeptide repeat proteins from the C9ORF72 expanded repeat is associated with cellular stress
AU - Sonobe, Yoshifumi
AU - Ghadge, Ghanashyam
AU - Masaki, Katsuhisa
AU - Sendoel, Ataman
AU - Fuchs, Elaine
AU - Roos, Raymond P.
N1 - Funding Information:
RPR, YS, GG and KM are funded by a grant from the ALS Association and gifts from Steps 4 Doug, Families Unite Against ALS, John and Patricia McDonald, Gerry Kaufman, Arnold Sarnoff, Susan Warso, and Marc and Barbara Posner. This work was also partly supported by grants to EF from NYSTEM CO29559 . AS is currently supported by the People Programme (Marie Curie Actions) of the European Union 7th Framework Programme FP7 under REA grant agreement no. 629861 . EF is an Investigator of the Howard Hughes Medical Institute.
Publisher Copyright:
© 2018 Elsevier Inc.
PY - 2018/8
Y1 - 2018/8
N2 - Expansion of a hexanucleotide repeat (HRE), GGGGCC, in the C9ORF72 gene is recognized as the most common cause of familial amyotrophic lateral sclerosis (FALS), frontotemporal dementia (FTD) and ALS-FTD, as well as 5–10% of sporadic ALS. Despite the location of the HRE in the non-coding region (with respect to the main C9ORF72 gene product), dipeptide repeat proteins (DPRs) that are thought to be toxic are translated from the HRE in all three reading frames from both the sense and antisense transcript. Here, we identified a CUG that has a good Kozak consensus sequence as the translation initiation codon. Mutation of this CTG significantly suppressed polyglycine-alanine (GA) translation. GA was translated when the G4C2 construct was placed as the second cistron in a bicistronic construct. CRISPR/Cas9-induced knockout of a non-canonical translation initiation factor, eIF2A, impaired GA translation. Transfection of G4C2 constructs induced an integrated stress response (ISR), while triggering the ISR led to a continuation of translation of GA with a decline in conventional cap-dependent translation. These in vitro observations were confirmed in chick embryo neural cells. The findings suggest that DPRs translated from an HRE in C9ORF72 aggregate and lead to an ISR that then leads to continuing DPR production and aggregation, thereby creating a continuing pathogenic cycle.
AB - Expansion of a hexanucleotide repeat (HRE), GGGGCC, in the C9ORF72 gene is recognized as the most common cause of familial amyotrophic lateral sclerosis (FALS), frontotemporal dementia (FTD) and ALS-FTD, as well as 5–10% of sporadic ALS. Despite the location of the HRE in the non-coding region (with respect to the main C9ORF72 gene product), dipeptide repeat proteins (DPRs) that are thought to be toxic are translated from the HRE in all three reading frames from both the sense and antisense transcript. Here, we identified a CUG that has a good Kozak consensus sequence as the translation initiation codon. Mutation of this CTG significantly suppressed polyglycine-alanine (GA) translation. GA was translated when the G4C2 construct was placed as the second cistron in a bicistronic construct. CRISPR/Cas9-induced knockout of a non-canonical translation initiation factor, eIF2A, impaired GA translation. Transfection of G4C2 constructs induced an integrated stress response (ISR), while triggering the ISR led to a continuation of translation of GA with a decline in conventional cap-dependent translation. These in vitro observations were confirmed in chick embryo neural cells. The findings suggest that DPRs translated from an HRE in C9ORF72 aggregate and lead to an ISR that then leads to continuing DPR production and aggregation, thereby creating a continuing pathogenic cycle.
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U2 - 10.1016/j.nbd.2018.05.009
DO - 10.1016/j.nbd.2018.05.009
M3 - Article
C2 - 29792928
AN - SCOPUS:85047638518
SN - 0969-9961
VL - 116
SP - 155
EP - 165
JO - Neurobiology of Disease
JF - Neurobiology of Disease
ER -