The RNA helicase DHX36–G4R1 modulates C9orf72 GGGGCC hexanucleotide repeat–associated translation

Tseng, Yi‐Ju; Sandwith, Siara N.; Green, Katelyn M.; Chambers, Antonio E.; Krans, Amy; Raimer, Heather M; Sharlow, Meredith E.; Reisinger, Michael; Richardson, Adam E.; Routh, Eric D.; Smaldino, Melissa A.; Wang, Yuh‐Hwa; Vaughn, James M.; Todd, Peter K.; Smaldino, Philip J.

doi:10.1016/j.jbc.2021.100914

Cited by 25 publications

(15 citation statements)

References 88 publications

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“…Additionally, stable knockdown of DHX36 in C9ORF72-ALS patient derived iPSC cells and induced motor neurons also showed a reduction in the polyGP RAN product and DHX36 protein levels were found to be elevated in C9ORF72-ALS spinal cord tissue ( Liu et al, 2021 ). The role of DHX36 in RAN translation was further confirmed using a FMRpolyG reporter construct expressing 100 CGG repeats, with knockdown of DHX36 impeding RAN translation ( Tseng et al, 2021 ). DHX36 has additionally been hypothesised to impact on translation elongation, with depletion therefore linked to ribosomal stalling and slower translation ( Liu et al, 2021 ; Tseng et al, 2021 ) and indeed DHX36 has been implicated in facilitating translation elongation of G4-containing mRNAs ( Endoh et al, 2013 ).…”

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 89%

“…The role of DHX36 in RAN translation was further confirmed using a FMRpolyG reporter construct expressing 100 CGG repeats, with knockdown of DHX36 impeding RAN translation ( Tseng et al, 2021 ). DHX36 has additionally been hypothesised to impact on translation elongation, with depletion therefore linked to ribosomal stalling and slower translation ( Liu et al, 2021 ; Tseng et al, 2021 ) and indeed DHX36 has been implicated in facilitating translation elongation of G4-containing mRNAs ( Endoh et al, 2013 ). Interestingly, DHX36 may impact on microsatellite repeat expansions at multiple steps of RNA metabolism as it does with canonical transcripts.…”

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 89%

“…In the context of RAN translation, DHX36 has been shown to bind the C9ORF72 -repeat G4-quadruplexes with high affinity ( Liu et al, 2021 ; Tseng et al, 2021 ) and unwind the secondary structure by hydrolyzing ATP ( Liu et al, 2021 ). DHX36 facilitates RAN translation of the C9ORF72 -repeat transcripts, with stable depletion of DHX36 suppressing RAN translation of HeLa cells expressing a polyGP C9-RAN 70 reporter system either stably ( Liu et al, 2021 ) or a C9-RAN 70 reporter system transiently in all three reading ( Tseng et al, 2021 ). Stable knockout of DHX36 in Jurkat cells replicated this suppression, in a repeat length dependent manner; while overexpression of DHX36 increased RAN translation through its helicase domain ( Tseng et al, 2021 ).…”

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 99%

“…DHX36 facilitates RAN translation of the C9ORF72 -repeat transcripts, with stable depletion of DHX36 suppressing RAN translation of HeLa cells expressing a polyGP C9-RAN 70 reporter system either stably ( Liu et al, 2021 ) or a C9-RAN 70 reporter system transiently in all three reading ( Tseng et al, 2021 ). Stable knockout of DHX36 in Jurkat cells replicated this suppression, in a repeat length dependent manner; while overexpression of DHX36 increased RAN translation through its helicase domain ( Tseng et al, 2021 ). Additionally, stable knockdown of DHX36 in C9ORF72-ALS patient derived iPSC cells and induced motor neurons also showed a reduction in the polyGP RAN product and DHX36 protein levels were found to be elevated in C9ORF72-ALS spinal cord tissue ( Liu et al, 2021 ).…”

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 99%

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RNA Helicases in Microsatellite Repeat Expansion Disorders and Neurodegeneration

et al. 2022

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Short repeated sequences of 3−6 nucleotides are causing a growing number of over 50 microsatellite expansion disorders, which mainly present with neurodegenerative features. Although considered rare diseases in relation to the relatively low number of cases, these primarily adult-onset conditions, often debilitating and fatal in absence of a cure, collectively pose a large burden on healthcare systems in an ageing world population. The pathological mechanisms driving disease onset are complex implicating several non-exclusive mechanisms of neuronal injury linked to RNA and protein toxic gain- and loss- of functions. Adding to the complexity of pathogenesis, microsatellite repeat expansions are polymorphic and found in coding as well as in non-coding regions of genes. They form secondary and tertiary structures involving G-quadruplexes and atypical helices in repeated GC-rich sequences. Unwinding of these structures by RNA helicases plays multiple roles in the expression of genes including repeat-associated non-AUG (RAN) translation of polymeric-repeat proteins with aggregating and cytotoxic properties. Here, we will briefly review the pathogenic mechanisms mediated by microsatellite repeat expansions prior to focus on the RNA helicases eIF4A, DDX3X and DHX36 which act as modifiers of RAN translation in C9ORF72-linked amyotrophic lateral sclerosis/frontotemporal dementia (C9ORF72-ALS/FTD) and Fragile X-associated tremor/ataxia syndrome (FXTAS). We will further review the RNA helicases DDX5/17, DHX9, Dicer and UPF1 which play additional roles in the dysregulation of RNA metabolism in repeat expansion disorders. In addition, we will contrast these with the roles of other RNA helicases such as DDX19/20, senataxin and others which have been associated with neurodegeneration independently of microsatellite repeat expansions. Finally, we will discuss the challenges and potential opportunities that are associated with the targeting of RNA helicases for the development of future therapeutic approaches.

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Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 89%

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 89%

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 99%

Section: Rna Helicases Associated With Microsatellite Repeat Expansio...mentioning

confidence: 99%

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RNA Helicases in Microsatellite Repeat Expansion Disorders and Neurodegeneration

et al. 2022

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“…Other modifiers of DPR production were identified by two independent genome‐wide CRISPR‐Cas9 screens (Kramer et al , 2018 ; Cheng et al , 2019 ; Wilson et al , 2019 ). In addition, the RNA helicase DHX36 has been shown to favour (G4C2) n and FMR1‐associated RAN translation (Tseng et al , 2021 ), whereas the RNA helicase DDX3X inhibits (G4C2) n RAN translation (Cheng et al , 2019 ) but it promotes FMR1‐associated RAN translation (Linsalata et al , 2019 ).…”

Section: Introductionmentioning

confidence: 99%

C9orf72 ALS/FTD dipeptide repeat protein levels are reduced by small molecules that inhibit PKA or enhance protein degradation

et al. 2021

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Intronic GGGGCC (G4C2) hexanucleotide repeat expansion within the human C9orf72 gene represents the most common cause of familial forms of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9ALS/FTD). Repeat-associated non-AUG (RAN) translation of repeat-containing C9orf72 RNA results in the production of neurotoxic dipeptide-repeat proteins (DPRs). Here, we developed a high-throughput drug screen for the identification of positive and negative modulators of DPR levels. We found that HSP90 inhibitor geldanamycin and aldosterone antagonist spironolactone reduced DPR levels by promoting protein degradation via the proteasome and autophagy pathways respectively. Surprisingly, cAMP-elevating compounds boosting protein kinase A (PKA) activity increased DPR levels. Inhibition of PKA activity, by both pharmacological and genetic approaches, reduced DPR levels in cells and rescued pathological phenotypes in a Drosophila model of C9ALS/FTD. Moreover, knockdown of PKA-catalytic subunits correlated with reduced translation efficiency of DPRs, while the PKA inhibitor H89 reduced endogenous DPR levels in C9ALS/FTD patient-derived iPSC motor neurons. Together, our results suggest new and druggable pathways modulating DPR levels in C9ALS/FTD.

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Partners in crime: Proteins implicated in RNA repeat expansion diseases

et al. 2022

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Short tandem repeats are repetitive nucleotide sequences robustly distributed in the human genome. Their expansion underlies the pathogenesis of multiple neurological disorders, including Huntington's disease, amyotrophic lateral sclerosis, and frontotemporal dementia, fragile X-associated tremor/ ataxia syndrome, and myotonic dystrophies, known as repeat expansion disorders (REDs). Several molecular pathomechanisms associated with toxic RNA containing expanded repeats (RNA exp ) are shared among REDs and contribute to disease progression, however, detailed mechanistic insight into those processes is limited. To deepen our understanding of the interplay between toxic RNA exp molecules and multiple protein partners, in this review, we discuss the roles of selected RNA-binding proteins (RBPs) that interact with RNA exp and thus act as "partners in crime" in the progression of REDs. We gather current findings concerning RBPs involved at different stages of the RNA exp life cycle, such as transcription, splicing, transport, and AUG-independent translation of expanded repeats. We argue that the activity of selected RBPs can be unique or common among REDs depending on the expanded repeat type. We also present proteins that are functionally depleted due to sequestration on RNA exp within nuclear foci and those which participate in RNA exp -dependent innate immunity activation.Abbreviations: 3 0 UTR/5 0 UTR, 3 0 /5 0 untranslated regions; AS, alternative splicing; ASO, antisense oligonucleotide; C9-ALS/FTD, C9orf72-linked amyotrophic lateral sclerosis and frontotemporal dementia; CAG exp , expanded CAG repeats; CCUG exp , expanded CCUG repeats; CGG exp , expanded CGG repeats; CTG exp , expanded CTG repeats; CUG exp , expanded CUG repeats;

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The RNA helicase DHX36–G4R1 modulates C9orf72 GGGGCC hexanucleotide repeat–associated translation

Cited by 25 publications

References 88 publications

RNA Helicases in Microsatellite Repeat Expansion Disorders and Neurodegeneration

RNA Helicases in Microsatellite Repeat Expansion Disorders and Neurodegeneration

C9orf72 ALS/FTD dipeptide repeat protein levels are reduced by small molecules that inhibit PKA or enhance protein degradation

Partners in crime: Proteins implicated in RNA repeat expansion diseases

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