Essential Roles and Risks of G-Quadruplex Regulation: Recognition Targets of ALS-Linked TDP-43 and FUS

Ishiguro, Akira; Ishihama, Akira

doi:10.3389/fmolb.2022.957502

Cited by 7 publications

(11 citation statements)

References 114 publications

(155 reference statements)

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“…1 D). The binding of G4-RNA to specific interacting proteins with multiple binding modules often does not migrate normally when using a non-denaturing acrylamide gel 6 . As a result, this attempt was effective.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, identifying and analyzing the state of RNA molecules common to all is essential. Indeed, without exception, all these RNAs and RBPs are associated with G-quadruplexes (G4) and are components of ribonucleoprotein (RNP) granules assembled through liquid–liquid phase separation (LLPS) 6 (Table S1 ). This is surprising because there are not many RBPs that specifically recognize G4 7 , 8 .…”

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confidence: 99%

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ALS-linked TDP-43 mutations interfere with the recruitment of RNA recognition motifs to G-quadruplex RNA

Ishiguro

Ishihama

2023

Sci Rep

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TDP-43 is a major pathological protein in sporadic and familial amyotrophic lateral sclerosis (ALS) and mediates mRNA fate. TDP-43 dysfunction leads to causes progressive degeneration of motor neurons, the details of which remain elusive. Elucidation of the molecular mechanisms of RNA binding could enhance our understanding of this devastating disease. We observed the involvement of the glycine-rich (GR) region of TDP-43 in the initial recognition and binding of G-quadruplex (G4)-RNA in conjunction with its RNA recognition motifs (RRM). We performed a molecular dissection of these intramolecular RNA-binding modules in this study. We confirmed that the ALS-linked mutations in the GR region lead to alteration in the G4 structure. In contrast, amino acid substitutions in the GR region alter the protein structure but do not void the interaction with G4-RNA. Based on these observations, we concluded that the structural distortion of G4 caused by these mutations interferes with RRM recruitment and leads to TDP-43 dysfunction. This intramolecular organization between RRM and GR regions modulates the overall G4-binding properties.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

ALS-linked TDP-43 mutations interfere with the recruitment of RNA recognition motifs to G-quadruplex RNA

Ishiguro

Ishihama

2023

Sci Rep

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Section: Resultsmentioning

confidence: 99%

“…G4 ligands have been shown to ameliorate the presence of ALS aggregates in cells 26,52 . The ligands have been speculated to act by disrupting the toxic downstream functions of C9orf72 - thought to underpin aggregation 52 . Having demonstrated that mG4s alone are able to prompt aggregation in protein-free samples, we asked whether G4 ligands could destabilise the condensates by promoting the formation of unimolecular as opposed to multimolecular G-quadruplexes.…”

Section: Resultsmentioning

confidence: 99%

The ALS/FTD-related C9orf72 hexanucleotide repeat expansion forms RNA condensates through multimolecular G-quadruplexes

Raguseo¹,

Tanase²,

Malouf³

et al. 2023

Preprint

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Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are just two of the neurodegenerative diseases characterised by the presence of pathological aggregates. 40% of familiar cases in ALS and FTD have been correlated to expansion of the hexanucleotide repeat (GGGGCC)n, which has been previously shown to assemble into G-quadruplexes (G4s) structures. In this study we investigated the role of nucleic acids and secondary structure formation in the generation of ALS/FTD aggregates, something that has often been relegated as a peripheral effect in the protein-led aggregation. We showed a correlation between the emergence of multimolecular G4s (mG4s) formed by the DNA (GGGGCC)n repeats and the formation of protein free insoluble aggregates. We revealed that the aggregation is dependent on K+ concentration and repeat-length, suggesting that G4-formation plays a role in the the formation of aggregates. G4-structures were detected in the aggregates by staining with the G4-specific fluorescent dye NMM. G4-unfolding promoted by NMM-mediated guanine photo-oxidation led to prompt disassembly of the insoluble aggregates, further confirming a G4-based mechanism. To reinforce the physiological relevance of our observations, we characterised the aggregation of RNA (GGGGCC)n, which is thought to contribute to pathological aggregation in ALS/FTD. We observed that RNA repeats can aggregate at significant lower concentrations compared to DNA, suggesting that under physiological conditions RNA repeats can aggregate in the absence of any protein. Our findings constitute the first evidence supporting the formation of mG4-structures to drive protein-free aggregation, highlighting the potential of mG4s as therapeutic target to for the treatment of ALS and FTD.

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“…Furthermore, the FUS is an important model for investigating the LLPS behavior of IDPs/IDRs, and there are abundant studies for LLPS using the FUS model. Some functional MLOs containing FUS are modulated by the recognition of FUS to special RNA fragments [ 6 , 16 , 26 ]. Kang et al found that the LLPS of FUS whose aggregation leads to ALS/FTD is enhanced at low concentrations for ATP but is dissolved at high concentrations [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Mass Change on Liquid–Liquid Phase Separation of the RNA-Binding Protein Fused in Sarcoma

et al. 2023

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In recent years, many experimental and theoretical studies of protein liquid–liquid phase separation (LLPS) have shown its important role in the processes of physiology and pathology. However, there is a lack of definite information on the regulation mechanism of LLPS in vital activities. Recently, we found that the intrinsically disordered proteins with the insertion/deletion of a non-interacting peptide segment or upon isotope replacement could form droplets, and the LLPS states are different from the proteins without those. We believed that there is an opportunity to decipher the LLPS mechanism with the mass change perspective. To investigate the effect of molecular mass on LLPS, we developed a coarse-grained model with different bead masses, including mass 1.0, mass 1.1, mass 1.2, mass 1.3, and mass 1.5 in atomic units or with the insertion of a non-interacting peptide (10 aa) and performed molecular dynamic simulations. Consequently, we found that the mass increase promotes the LLPS stability, which is based on decreasing the z motion rate and increasing the density and the inter-chain interaction of droplets. This insight into LLPS by mass change paves the way for the regulation and relevant diseases on LLPS.

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Essential Roles and Risks of G-Quadruplex Regulation: Recognition Targets of ALS-Linked TDP-43 and FUS

Cited by 7 publications

References 114 publications

ALS-linked TDP-43 mutations interfere with the recruitment of RNA recognition motifs to G-quadruplex RNA

ALS-linked TDP-43 mutations interfere with the recruitment of RNA recognition motifs to G-quadruplex RNA

The ALS/FTD-related C9orf72 hexanucleotide repeat expansion forms RNA condensates through multimolecular G-quadruplexes

Effects of Mass Change on Liquid–Liquid Phase Separation of the RNA-Binding Protein Fused in Sarcoma

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