Different recognition modes of G‐quadruplex RNA between two ALS/FTLD‐linked proteins TDP‐43 and FUS

Abstract

Amyotrophic lateral sclerosis/frontotemporal lobar degeneration‐linked proteins, TDP‐43 and fused in sarcoma (FUS), bind to G‐quadruplex‐containing mRNAs and transport them to distal neurites for local translation. The specificity and mechanism of G4‐RNA binding, however, remain largely unsolved. Using purified full‐length TDP‐43 and FUS and a set of seven G4‐DNA/RNA, we compared their recognition properties of G4‐RNAs. Both TDP‐43 and FUS recognized and bound to G4‐DNA/RNAs, but the target selectivity differed between two proteins. TDP‐43 recognized only parallel‐stranded G4‐DNA/RNAs, leading to stabilize the G4 conformation. In contrast, FUS bound to all three types, parallel, hybrid, and antiparallel, of G4‐DNA/RNAs, resulting in deformation of the G4 structure. We then concluded that the target selectivity and the influence on G4 RNA structure differed between TDP‐43 and FUS.

ALS-linked FUS mutations dysregulate G-quadruplex-dependent liquid–liquid phase separation and liquid-to-solid transition

“…Recently, however, we succeeded to purify the full-length tag-free human FUS in soluble form ( Fig. 1 B ) ( 31 ). At the final purification step, FUS was prepared in a storage buffer containing β-cyclodextrin (βCD), a cyclic oligosaccharide, consisting of a macrocyclic ring of glucose subunits and forming hydrophobic cavities.…”

“…1A). With use of full-length tag-free FUS protein, we recently found the involvement of multiple structural domains of FUS other than the RRM and Zn finger domains in specific and stable interaction with highly structured DNA/RNA probes (31). Interestingly all ALS-linked missense and internal deletion/insertion mutations in FUS are present in the J o u r n a l P r e -p r o o f so-called disordered region (Fig.…”

“…Previously, we demonstrated that FUS-RNA binding is extremely dependent on the RNA conformation (31). Some of the mRNAs that are transported to the distal areas for local J o u r n a l P r e -p r o o f translation have more specific functions than general localization signals (57).…”

“…The recognition of G4 structure enhances the formation of FUS condensate, but simple G-rich sequence does not induce this LLPS process. Therefore, FUS is able to bind to G-rich RNA hairpin structure (31,74), but this binding completely loses the ability to enhance the condensate formation J o u r n a l P r e -p r o o f (see Fig. 3).…”

The Regulatory Role of RNA Metabolism Regulator TDP-43 in Human Cancer

“…The mRNA transport process is critical for physiological processes as well as cancer genesis and maintenance. TDP-43 was reported to bind and transport G-quadruplex-containing mRNAs into neurites for local translation (47). G-quadruplex (G4) was known to influence RNA post-transcriptional mechanisms, thereby impacting neurodegenerative disease and cancer (48).…”