Fragile X mental retardation protein recognizes a G quadruplex structure within the survival motor neuron domain containing 1 mRNA 5′-UTR

Abstract

G quadruplex structures have been predicted by bioinformatics to form in the 5′- and 3′-untranslated regions (UTRs) of several thousand mature mRNAs and are believed to play a role in translation regulation. Elucidation of these roles has primarily been focused on the 3′-UTR, with limited focus on characterizing the G quadruplex structures and functions in the 5′-UTR. Investigation of the affinity and specificity of RNA binding proteins for 5′-UTR G quadruplexes and the resulting regulatory effects have also been limited. Among the mRNAs predicted to form a G quadruplex structure within the 5′-UTR is the survival motor neuron domain containing 1 (SMNDC1) mRNA, encoding a protein that is critical to the spliceosome. Additionally, this mRNA has been identified as a potential target of the fragile X mental retardation protein (FMRP), whose loss of expression leads to fragile X syndrome. FMRP is an RNA binding protein involved in translation regulation that has been shown to bind mRNA targets that form G quadruplex structures. In this study we have used biophysical methods to investigate G quadruplex formation in the 5′-UTR of SMNDC1 mRNA and analyzed its interactions with FMRP. Our results show that SMNDC1 mRNA 5′-UTR forms an intramolecular, parallel G quadruplex structure comprised of three G quartet planes, which is bound specifically by FMRP both in vitro and in mouse brain lysates. These findings suggest a model by which FMRP might regulate the translation of a subset of its mRNA targets by recognizing the G quadruplex structure present in their 5′-UTR, and affecting their accessibility by the protein synthesis machinery.

G-quadruplexes offer a conserved structural motif for NONO recruitment to NEAT1 architectural lncRNA

“…Five sequences with the highest G-scores were chosen for further characterization: NEAT1_425, NEAT1_2070, NEAT1_2171, NEAT1_3226 and NEAT1_22619. RNA molecules containing the sequence characteristics required to form monomeric intramolecular G-quadruplexes have not, to the best of our knowledge, been found to produce multi-strand intermolecular G-quadruplexes, retaining their intramolecular G-quadruplex form at concentrations much higher than those used in this work ( 91 , 92 ). Accordingly, the oligonucleotides examined here are unlikely to form intermolecular G-quadruplexes.…”

Oxidative Stress: Role and Response of Short Guanine Tracts at Genomic Locations

“…Various small molecules such as Quarfloxin, BRACO-19, Berberine, Telomstatin, and Sanguinarine [82,83] and proteins (Pif1 helicase, FMRP, RHAU etc.) specifically interact with these non-B-DNA structures in biological system to stabilize or destabilize these structures [84,85,86].…”

G-Quadruplexes as pathogenic drivers in neurodegenerative disorders

“…FMRP has also been shown to bind to G4s located in the 5′-UTR and 3′-UTR of its other target mRNAs. For example, the FMRP RGG box has been observed to bind to an intramolecular, parallel G4 formed in the 5′-UTR of survival motor neuron domain containing 1 ( SMNDC1 ) in vitro ( 97 ). G4 motifs formed in the 5′-UTR of mRNAs typically operate as inhibitory translational elements, and FMRP binding may repress translation by impeding the accessibility of the translation initiation sites.…”