Guanine Nucleotide-Binding Protein-Like 1 (GNL1) binds RNA G-quadruplex structures in genes associated with Parkinson's disease

RNAs are highly regulated at the post-transcriptional level in neurodegenerative diseases and just a few mutations can significantly affect the fate of neuronal cells. To date, the impact of G-quadruplex (G4) regulation in neurodegenerative diseases like Parkinson's disease (PD) has not been analysed. In this study, in silico potential G4s located in deregulated genes related to the nervous system were initially identified and were found to be significantly enriched. Several G4 sequences found in the 5MODIFIER LETTER PRIME untranslated regions (5MODIFIER LETTER PRIMEUTR) of mRNAs associated with Parkinson's disease were demonstrated to in fact fold in vitro by biochemical assays. Subcloning of the full-length 5MODIFIER LETTER PRIMEUTRs of these candidates upstream of a luciferase reporter system led to the demonstration that the G4s of both Parkin RBR E3 Ubiquitin Protein Ligase (PRKN) and Vacuolar Protein Sorting-Associated Protein 35 (VPS35) significantly repressed the translation of both genes in SH-SY5Y cells. Subsequently, a strategy of using label-free RNA affinity purification assays with either of these two G4 sequences as bait isolated the Guanine Nucleotide-Binding Protein-Like 1 (GNL1). The latter was shown to have a higher affinity for the G4 sequences than for their mutated version. This study sheds light on new RNA G-quadruplexes located in genes dysregulated in Parkinson disease and a new G4-binding protein, GNL1.

Automated summary

This study identified the presence of G-quadruplex regulation in neurodegenerative diseases and demonstrated the folding of G4 sequences in the 5' untranslated regions of mRNAs associated with Parkinson's disease. The G4s significantly repressed the translation of Parkin RBR E3 Ubiquitin Protein Ligase (PRKN) and Vacuolar Protein Sorting-Associated Protein 35 (VPS35) in neuronal cells, and a novel G4-binding protein, GNL1, was identified through RNA affinity purification assays.