RNA G-quadruplex (rG4) structures can influence the fate and functions of mRNAs, especially the translation process. The presence of rG4 structures in 5'-untranslated regions (5'-UTRs) of mRNAs generally represses translation. However, rG4 structures can also promote internal ribosome entry site (IRES)-mediated translation as one of its determinants. Here, we report the identification of an evolutionary conserved rG4-forming sequence motif at the extreme 5'-end of the unusually long 5'-UTR (1.7 kb) in the transcript of human gene encoding the cellular inhibitor of apoptosis protein-1 that promotes cell survival by suppressing apoptosis and is overexpressed in various cancer cells. Expectedly, NMR study, CD spectroscopy, and UV melting assay confirm the formation of a potassium ion-dependent intramolecular and parallel rG4 structure at the sequence stretch. Moreover, the G4-RNA-specific precipitation using biotin-linked biomimetic BioCyTASQ validates the formation of the rG4 structure in the 5'-UTR in cells. Interestingly, disruption of the rG4 structure in the 5'-UTR results in a dramatic reduction in translation of the downstream luciferase reporter in cells, suggesting a translation-promoting effect of the rG4 structure, contrary to many earlier reports. Furthermore, enhancement of translation by the rG4 structure occurs in an IRES-independent manner.
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http://dx.doi.org/10.1021/acs.biochem.3c00521 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Max Perutz Labs, Vienna Biocenter Campus, Vienna 1030, Austria.
RNA G-quadruplexes (rG4s), the four-stranded structures formed by guanine-rich RNA sequences, are recognized by regions in RNA-binding proteins (RBPs) that are enriched in arginine-glycine repeats (RGG motifs). Importantly, arginine and glycine are encoded by guanine-rich codons, suggesting that some RGG motifs may both be encoded by and interact with rG4s in autogenous messenger RNAs (mRNAs). By analyzing transcriptome-wide rG4 datasets, we show that hundreds of RGG motifs in humans are at least partly encoded by rG4s, with an increased incidence for longer RGG motifs (~10 or more residues).
View Article and Find Full Text PDFInt J Biol Macromol
January 2025
School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, China; Smart Medical Innovation Technology Center, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:
G-quadruplexes (G4s) are non-canonical nucleic acid secondary structures formed by guanine-rich DNA or RNA sequences. These structures play pivotal roles in cellular processes, including DNA replication, transcription, RNA splicing, and protein translation. High-throughput sequencing has significantly advanced the study of G4s by enabling genome-wide mapping and detailed characterization.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Guangdong Provincial Key Laboratory of Digestive Cancer Research, Digestive Diseases Center, Scientific Research Center, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, Guangdong, 518107, P. R. China.
Precise control of Cas12a activity is essential for the improvement of the detection limit of clinical diagnostics and the minimization of errors. This study addresses the challenge of controlling Cas12a activity, especially in the context of nucleic acid detection where the inherent incompatibility between isothermal amplification and CRISPR reactions complicates accurate diagnostics. An RNA G-quadruplex (RG4) structure at the 5' end of crRNA is introduced to modulate Cas12a activity accurately without the need for chemical modifications.
View Article and Find Full Text PDFSTAR Protoc
December 2024
Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA. Electronic address:
Here, we present a protocol for using d-rG4-seq, a technique for mapping RNA G-quadruplex (rG4) for chromatin-bound RNA. We describe steps for identifying in vivo rG4 structures based on differential sensitivity of rG4 to dimethyl sulfate (DMS) modification, folding in the presence of monovalent cations, K+ versus Li+, and reverse transcriptase (RT) readthrough when folded. We then detail procedures for isolating RNA from the chromatin-bound fractions to enrich for epigenetic regulators and comparing in vitro versus in vivo profiles.
View Article and Find Full Text PDFIn Silico Pharmacol
November 2024
Department of Microbiology and Immunology, Dalhousie University, Halifax, Canada.
Cancer is a major global health burden, causing significant economic losses and premature deaths worldwide. Maintenance of telomeric repeats by telomerase makes the cancer cells immortal. Non-nucleoside mushroom metabolites were screened for their ability to stabilize RG4 structures, making telomeres inaccessible to telomerase and inducing telomere shortening in cancer cells.
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