Four translation initiation pathways employed by the leaderless mRNA in eukaryotes
SCIENTIFIC REPORTS
Authors: Akulich, Kseniya A.; Andreev, Dmitry E.; Terenin, Ilya M.; Smirnova, Victoria V.; Anisimova, Aleksandra S.; Makeeva, Desislava S.; Arkhipova, Valentina I.; Stolboushkina, Elena A.; Garber, Maria B.; Prokofjeva, Maria M.; Spirin, Pavel V.; Prassolov, Vladimir S.; Shatsky, Ivan N.; Dmitriev, Sergey E.
Abstract
mRNAs lacking 5' untranslated regions (leaderless mRNAs) are molecular relics of an ancient translation initiation pathway. Nevertheless, they still represent a significant portion of transcriptome in some taxons, including a number of eukaryotic species. In bacteria and archaea, the leaderless mRNAs can bind non-dissociated 70 S ribosomes and initiate translation without protein initiation factors involved. Here we use the Fleeting mRNA Transfection technique (FLERT) to show that translation of a leaderless reporter mRNA is resistant to conditions when eIF2 and eIF4F, two key eukaryotic translation initiation factors, are inactivated in mammalian cells. We report an unconventional translation initiation pathway utilized by the leaderless mRNA in vitro, in addition to the previously described 80S-, eIF2-, or eIF2D-mediated modes. This mechanism is a bacterial-like eIF5B/IF2-assisted initiation that has only been reported for hepatitis C virus-like internal ribosome entry sites (IRESs). Therefore, the leaderless mRNA is able to take any of four different translation initiation pathways in eukaryotes.
Mining the role of RECQL5 in gastric cancer and seeking potential regulatory network by bioinformatics analysis
EXPERIMENTAL AND MOLECULAR PATHOLOGY
Authors: Lin, Yijia; Chen, Honglei; Wang, Xinyou; Xiang, Jun; Wang, Huashe; Peng, Junsheng
Abstract
Aim: The role of RecQ protein-like 5 (RECQL5) in gastric carcinoma (GC) is still unclear. Here, we investigated the role of RECQL5 in human GC and its potential regulatory network via bioinformatics analysis. Methods: Bioinformatic analysis was performed using data in the Oncomine database, Kaplan- Meier Plotter online software, MethHC database, catalogue of somatic mutations in cancer (COSMIC), cbioportal database and String database. Then, we verified the association between RECQL5 expression and GC prognosis by immunohistochemistry (IHC). The independent prognostic factors were determined by Cox multivariate analysis. Results: It was found that both the mRNA and protein expression levels of RECQL5 were downregulated in GC samples (P < .05). Low RECQL5 expression indicated a poor prognosis in GC patients and is the independent prognostic factors for GC. No correlation between RECQL5 mRNA and DNA methylation was found using the MethHC database. The analysis of the COSMIC database showed a high proportion of missense mutation in GC. The functional enrichment analysis predicted that RECQL5 plays a role in DNA repair and cellular responses to DNA damage stimulus. RECQL5 might be enriched in homologous recombination pathways and Fanconi anemia pathway. Bioinformatics analysis identified 5 genes, namely POLR2D, POLR2G, DXO, KIN, and EIF2D, that were significantly correlated with RECQL5. Conclusion: The low expression of RECQL5 predicts poor overall survival in GC. RECQL5 may be a novel tumor suppressor for patients with GC.