Eukaryotic Translation Initiation Factor 3 Subunit B Promotes Head And Neck Cancer Via CEBPB Translation

Background: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer type worldwide. Deregulation of mRNA translation is a frequent feature of cancer. Eukaryotic Translation Initiation Factor 3 Subunit B (EIF3B) has reported as oncogenes in cancer. However, the role of EIF3B in HNSCC remains unclear. Methods: In this study, the clinical significance of EIF3B expression in TCGA was analyzed. Then the expression of EIF3B was knockdown, and its role in HNSC was revealed. To explore the molecular mechanism of EIF3B, we applied RNA sequencing and proteomics, and deregulated pathways were acquired. RNA immunoprecipitation (RIP) sequencing was conducted to uncover the targeting mRNAs of EIF3B. Potential targets of EIF3B were validated with TCGA datasets.Results: EIF3B serves a hazardous prognostic marker in HNSCC. Besides, EIF3B promotes HNSCC proliferation and progression in vitro and in vivo. EIF3B promotes CEBPB translation and activate MAPK pathway. IL6R and CCNG2 is a target of EIF3B regulated CEBPB translation. Conclusion: In sum, this study reveals EIF3B as a novel oncogene in HNSCC, by promoting CEBPB translation and IL6R expression.

The eukaryotic translation initiation factor eIF4E reprogrammes the splicing machinery and drives alternative splicing

Aberrant RNA splicing contributes to the pathogenesis of many malignancies including Acute Myeloid Leukemia (AML). While mutation is the best described mechanism underpinning aberrant splicing, recent studies show that predictions based on mutations alone likely underestimate the extent of this dysregulation1 . Here, we show that elevation of the eukaryotic translation initiation factor eIF4E reprogrammes splicing of nearly a thousand RNAs in model cell lines. In AML patient specimens which did not harbour known splice factor mutations, ~4000 transcripts were differentially spliced based on eIF4E levels and this was associated with poor prognosis. Inhibition of eIF4E in cell lines reverted the eIF4E-dependent splice events examined. Splicing targets of eIF4E act in biological processes consistent with its role in malignancy. This altered splicing program likely arose from eIF4E-dependnet increases in the production of many components of the spliceosome including SF3B1 and U2AF1 which are frequently mutated in AML. Notably, eIF4E did not drive mutation of these factors, only their production. eIF4E also physically associated with many splice factors including SF3B1, U2AF1, and UsnRNAs. Importantly, many eIF4E-dependent splice events differed from those arising from SF3B1 mutation, and were more extensive highlighting that these splicing profiles arise from distinct mechanisms. In all, our studies provide a paradigm for how dysregulation of a single factor, eIF4E, can alter splicing.

Targeted Knockout of Eukaryotic Translation Initiation Factor 4E Confers Bymovirus Resistance in Winter Barley

The Eukaryotic Translation Initiation Factor 4E (EIF4E) is a well-known susceptibility factor for potyvirus infections in many plant species. The barley yellow mosaic virus disease, caused by the bymoviruses Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), can lead to yield losses of up to 50% in winter barley. In autumn, the roots of young barley plants are infected by the soil-borne plasmodiophoraceous parasite Polymyxa graminis L. that serves as viral vector. Upon viral establishment and systemic spreading into the upper parts of the plants, yellow mosaics occur as first symptoms on leaves. In the further course of plant development, the disease entails leaf necrosis and increased susceptibility to frost damage. Thanks to the rym4 and rym5 allelic variants of the HvEIF4E gene, more than two thirds of current European winter barley cultivars are resistant to BaYMV and BaMMV. However, several strains of BaYMV and BaMMV have already overcome rym4- and rym5-mediated resistance. Accordingly, new resistance-conferring alleles are needed for barley breeding. Therefore, we performed targeted mutagenesis of the EIF4E gene by Cas9 endonuclease in BaMMV/BaYMV-susceptible winter barley cv. “Igri”. Small insertions were generated, resulting in a shift of the translational reading frame, thereby causing the loss-of-function of EIF4E. The mutations occurred in the homozygous state already in the primary mutants. Their progeny proved invariably homozygous and fully resistant to mechanical inoculation with BaMMV. EIF4E knockout plants showed normal growth habit and produced grains, yet exhibited a yield penalty.

The regulation of the mammalian maternal-to-embryonic transition by eukaryotic translation initiation factor 4E

Eukaryotic translation initiation factor 4E (eIF4E) mediates CAP-dependent translation. Genetic and inhibitor studies show its expression was required for the successful transition from maternal to embryonic control of mouse embryo development. eIF4E was in the oocyte and in the cytoplasm soon after fertilization, and at each stage of early development. Functional knockout (Eif4e−/-) by PiggyBac (PB) [Act-RFP] transposition caused peri-implantation embryonic lethality due to the failure of normal epiblast formation. Maternal stores of eIF4E supported development up to the 2-4-cell stage after which new expression occurred from both alleles. Inhibition of the maternally acquired stores of eIF4E (4EGI-1 inhibitor) resulted in a block at the 2-cell stage. eIF4E activity was required for new protein synthesis in the 2-cell embryo and knockout embryos had lower translational activity than wildtype embryos. 4E-BP1 is a hypophosphorylation-dependent negative regulator of eIF4E. mTOR activity was required for 4E-BP1 phosphorylation and inhibiting mTOR retarded embryo development. This study shows that eIF4E activity is regulated at key embryonic transitions in the mammalian embryo and is essential for the successful transition to embryonic control of development.