Transcriptional and post-transcriptional control of eEF1A2 expression during myoblast diffrerentiation

During postnatal development, the switch of the expression from isoform A1 to the isoform A2 of eukaryotic translation elongation factor (eEF1A) is observed in neuronal and muscle tissues. The switch of the expression is a vital fundamental process, as mutant mice, with the partial EEF1A2 deletion dies on the 28th day after birth. Mechanism of the inhibition of A1 and stimulation of A2 expression during the first days of postnatal development is unknown. The existence of potential miRNA binding sites in the 3’UTR of mRNAs encoding the isoforms assumes a post-transcriptional control of abovementioned phenomenon. Aim. To check the possibility of post-transcriptional regulation of the isoforms A1 and A2 expression during differentiation of the human immortalized myoblasts cell line LHCN. Methods. The level of gene expression was quantified by qPCR, the existence of post-transcriptional regulation was demonstrated with Dual-Luciferase® Reporter Assay. Results. Using immortalized human myoblasts cell line LHCN, the induction of isoform A2 of eEF1 during differentiation of myoblasts was shown. The existence of transcriptional and post-transcriptional control of the abovementioned process was confirmed. Downregulation of mir-661 and mir-744 that have binding sites in the 3’ UTR of EEF1A2 mRNA, during differentiation suggests a potential role of microRNAs in the eEF1A2 induction during myoblast differentiation. Conclusions. Induction of A2 isoform of eEF1 during differentiation of myoblasts occurs on transcriptional and post-transcriptional level

Isoforms of elongation factor eEF1A may be differently regulated at post-transcriptional level in breast cancer progression

Eukaryotic translation elongation factor 1A exists as two 98 % homologous isoforms: eEF1A1 (A1) and eEF1A2 (A2) which are tissue and development specific. Despite high homology in an open reading frame (ORF) region, mRNAs coding for eEF1A1 and eEF1A2 are different in their untranslated regions (UTR), suggesting a possibility of their dissimilar post-transcriptional regulation. Aim. To analyze the existence of cis-acting motifs in the UTRs of EEF1A1/A2 mRNAs, to confirm the possibility of post-transcriptional control of eEF1A1 and eEF1A2 expression. Methods. An ensemble of bioinformatic methods was applied to predict regulatory motifs in the UTRs of EEF1A1/A2 mRNAs. Dual-luciferase reporter assay was employed to detect post-transcriptional regulation of eEF1A1/A2 expression. Results. Numerous regulatory motifs in the UTR of EEF1A1/A2 mRNAs were found bioinformatically. The experimental evidence was obtained for the existence of negative regulation of EEF1A1 and positive regulation of EEF1A2 mRNA in the model of breast cancer development. Conclusions. EEF1A1 and EEF1A2 mRNAs contain distinct motifs in the UTRs and are differently regulated in cancer suggesting the possibility of their control by different cellular signals

PTI-1: novel way to oncogenicity

Aim. The prostate tumor-inducing oncogene (PTI-1), presumably encoding a truncated form of eukaryotic translation elongation factor 1A1 (eEF1A1), was discovered as a gene overexpressed in prostate tumor samples and absent in normal tissues. The mechanism of PTI-1 oncogenicity remains obscure. Methods. Several bioinformatics methods were applied to analyze the PTI-1 mRNA structure, translation efficiency and coding potential. Results. In silico analysis of 5'UTR of its mRNA suggest that PTI-1 mRNA most probably belongs to the class of templates with low translation efficiency. Additionally, novel open reading frame (ORF) starting with alternati- ve initiation site situated upstream of the main ORF start codon was found. Finally, the peptide that does not resemble eEF1A1 but is partially homologous to relaxin can be synthesized. Conclusions. We suggest that the alternative upstream start codon may initiate synthesis of a peptide (uPTI-1) homologous to relaxin, the hormone shown to promote the prostate cancer progression. uPTI-1 protein may interact with the respective relaxin-specific receptors, suggesting that the tumorigenic outcome of PTI-1 is possibly realized via the relaxin-dependent pathway