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International audience; miRNAs regulate gene expression by binding with mRNAs of many genes. Studying their effects on genes involved in oncogenesis is important in cancer diagnostics and therapeutics. The RNAHybrid 2.1 program was used to predict the strong miRNA binding sites (p < 0.0005) in target mRNAs. The program Finder 2.2 was created to verify 784 intergenic miRNAs (ig-miRNA) origin. Among 54 considered oncogenes and tumor suppressor genes, 47 genes are the best targets for ig-miRNAs. Accordingly, these genes are strongly regulated by 111 ig-miRNAs. Some miRNAs bind several mRNAs, and some mRNAs have several binding sites for miRNAs. Of the 54 mRNAs, 21.8%, 43.0%, and 35.2% of the miRNA binding sites are present in the 5'UTRs, CDSes, and 3'UTRs, respectively. The average density of the binding sites for miRNAs in the 5'UTR was 4.4 times and 4.1 times greater than in the CDS and the 3'UTR, respectively. Three types of interactions between miRNAs and mRNAs were identified, which differ according to the region of the miRNA bound to the mRNA: 1) binding occurs predominantly via the 3'-region of the miRNA; 2) binding occurs predominantly through the central region of the miRNA; and 3) binding occurs predominantly via the 5'-region of the miRNA. Several miRNAs effectively regulate only one gene, and this information could be useful in molecular medicine to modulate translation of the target mRNA. We recommend described new sites for validation by experimental investigation.; miRNAs regulent l'expression des genes par fixation avec le mRNAs de nombreux gènes. L'étude de leur effet sur les gènes impliqués dans l'oncogénèse est importante pour le diagnostic du cancer et sa thérapeutique. Le programme RNAHybrid 2.1 a été utilisé pour prédire des sites de fixation forts de miRNA (p < 0.0005) dans des mRNAs cibles. Le program Finder 2.2 a été écrit pour vérifier l'origine 784 miRNAs intergeniques (ig-miRNA) . Plusieurs miRNAs ne reegulent effectivement qu'un seul gène et cette information pourrait être utile en médecine moléculaire pour modérer la traduction du mRNA cible.

OnlyPTPN12, MSH6, andZEB1have significant miR-1279 binding sites among paralogous genes of human tyrosine phosphatase family, DNA mismatch repair family, and zinc finger family, respectively. All miRNA binding sites are located within CDSs of studied mRNAs. Nucleotide sequences of hsa-miR-1279 binding sites with mRNAs of humanPTPN12, MSH6, andZEB1genes encode TKEQYE, EGSSDE, and GEKPYE oligopeptides, respectively. The conservation of miRNA binding sites encoding oligopeptides has been revealed. MRNAs of many paralogs of zinc finger gene family have from 1 to 12 binding sites coding the same GEKPYE hexapeptide. MRNAs ofPTPN12, MSH6, andZEB1orthologous genes from different animal species have binding sites for hsa-miR-1279 which consist of homologous oligonucleotides encoding similar human oligopeptides TKEQYE, EGSSDE, and GEKPYE. MiR-548j, miR-548m, and miR-548d-5p have homologous binding sites in the mRNA ofPTPN12orthologous genes which encode PRTRSC, TEATDI, and STASAT oligopeptides, respectively. All regions of miRNA are important for binding with the mRNA.

Regulatory relationships of 686 intronic miRNA and 784 intergenic miRNAs with mRNAs of 51 intronic miRNA coding genes were established. Interaction features of studied miRNAs with 5'UTR, CDS and 3'UTR of mRNA of each gene were revealed. Functional regions of mRNA were shown to be significantly heterogenous according to the number of binding sites of miRNA and to the location density of these sites.