The chicken miR-150 targets the avian orthologue of the functional zebrafish MYB 3'UTR target site
- Equal contributors
1 Université François Rabelais, Equipe Transcription, Lymphome Viro-induit, UFR Sciences et Techniques, Parc de Grandmont, F-37200 Tours, France
2 INSERM, U618 Protéases et Vectorisation Pulmonaire, UFR de Médecine, F-37000 Tours, France
3 INRA, Département de Santé Animale, F-37380 Nouzilly, France
4 INRA, Laboratoire de Virologie Moléculaire, UR-IASP 213, F-37380 Nouzilly, France
5 Université de Namur, Département Vétérinaire, Faculté des Sciences, FUNDP, 5000 Namur, Belgique
BMC Molecular Biology 2010, 11:67 doi:10.1186/1471-2199-11-67Published: 2 September 2010
The c-myb proto-oncogene is the founding member of a family of transcription factors involved principally in haematopoiesis, in diverse organisms, from zebrafish to mammals. Its deregulation has been implicated in human leukaemogenesis and other cancers. The expression of c-myb is tightly regulated by post-transcriptional mechanisms involving microRNAs. MicroRNAs are small, highly conserved non-coding RNAs that inhibit translation and decrease mRNA stability by binding to regulatory motifs mostly located in the 3'UTR of target mRNAs conserved throughout evolution. MYB is an evolutionarily conserved miR-150 target experimentally validated in mice, humans and zebrafish. However, the functional miR-150 sites of humans and mice are orthologous, whereas that of zebrafish is different.
We identified the avian mature miRNA-150-5P, Gallus gallus gga-miR-150 from chicken leukocyte small-RNA libraries and showed that, as expected, the gga-miR-150 sequence was highly conserved, including the seed region sequence present in the other miR-150 sequences listed in miRBase. Reporter assays showed that gga-miR-150 acted on the avian MYB 3'UTR and identified the avian MYB target site involved in gga-miR-150 binding. A comparative in silico analysis of the miR-150 target sites of MYB 3'UTRs from different species led to the identification of a single set of putative target sites in amphibians and zebrafish, whereas two sets of putative target sites were identified in chicken and mammals. However, only the target site present in the chicken MYB 3'UTR that was identical to that in zebrafish was functional, despite the additional presence of mammalian target sites in chicken. This specific miR-150 site usage was not cell-type specific and persisted when the chicken c-myb 3'UTR was used in the cell system to identify mammalian target sites, showing that this miR-150 target site usage was intrinsic to the chicken c-myb 3'UTR.
Our study of the avian MYB/gga-miR-150 interaction shows a conservation of miR-150 target site functionality between chicken and zebrafish that does not extend to mammals.