Two new miR-16 targets: caprin-1 and HMGA1, proteins implicated in cell proliferation.
BACKGROUND
miRNAs (microRNAs) are a class of non-coding RNAs that inhibit gene expression by binding to recognition elements, mainly in the 3' UTR (untranslated region) of mRNA. A single miRNA can target several hundred mRNAs, leading to a complex metabolic network. miR-16 (miRNA-16), located on chromosome 13q14, is involved in cell proliferation and apoptosis regulation; it may interfere with either oncogenic or tumour suppressor pathways, and is implicated in leukaemogenesis. These data prompted us to search for and validate novel targets of miR-16.


RESULTS
In the present study, by using a combined bioinformatics and molecular approach, we identified two novel putative targets of miR-16, caprin-1 (cytoplasmic activation/proliferation-associated protein-1) and HMGA1 (high-mobility group A1), and we also studied cyclin E which had been previously recognized as an miR-16 target by bioinformatics database. Using luciferase activity assays, we demonstrated that miR-16 interacts with the 3' UTR of the three target mRNAs. We showed that miR-16, in MCF-7 and HeLa cell lines, down-regulates the expression of caprin-1, HMGA1a, HMGA1b and cyclin E at the protein level, and of cyclin E, HMGA1a and HMGA1b at the mRNA levels.


CONCLUSIONS
Taken together, our data demonstrated that miR-16 can negatively regulate two new targets, HMGA1 and caprin-1, which are involved in cell proliferation. In addition, we also showed that the inhibition of cyclin E expression was due, at least in part, to a decrease in its mRNA stability.
Kaddar
Tagrid
T
LBMC, CNRS UMR5239, IFR128, Faculté de Médecine Lyon Sud, Université Lyon 1, Pierre Bénite, France.
Rouault
Jean-Pierre
JP
Chien
Wei Wen
WW
Chebel
Amel
A
Gadoux
Mylène
M
Salles
Gilles
G
Ffrench
Martine
M
Magaud
Jean-Pierre
JP
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D025741:HMGA1a Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025742:HMGA1b Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D016415:Sequence Alignment
C486562:CAPRIN1 protein, human; D018797:Cell Cycle Proteins; C505362:MIRN16 microRNA, human; D035683:MicroRNAs; D025742:HMGA1b Protein; D025741:HMGA1a Protein