MicroRNA-548k upregulates a spliced variant of human CD2-associated protein by targeting its promoter

MicroRNAs (miRNAa) regulate gene expression by repressing the translation or directing the degradation of mRNA in the cytoplasm. However, recent studies have shown that miRNAs act to regulate transcription at target gene promoters.

To investigate whether miR-548k regulates CD2AP002 expression at the transcriptional level.

The CD2AP002 promoter region was cloned and its promoter activity was examined in HEK293 cells using luciferase assay. The CD2AP002 promoter region was characterized bioinformatically. The HEK293 cells were treated with a miR-548k mimic or inhibitor and the luciferase activity of the CD2AP002 promoter and the mRNA expression of CD2AP002 were assayed. A chromatin immunoprecipitation assay was performed with antibody against RNA polymerase II at the CD2AP002 promoter region in HEK293 cells.

The CD2AP002 promoter region contained 2 putative miR-548k binding sites, and mutational analysis revealed that both of those sites contributed to transcriptional activity. The miR-548k mimics increased CD2AP002 promoter activity and mRNA expression. In contrast, the miR-548k inhibitor significantly reduced CD2AP002 promoter activity and mRNA expression. Finally, the chromatin immunoprecipitation assay showed that the enrichment of RNA polymerase II at the CD2AP002 promoter region was enhanced in the HEK293 cells treated with the miR-548k mimic.

This is the first study to demonstrate that miR-548k upregulates CD2AP002 expression by targeting its promoter.