RNA-Seq for the identification of novel Mediator transcripts in endothelial progenitor cells.

Mediator (MED) complex is a multiprotein playing a key role in the eukaryotic transcription. Alteration of MED function may have enormous pathophysiological consequences and several MED genes have been implicated in human diseases. Here, we have combined computational and experimental approaches to identify and characterize, new transcripts generated by alternative splicing (AS) for all MED genes, through the analysis of our recently published RNA-Sequencing datasets of endothelial progenitor cells (EPCs). This combined strategy allowed us to identify novel transcripts for MED4, MED9, MED11, MED14, MED27 and CDK8 most of them generated by AS. All the newly identified transcripts, except MED11, are predicted to encode novel protein isoforms. The identification of novel MED variants could lead to the finding of other MED complexes with different functions depending on their subunit composition. Finally, the expression profile of all MED genes, together with an extensive gene expression analysis, may be useful to better classify the diverse subsets of cell populations that contribute to neovascularization.