Combined mRNA and microRNA profiling reveals that miR-148a and miR-20b control human mesenchymal stem cell phenotype via EPAS1.

Mesenchymal stem cells (MSCs) are present in a wide variety of tissues during development of the human embryo starting as early as the first trimester. Gene expression profiling of these cells has focused primarily on the molecular signs characterizing their potential heterogeneity and their differentiation potential. In contrast, molecular mechanisms participating in the emergence of MSC identity in embryo are still poorly understood. In this study, human embryonic stem cells (hESs) were differentiated toward MSCs (ES-MSCs) to compare the genetic patterns between pluripotent hESs and multipotent MSCs by a large genomewide expression profiling of mRNAs and microRNAs (miRNAs). After whole genome differential transcriptomic analysis, a stringent protocol was used to search for genes differentially expressed between hESs and ES-MSCs, followed by several validation steps to identify the genes most specifically linked to the MSC phenotype. A network was obtained that encompassed 74 genes in 13 interconnected transcriptional systems that are likely to contribute to MSC identity. Pairs of negatively correlated miRNAs and mRNAs, which suggest miRNA-target relationships, were then extracted and validation was sought with the use of Pre-miRs. We report here that underexpression of miR-148a and miR-20b in ES-MSCs, compared with ESs, allows an increase in expression of the EPAS1 (Endothelial PAS domain 1) transcription factor that results in the expression of markers of the MSC phenotype specification.