Learning the molecular mechanisms of the reprogramming factors: let's start from microRNAs
Abstract
Induced reprogramming of somatic cells has had a great impact on stem cell research, and the reprogramming technologies have evolved from four transgenic factors (Oct4, Sox2, Klf4, and c-Myc; OSKM) to just a few microRNAs (mainly miR-290/302 seed family). Despite these advances, the molecular events occurring during various stages of reprogramming remain largely unknown. Here, we concisely review current knowledge of miRNA regulation from the initiation phase of OSKM-induced reprogramming, through the transitional stage, to final maturation. At the start of reprogramming, the microRNAs miR-21, miR-29a, let-7a, and miR-34 act as guards to secure the somatic identity and genomic integrity of the cell of origin. As reprogramming proceeds, miR-155, miR-10b, miR-205, and miR-429 modulate the epithelial–mesenchymal/mesenchymal–epithelial transition (EMT/