MicroRNA-dependent inhibition of PFN2 orchestrates ERK activation and pluripotent state transitions by regulating endocytosis

Profilin2 (PFN2) is a target of the embryonic stem cell (ESC) enriched miR-290 family of miRNAs and an actin/dynamin binding protein implicated in endocytosis. Here, we show that the miR-290-PFN2 pathway regulates many aspects of ESC biology. In the absence of microRNAs, PFN2 is upregulated in ESCs, with a resulting decrease in endocytosis. Reintroduction of miR-290, knockout of PFN2, or disruption of the PFN2 dynamin interacting domain in miRNA deficient cells reverses the endocytosis defect. The loss of miRNA suppression of PFN2 and associated reduction in endocytosis impairs ERK signaling, which in turn inhibits ESC cell cycle progression and differentiation from a naive to formative state. Mutagenesis of the single canonical conserved 3′UTR miR-290 binding site of PFN2 in otherwise wild-type cells recapitulates these phenotypes. Together, these findings define an axis of post-transcriptional control, endocytosis, and signal transduction that is essential for ESC self-renewal and differentiation.