Fig. 7.

miR-205 induces ExEn formation from Arf-null ES progenitors. (A) Arf-null ES cells infected with a naked control (Ctl) GFP vector or one encoding miR-205 from a miR-30 backbone together with GFP were sorted 2 d after infection, placed in culture, and visualized 2 d later by phase contrast microscopy at magnification of 50× (Left) or 100× (Right). Cells with the characteristic morphology of ExEn cells appeared in response to miR-205. (B) EBs derived from WT or Arf-null ES cells and infected with control or miR-205–encoding vectors (indicated at the top) were stained for Dab2 protein expression. WT cells (Left) and Arf-null EBs transduced with miR-205 (Right) expressed Dab2 at their periphery, whereas Arf-null cells, whether uninfected or transduced with a control vector, did not (second and third from left). (Scale bars, 50 µm.) (C) Quantitative RT-PCR was used to quantify mRNA expression of five ExEn markers (indicated at the top) in vector-transduced Arf-null ES cells grown in the presence of LIF (day 0) and in EBs derived from them (day 4). Cells were transduced with a control virus (Ctl) or a vector encoding miR-205 (205) as indicated in the legend. Error bars, mean ± SEM (n = 3 experiments).