Figure 6.

miR-34b/c-Derived iDA Cells Are Functionally Active

(A and B) MEFs derived from TH-GFP mice were transdifferentiated in the presence of AN or AN34 and immunostained with and anti-DA antibody. Arrowheads indicate double-positive (DA⁺; TH-GFP⁺) cells. Scale bar represents 50 μm. Quantification of DA⁺; TH-GFP⁺ cells is shown in (B). Data represent mean ± SEM from three independent experiments. ^∗p < 0.05; ^∗∗p < 0.01 (Newman-Keuls test).

(C) HPLC analysis of dopamine content in AN- and AN34-derived iDA cells; Data represent mean ± SEM from three independent experiments; ^∗∗p < 0.01 (Student's t test).

(D–H) Spontaneous firing activity of iDA neurons during extracellular single-unit recording is reversibly inhibited by TTX (D). In whole-cell recordings, injection of depolarizing current steps from a holding potential of −54 mV evoked trains of action potentials (E, left) that were blocked by TTX (E, right), suggesting that they are mediated by fast Na⁺ currents. Hyperpolarization-activated membrane currents (F) and sag potentials (G) indicate the expression of I_h in iDA neurons. Typical voltage-dependent inward and outward currents (H) are also present in iDA neurons.