Figure 4.

let-7c overexpression impairs neuronal development and synaptic function in H1 embryonic stem (ES) cell-derived human induced neurons. (A) Representative image of neurons expressing control or hsa-Let7c lentiviruses (green). (B–D) MAP2-correlated synapse density and puncta characteristics display a selective decrease in number of synaptic puncta. (E–G) Neuronal soma size, primary dendrite formation and total segmented MAP2-positive area reveal a mild impairment of primary dendrite outgrowth. (H–J) Intrinsic membrane properties measured under voltage-clamp at −70 mV (capacitance and input resistance) or current clamp (RMP) are not altered. (K) Representative traces of stepwise current injection protocol for evoked AP measurement of neuronal excitability. (L–N) Spontaneous and evoked AP incidence and rheobase values display a marked reduction in cell excitability. (O) Representative traces of spontaneous postsynaptic currents (sPSCs) measured at −70 mV. (P–R) Summary data for incidence (proportion of cells with detectable responses) frequency, and amplitude of sPSCs. All data are displayed as mean ± SEM and represent the results of three independent experiments. Statistical tests were performed using two-tailed Student’s t-test, where *p < 0.05 and **p < 0.01.