fig3

Figure 3. Schematic representation of differentiation procedures for generation of GABAergic and glutamatergic human induced pluripotent stem cell (hiPSC) neurons. Pluripotent hiPSCs can be induced via dual SMAD inhibition to produce telencephalic neural progenitors cells (NPCs) which are positive for FOXG1 - a brain-specific transcriptional repressor essential for the early development of the telencephalon - marking this population. Notably, FOXG1 gene is associated with the FOXG1 syndrome, which has previously been described as a congenital variant of Rett syndrome. In the further differentiation steps, the absence of a SHH (sonic hedgehog) agonist facilitates dorsal patterning of the NPCs, characterized by expression of the markers PAX8 (a human neuroectoderm cell fate determinant) and EMX1/2 (transcription factors expressed primarily in dorsal telencephalon. On the contrary, activation of SHH signaling via the addition of SSH agonists induces ventralization of NPCs, characterized by expression of NKX2-1 (a transcription factor that specifies ventral lineages during development). Dorsal progenitors can be further differentiated into glutamatergic neurons, whilst ventral precursors can be differentiated into GABAergic neurons