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. Author manuscript; available in PMC: 2014 Apr 29.
Published in final edited form as: Dev Cell. 2013 Apr 29;25(2):182–195. doi: 10.1016/j.devcel.2013.02.015

Figure 7. Transcriptional network controlling the balance of inhibitory and excitatory neurons in the dorsal spinal cord.

Figure 7

Progenitors in the ventricular zone express Ascl1. In the absence of Ptf1a, these cells become excitatory neurons (dP5 lineage) through Ascl1 induction of the HD factors Tlx1/3 and Lmx1b. Tlx1/3 repress the Lbx1-dependent induction of Pax2 and the inhibitory neuronal program. Ascl1 regulates Tlx3 directly whereas Tlx1 may be indirect. Ptf1a is upregulated in a subset of the Ascl1 progenitor cells directing their fate to inhibitory neurons (dP4 lineage) through induction the HD factors Pax2 and Lhx1/5. Additionally, Ptf1a directly increases levels of Prdm13 that in turn suppresses Tlx1 and Tlx3, ensuring a suppression of the glutamatergic program in the inhibitory neurons. Prdm13 works through at least two mechanisms; one being Ascl1-dependent possibly involving a novel transcriptional repressor complex for Tlx3-like genes, and the other Ascl1-independent requiring some other activator (green circle) for Tlx1-like genes.