Combinatorial expression of transcription factors in ventral spinal
neurons. (A-I) Expression of Irx3, Olig2, Chx10, Hb9, Lmo4, Isl1/2,
Lhx3 and NLI in E11.5 mouse cervical spinal cord. MNs and V2a INs each express
unique combinations of these factors. Expression of Lmo4 is assessed by both
in situ hybridization (C) and immunohistochemistry (D,H). The locations of
ventricular progenitor cells for MNs (pMN) and V2a INs (p2) are marked by two
horizontal lines. Dashed lines indicate the boundary of the spinal cord.
(J) The schematic diagram shows that the pMN domain generates
motoneurons (MN, green), whereas p2 cells give rise to V2a INs (red). A
summary of the combinatorial expression profile of transcription factors is
shown along with neuronal-subtype markers and predicted higher-order
regulatory complexes based on known protein-protein interactions. Scale bars:
in I, 50 μm for A-C,E,I; in H, 40 μm for D,F-H.