The homeodomain transcription factor Gbx1 identifies a subpopulation of late-born GABAergic interneurons in the developing dorsal spinal cord

The dorsal spinal cord processes somatosensory information and relays it to higher brain centers and to motoneurons in the ventral spinal horn. These functions reside in a large number of distinct sensory interneurons that are organized in specific laminae within the dorsal spinal horn. Homeodomain and bHLH transcription factors can control the development of neuronal cell types in the dorsal horn. Here, we demonstrate that the murine homeodomain transcription factor Gbx1 is expressed specifically in a subset of Lbx1(+) (class B) neurons in the dorsal horn. Expression of Gbx1 in the dorsal spinal cord depends on Lbx1 function. Immunohistological analyses revealed that Gbx1 identifies a distinct population of late-born, Lhx1/5(+), Pax2(+) neurons. In the perinatal period as well as in the adult spinal cord, Gbx1 marks a subpopulation of GABAergic neurons. The expression of Gbx1 suggests that it controls development of a specific subset of GABAergic neurons in the dorsal horn of the spinal cord.