PHOX2A single-handedly builds a brain nucleus Available to Purchase

In vertebrate brains, neuronal cell bodies that share functional properties form clusters called nuclei. Although nuclei organize much of the brain's circuitry, little is known about their development. Now, Cliff Ragsdale and colleagues report that a single homeodomain transcription factor — PHOX2A — regulates the nucleogenesis of the chick oculomotor complex (OMC; see p. 1205). The chick midbrain OMC contains two subnuclei — a dorsal Edinger-Westphal nucleus of visceral oculomotor neurons that control pupil dilation and a ventral nucleus of somatic oculomotor neurons that innervate the eye's external muscles. The researchers show that exogenous delivery of Phox2a to the embryonic chick midbrain drives the development of a complete, spatially organized midbrain OMC. Phox2a overexpression, they report, is also able to generate ectopic motoneurons that innervate extraocular muscles directly. Combined with previous findings in mouse and human, these results show that a single transcription factor can both specify motoneuron cell...