Hindbrain interneurons and axon guidance signaling critical for breathing

Breathing is a bilaterally synchronous behavior that relies on a respiratory rhythm generator located in the brainstem. An essential component of this generator is the preBotzinger complex (preBotC), which paces inspirations. Little is known about the developmental origin of the interneuronal populations forming the preBotC oscillator network. We found that the homeobox gene Dbx1 controls the fate of glutamatergic interneurons required for preBotC rhythm generation in the mouse embryo. We also found that a conditional inactivation in Dbx1-derived cells of the roundabout homolog 3 (Robo3) gene, which is necessary for axonal midline crossing, resulted in left-right de-synchronization of the preBotC oscillator. Together, these findings identify Dbx1-derived interneurons as the core rhythmogenic elements of the preBotC oscillator and indicate that Robo3-dependent guidance signaling in these cells is required for bilaterally synchronous activity.