Regulation of the Serotonin Neuron Fate in Stem Cells by foxa2 and shh

Abstract

Serotonin neurotransmission plays an important role in controlling mood, cognition, and various physiological functions. The development of serotonin neurons in the embryo, however, is not well understood. Serotonin neurons are born on the ventral side of the fetal hindbrain. Prior reports suggested that mechanisms responsible for the induction of dopamine neurons in the midbrain are also responsible for the generation of serotonin neurons in the hindbrain. We have previously shown that dopamine neurons are derivatives of the medial floor plate of the midbrain and that the floor plate-specific transcription factor, foxa2, is necessary and sufficient for the development and differentiation of dopamine neurons. Here, we have examined the development of serotonin neurons with respect to the hindbrain floor plate. We show that serotonin neurons are derivatives of the lateral floor plate of the hindbrain. We further show that foxa2 is necessary and sufficient for the development of serotonin neurons. Finally, we show that increased shh signaling can induce serotonin neurons in midbrain, as well. These results demonstrate that while the organization and potential of the floor plate differs between the hindbrain and midbrain, progenitors of serotonin neurons, like those of dopamine neurons, are also critically regulated by foxa2.