Tracing lineages to uncover neuronal identity

Abstract

Many previous studies have focused on understanding how midbrain dopamine neurons, which are implicated in many neurological conditions, are generated during embryogenesis. One of the remaining questions concerns how different dopamine neuron subtypes are specified. A recent paper in Neural Development has revealed features of a spatial and temporal lineage map that, together with other studies, begins to elucidate the developmental origin of distinct neuronal subtypes within the developing midbrain.

Figure 1

Acquisition of neurogenic potential in midbrain floorplate cells. From analysis of gene expression, the midbrain DA neuron progenitor domain can be subdivided into medial (DA^M) and lateral (DA^L) domains. Left, at early embryonic stages, medial DA progenitor cells resemble floorplate cells expressing high levels of Shh (pale gray). Right, downregulation of Shh (striped pale grey) in the medial progenitor domain at later stages in embryogenesis promotes neurogenesis from the medial progenitor domain.