Expression of dopamine pathway genes in the midbrain is independent of known ETS transcription factor activity

In nematodes, the ETS-family transcription factor ast-1 regulates multiple genes comprising the dopamine (DA) neuron phenotype, including biosynthetic enzymes and transporters. ETS transcription factors are hypothesized to play a similar role in vertebrates, and based on its expression in the adult mouse midbrain, Etv5/ERM has been proposed as a regulator of DA gene expression in the substantia nigra (SN) and ventral tegmental area (VTA). Here we show that Etv5 expression is not detectable until postnatal stages in the midbrain, well after development of the DA system, and that Etv5 knock-out and control mice show comparable tyrosine hydroxylase and dopamine transporter expression in the embryonic and adult midbrain. Other known members of the ETS family do not have expression patterns that are consistent with a role in DA gene regulation in the SN/VTA. These findings suggest that the ETS factors, while required for the generation of the DA phenotype in nematodes, do not play such a role in the mouse midbrain.