12-P006 Analysis of morphological phenotypes in Tsukushi (TSK) KO mice brain

and ectopic expression, we demonstrated that Gata2 regulates GABAergic neuron development in the midbrain, but not in the rhombomere1. Without Gata2, all the precursors in the embryonic midbrain fail to activate GABAergic neuron-specific gene expression and switch to a glutamatergic phenotype instead. Surprisingly, this fate switch is also observed throughout the neonatal midbrain, except for the GABAergic neurons located in the ventral dopaminergic nuclei, suggesting a distinct developmental pathway for these neurons. We have further investigated the origin, developmental history and regulatory mechanisms of these GABAergic neurons associated with the ventral dopaminergic nuclei. The presented studies identify Gata2 as an essential postmitotic selector of the GABAergic neurotransmitter identity and demonstrate developmental heterogeneity of the GABAergic neurons in the midbrain.