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Uncx4.1, Midbrain, mDA neurons, Ngn2, Pax6, Differentiation, Expression
Abstract:
Background: The homeobox containing transcription factor Uncx4.1 is, amongst others, expressed in the mouse
midbrain. The early expression of this transcription factor in the mouse, as well as in the chick midbrain, points to a
conserved function of Uncx4.1, but so far a functional analysis in this brain territory is missing. The goal of the
current study was to analyze in which midbrain neuronal subgroups Uncx4.1 is expressed and to examine whether
this factor plays a role in the early development of these neuronal subgroups.
Results: We have shown that Uncx4.1 is expressed in GABAergic, glutamatergic and dopaminergic neurons in the
mouse midbrain. In midbrain dopaminergic (mDA) neurons Uncx4.1 expression is particularly high around E11.5
and strongly diminished already at E17.5. The analysis of knockout mice revealed that the loss of Uncx4.1 is
accompanied with a 25% decrease in the population of mDA neurons, as marked by tyrosine hydroxylase (TH),
dopamine transporter (DAT), Pitx3 and Ngn2. In contrast, the number of glutamatergic Pax6-positive cells was
augmented, while the GABAergic neuron population appears not affected in Uncx4.1-deficient embryos.
Conclusion: We conclude that Uncx4.1 is implicated in the development of mDA neurons where it displays a
unique temporal expression profile in the early postmitotic stage. Our data indicate that the mechanism underlying
the role of Uncx4.1 in mDA development is likely related to differentiation processes in postmitotic stages, and
where Ngn2 is engaged. Moreover, Uncx4.1 might play an important role during glutamatergic neuronal
differentiation in the mouse midbrain.
