Pivotal role of early B-cell factor 1 in development of striatonigral medium spiny neurons in the matrix compartment.

The mammalian striatum plays a critical function in motor control, motor and reward learning, and cognition. Dysfunction and degeneration of the striatal neurons are implicated in major neurological and psychiatric disorders. The vast majority of striatal neurons are medium spiny neurons (MSNs). MSNs can be further subdivided into distinct subtypes based on their physical localization in the striatal patch vs. matrix compartments and based on their axonal projections and marker gene expression (i.e., striatonigral MSNs vs. striatopallidal MSNs). Despite our extensive knowledge on the striatal cytoarchitecture and circuitry, little is known about the molecular mechanisms controlling the development of the MSN subtypes in the striatum. Early B-cell factor 1 (Ebf1) is a critical transcription factor implicated in striatal MSN development. One study shows that Ebf1 is critical for the differentiation of MSNs in the matrix, and our separate study demonstrates that Ebf1 is selectively expressed in the striatonigral MSNs and is essential for their postnatal differentiation. In the present study, we further validate the striatonigral MSN deficits in Ebf1(-/-) mice using multiple striatonigral MSN reporter mice. Moreover, we demonstrate that the striatonigral MSN deficits in these mice are restricted to those in the matrix, with relative sparing of those in the patch. Finally, we demonstrate that Ebf1 deficiency also results in reduced expression of another striatonigral-specific transcription factor, zinc finger binding protein 521 (Zfp521), which is a known Ebf1 functional partner. Overall, our study reveals that Ebf1 may play an essential role in controlling the differentiation of the striatonigral MSNs in the matrix compartment.