A Novel and Multivalent Role of Pax6 in Cerebellar Development.

Pax6 is a key molecule in development. Pax6 is best known as the master control gene in eye development with mutations causing aniridia in humans. Pax6 also plays important developmental roles in the cortex and olfactory bulb. During cerebellar development, Pax6 is robustly expressed in the germinal zone of all glutamatergic neurons [cerebellar nuclear (CN) neurons, granule cells, and unipolar brush cells (UBCs)]. Past work has not found abnormalities in the CN and UBC populations. Our study reveals that the Pax6-null mutation dramatically affects these cells and identifies Pax6 as a key regulator of cell survival in CN neurons and of cell production in UBCs. The present study shows how Pax6 is key to the development of glutamatergic cells in the cerebellum.