The histone demethylase Kdm6b regulates a mature gene expression program in differentiating cerebellar granule neurons.

The histone H3 lysine 27 (H3K27) demethylase Kdm6b (Jmjd3) can promote cellular differentiation, however its physiological functions in neurons remain to be fully determined. We studied the expression and function of Kdm6b in differentiating granule neurons of the developing postnatal mouse cerebellum. At postnatal day 7, Kdm6b is expressed throughout the layers of the developing cerebellar cortex, but its expression is upregulated in newborn cerebellar granule neurons (CGNs). Atoh1-Cre mediated conditional knockout of Kdm6b in CGN precursors either alone or in combination with Kdm6a did not disturb the gross morphological development of the cerebellum. Furthermore, RNAi-mediated knockdown of Kdm6b in cultured CGN precursors did not alter the induced expression of early neuronal marker genes upon cell cycle exit. By contrast, knockdown of Kdm6b significantly impaired the induction of a mature neuronal gene expression program, which includes gene products required for functional synapse maturation. Loss of Kdm6b also impaired the ability of Brain-Derived Neurotrophic Factor (BDNF) to induce expression of Grin2c and Tiam1 in maturing CGNs. Taken together, these data reveal a previously unknown role for Kdm6b in the postmitotic stages of CGN maturation and suggest that Kdm6b may work, at least in part, by a transcriptional mechanism that promotes gene sensitivity to regulation by BDNF.