Commentary Cell Science Reviews Vol 5 No 4 ISSN 1742-8130

Hippocampal neurogenesis and plasticity: role for activity induced Gadd45b

The subgranular zone (SGZ) of the hippocampus is one of two regions in the mammalian brain where neurogenesis persists into adulthood. Activation of mature neurons in the adult brain can modulate neurogenesis in the SGZ but the underlying molecular mechanisms have been unclear. In a recent report Ma et al. have proposed Gadd45b mediated demethylation as a mechanism stimulating neurogenesis after transient neuronal activity. The authors show that null mutation of GADD45b does not affect basal levels of neurogenesis or dendritic development in the SGZ, but does significantly diminish activity induced changes in both neurogenesis and dendritic development. Regulatory elements of two growth factors, brain derived neurotrophic factor (BDNF) and fibroblast growth factor-1 (FGF-1), are targeted for demethylation in the presence of Gadd45b thereby increasing their expression in response to neuronal activation. In toto these observations define a novel mechanism for prolonged modulation of neurogenesis after transient neuronal activity.

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