A team of North Carolina State University researchers has discovered more about how the Foxj1 gene — connected to the production of new brain cells in adults — does its job.

The team had previously discovered that the gene was an “off switch” that told neuronal stem cells to stop reproducing and triggered the development of a stem cell “niche” in the olfactory bulbs. However, further experiments with newly developed genetically modified mice unexpectedly revealed that a fraction of Foxj1-expressing cells actually functioned as stem cells until the mouse reached the age equivalent of a human toddler, not throughout adulthood.

The team found that in addition to being an off switch, the Foxj1 cellular lineage (that is, Foxj1 expressing cells and their descendents) performs an important function as a “conductor,” instructing other stem cells in the olfactory bulb by secreting various molecules that affect the other stem cells’ behavior and ensure their correct development into neurons.

The researchers determined that a small number of Foxj1-expressing cells and their neuronal offspring direct other stem cells to continue reproducing, and may be telling them when to become functionally integrated neurons.

“This finding is important because for the most part our brains cannot generate new neurons, nor can we efficiently use transplanted neurons to repair damage,” said Dr. Troy Ghashghaei.

Ref.: H. T. Ghashghaei, et al., Specification of a Foxj1-Dependent Lineage in the Forebrain Is Required for Embryonic-to-Postnatal Transition of Neurogenesis in the Olfactory Bulb, Journal of Neuroscience, 2011; 31 (25): 9368 [DOI: 10.1523/JNEUROSCI.0171-11.2011]