It opens the door to developing new therapies for neurodevelopmental disorders like autism, learning disabilities, and cerebral palsy.

Stem cells in the brain, called neural stem cells (NSCs), have the ability to proliferate, differentiate, and undergo a process of cell death. Most of the NSCs in our brains exist in a dormant state, waiting for a signal that will reactivate them to undertake neurogenesis or the formation of new nerve cells.

Evidence suggests that defective NSC reactivation may be associated with age-related cognitive decline and neurodevelopmental disorders, making identifying the mechanisms underlying the process important. Now, researchers from the Duke-NUS Medical School and the Mechanobiology Institute at the National University of Singapore (NUS) have gone further, discovering a method of activating dormant NSCs.

"Our findings add new knowledge to the limited body of research on mechanisms governing the reactivation of dormant neural stem cells," said Professor Wang Hongyan, acting program director of the Neuroscience and Behavioral Disorders Research Program at Duke-NUS and the study's corresponding author.

For the present study, the researchers experimented on fruit flies (Drosophila). In Drosophila, the presence of dietary amino acids is sensed by the fat body, a functional equivalent of the human liver and adipose tissue, which triggers the production of insulin-like peptides by cells in the blood-brain barrier. These peptides, in turn, activate the insulin-like growth factor 1 (IGF-1) signaling pathway in NSCs and triggers their reactivation. Human NSCs are also activated by IGF-1 signaling.

Dormant NSCs in Drosophila have a protrusion that extends from the cell body; the researchers had recently demonstrated that the protrusion is enriched with actin microfilaments. Actin is a protein that, among other functions, provides mechanical support and determines cell shape. The arrangement of actin within cells is regulated by another type of protein called formin, which accelerates the assembly of a particular actin, filamentous actin (f-actin).