Lgl, Pins and aPKC regulate neuroblast self-renewal versus differentiation

New nerves for old The adult mammalian brain has a remarkable regenerative capacity, a fact that sustains hopes that neuronal replacement stem-cell therapy could become a reality. How new nerve cells integrate into existing brain circuits, however, is poorly understood. A new study in mice shows that newborn neurons are sensitive to existing neuronal activity, via the neurotransmitter GABA, and that this is key to these new cells' integration in adult neuronal circuits in vivo. An important question in stem cell and cancer biology is how a cell chooses to proliferate or differentiate. Drosophila larvae provide a good model for the study of this question, as neuroblasts in the brain undergo self-renewal at each cell division to produce another neuroblast and a differentiating daughter cell. Work on a series of Drosophila mutants shows that neuroblast renewal is controlled by the genes pins, lgl, and aPKC, previously shown to regulate asymmetric cell division. Overexpression of aPKC induces neuroblast self-renewal, a line of research that might eventually lead to ways of controlling neural stem cells used therapeutically.