Mechanism Explains Selective Pruning of Neuronal Stem Cells

In mitotic cells, asymmetric distribution of PAR-4 and nestin resulted in one nestin(-)/PAR-4(+) daughter cell, in which ceramide elevation induced apoptosis. The other cell was nestin(+), but PAR-4(-), and was not apoptotic. This asymmetric distribution of PAR-4 coupled with a simultaneous elevation of endogenous ceramide provided a possible mechanism underlying asymmetric differentiation and apoptosis of neuronal stem cells in the developing brain. These findings were published July 28, 2003, in the online edition of the Journal of Cell Biology.

"During normal development in the central nervous system there is a great deal of cell death that occurs that seems to be required to create the final shape and structure of the brain,” explained senior author Dr. Brian G. Condie, a developmental neurobiologist at the University of Georgia. "One of the ideas behind why there is an excess of cells generated during development is that it may be a mechanism for compensating for environmental stresses or other types of stresses that an embryo may encounter during development. So you actually generate an excess of the cells you need and then prune those cells back to an appropriate number and location for the brain to develop in a normal fashion.”





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