WHY SOME STEM CELLS DIE IN DEVELOPING BRAIN (HealthDayNews)

<b> August 04 2003</b> – U.S. researchers have identified a signal that causes half the stem cells in the developing brains of embryonic mice to self-destruct at a stage when the survival of those stem cells would do more harm than good.
Pinpointing the factors that cause this kind of timely, massive cell suicide helps scientists better understand the process of embryo development. It also provides clues about cell death and the brain's possible recovery in diseases such as Alzheimer's, Parkinson's and stroke.

The researchers at the Medical College of Georgia and the University of Georgia found the lipid ceramide and the protein PAR-4 — both of which have already been fingered as playing a role in cell death — become deadly partners inside dividing stem cells in the developing brains of mice.

Their study appears in the Aug. 4 issue of the Journal of Cell Biology.

"If PAR-4 is there and ceramide is high, the cell is lost, doomed to die. You can eliminate one of them, you can knock down the expression of PAR-4 or ceramide and the other stays up but the cell doesn't die. But if both signals are together up-regulated, then the cell is destined to die," researcher Dr. Erhard Bieberich, a biochemist at the Medical College of Georgia, says in a statement.