Protein can nurture or devastate brain cells, depending on its 'friends,' resear...( DALLAS Nov. 11 2008 Researchers at...),Health

DALLAS Nov. 11, 2008 Researchers at UT Southwestern Medical Center have uncovered new insights into the "Dr. Jekyll and Mr. Hyde" nature of a protein that stimulates stem-cell maturation in the brain but, paradoxically, can also lead to nerve-cell damage.

In two separate studies in mice scheduled to appear online this week and in an upcoming issue of the Proceedings of the National Academy of Sciences, UT Southwestern research teams studied the protein Cdk5 and discovered both helpful and detrimental mechanisms it elicits in nerve cells.

Dr. Amelia Eisch, assistant professor of psychiatry at UT Southwestern, and her colleagues uncovered a beneficial mechanism of the helpful "Dr. Jekyll" side of the Cdk5 protein, which is also thought to kill brain cells and contribute to neurodegenerative diseases such as Alzheimer's. In the current study, Dr. Eisch found that Cdk5, together with its activating partner molecule p35, helps immature nerve cells become fully functional.

In a separate study, Dr. James Bibb, associate professor of psychiatry at UT Southwestern, found yet another harmful action of the Cdk5 protein. It can stunt learning and reduce motor control.

Cdk5 is a kinase, which means its job is to interact with all sorts of other proteins inside cells and modify them through a process called protein phosphorylation. Whether Cdk5 nurtures or devastates depends on the state of its partner and the proteins it modifies.

"Like all of us, Cdk5 can influence others, in this case other proteins," Dr. Eisch said. "When Cdk5 messes with hooligans, it causes big trouble. When it hangs with the straight-A students, it actually helps other cells reach their full potential."

Dr. Eisch studied different stages of neurogenesis, or the formation of new nerve cells, in the brains of adult mice and found that the absence of Cdk5 prevents neural stem cells from maturing. She and her group used advanced genetic e
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