A protein whose overexpression is associated with many forms of cancer also controls the formation of connections between brain cells.

Cyclin E drives cell proliferation and is found mostly in dividing cells, but is also present in the adult brain. Jarrod Marto and Piotr Sicinski at the Dana-Farber Cancer Institute in Boston, Massachusetts, and their colleagues reveal that, in non-dividing neurons in the mouse brain, the protein is involved in memory formation. Neurons from mice in which the cyclin E gene was knocked out formed fewer synapses, or connections, and showed reduced synaptic transmission compared with normal mice. The knockout mice also exhibited memory impairments.

The authors show that cyclin E normally inhibits the enzyme Cdk5, which regulates neuronal development.

Dev. Cell 10.1016/j.devcel.2011.08.009 (2011)