The results published by Diane Hanger and her colleagues in EMBO
reports show that treatment of neurons with known biological
signaling molecules increases the release of tau into the
culture medium. The release of tau from cortical neurons is
therefore a physiological process that can be regulated by
neuronal activity. Tau proteins stabilize microtubules, the long
threads of polymers that help to maintain the structure of the
cell. However, in Alzheimer’s disease or certain types of
dementia, tau accumulates in neurons or glial cells, where it
contributes to neurodegeneration. In addition to intracellular
aggregation, recent experiments have shown that tau is released
from neuronal cells and taken up by neighboring cells, which
allows the spread of aggregated tau across the brain. This
release could occur passively from dying neuronal cells, though
some evidence suggests it might take place before neuronal cell
death and neurodegeneration. The new findings indicate that tau
release is an active process in he