The experiments that establish this mechanism are ingenious, and involve genetically engineered mice that can create the human tau protein in a localised area called the entorhinal cortex. Cells in the entorhinal cortex of the mice started dying due to the tau protein. In due course, the disease spread to other areas via the neuronal network. Since other cells could not make the tau protein themselves, the only way the tau could show up in other areas was via transmission from nerve cell to nerve cell. It may then be possible to halt the diseases by preventing cell to cell transmission, e.g. by blocking the tau with an antibody. This might provide the key to the prevention of degenerative nerve diseases (and help find those elusive keys!).
This blog post is by Neelima Gupte and Sumathi Rao.