Fall 1996 Volume 5, Number 4
Recently researchers discovered two genes, presenilin 1 (PS1) and presenilin 2 (PS2), that, when defective, cause inherited, or "familial," Alzheimer's disease. At Harvard Medical School, where one search was based, investigators are already starting to answer the next question: What do presenilin proteins actually do in the central nervous system?
| Bradley Hyman, collaborating with Rudolph Tanzi and Wilma Wasco at Massachusetts General Hospital, has now demonstrated that both presenilins are expressed in the brain -- primarily in nerve cells. Homing in on presenilin's distribution within nerve cells, the group has found that the protein is localized to two areas involved in protein processing and trafficking. This new information begins to define where the presenilins are made; from there the hunt can follow the proteins' action in an effort to catch the point at which the fatal error leading to Alzheimer's kicks in. | 
Dots reveal the location of presenilin-1 (PS-1) protein inthe brain of a mouse (Courtesy of B. Hyman) |
The collaborators also found that presenilin's distribution in nerve cells is very similar to that of other genes involved in Alzheimer's, particularly the much-studied amyloid precursor protein (APP). The distributions of presenilin1 and presenilin 2 are virtually identical to each other and to APP. This has the interesting implication that presenilins and APP could work as team in some crucial fashion that, when understood, would give Alzheimer's studies a significant boost.