A new study led by scientists at the University of Pennsylvania Medical Center reveals pivotal characteristics of the disease mechanism underlying a hereditary dementia similar to and often confused clinically with Alzheimer's disease. With a clearer view of the pathology involved, the development of drug therapies to counter the problem becomes possible. Indeed, candidate compounds are already being appraised in the laboratory for their therapeutic potential.
A report on the study appears in the December 4 issue of Science.
The research team investigated a dementia linked to more than 10 different genetic flaws on chromosome 17 known as frontotemporal dementia and parkinsonism (FTDP-17). They found that, in FTDP-17, mutant versions of a protein called tau are unable to fulfill one of the protein's crucial roles, which is to stabilize structural elements in neurons called microtubules. In addition to shoring up the scaffolding of a cell, microtubules also form the basis of an intracellular transport system -- especially important in neurons, which have extensions called axons that can reach a full meter through the body. With microtubule assembly disrupted, these cells can die.
"The bottom line here is that there is loss of tau function with these mutations, and the function of tau is to stabilize microtubules," says Virginia M.-Y. Lee, PhD, a professor of pathology and laboratory medicine and senior author on the study. "In neurons, with their long, delicate axons, microtubules are extremely important not only as structural entities but also as a kind of railroad along which the cells move various materials critical to their survival."
The tau protein is also the main component of the abnormal tangles in
neurons that, along with amyloid plaques, define Alzheimer's disease. Tau
tangles are seen in other dementing diseases, too, such as Pick's disease. Prior
to this study, however, scientists had been unable to
Contact: Franklin Hoke
University of Pennsylvania School of Medicine