Alzheimer's disease with amyloid beta peptide

Two new studies have examined protein blocks called "amyloid beta peptides" in the brains of people with alzheimer's and other neurodegenerative diseases. One study gave drugs for alzheimer's a warning, and another showed that human beta amyloid peptides can "infect" transgenic mice.

Beta secretase has been of interest as a possible drug target for the treatment of senile dementia because it is the key to the production of beta amyloid peptides. However, the role of the enzyme in healthy brains has not been known, so the possible side effects of such drugs have been a mystery. Michael Willem and colleagues in Germany, the United States, and Belgium report that secretase is associated with myelin formation, the process by which fatty substances called myelin are coated to protect newborn nerve cells. This process is mediated by a protein called neuregulin, and the authors found that secretase ACTS on neuregulin in mice. They also report that myelin formation in mice lacking the secretase gene is defective in mice with a mutation similar to neuregulin. The authors note that drug researchers should carefully consider this important role of secretase and the possible side effects of any drug that blocks this enzyme.

In another study, the authors reported that injecting amyloid peptide extracts from cadavers of alzheimer's patients into the brains of transgenic mice caused demented damage in mice. Scientists know a lot about how these proteins, which are involved in alzheimer's and other neurodegenerative diseases, misfold and stick together, and the new findings provide clues about how amyloid beta peptides bind together in vials. Melanie meyer-luhmann and her colleagues in Europe and the United States report that human amyloid peptide extracts injected into the brains of transgenic mice expressing human amyloid peptide precursor proteins provide the "seed" for focal formation. The results also suggest that there are different amyloid beta peptides that behave differently. Amyloid peptide extract is similar to the misfolded protein prions that cause mad cow disease, but so far there is no evidence that amyloid peptide extract is as infectious as prions