Protein Complex Causes Memory Loss in Mice

A-beta*56 complex found in middle-aged mice with Alzheimer-like disease

THURSDAY, March 16 (HealthDay News) -- A complex of proteins found in the brains of mice that develop an Alzheimer-like disease as they age can cause temporary memory loss when injected into normal mice, according to a study in the March 16 issue of Nature.

Karen H. Ashe, M.D., Ph.D., of the University of Minnesota Medical School in Minneapolis, and colleagues studied mice transgenic for the human amyloid-beta precursor protein variant linked to Alzheimer disease, to investigate the cause of memory decline absent neuronal loss in middle age.

The researchers used the mice's gradual loss of memory with age to identify a protein complex, which they termed A-beta*56. The complex appeared to form outside cells and consist of a cluster of 12 amyloid-beta peptides. When injected into normal mice, the A-beta*56 complex caused a transient disruption of memory.

"That A-beta* is a highly specific form of amyloid-beta offers the potential for developing precise diagnostic methods to detect its correlate in humans with pre-clinical Alzheimer disease, presenting the possibility of targeting A-beta* and aborting the disease before permanent structural changes have developed," Ashe and colleagues write.

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