What is the common thread among Alzheimer's, Parkinson's and Huntington's diseases, Creutzfeldt-Jakob syndrome and even type 2 diabetes? Patients who suffer from these diseases typically harbor a bodily buildup of oddly formed proteins called amyloid fibrils, which resemble long, twisted ribbons. Although the proteins making up the fibrils differ in each disease, a new study suggests that fibrils of all types share a feature—the tiny molecular backbones that seed the production of the fibrils and sew them together.
Chemist David Eisenberg and his colleagues at the University of California, Los Angeles, previously identified these fibril backbones in yeast afflicted with an amyloid disease. Unlike any other known protein formation, the structures resemble watertight zippers running perpendicular to the fibril itself. Now Eisenberg's team has made crystals of 30 such zippers associated with eight different human amyloid diseases and has compared their configuration using x-rays.
“Although the proteins that form these fibrils are very different, the atomic-level structures are very similar in each case,” Eisenberg says.
Scientists are not yet certain whether amyloid fibrils cause the symptoms of the diseases in which they are found or are simply a by-product of some unidentified underlying mechanism, but many experts believe that preventing fibril formation could stop these diseases from progressing.
By pinpointing the specific part of each protein that causes fibril formation and showing that these parts are similar across so many diseases, these new findings could bring us much closer to cures for the 25 known human amyloid diseases. People at risk for an amyloid disease could be identified early on with a compound that binds to the zippers, Eisenberg notes. They could then be treated with another agent that prevents new zippers from forming, which, he says, “would be a very big thing.”
