Glycation stimulates amyloid formation

Amyloidosis comprises a group of systemic and localized diseases with varied clinical presentations. In these diseases, amyloid forms when proteins with a largely alpha-helical structure lose their original conformation and are converted into a predominantly beta-sheet form, thereby increasing their propensity to form highly insoluble and fibrillar aggregates. Most soluble amyloid precursor proteins have substantial beta-pleated sheet secondary structure, and extensive beta-pleated sheet structure occurs in all of the deposited fibrils. The aberrant deposition of proteins as cellular inclusions or plaques in the form of amyloid fibrils is a characteristic hallmark of all amyloid diseases (or amyloidoses) and of the so-called conformational diseases. Environmental and genetic factors are known to be involved, but the mechanism by which this process happens still is poorly understood. Here we report a new finding from the Dutch group of Gebbink and colleagues, which points to the posttranslational process of glycation as a key mechanism in the formation of amyloid. These researchers showed that glycation causes albumin, a globular protein with a largely alpha-helical structure, to adopt a beta-pleated sheet structure and the quaternary structural element known as the cross-beta conformation. These are features commonly shared by all amyloids. This research is the first to show glycation as a predisposing factor for amyloidosis.