Amyloid fibril proteins.

Amyloidosis refers to a group of protein folding diseases. Various innocuous and soluble proteins in physiological conditions polymerize to insoluble amyloid fibrils in several serious diseases, including Alzheimer's disease (AD) and prion diseases. In addition, senile amyloidosis is a form of amyloidosis in which the incidence and severity of amyloid deposition increases with age without any apparent predisposing conditions and it was thought that the amyloidosis was related to some physiological changes which accompany ageing. Although the etiology and pathogenesis of amyloid disease are not fully understood, drastic structural changes of the amyloid proteins from the normal forms to the unique beta-sheet fibrils is the most important event in amyloid diseases. The present article introduces the three amyloid diseases, AD, prion diseases and mouse senile amyloidosis in which Abeta, PrP(Sc) and AApoAII amyloid fibrils deposit respectively. We discuss the nucleation dependent polymerization model as a model that explains the kinetics of fibrillization of these amyloid proteins. Exogenous amyloid fibrils may act as templates (nuclei) and change the conformation of endogenous amyloid protein to polymerize into amyloid fibrils. This hypothesis makes the boundary between transmissible and non-transmissible amyloidosis ambiguous and proposes the common pathogenesis for them. Copyright 2002 Published by Elsevier Science Ireland Ltd.