Overproduction of perlecan core protein in cultured cells and transgenic mice

Heparan sulphate proteoglycan (HSPG) and amyloid P component are the only m acromolecules consistently associated with all varieties of amyloid, irresp ective of the type of amyloid protein, suggesting that HSPG may play a path ogenetic role in amyloid formation through a common mechanism. In the case of Alzheimer's disease (AD), HSPG, such as perlecan, co-accumulates with am yloid-beta protein (A beta), a main constituent of amyloid plaques, and pai red helical filaments (PHFs), Additionally, in vitro, HSPG accelerates both AB fibril and PI-IF formation and protects A beta from degradation, Theref ore, this study first established lines of P19 mouse embryonic carcinoma ce lls stably carrying an expression vector encoding the complete perlecan cor e protein (similar to 400 kD), In the cell lysates, overexpressed perlecan was identified as an similar to 400 kD protein without glycosaminoglycan si de-chains, while in the media, secreted perlecan was mostly glycosylated, s uggesting that the secretion and glycosylation of perlecan are coupled. Nex t, transgenic mice were produced using the same expression vector. Marked p erlecan overexpression occurred in the cytoplasm of multiple tissues includ ing the brain, heart, kidney, and pancreas, without a discernible increase of perlecan in extracellular matrices. The transgenic mice up to 18 months of age did not develop amyloid or AD-like pathology in the brain or elsewhe re, based on histochemical and immunohistochemical analyses. Thus, overprod uction of perlecan core protein is insufficient to lead to amyloidosis and AD-like pathology, Copyright (C) 2001 John Wiley & Sons, Ltd.