| Popis: |
Amyloid precursor protein (APP) processing is of major interest in Alzheimer's disease research, since sequential cleavages by β- and γ-secretase lead to the formation of the 4-kDa amyloid Aβ protein peptide that accumulates in Alzheimer's disease brain. The processing of APP involves proteolytic conversion by different secretases leading to α-, β-, γ-, δ-, and ϵ-cleavages. Since modulation of these cleavages represents a rational therapeutic approach to control amyloid formation, its interference with the processing of the members of the APP gene family is of considerable importance. By using C-terminally tagged constructs of APLP-1 and APLP-2 and the untagged proteins, we have characterized their proteolytic C-terminal fragments produced in stably transfected SH-SY5Y cells. Pharmacological manipulation with specific protease inhibitors revealed that both homologues are processed by α- and γ-secretase-like cleavages, and that their intracellular domains can be released by cleavage at ϵ-sites. APLP-2 processing appears to be the most elaborate and to involve alternative cleavage sites. We show that APLP-1 is the only member of the APP gene family for which processing can be influenced by N-glycosylation. Additionally, we were able to detect p3-like fragments of APLP-1 and p3-like and Aβ-like fragments of APLP-2 in the media of stably transfected SH-SY5Y cells. |
