EXPRESSION, PURIFICATION, AND NEUROTROPHIC ACTIVITY OF AMYLOID PRECURSOR PROTEIN-SECRETED FORMS PRODUCED BY YEAST

The secreted form of amyloid precursor protein (APP(s)) including most of the extracellular domain of APP is released from the cell surface, suggesting physiological significance of APP(s) in vivo. We used the methylotrophic yeast Pichia pastoris as a host system for the producti on of recombinant APP(s) (rAPP(s)). Two rAPP(s)s derived from isoforms of APP (APP695 and APP770) were secreted into the culture medium from the yeast, which carried cDNA encoding the N-terminal portion of APP under the control of a P. pastoris alcohol oxidase promoter. Like APP( s)s produced by the transfected COS-1 cells, the purified rAPP(s)s fro m yeast were shown to be biologically active in terms of neurite outgr owth of embryonic rat neocortical explants. These rAPP(s)s could be va luable tools for investigating the biological functions of APP(s)s. (C ) 1995 Academic Press, Inc.