EXPRESSION OF BETA-AMYLOID PRECURSOR PROTEIN GENE IS DEVELOPMENTALLY-REGULATED IN HUMAN MUSCLE-FIBERS IN-VIVO AND IN-VITRO

Regenerating muscle fibers in 25 human muscle biopsies, obtained from patients with a variety of neuromuscular diseases, manifested increase d mRNA for the beta-amyloid precursor protein (beta APP) that contains the Kunitz-type protease inhibitor (KPI) motif, whereas adult human m uscle fibers were negative in their vast non-extrajunctional region. A neurally cultured normal human muscle fibers also expressed strong KPI -beta APP mRNA signal, which became significantly downregulated during muscle differentiation. Our study demonstrates that in human muscle K PI-beta APP mRNA if developmentally regulated, and it suggests that be ta APP may play a role in human muscle development. (C) 1994 Academic Press, Inc.