EXPRESSION OF THE INTERMEDIATE FILAMENT-ASSOCIATED PROTEIN RELATED TOBETA-AMYLOID PRECURSOR PROTEIN IS DEVELOPMENTALLY-REGULATED IN CULTURED-CELLS

It was previously reported that a monoclonal antibody to beta-amyloid precursor protein (mab22C11; Boehringer Mannheim, Indianapolis, IN) la bels an intermediate filament-associated protein (beta APP-IFAP) in cu ltured human skin fibroblasts (Dooley et al.: J Neurosci Res 33:60-67, 1992). The time course of its expression and association with differe nt classes of intermediate filaments has been assessed in neurons, Sch wann cells, and astrocytes in dissociated cultures of murine brain and spinal cord-dorsal root ganglia; in primary cultures of human muscle; and in the epithelial cell line PtK1. beta APP-IFAP was expressed in all non-neuronal cell types examined. Mab22C11 immunoreactivity was mi nimal or absent following dissociation or subculture, but gradually in creased with time. In fibroblasts, myoblasts, and epithelial cells, th e distribution eventually resembled that of vimentin. With the excepti on of glial fibrillary acidic protein (GFAP), beta APP-IFAP was not as sociated with the intermediate filament proteins characteristically fo und in differentiated cells, i.e., desmin, the cytokeratins, and neuro filament proteins. No labeling of neurons by mab22C11 was observed at any stage of in vitro maturation. In sections of Alzheimer's brain, th e antibody labeled a subpopulation of reactive astrocytes. It is sugge sted that beta APP-IFAP may be the product of a member of the beta APP multigene family expressed developmentally in non-neuronal cells. (C) 1994 Wiley-Liss, Inc.