Differential distribution of cellular forms of beta-amyloid precursor protein in murine glial cell cultures.

The production and localization of cell-associated forms of beta-amyloid precursor protein (APP) of Alzheimer's disease was investigated in primary cultures of mouse glial cells. In both oligodendrocytes and astrocytes, immunofluorescence staining with an antibody against the carboxy terminus of APP revealed an intense cytoplasmic immunoreactivity. Immunoblotting of the cell extracts detected differences in the composition of APP between oligodendrocytes and astrocytes, notably the abundance of 107 kDa subtype in oligodendrocytes. Differences in immunoblot patterns were also noted between two buffer-insoluble, membrane-rich subcellular fractions of the glial cells, nuclear-mitochondrial and microsomal; the 119 kDa APP was enriched in the former, whereas the 73 and 115 kDa APPs in the latter. The results suggest that each APP subspecies may play a distinct functional role in different cell types and subcellular fractions.