Aß Immunoreactive Material Is Present in Several Intracellular Compartments in Transfected,Neuronally Differentiated,P19 Cells Expressing the Human Amyloid ß-Protein Precursor

Abstract

Processing of the amyloid ß-protein precursor is believed to play a critical role in the development of Alzheimer's disease neuropathology. The localization of the human Aß epitope within mature neuroectodermally differentiated embryonal carcinoma (P19) cells, stably transfected with the cDNA coding for a wild form human amyloid ß-protein precursor (AßPP 751) was investigated. For this, we applied high resolution electron microscopy and immunocytochemistry with a newly developed, highly specfic monoclonal antibody (McSA1). We observed immunoreactive signals in a number of subcellular organelles such as early endosomes, the trans-Golgi network and in the dilated rough endoplasmic reticulum, but not in lysosomes. Occasionally Aß immunoreactivity was associated with microtubules and filaments, with the outer mitochondrial membrane, and with the nuclear envelope. These observations expand on current data regarding intracellular trafficking of AßPP fragments and provoke further questions regarding the role of intracellular Aß peptides in basal conditions and pathological states.