Expression of presenilin 1 in nervous system during rat development

Alzheimer's disease (AD) is a polygenic disorder involving at least four different genes. Among them, missense mutations in the presenilins segregate with the vast majority of early onset cases of familial AD. To elucidate possible function(s) of presenilin 1 (PS1), we have studied its expression during the development of the rat nervous system. Analysis by in situ hybridization showed expression of PS1 in a variety of cell types and tissues during development, with prominent expression in the nervous system. During late embryogenesis, the ventricular zone presented the highest levels of expression, paralleling the pattern previously reported for Notch. Later, during postnatal development, we observed a peak of PS1 expression at postnatal day 10, particularly in the cerebellum and hippocampus, a time when proliferation and migration are still ongoing and synapse formation is being completed. We propose that presenilins participate in at least two different developmental processes: (1) one involved in neurogenesis and skeleton formation during embryonic development, probably involving coordinate expression with Notch, and (2) a second one in the postnatal central nervous system, perhaps involved in neuritogenic and/or synaptogenic stages, most likely playing a role in amyloid precursor protein processing and amyloid beta production.