Regional distribution of presenilin-1 messenger RNA in the embryonic rat brain: Comparison with beta-amyloid precursor protein messenger RNA localization

The messenger RNA expression of presenilin-1, an important gene responsible for early-onset familial Alzheimer's disease, was investigated in the embr yonic rat brain with in situ hybridization histochemistry using an oligonuc leotide probe specific to the messenger RNA. It was also compared with that of beta-amyloid precursor protein messenger RNA. Presenilin-1 and beta-amy loid precursor protein messenger RNA were abundantly expressed throughout t he central nervous system in the embryonic day 13, 17 and 20 rat brain. Pre senilin-1 messenger RNA was strongly expressed in both neuroepithelium and differentiating fields. In contrast, beta-amyloid precursor protein messeng er RNA was preferentially expressed in differentiating fields, while low ex pression of beta-amyloid precursor protein messenger RNA was seen in neuroe pithelium. Although the expression patterns of these two messenger RNAs wer e basically similar, there seemed to be a tendency that presenilin-1 messen ger RNA was preferentially expressed in immature neurons, while beta-amyroi d precursor protein messenger RNA was preferentially expressed in mature ne urons, suggesting that presenilin-1 is expressed earlier than beta-amyloid precursor protein and that presenilin-1 is involved in beta-amyloid precurs or protein processing. These data raise the possibility that presenilin-1 a nd beta-amyloid precursor protein co-operatively play pivotal roles in rat neurogenesis. (C) 1999 IBRO. Published by Elsevier Science Ltd.