Ribosomal RNA in Alzheimer's disease and ageing

Ribosomal RNA genes are involved in cell transcription and translation proc esses and can modulate gene expression. In an earlier cytogenetic study,(Pa yao, S.L.M., Smith, M.de A.C., Kormann-Bortolotto, M.H., Toniolo, J., 1994 (Investigation of the nucleolar organizer regions in Alzheimer's disease. G erontology 40, 13-17), reported a decreased activity of ribosomal genes in Alzheimer's disease (AD). We studied the ratio of mature rRNA 28S and 18S i n peripheral blood samples derived from eight patients with AD, eight healt hy elderly sisters of these patients (SA), eight healthy elderly (EC) and e ight healthy young (YC) controls, all female. Our results showed a statisti cally significant decrease of mature rRNA 28S and 18S ratio in the elderly groups (AD, SA, EC) in relation to the young one, probably by fragmentation of 28S rRNA. The Alzheimer's patient group had the lowest 28S/18S ratio. T hus, we can suggest that there is a possible change in the transcriptional or maturation process, or a preferential degradation of the 28S subunit wit h ageing. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.