Decreased RNA, and increased RNA oxidation, in ribosomes from early Alzheimer's disease

All cells rely on efficient protein synthesis in order to maintain cellular homeostasis. Recent studies from our laboratory indicate that declines in protein synthesis and ribosome function occur in the earliest stage of Alzheimer's disease (AD). Additional studies indicate a potential role for ribosomal RNA oxidation as a potential mediator of decreased protein synthesis in AD. The ribosome is a complex of proteins and nucleic acids that mediates all protein synthesis. At present it is unclear if significant alterations in ribosomal RNA occurs within the ribosome complex during the progression of AD. In this study we examined the amount of ribosomal RNA in the different ribosomal fractions generated from control subjects, individuals with mild cognitive impairment (MCI), and individuals with AD. Studies were conducted in the inferior parietal lobule of each subject. Together, these data demonstrate that during the progression of AD there is a gross decline in the amount of ribosomal RNA within the ribosome complex. Additionally, these studies provide evidence for gross elevations in RNA oxidation within the ribosome complex of MCI and AD. Together, these data strongly suggest a role for RNA alterations within the ribosome as a mediator of decreased protein synthesis in both MCI and AD.