Molecular misreading: the frequency of dinucleotide deletions in neuronal mRNAs for beta-amyloid precursor protein and ubiquitin B.

Abstract

Human neuronal cells contain mutant beta-amyloid precursor protein (APP) and ubiquitin B (UBB) mRNAs, in which dinucleotide deletions ('Delta') are generated in/around GAGAG-motifs by an unknown mechanism referred to as 'Molecular Misreading.' The encoded frameshifted (+1) proteins accumulate in the neuropathological hallmarks of Alzheimer's disease (AD) and in other neurodegenerative and age-related diseases. To measure the concentration of Delta mRNAs, we developed a highly sensitive and specific assay, utilizing peptide nucleic acid-mediated PCR clamping, followed by cloning and colony hybridization with sequence-specific oligonucleotide probes. We found only a few molecules of Delta mRNA/microg of cellular RNA, at levels <10(-5) to 10(-6) x the concentration of WT mRNA, in RNA extracted from: (i) cultured human neuroblastoma cells grown under a variety of conditions, (ii) the frontal half of brains from wild type and XPA(-/-) DNA repair-deficient mice, and (iii) post-mortem temporal cortices from humans. Importantly, in RNA from the temporal cortices of AD and Down Syndrome patients that contain betaAPP+1 and UBB+1 immunoreactive cells, we found the same low levels of Delta mRNA. We infer that the accumulation of +1 proteins in neurons of these patients is not caused by an increase in the concentration of Delta mRNAs.

• Authors: Lisya Gerez, Annett de Haan, Elly M Hol, David F Fischer, Fred W van Leeuwen, Harry van Steeg, Rob Benne
• Journal: Neurobiology of aging (Neurobiol Aging) Vol. 26 Issue 2 Pg. 145-55 (Feb 2005) ISSN: 0197-4580 [Print] United States
• PMID: 15582744 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amyloid beta-Protein Precursor
• DNA-Binding Proteins
• Dinucleoside Phosphates
• RNA, Messenger
• UBB protein, human
• Ubiquitin
• XPA protein, human
• Xeroderma Pigmentosum Group A Protein
• Xpa protein, mouse

Topics

• Adult
• Aged
• Aged, 80 and over
• Alzheimer Disease (genetics, metabolism)
• Amyloid beta-Protein Precursor (genetics, metabolism)
• Animals
• Brain (cytology, metabolism)
• Cell Line
• DNA-Binding Proteins (genetics, metabolism)
• Dinucleoside Phosphates (metabolism)
• Down Syndrome (genetics, metabolism)
• Electrophoresis (methods)
• Female
• Gene Deletion
• Humans
• Male
• Mice
• Middle Aged
• Molecular Biology (methods)
• Neurons (metabolism)
• Nucleic Acid Hybridization (methods)
• Postmortem Changes
• RNA, Messenger (metabolism)
• Reverse Transcriptase Polymerase Chain Reaction (methods)
• Ubiquitin (genetics, metabolism)
• Xeroderma Pigmentosum Group A Protein