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Novel frameshift mutations near short simple repeats
W H van Den Hurk1, H J Willems, M Bloemen
1Department of Molecular Animal Physiology, University of Nijmegen, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands.
The Journal of Biological Chemistry
|January 15, 2001
Summary
Molecular misreading, a process causing gene transcript errors, is common in aging and linked to Alzheimer's and Down syndrome. These errors can produce toxic protein fragments, contributing to neurodegenerative diseases.
Area of Science:
- Molecular Biology
- Neuroscience
- Genetics
Background:
- Alzheimer's disease and Down syndrome feature protein deposits in the cerebellar cortex.
- These deposits contain fragments of ubiquitin-B and amyloid precursor protein (APP) with aberrant carboxyl termini.
- Aberrant fragments arise from frameshift mutations (e.g., DeltaGU, DeltaGA) in mRNA, a process termed molecular misreading.
Purpose of the Study:
- To screen gene transcripts for molecular misreading in aged controls, Alzheimer's disease, and Down's syndrome.
- To identify novel frameshift mutations in ubiquitin-B and APP genes.
- To investigate the relationship between mutations and repeat sequences in mRNA.
Main Methods:
- Utilized a bacterial expression system with green fluorescent protein as a reporter.
- Screened gene transcripts from aged individuals, Alzheimer's disease patients, and Down syndrome patients.
- Analyzed transcripts for frameshift mutations in ubiquitin-B and APP genes.
Main Results:
- Discovered novel frameshift mutations (e.g., DeltaGA, DeltaG, DeltaGU) in ubiquitin-B and APP gene transcripts.
- Identified mutations near various short simple repeats, not exclusively GAGAG motifs.
- Some novel aberrant APP fragments can potentially generate neurotoxic beta-amyloid peptide.
Conclusions:
- Molecular misreading is a widespread phenomenon during the aging process.
- Frameshift mutations in ubiquitin-B and APP are associated with aging and neurodegenerative conditions.
- The findings suggest a novel mechanism contributing to neurotoxicity in aging and related diseases.