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Disproportionate relationship between APOBEC-1 expression and apolipoprotein B mRNA editing activity
J F Siddiqui1, D Van Mater, M P Sowden
1Department of Biochemistry and Biophysics, Health Science, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York 14642, USA.
Experimental Cell Research
|September 30, 1999
Summary
Altering APOBEC-1 protein levels affects apolipoprotein B (apoB) mRNA editing. Increasing APOBEC-1 boosts editing but also causes promiscuous editing at unintended sites.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Apolipoprotein B (apoB) mRNA editing is a crucial post-transcriptional modification.
- This process is catalyzed by the enzyme APOBEC-1 within the C/U editosome complex.
- Understanding the regulation of APOBEC-1 is key to controlling apoB mRNA editing fidelity.
Purpose of the Study:
- To quantify the impact of APOBEC-1 protein abundance on apoB mRNA editing.
- To investigate the relationship between enzyme levels and editing efficiency.
- To determine if increased APOBEC-1 leads to off-target editing events.
Main Methods:
- Utilized transfected McArdle rat hepatoma cells expressing a GFP-APOBEC-1 chimera.
- Employed flow cytometry to sort cells into populations with varying GFP-APOBEC-1 expression levels.
- Quantified the proportion of edited apoB mRNA in relation to GFP-APOBEC-1 protein levels.
Main Results:
- A positive correlation was observed between GFP-APOBEC-1 expression and the proportion of edited apoB mRNA.
- A disproportionately high number of enzyme molecules were required for increased editing efficiency.
- Overexpression of GFP-APOBEC-1 resulted in promiscuous editing at inappropriate sites.
Conclusions:
- Experimental manipulation of APOBEC-1 abundance can increase apoB mRNA editing but may compromise fidelity.
- Promiscuous editing appears to be an inevitable consequence of APOBEC-1 overexpression without other regulatory factors.
- Coordinate expression of APOBEC-1 and auxiliary proteins, or regulation of their interactions, is likely necessary for precise editing control.
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