Decoupling expression and editing preferences of ADAR1 p150 and p110 isoforms

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Human adenosine deaminase acting on RNA 1 (ADAR1) regulates cellular responses to RNA through adenosine-to-inosine deamination.
• ADAR1 dysfunction is linked to autoinflammatory and skin pigmentation disorders.
• The distinct roles of ADAR1 isoforms, p150 and p110, in RNA editing are not fully understood due to coexpression challenges.

Purpose of the Study:

• To elucidate the specific contributions of ADAR1 isoforms (p150 and p110) to the RNA editing landscape.
• To develop a method for selectively analyzing the editing activity of the p150 isoform.

Main Methods:

• Engineered synonymous mutations in the p150-encoding mRNA to reduce leaky ribosome scanning and p110 coexpression.
• Generated ADAR1 knockout cells reconstituted with modified p150 and p110 constructs.
• Performed RNA editing analysis on reconstituted cells to compare isoform-specific editing activities.

Main Results:

• Synonymous mutations significantly reduced p110 coexpression from the p150 mRNA.
• Isoform-selective editing analysis revealed p150 selectively edits over half of A-to-I sites.
• The remaining A-to-I sites are edited by either p150 or p110, indicating overlapping functions.

Conclusions:

• The p150 isoform plays a major, selective role in ADAR1-mediated RNA editing.
• The developed method enables isoform-specific editing analysis and can be adapted for other cellular contexts.
• Understanding isoform-specific functions is crucial for deciphering ADAR1's role in health and disease.