ADAR2 regulates RNA stability by modifying access of decay-promoting RNA-binding proteins

Area of Science:

• Molecular Biology
• RNA Biology
• Gene Regulation

Background:

• Adenosine deaminases acting on RNA (ADARs) modify RNA by converting adenosine to inosine (A-to-I).
• The function of ADARs in non-coding RNA regions, such as introns and untranslated regions (UTRs), remains largely unclear.
• ADAR2 is known to edit specific RNA targets, but its role in transcript stability is an active area of research.

Purpose of the Study:

• To investigate the role of ADAR2 in the regulation of nuclear-retained Cat2 (Ctn) RNA.
• To determine whether ADAR2-mediated stabilization of Ctn RNA is dependent on its RNA editing activity.
• To elucidate the mechanism by which ADAR2 influences Ctn RNA stability and identify other similarly regulated RNAs.

Main Methods:

• RNA immunoprecipitation (RIP) to assess ADAR2-RNA interactions.
• Quantitative PCR (qPCR) to measure Ctn RNA abundance and half-life.
• Western blotting to detect protein levels.
• Transcriptomic analysis to identify global RNA targets.

Main Results:

• ADAR2 directly interacts with and binds to the 3' UTR of Ctn RNA.
• The absence of ADAR2 leads to significantly reduced abundance and half-life of Ctn RNA.
• ADAR2 stabilizes Ctn RNA in an RNA editing-independent manner.
• Unedited Ctn RNA exhibits increased binding to HuR and Poly(A) specific ribonuclease deadenylase (PARN), which destabilize the RNA.
• ADAR2 antagonizes the destabilizing effects of HuR and PARN on Ctn RNA.
• Transcriptomic analysis revealed other RNAs regulated by a similar ADAR2-mediated stabilization mechanism.

Conclusions:

• ADAR2 enhances the stability of specific target RNAs, including Ctn RNA, by preventing their interaction with RNA-destabilizing proteins like HuR and PARN.
• This RNA stabilization mechanism is independent of ADAR2's RNA editing activity.
• ADAR2 plays a crucial role in regulating RNA stability beyond its canonical editing function, impacting gene expression through transcript stabilization.