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Updated: Jun 16, 2025

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
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An ADAR1 dsRBD3-PKR kinase domain interaction on dsRNA inhibits PKR activation

Ketty Sinigaglia1, Anna Cherian1, Qiupei Du1

  • 1Central European Institute for Technology at Masaryk University (CEITEC MU), Building E35, Kamenice 735/5, 625 00 Brno, Czechia; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czechia.

Cell Reports
|August 15, 2024
PubMed

Insights

Adenosine deaminase acting on RNA 1 (ADAR1) inhibits Protein Kinase R (PKR) activation, preventing embryonic lethality in mice. This interaction is crucial for maintaining intestinal integrity and long-term survival by regulating interferon responses.

Area of Science:

  • Molecular Biology
  • Immunology
  • Genetics

Background:

  • Aberrant interferon induction leads to embryonic lethality in Adar null mutant mice.
  • Mice lacking both Adar and Mavs exhibit early postnatal lethality, with intestinal damage linked to Protein Kinase R (PKR) activation.

Purpose of the Study:

  • To investigate the protective role of Adenosine deaminase acting on RNA 1 (ADAR1) against PKR-mediated lethality.
  • To elucidate the molecular mechanism of ADAR1-mediated PKR inhibition.

Main Methods:

  • Generation and analysis of Adar, Mavs, and Eifak2 (PKR) mutant mouse models.
  • Co-immunoprecipitation assays to detect protein interactions.
  • AlphaFold structural modeling to predict binding interfaces.
  • In vitro experiments using human ADAR1 in A549 cells to assess PKR activation.

Main Results:

  • Triple mutant mice (Adar Mavs Eifak2) show rescued lethality and intestinal defects, indicating PKR's central role.
  • ADAR1 and PKR co-immunoprecipitate, suggesting a direct interaction.
  • Structural modeling proposes an inhibitory interaction between ADAR1's dsRBD3 and PKR's kinase domain.
  • ADAR1 expression inhibits endogenous PKR activation in human cells, dependent on dsRNA binding and a specific ADAR1-PKR contact.

Conclusions:

  • ADAR1 directly interacts with and inhibits PKR activation, preventing lethal interferon responses.
  • The interaction requires ADAR1 dsRNA binding and a specific contact interface involving ADAR1 dsRBD3.
  • This mechanism highlights ADAR1's critical role in innate immunity and preventing PKR-driven pathology.
Keywords:
ADAR RNA editingAdar mutantAicardi-Goutieres Syndrome (AGS)CP: Molecular biologyMavsdsRNAdsRNA-binding proteininnate immune sensorsprotein kinase R

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