Z-Form Stabilization By The Zα Domain Of Adar1p150 Has Subtle Effects On A-To-I Editing

The role of Adenosine Deaminase Acting on RNA 1 (ADAR1)'s Z-conformation stabilizing Zα domain in A-to-I editing is unclear. Previous studies on Zα mutations faced limitations, including variable ADAR1p150 expression, differential editing analysis challenges, and unaccounted changes in ADAR1p150 localization. To address these issues, we developed a Cre-lox system in ADAR1p150 KO cells to generate stable cell lines expressing Zα mutant ADAR1p150 constructs. Using total RNA sequencing analyzing editing clusters as a proxy for dsRNAs, we found that Zα mutations slightly decreased overall A-to-I editing, consistent with recent findings. These decreases correlated with mislocalization of ADAR1p150 rather than reduced editing specificity, and practically no statistically significant differentially edited sites were identified between wild-type and Zα mutant ADAR1p150 constructs. These results suggest that Zα's impact on editing is minor and that phenotypes in Zα mutant mouse models and human patients may arise from editing-independent inhibition of Z-DNA-Binding Protein 1 (ZBP1), rather than changes in RNA editing.