RNA Editing And Interferon Response: Modulation By Thermal Stress
2The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University
Abstract
RNA editing by adenosine deaminase acting on RNA (ADAR) enzymes is an essential cellular process that converts adenosine to inosine in double-stranded RNA (dsRNA), typically formed by transcribed inverted retroelements. A-to-I deamination by ADAR1 prevents dsRNA recognition by sensors that could otherwise activate an inappropriate anti-viral Type-I interferon (IFN-I) response.
ADAR1 deficiency is linked to type I interferonopathies, characterized by excessive inflammatory responses. Using a mouse model with pancreatic beta-cell-specific inactivation of Adar (beta-AdarKO), we previously showed that deficient RNA editing in these cells triggers a robust IFN-I response, leading to islet inflammation, beta-cell destruction, and diabetes, resembling early-stage human T1D.
Since inflammation is often accompanied by fever, and RNA editing has been shown to be temperature-sensitive, we investigated the effects of heat stress on RNA editing and the dsRNA-induced antiviral IFN-I response.
Materials and Methods
Pancreatic islets isolated from wild-type or beta-AdarKO mice were incubated at 37°C or 39°C for 24 -72 hours. RNA sequencing was performed to assess RNA editing and gene expression. Additionally, wild-type islets incubated at 37°C or 39°C were treated with exogenous IFN-I and the expression of interferon-stimulated genes (ISG) was measured using RT-qPCR.
Results and discussion
24h incubation of Adar mutant islets at 39°C versus 37°C dramatically reduced the expression of interferon-stimulated genes, while showing robust expression of heat shock response gene. IFN-I expression was greatly reduced, suggesting that heat affects a molecular event upstream of IFN transcription. Consistent with this idea, in wild-type islets temperature had no effect on IFN-I-induced ISG expression levels. Elevated temperature did not affect RNA editing levels in wild-type islets.
Conclusions
Our findings reveal that febrile temperatures blunt the IFN-I response in Adar-deficient beta-cells. Future research will explore whether this temperature-sensitive response applies to a broader range of cellular systems, specifically cells infected with RNA viruses. We speculate that moderating IFN responses during viral infection, while preserving the response to true viral infection, may help fine-tune inflammation and prevent excessive immune reactions.