m6A modification of SARS-CoV-2 RNA:  Exploring the epitranscriptomic regulation of proinflammatory cytokine production

Lokender Singh

m6A modification of SARS-CoV-2 RNA: Exploring the epitranscriptomic regulation of proinflammatory cytokine production

Date

2024-04

Authors

Lokender Singh

Publisher

Lala Lajpat Rai University of Veterinary & Animal Sciences, Hisar

Abstract

A major risk factor of the severity/death of COVID-19 patients is associated with an increased level of inflammatory mediators including cytokines and chemokines also referred to as hypercytokinemia or cytokine storm, molecular mechanism of which is not well understood. Epitranscriptomic modifications are post-transcriptional modifications that occur on RNA molecules, which can have profound impacts on their structure, stability, and function and have emerged as the key players in regulating virus replication. In this study, it was demonstrated that SARS-CoV-2 infection to A549 cells results in methylation (m6A modification) of viral RNA and that, m6A modification in SARS CoV-2 genome is a dynamic event (switch on off phenomenon). SARS-CoV-2 infection to A549 cells also induces production of proinflamamtory cytokines (IL-6 and TNF-α). The m6A modification in SARS-CoV-2 genome and production of production of proinflamamtory cytokines genes appears to correlate with each other, indicating the role of m6A modification in induction of cytokines in the target cells. Further, the transfection of methylated- but not unmethylated RNA into A549 cells resulted in induction of IL-6, which suggests that IL-6 induction is m6A-depeendent. The levels of IL-1β and TNF α were comparable in cells that received either methylated but not unmethylated RNA, which suggested that induction of IL-1β and TNF-α is m6A-indepenedent. DZNep (a small molecule chemical inhibitor of methylation) suppressed SARS-CoV-2 yield by inhibiting synthesis of viral RNA. It also suppressed the levels of m6A-modidfes SARS-CoV-2 RNA, concomitant with decreasing the levels of IL-6. In conclusion, this study provides novel insights on epitranscriptomic control of proinflammatory cytokines (cytokine storm) production in SARS-CoV-2 infected cells. The cytokine storm may be therapeutically managed by inhibiting cellular enzymes responsible for methylation (m6A) of SARS-CoV-2 RNA in the target cells.