m6A-modified RIOK3 activated the NF-κB-signaling pathway by CDC42, promoting the replication and proliferation of enterovirus.

Enterovirus infections are implicated in the pathogenesis of inflammatory diseases, such as viral myocarditis, meningitis, and pancreatitis. These infections activate innate and inflammatory immune responses upon viral entry into host cells. However, the precise mechanisms through which enteroviruses induce inflammation to facilitate viral replication remain unclear. N(6)-methyladenosine (m6A), one of the most abundant internal modifications on eukaryotic mRNAs, is regulated by METTL3, a key "writer" enzyme in the m6A methyltransferase complex. This study identifies RIO kinase 3 (RIOK3), a serine-threonine protein kinase, involved in innate immunity, inflammation, and cell cycle regulation, as a critical factor in Coxsackievirus B3 (CVB3) infection. CVB3 infection significantly increases RIOK3 expression both in vivo and in vitro, accompanied by elevated m6A modifications on RIOK3 mRNA. METTL3-mediated m6A modification enhances RIOK3 transcription, which in turn downregulates CDC42, a small GTPase of the Rho subfamily, that regulates key cellular processes, including antiviral signaling. This suppression of CDC42 promotes CVB3 replication. Additionally, RIOK3 and CDC42 modulate the NF-κB signaling pathway, a pivotal regulator of inflammatory and immune responses during infection. These findings reveal that m6A-modified RIOK3 promotes enterovirus replication by activating the NF-κB signaling pathway via CDC42 suppression, providing novel insights into the molecular mechanisms of enterovirus pathogenesis.