RNA-induced liquid phase separation of SARS-CoV-2 nucleocapsid protein facilitates NF-kB hyper-activation and inflammation

The ongoing 2019 novel coronavirus disease(COVID-19)caused by SARS-CoV-2 has posed a worldwide pandemic and a major global public health threat.The severity and mortality of COVID-19 are associated with virus-induced dysfunctional inflammatory responses and cytokine storms.However,the interplay between host inflammatory responses and SARS-CoV-2 infection remains largely unknown.Here,we demonstrate that SARS-CoV-2 nucleocapsid(N)protein,the major structural protein of the virion,promotes the virus-triggered activation of NF-kB signaling.After binding to viral RNA,N protein robustly undergoes liquid-liquid phase separation(LLPS),which recruits TAK1 and IKK complex,the key kinases of NF-kB signaling,to enhance NF-kB activation.Moreover,1,6-hexanediol,the inhibitor of LLPS,can attenuate the phase separation of N protein and restrict its regulatory functions in NF-kB activation.These results suggest that LLPS of N protein provides a platform to Induce NF-kB hyper-activation,which could be a potential therapeutic target against COVID-19 severe pneumonia.