Phase-separated nucleocapsid protein of SARS-CoV-2 suppresses cGAS-DNA recognition by disrupting cGAS-G3BP1 complex

Currently,the incidence and fatality rate of SARS-CoV-2 remain continually high worldwide.COVID-19 patients infected with SARS-CoV-2 exhibited decreased type I interferon(IFN-I)signal,along with limited activation of antiviral immune responses as well as enhanced viral infectivity.Dramatic progresses have been made in revealing the multiple strategies employed by SARS-CoV-2 in impairing canonical RNA sensing pathways.However,it remains to be determined about the SARS-CoV-2 antagonism of cGAS-mediated activation of IFN responses during infection.In the current study,we figure out that SARS-CoV-2 infection leads to the accumulation of released mitochondria DNA(mtDNA),which in turn triggers cGAS to activate IFN-I signaling.As countermeasures,SARS-CoV-2 nucleocapsid(N)protein restricts the DNA recognition capacity of cGAS to impair cGAS-induced IFN-I signaling.Mechanically,N protein disrupts the assembly of cGAS with its co-factor G3BP1 by undergoing DNA-induced liquid-liquid phase separation(LLPS),subsequently impairs the double-strand DNA(dsDNA)detection ability of cGAS.Taken together,our findings unravel a novel antagonistic strategy by which SARS-CoV-2 reduces DNA-triggered IFN-I pathway through interfering with cGAS-DNA phase separation.

Osteogenic effects of antihypertensive drug benidipine on mouse MC3T3-E1 cells in vitro

Hypertension is a prevalent systemic disease in the elderly,who can suffer from several pathological skeletal conditions simultaneously,including osteoporosis.Benidipine(BD),which is widely used to treat hypertension,has been proved to have a beneficial effect on bone metabolism.In order to confirm the osteogenic effects of BD,we investigated its osteogenic function using mouse MC3T3-E1 preosteoblast cells in vitro.The proliferative ability of MC3T3-E1 cells was significantly associated with the concentration of BD,as measured by methylthiazolyldiphenyl-tetrazolium bromide(MTT)assay and cell cycle assay.With BD treatment,the osteogenic differentiation and maturation of MC3T3-E1 cells were increased,as established by the alkaline phosphatase(ALP)activity test,matrix mineralized nodules formation,osteogenic genetic test,and protein expression analyses.Moreover,our data showed that the BMP2/Smad pathway could be the partial mechanism for the promotion of osteogenesis by BD,while BD might suppress the possible function of osteoclasts through the OPG/RANKL/RANK(receptor activator of nuclear factor-κB(NF-κB))pathway.The hypothesis that BD bears a considerable potential in further research on its dual therapeutic effect on hypertensive patients with poor skeletal conditions was proved within the limitations of the present study.