AIM:To investigate the effect of plasmin on epithelial sodium channel γ-subunit(γ-ENaC)acti-vation in mouse M-1 cells and the role of nuclear factor-κB(NF-κB).METHODS:Mouse M-1 cells were divided into three experimental parts.In the first part,the cells were divided into a control group,a plasmin group,and a plasmin+BAY 11-7082(NF-κB inhibitor)group to explore the effects of plasmin on inflammatory factors and γ-ENaC.In the sec-ond part,the cells were divided into a control group,a BAY 11-7082 group and a BAY 11-7082+plasmin group.M-1 cells were pretreated with BAY 11-7082 to explore the role of NF-κB in the regulation of γ-ENaC expression by plasmin.In the third part,the cells were divided into a control group,a plasmin group and an interleukin-6(IL-6)group.M-1 cells were treated with plasmin or IL-6 to explore the regulatory effect of IL-6 downstream of NF-κB on γ-ENaC.After drug interven-tion,the levels of IL-6,tumor necrosis factor-α(TNF-α),monocyte chemoattractant protein-1(MCP-1)and IL-1β in cell culture supernatants were detected by ELISA.The protein levels of phosphorylated inhibitor of nuclear factor-κB α(p-IκBα)/IκBα,p-NF-κB p65/NF-κB p65,and γ-ENaC was detected by Western blot.The distribution of γ-ENaC on the membrane was detected by immunofluorescence staining.RESULTS:Compared with control group,the levels of IL-6,TNF-α,MCP-1 and IL-1β in the supernatants of cells treated with 10 mg/L plasmin for 24 h were increased(n=3,P<0.01),the protein levels of p-IκBα/IκBα,p-NF-κB p65/NF-κB p65 and γ-ENaC were increased(n=5,P<0.01),and the distribution of γ-ENaC on the membrane was increased.Compared with plasmin group,the levels of IL-6,TNF-α,MCP-1,IL-1β,p-IκBα/IκBα,p-NF-κB p65/NF-κB p65 and γ-ENaC,and the γ-ENaC distribution on the membrane were lowered in plasmin and BAY 11-7082 coculture group(n=3,P<0.05 or P<0.01).Compared with control group,the ratio of p-NF-κB p65/NF-κB p65 decreased in BAY 11-7082 group(n=5,P<0.05),whereas there was no significant change in γ-ENaC.After stimulation with plasmin,the levels of p-IκBα/IκBα,p-NF-κB p65/NF-κB p65 and γ-ENaC in-creased(n=5,P<0.05 or P<0.01),and the γ-ENaC distribution on the membrane increased.Treatment with IL-6,downstream of NF-κB,increased the protein expression of γ-ENaC(n=5,P<0.05)and the distribution of γ-ENaC on the membrane after 24 h of intervention.CONCLUSION:The regulation of γ-ENaC expression by plasmin in mouse M-1 cells is related to the abnormal increase in inflammatory factors after NF-κB activation.

AIM:To investigate the effect of plasmin on epithelial sodium channel γ-subunit(γ-ENaC)acti-vation in mouse M-1 cells and the role of nuclear factor-κB(NF-κB).METHODS:Mouse M-1 cells were divided into three experimental parts.In the first part,the cells were divided into a control group,a plasmin group,and a plasmin+BAY 11-7082(NF-κB inhibitor)group to explore the effects of plasmin on inflammatory factors and γ-ENaC.In the sec-ond part,the cells were divided into a control group,a BAY 11-7082 group and a BAY 11-7082+plasmin group.M-1 cells were pretreated with BAY 11-7082 to explore the role of NF-κB in the regulation of γ-ENaC expression by plasmin.In the third part,the cells were divided into a control group,a plasmin group and an interleukin-6(IL-6)group.M-1 cells were treated with plasmin or IL-6 to explore the regulatory effect of IL-6 downstream of NF-κB on γ-ENaC.After drug interven-tion,the levels of IL-6,tumor necrosis factor-α(TNF-α),monocyte chemoattractant protein-1(MCP-1)and IL-1β in cell culture supernatants were detected by ELISA.The protein levels of phosphorylated inhibitor of nuclear factor-κB α(p-IκBα)/IκBα,p-NF-κB p65/NF-κB p65,and γ-ENaC was detected by Western blot.The distribution of γ-ENaC on the membrane was detected by immunofluorescence staining.RESULTS:Compared with control group,the levels of IL-6,TNF-α,MCP-1 and IL-1β in the supernatants of cells treated with 10 mg/L plasmin for 24 h were increased(n=3,P<0.01),the protein levels of p-IκBα/IκBα,p-NF-κB p65/NF-κB p65 and γ-ENaC were increased(n=5,P<0.01),and the distribution of γ-ENaC on the membrane was increased.Compared with plasmin group,the levels of IL-6,TNF-α,MCP-1,IL-1β,p-IκBα/IκBα,p-NF-κB p65/NF-κB p65 and γ-ENaC,and the γ-ENaC distribution on the membrane were lowered in plasmin and BAY 11-7082 coculture group(n=3,P<0.05 or P<0.01).Compared with control group,the ratio of p-NF-κB p65/NF-κB p65 decreased in BAY 11-7082 group(n=5,P<0.05),whereas there was no significant change in γ-ENaC.After stimulation with plasmin,the levels of p-IκBα/IκBα,p-NF-κB p65/NF-κB p65 and γ-ENaC in-creased(n=5,P<0.05 or P<0.01),and the γ-ENaC distribution on the membrane increased.Treatment with IL-6,downstream of NF-κB,increased the protein expression of γ-ENaC(n=5,P<0.05)and the distribution of γ-ENaC on the membrane after 24 h of intervention.CONCLUSION:The regulation of γ-ENaC expression by plasmin in mouse M-1 cells is related to the abnormal increase in inflammatory factors after NF-κB activation.