RNF125通过泛素化修饰caspase-1 p33活性亚基促进炎症应答

The ubiquitination modification of caspase-1 p33 subunit by RNF125 to promote inflammatory response

为探讨RNF125在调控caspase-1中的功能及作用机制,利用免疫共沉淀、GST pull-down和免疫荧光等技术证明RNF125和caspase-1 p33亚基之间的相互作用;分析RNF125对p33亚基泛素化修饰的方式;通过siRNA技术降低THP-1细胞中RNF125的表达,检测RNF125敲低前后细胞受LPS+ATP刺激时IL-1β的分泌情况;以腹腔注射叶酸的方式构建RNF125^(+/+)和RNF125^(-/-)小鼠的肾炎模型,分析血清中尿素水平,称量小鼠体重和肾脏重量并计算肾重比.结果显示,RNF125可与caspase-1 p33亚基直接相互作用,且RNF125抑制了caspase-1 p33亚基的K48聚泛素化修饰;与对照组相比,敲低RNF125表达的THP-1细胞在受到LPS+ATP刺激时,分泌的IL-1β显著减少;肾炎模型的结果显示,RNF125敲除型小鼠的肾脏肿胀不明显,尿素水平和肾重比均显著低于野生型小鼠.该研究首次发现了E3泛素连接酶RNF125与caspase-1活性亚基p33之间的相互作用,并证明它可通过影响caspase-1 p33亚基的泛素化修饰促进炎症反应的信号传导.

In order to explore the function and mechanism of RNF125 in regulating caspase-1,the interaction between RNF125 and caspase-1 p33 subunits was proved by co-immunoprecipitation,GST pull-down and immunofluorescence.The ubiquitin modification of p33 subunit by RNF125 was analyzed.RNF125 knockdown in THP-1 cells was performed by siRNA technique,and the secretion of IL-1βin THP-1 cells stimulated by LPS+ATP was detected by ELISA.The nephritis models of RNF125^(+/+)and RNF125^(-/-)mice were established by intraperitoneal injection of folic acid.The level of urea in serum was analyzed,and the kidney/body weight ratio was calculated.The results showed that RNF125 could directly interact with caspase-1 p33 subunit,and RNF125 inhibited the K48 polyubiquitin modification of caspase-1 p33 subunit.Compared with the control group,THP-1 cells with low RNF125 expression secreted significantly less IL-1βwhen stimulated by LPS+ATP.Nephritis model results showed that the kidney swelling,urea level and kidney weight ratio of RNF125^(-/-)mice were all significantly lower than those of wild type mice.To sum up,this study first time illustrated the interaction between E3 ubiquitin ligase RNF125 and caspase-1 active subunit p33,and proved that it could promote the signal transduction of inflammatory response by affecting the ubiquitin modification of caspase-1 p33 subunit.