泛素连接酶Smurf1与接头蛋白TRAF1相互作用并介导其泛素化降解

Ubiquitin ligase Smurf1 interacts with adaptor protein TRAF1 and promotes its ubiquitin-mediated degradation

目的研究泛素连接酶Smurf1与接头蛋白TRAF1之间的相互作用,并检测TRAF1蛋白水平是否受Smurf1调控。方法在HEK293T细胞中共表达TRAF1与Smurf1,通过免疫共沉淀测定二者结合,并检测与Smurf1共表达时TRAF1蛋白水平变化,最后用AP-1报告基因测定TRAF1功能是否受Smurf1调控。结果 TRAF1可以特异性地与Smurf1相互作用,其在细胞内的蛋白水平可以被Smurf1所降低,而且TRAF1在AP-1报告基因中的抑制功能可以被Smurf1逆转。结论 TRAF1与Smurf1相互作用导致TRAF1在细胞内的蛋白水平降低而且在AP-1通路中的抑制作用减弱。

Objective To determine the interaction between the ubiquitin ligase Smurf1 and adaptor protein TRAF1,and to detect the effect of Smurf1 on TRAF1 protein level in human cells.Methods The TRAF1 and Smurf1 in HEK293T cells were co-expressed to determine the interaction through co-immunoprecipitation assay.The alteration of TRAF1 protein level was detected in the presence or absence of ectopic Smurf1.Finally the Smurf1 effect on TRAF1 function in AP-1 pathway was determined by reporter gene assay.Results The TRAF1 interacted with Smurf1 specifically,and its protein level in cells was downregulated by Smurf1.The inhibitory effect of TRAF1 on AP-1 transcriptional factor activity was reversed by Smurf1.Conclusion Ubiquitin ligase Smurf1 could interact with adaptor protein TRAF1 and promote the degradation of TRAF1 protein.This interaction could inhibit the function of TRAF1 in AP-1 pathway.