Function And Mechanism Of Ubiquitin Ligase Smurf1 In The Development Of Sepsis

Background: The post-translational modifications including acetylation,phosphorylation,ubiquitination,neddylation and other modifications play vital roles in maintaining normal function of the body.In which the ubiquitin-proteasome pathway is the most well studied mechanism for its function of maintaining cellular homeostasis.There are three kinds of enzyme in the ubiquitin pathway,among which the E3 ubiquitin ligases are final effectors as they determine the substrate specificity.The E3 can be divided into two types,the RING-type ligases and HECT-type ligases.Smurf1 is a HECT type E3 ligase subordinating to the NEDD4 superfamily.Recent studies acclaimed Smurf1 as a pivotal factor in inhibiting inflammatory response.Sepsis is an acute lethality of the inflammatory disease is less known.It is an infection caused by systemic multiple organ dysfunction,not only extremely dangerous,the treatment is also very difficult.Objective: Using genetic modified mice,we demonstrated series of experiments including LPS inducing sepsis model,in order to find out effect of neddylation and ubiquitination of Smurf1 in inflammatory response,and to testify the function of Smurf1 on the body's inflammatory response.Methods: First,we constructed Smurf1 C426 A mice and Smurf1 knockout mice.Then injected LPS or Gram-negative bacilli to create a sepsis model.We observed the response of immune system by detecting the amount of TNF-?,IL-6,IL-12p40 in serum,and counted the survival rates of mice.We also valued the intestinal injury that induced by DSS.At the same time,we isolated the mouse BMDM(bone marrow-derived macrophages),and stimulated with LPS.Elisa was done on that to detect cell supernatant in the inflammatory factors TNF?,IL-6,IL-12p40,and WB was conducted to detect i NOS and I?B?.Results:We found that Smurf1 knockout mice produced susceptibility to inflammation as well as Smurf1 C426 A mice.Smurf1 knockout mice and Smurf1 C426 A mice secreted more inflammatory factors in serum upon LPS stimulation.Sepsis causes serious organ damage.Above all,Smurf1 plays an important role in the development of sepsis,which is very important for the regulation of immune response.