Discovery Of The Susceptibility Gene TAX1BP1 In Systemic Lupus In Erythematosus And Its Tunctions

ObjectiveSystemic lupus erythematosus(SLE)is a typical autoimmune disease that can affect multiple organs and systems in the whole body,and has a genetic predisposition.More than 80 susceptible genes related to SLE have been identified using genetic gene linkage analysis and genome-wide association studies.The study of the mechanism of these genes provides a basis for the pathogenesis and treatment of SLE.We performed whole exome sequencing on 3 patients and 2 normal persons in the family of SLE by adopting new-generation sequencing technology-whole exome sequencing,and the sequencing data was filtered and analyzed in a multi-step process to screen out the possible susceptibility genes which are related to systematic lupus erythematosus,and the candidate susceptibility genes would be verified.MethodsThree patients with SLE and two normal persons in a family were subjected to Whole exome sequencing to identify the candidate susceptibility genes.The known mutations in the sequencing results were screened using databases such as OMIM,dbSNP147,dbSNP and 1000Genome Project.We use SIFT,PolyPhen-2,Mutation Taster to predict the function of the suspected mutation site,select the candidate mutations with higher pathogenicity.Finally using the Sanger sequencing to exclude the false positive results and check it on the HGMD database,Pubmed database and Google scholar.The candidate gene TAX1BP1 was tested by experiments to verify its effect on B cell function.The spleen CD19~+B cells from female mouses and Raji cell lines were transfected with siRNA and lentivirus to down-regulate the expression of this gene.CCK8,Flow Cytometry and ELISA were used to evaluate the expression of B cell proliferation and B cell surface costimulatory molecules,Cell cycle,and immunoglobulin secretion.Results1.After analysis of whole-genome exome sequencing results and verification of sanger sequencing,we found 16 susceptibility genes related to lupus,TRIOBP,GCKR,ANXA6,THEMIS,TAX1BP1,MYO1G,FOCAD,TRPM6,VPS37C,ZDHHC24,GPR137C,UNC79,AK7,GRAMD2,GSS,POU6F2.2.The expression of TAX1BP1 in CD19~+B cells and Raji cells was down-regulated by siRNA and lv-shRNA.Compared with the control group,knocking down TAX1BP1 promoted the proliferation of B cells(P=0.008)and the proliferation of Raji cells(P<0.001),up-regulated the expression of CD69 and CD80 molecules on the surface of B cells,The expression of CD69 in B cells in the experimental group was statistically significant compared with that in the control group(P<0.01).and promoted the generation of immunoglobulins lgG and lgM(P<0.05).Conclusion1.We acquired 16 possible susceptibility genes which are related with SLE,which are TRIOBP,GCKR,ANXA6,THEMIS,TAX1BP1,MYO1G,FOCAD,TRPM6,VPS37C,ZDHHC24,GPR137C,UNC79,AK7,GRAMD2,GSS,POU6F.2.2.TAX1BP1 can regulate B cell function by inhibiting B cell proliferation,activation,antibody production and other aspects.