Pathogenic Mutation Screening Of A Hereditary Angioedema Family And The Gene Function Study

Hereditary angioedema(HAE)is a rare but life-threatening dominant hereditary disease.Its main manifestation is vascular edema,which is caused by body fluid infiltrating into the dermis and subcutaneous space.The decrease of C1 esterase inhibitor(C1INH)will lead to the loss of kallikrein activity,resulting in the cleavage of high molecular weight kininogen and the release of bradykinin,leading to the occurrence of vascular edema.SERPING1 gene is the pathogenic gene of HAE,and C1 INH is encoded by SERPING1 gene.The mutation of SERPING1 gene will lead to the change of C1 INH function,and then lead to the occurrence of HAE.In this research,we received a case of hereditary angioedema from a family of 13 people.A new unreported mutation c.708T>G p.Phe236 Leu of SERPING1 gene was found by exploring the rare autosomal dominant disease hereditary angioedema.Another two SERPING1 gene mutations c.550G>A p.Gly184 Arg and c.566C>A p.Thr189 Asn were selected from the case reports of hereditary angioedema.The function of the three mutation was studied together,including analysis bioinformatics,construct the mutant plasmids and explore the effect of SERPING1 gene mutation on protein function.From the aspect of single transfection mutant plasmids,the amount of protein in single transfection mutant plasmids were less than that in wild-type(WT)plasmids,but if cotransfection,the protein quality of mutant plasmids c.G550A+WT、c.C566A+WT、c.T708G+WT were higher than the wild-type plasmid.The content of C1 INH in the mutant plasmid was significantly less than that in the wild-type plasmid.After single transfected of mutant plasmids c.G550A、c.C566A、c.T708 G,the expression of C1 INH in cells decreased;on the contrary,after co-transfection of mutant plasmids,the amount of protein in cells increased.There may be a certain aggregation phenomenon of protein in cells after co-transfection of mutant plasmids.Therefore,we localized the protein in subcellular to explore this phenomenon.In addition,compared with wild-type plasmid with SERPING1 gene mutant plasmids c.G550A、c.C566 A and c.T708 G,the expression of p38,JNK and NFκB decreased,on the contrary,IκBα increased.All in all,we found a new unreported mutation c.708T>G p.Phe236 Leu,expanded the mutation spectrum of SERPING1 gene.Through functional research,it was found that the mutation of SERPING1 gene could reduce the expression of protein C1 INH,and reduce the accumulation of C1 INH in the cell and decrease of extracellular secretion;we also found that the mutation of SERPING1 gene could affect the activity of NFκB signaling pathway,indicating that NFκB signaling pathway may be related to the pathogenesis of hereditary angioedema.