Construction And Functional Study Of Human SBLyS Mutants

B-lymphocyte stimulator (BLyS) is a 285 amino acid member of the tumor necrosis factor (TNF) ligand superfamily, also known as THANK, BAFF, TALL-1 or zTNF4. BLyS is type II transmembrane protein and has been found both on cell surfaces and in serum or other body fluid. BLyS binds to three different receptors, BAFF-R, TACI, and BCMA. All of these receptors are expressed on B cells. BLyS can regulate proliferation and differentiation of lymphocytes and can regulate antibody secretion. Studies have revealed that lacking of BLyS can lead to immunodeficiency while overexpression in vivo can promotes autoimmune diseases,such as systemic lupus erythematosus (SLE),rheumatoid arthritis (RA) and sjogren's syndrome (SS). Concentration of BlyS is high in the serum of the patients with the autoimmune diseases. Therefore, we can increase the activity of BLyS to stimulate lymphocyte proliferation and immunoglobulin production for the B lymphocyte-derived immunodeficiency. On the other hand we can inhibit BLyS activity for the autoimmune diseases.In this study, the cDNAs encoding the mutants of human soluble B-lymphocyte stimulator(s?BLyS,sBLyS-G,sBLyS-S)were cloned and expressed by prokaryotic expression system. After purified, the function of the recombinant s?BLyS,sBLyS-G,sBLyS-S were analyzed. Otherwise, the cDNAs encoding human soluble B-lymphocyte stimulator and its mutants(s?BLyS,sBLyS-G,sBLyS-S) added 6×His tag were cloned and construction by eukaryotic expression system.The major results were summarized as follows:1. The mutants of BLyS were successfully constructed by one-step opposite direction PCR . In one mutant(s?BLyS), the 142~160th amino-acid residue encoding sequences was deleted; and in the others(sBLyS-G,sBLyS-S), the 146th Cys-encoding sequences was taken place by Gly-encoding sequences and Ser-encoding sequences respectively.After sequenced and contrasted in GenBank, the mutants were considered fit for the experiment design.