title: First BAFF gene cloned from an aquatic mammal.
abstract: The finless porpoise (Neophocaena phocaenoides) is one of the smallest cetacean species. Research into the immune system of the finless porpoise is essential to the protection of this species, but, to date, no genes coding for proteins from the tumor necrosis factor family (TNF family) have yet been reported from finless porpoises. The TNF B cell activating factor (BAFF) is critical to B cell survival, proliferation, maturation, and immunoglobulin secretion and to T cell activation. It acts through its three receptors, BAFF-R, BCMA, and TACI. In the present study, the full-length cDNA of BAFF (designated NpBAFF) from the finless porpoise was cloned using RT-PCR and rapid amplification of cDNA ends (RACE) techniques, and its biological activities have been characterized. To our knowledge, this is the first report of any BAFF gene being cloned from an aquatic mammal. The full-length cDNA of NpBAFF consists of 1502 bases including an 852 bp open reading frame encoding 283 amino acids. This protein was found to contain a predicted transmembrane domain, a putative furin protease cleavage site, and a typical TNF homology domain corresponding to other, known BAFF homologues. Sequence comparison indicated that the amino acid sequence of NpBAFF was very similar to its bovine (87.68%), porcine (76.33%), hircine (87.68%) and canine (82.19%) counterparts. The predicted three-dimensional (3D) structure of the NpsBAFF monomer, analyzed by comparative protein modeling, revealed that it was very similar to its human counterpart. Phylogenetic analysis indicated that NpBAFF showed a notable homology with Artiodactyla BAFFs. The SUMO-NpsBAFF was efficiently expressed in Escherichia coli BL21 (DE3) and confirmed by SDS-PAGE and Western blot analysis. Laser scanning confocal microscopy analysis showed that NpsBAFF could bind to its receptors on B cells. In vitro, MTT assays indicated that SUMO-NpsBAFF could promote the survival or proliferation of mouse splenic B cells grown with anti-mouse IgM. These findings indicate that NpBAFF plays an important role in the survival or proliferation of B cells and has functional cross-reactivity among cetaceans and other mammals. The present findings may provide valuable information for research into the immune system of the finless porpoise.
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210046, China.
authors.forename: Fengtao
authors.initials: F
authors.lastname: You
authors.forename: Wenhua
authors.initials: W
authors.lastname: Ren
authors.forename: Shasha
authors.initials: S
authors.lastname: Gu
authors.forename: Wenqian
authors.initials: W
authors.lastname: Wang
authors.forename: Lidan
authors.initials: L
authors.lastname: Zhou
authors.forename: Yijun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Weifeng
authors.initials: W
authors.lastname: Gan
authors.forename: Mingxing
authors.initials: M
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D053264:B-Cell Activating Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D002417:Cattle; D049109:Cell Proliferation; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004285:Dogs; D005455:Fluorescent Antibody Technique; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D008813:Mice, Inbred ICR; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D019576:Porpoises / Q000235:genetics*; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism
chemical_list: D053264:B-Cell Activating Factor; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; D025842:SUMO-1 Protein