The Design and Characterization of Receptor-selective APRIL Variants

• Published in: The Journal of biological chemistry 2012-10, Vol.287 (44), p.37434-37446
• Main Authors: Kimberley, Fiona C., van der Sloot, Almer M., Guadagnoli, Marco, Cameron, Katherine, Schneider, Pascal, Marquart, J.Arnoud, Versloot, Miranda, Serrano, Luis, Medema, Jan Paul
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Amino Acid Substitution; Animals; APRIL; B-Cell Maturation Antigen; B-Lymphocytes - metabolism; B-Lymphocytes - physiology; BCMA; Cell Survival; Computational Biology; Crystallography, X-Ray; HEK293 Cells; Humans; Hydrogen Bonding; Immunoglobulin A - biosynthesis; Innate Immunity; Mice; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutant Proteins - chemistry; Protein Binding; Protein Structure; Protein Structure, Tertiary; Protein Transport; Protein-Protein Interactions; Receptor Regulation; Signaling; TACI; TRAF; Transmembrane Activator and CAML Interactor Protein; Tumor Necrosis Factor Ligand Superfamily Member 13 - chemistry; Tumor Necrosis Factor Ligand Superfamily Member 13 - genetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.406090

A proliferation-inducing ligand (APRIL), a member of the TNF ligand superfamily with an important role in humoral immunity, is also implicated in several cancers as a prosurvival factor. APRIL binds two different TNF receptors, B cell maturation antigen (BCMA) and transmembrane activator and cylclophilin ligand interactor (TACI), and also interacts independently with heparan sulfate proteoglycans. Because APRIL shares binding of the TNF receptors with B cell activation factor, separating the precise signaling pathways activated by either ligand in a given context has proven quite difficult. In this study, we have used the protein design algorithm FoldX to successfully generate a BCMA-specific variant of APRIL, APRIL-R206E, and two TACI-selective variants, D132F and D132Y. These APRIL variants show selective activity toward their receptors in several in vitro assays. Moreover, we have used these ligands to show that BCMA and TACI have a distinct role in APRIL-induced B cell stimulation. We conclude that these ligands are useful tools for studying APRIL biology in the context of individual receptor activation. Background: APRIL binds two receptors, BCMA and TACI, so separating signaling outcomes is difficult. Results: We used an algorithm to design a variant of APRIL that specifically binds BCMA and two variants that selectively bind TACI. Conclusion: TACI and BCMA signals differ in the context of B cell stimulation. Significance: These variants will help decipher APRIL signaling in physiology and disease settings.