Molecular cloning and partial functional characterization of a proliferation inducing ligand (APRIL) in zebrafish (Danio rerio)

Abstract

Here we describe the identification of a Danio rerio homologue of a proliferation-inducing ligand (APRIL) of the TNF family (designated zAPRIL). Sequence analysis showed that the open reading frame of zAPRIL consists of 600 bases encoding a protein of 199-amino acids. Recombinant soluble APRIL (zsAPRIL) was constructed consisting of fluorescence-enhanced green fluorescent protein (EGFP) and cloned into a pET28a vector. SDS-PAGE and western blotting analysis indicated a high-level expression of soluble EGFP/zsAPRIL protein in Escherichia coli BL21 (DE3). Observation by confocal microscopy demonstrated that EGFP/zsAPRIL could successfully bind to the surface receptors of zebrafish lymphocytes. In vitro survival analysis revealed that purified EGFP/zsAPRIL was able to promote the survival of zebrafish lymphocytes in a dose-dependent manner. The biological role of APRIL does not seem to be restricted to proliferation induction. Zebrafish may could served as a model organism for further study of APRIL.