Molecular cloning and functional characterization of the porcine extracellular domain of Receptor Activator of NF-κB Ligand (sRANKL)

Receptor Activator of NF-κB Ligand (RANKL) plays a pivotal role as a regulator of osteoclast activity and is involved in osteoporosis. Here, we report the cloning and functional characterization of the complete extracellular domain of the porcine RANKL gene (sRANKL). The porcine sRANKL cDNA has an ORF of 744 nucleotides and shares 87%, 80% and 80% identity with human, rat and mouse RANKL coding sequences, respectively. The protein consists of 247 amino acids with 90%, 81% and 80% sequences similarities compared to human, mouse and rat RANKL, respectively. Over-expression of porcine sRANKL led to osteoclast formation. The osteoclasts showed a characteristic morphology, expressed the carbonic anhydrase type 2, were TRACP positive and exhibited a bone-resorbing activity.In conclusion, we first describe the molecular cloning and functional characterization of porcine sRANKL, which will help to understand the function of a RANKL gene in large animal models.