Function and Localization Analysis of Zebrafish Rspo1

R-spondin family factors, known as regulators of β-catenin signaling pathway, are conserved in vertebrate. They play roles in multiple processes during vertebrate development. Rspo1, a member of R-spondin family, regulates sex differentiation in both mammals (e.g. mouse) and reptiles (e.g. turtle). However, the role of Rspo1 in fish remains elusive. Our previous work showed the expression of Rspo1 in zebrafish (zRspo1). In this study, we further investigated potential function of zRspo1. We compared Rspo1 homologs in zebrafish and in human (hRspo1-4). By bioinformatics analysis, we predicted that zRspo1 functions on activating β-catenin signaling through a manner similar to hRSpo1. By histag indication, we detected zRspo1 on cell membrane and Golgi apparatus in zebrafish liver cells. This result suggests that zRspo1 may first secrete to the milieu and then extracellular zRspo1 activates β-catenin.