Characterization and expression pattern of a novel Frizzled 8 receptor gene in Schistosoma japonicum

Wnt signaling as mediated by the Frizzled family receptors plays a vital role in the early development of animal embryos, organ formation, tissue regeneration and other physiological processes. In the present study, a novel Frizzled member, SjFz8, was isolated and characterized in Schistosoma japonicum. SjFz8 encodes an 1162-amino-acid protein with typical characteristics of Frizzled proteins. Quantitative real-time polymerase chain reaction analysis indicated that SjFz8 transcript level was highest in 7-day-old schistosomula. In adult stages, SjFz8 mRNA expression remained at a low level after male–female pairing. The immunohistochemical localization of the Fz8 protein revealed that it existed in almost all tissues of S. japonicum, including subtegumental muscle, parenchyma, oral suckers, ventral suckers, testes of the male and ovaries of the female. We speculated that the Wnt signaling pathway that was mediated by Fz8 might take part in regulating histogenesis and organogenesis during the schistosomulum period, and play an important role in regulating further growth and development of male and female worms.