Wnt signaling in human development: Beta-catenin nuclear translocation in fetal lung, kidney, placenta, capillaries, adrenal, and cartilage

The Wnt signaling pathway is involved in both normal development and tumori genesis. Activation of the pathway results in stabilization and nuclear tra nslocation of beta-catenin protein. Nuclear localization of beta-catenin ha s been used to identify tumors in which mutations in APC or beta-catenin ac tivate Wnt signaling. We analyzed the subcellular localization of beta-cate nin immunohistochemically in human fetal and postnatal tissues to identify activation of Wnt signaling during development. Nuclear beta-catenin is pre sent in capillary endo thelium, mesenchyme surrounding renal tubules, adren al cortex, cartilage anlage, placental cytotrophoblast, and pulmonary acina r buds. These investigations suggest a defined role for Wnt signaling in hu man fetal development and provide a catalogue of non-neoplastic tissues wit h nuclear beta-catenin staining.