Expression of Foxi3 Is Regulated by Ectodysplasin in Skin Appendage Placodes

The study found that Foxi3, a transcriptional regulator, was expressed in developing ectodermal appendages such as teeth and hair follicles in mouse embryos, but not in the epidermis. Its expression was regulated by the ectodysplasin (Eda) pathway, with Eda and activin A identified as upstream regulators. Foxi3 expression was decreased in Eda loss-of-function embryos and increased in gain-of-function embryos, and was highly induced by Eda protein in embryonic skin explants. The findings suggested that the hypohidrotic ectodermal dysplasia (HED) phenotype might be partly due to compromised Foxi3 activity, and that Foxi3 could also play roles in the development of nails, eyes, and various glands.