Roles of Pitx2 during early development of tooth germ

Pitx2(bicoid-related transcription factor 2),a member of Nodal/Sonic hedgehog signaling pathway,regulates tissue and organ growth through affecting cell proliferation,differentiation,and migration during the vertebrate embryonic development.Mutation or deficiency of Pitx2 in mouse embryo will lead to a series of aberrant development,such as lung asymmetry,cardiac positioning and pituitary and tooth abnormalities.Moreover,Pitx2 is also involved in hematopoiesis and gonad morphogenesis.According to the existing reports,Pitx2 is composed of four isoforms: Pitx2a,Pitx2b,Pitx2c and Pitx2d,among which,Pitx2d isoform is specifically expressed in human cranial facial area.At the early stage of mice tooth development,Pitx2 is one of the molecular markers in odontogenic epithelium.Its expression level is closely associated with the formation of the tooth germ,which is also the truth when referred to its roles in human tooth development.In present review,we summarize the Pitx2 expression in mouse and human tooth development,and elucidate the interrelationship of Pitx2 with Fgf8,Msx1,Msx2 and Lef1 during the mice tooth development.