Adhesion G-protein coupled receptor, GPR56, is required for Müllerian duct development in the chick

The embryonic Mullerian ducts give rise to the female reproductive tract (Fallopian tubes, uterus and upper vagina in humans, the oviducts in birds). Embryonic Mullerian ducts initially develop in both sexes, but later regress in males under the influence of Anti-Mullerian Hormone. While the molecular and endocrine control of duct regression in males have been well studied, early development of the ducts in both sexes is less well understood. Here, we describe a novel role for the adhesion G protein coupled receptor, GPR56, in development of the Mullerian ducts in the chicken embryo. GPR56 is expressed in the ducts of both sexes from early stages. The mRNA is present during the elongation phase of duct formation and it is restricted to the inner Mullerian duct epithelium. The putative ligand, Collagen III, is abundantly expressed in the Mullerian duct at the same developmental stages. Knockdown of GPR56 expression using in ovo electroporation results in variably truncated ducts, with a loss of expression of both epithelial and mesenchymal markers of duct development. Over-expression of GPR56 in vitro results in enhanced cell proliferation and cell migration. These results show that GPR56 plays an essential role in avian Mullerian duct development through the regulation of duct elongation.