β-Catenin is essential for Mullerian duct regression during male sexual differentiation

During male sexual differentiation, the transforming growth factor-beta (TGF-beta) signaling molecule anti-Mullerian hormone (AMH; also known as Mullerian inhibiting substance, MIS) is secreted by the fetal testes and induces regression of the Mullerian ducts, the primordia of the female reproductive tract organs. Currently, the molecular identity of downstream events regulated by the AMH signaling pathway remains unclear. We found that male-specific Wnt4 expression in mouse Mullerian duct mesenchyme depends upon AMH signaling, implicating the WNT pathway as a downstream mediator of Mullerian duct regression. Inactivation of beta-catenin, a mediator of the canonical WNT pathway, did not affect AMH signaling activation in the Mullerian duct mesenchyme, but did block Mullerian duct regression. These data suggest that beta-catenin mediates AMH signaling for Mullerian duct regression during male sexual differentiation.