WT1 Maintains Adrenal-Gonadal Primordium Identity and Marks a Population of AGP-like Progenitors within the Adrenal Gland

Adrenal glands and gonads share a common primordium (AGP), but the molecular events driving differentiation are poorly understood. Here we demonstrate that the Wilms tumor suppressor WT1 is a key factor defining AGP identity by inhibiting the steroidogenic differentiation process. Indeed, ectopic expression of WT1 precludes differentiation into adrenocortical steroidogenic cells by locking them into a progenitor state. Chromatin immunoprecipitation experiments identify Tcf21 and Gli1 as direct targets of WT1. Moreover, cell lineage tracing analyses identify a long-living progenitor population within the adrenal gland, characterized by the expression of WT1, GATA4, GLI1, and TCF21, that can generate steroidogenic cells in vivo. Strikingly, gonadectomy dramatically activates these WT1+ cells and leads to their differentiation into gonadal steroidogenic tissue. Thus, our data describe a mechanism of response to organ loss by recreating hormone-producing cells at a heterotopic site. [Display omitted] •The adrenal capsule forms through condensation of WT1+ mesenchymal cells•WT1 marks bipotential steroidogenic progenitor cells in the adrenal capsule•Differentiation into steroidogenic cells recapitulates the developmental process•High levels of WT1 are incompatible with steroidogenic cell differentiation Bandiera et al. show that WT1 expression marks a common adrenal/gonad primordium and inhibits steroidogenic differentiation. Lineage tracing experiments show that WT1+ adrenogonadal progenitors persist in the adult adrenal capsule and can be activated (by gonadectomy, for example) to give rise to either adrenal or gonadal-like steroidogenic cells.