Targeted Disruption of YAP and TAZ Impairs the Maintenance of the Adrenal Cortex.

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are functionally redundant transcriptional regulators that are downstream effectors of the Hippo signaling pathway. They act as major regulators of stem cell maintenance, cell growth, and differentiation. To characterize their roles in the adrenal cortex, we generated a mouse model in which Yap and Taz were conditionally deleted in steroidogenic cells (Yap(flox/flox); Taz(flox/flox); Nr5a1(cre/+)). Male Yap(flox/flox); Taz(flox/flox); Nr5a1(cre/+) mice were characterized by an age-dependent degeneration of the adrenal cortex associated with an increase in apoptosis and a progressive reduction in the expression levels of steroidogenic genes. Evaluation of the expression levels of stem and progenitor cell population markers in the adrenal glands of Yap(flox/flox); Taz(flox/flox); Nr5a1(cre/+) mice also showed the downregulation of sonic hedgehog (Shh), a marker of the subcapsular progenitor cell population. Gross degenerative changeswere not observed in the adrenal glands of Yap(flox/flox); Taz(flox/flox); Nr5a1(cre/+) females, although steroidogenic capacity and Shh expression were reduced, suggesting that mechanisms of adrenocortical maintenance are sex specific. These results define a crucial role for YAP and TAZ in the maintenance of the postnatal adrenal cortex.