Rho/ROCK signaling and α-catenin mediate β-catenin-driven hyperplasia in the adrenal cortex via adherens junctions.

How β-catenin (βCat) mediates tissue hyperplasia is poorly understood. To explore this, we employed the adrenal cortex as a model system given its stereotypical spatial organization and the important role βCat plays in homeostasis and disease. For example, excessive production of aldosterone by the adrenal cortex (primary aldosteronism [PA]) is a major cause of cardiovascular morbidity and is associated with βCat gain of function (βCat-GOF). Adherens junctions (AJs) connect the actin cytoskeletons of adjacent zona glomerulosa (zG) cells via a cadherin-βCat-α-catenin complex and mediate aldosterone production. Whether βCat-GOF drives zG hyperplasia, a key feature of PA, via AJs is unknown. Here, we showed that aldosterone secretagogues (K+ and AngII) and βCat-GOF mediated AJ formation via Rho/ROCK/actomyosin signaling. In addition, Rho/ROCK inhibition led to altered zG rosette morphology and decreased aldosterone production. Mice with zG-specific βCat-GOF demonstrated increased AJ formation and zG hyperplasia, which was blunted by Rho/ROCK inhibition and deletion of α-catenin (αCat). βCat also impacted AJ formation independently of its role as a transcription factor. Furthermore, analysis of human aldosterone-producing adenomas revealed high levels of βCat expression were associated with increased membranous expression of K-cadherin. Together, our findings identified Rho/ROCK signaling and αCat as key mediators of AJ formation and βCat-driven hyperplasia.