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Aldosterone, which plays a central role in the regulation of blood pressure, is produced by zona glomerulosa (ZG) cells of the adrenal gland. When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and renal disease. Although sustained production of aldosterone requires persistent Ca2+ entry through low-voltage activated Ca2+ channels, isolated ZG cells are considered nonexcitable, with recorded membrane voltages that are too hyperpolarized to permit Ca2+ entry. Here, we show that mouse ZG cells within adrenal slices spontaneously generate membrane potential oscillations of low periodicity. This innate electrical excitability of ZG cells provides a platform for the production of a recurrent Ca2+ signal that can be controlled by Ang II and extracellular potassium, the 2 major regulators of aldosterone production. We conclude that native ZG cells are electrical oscillators, and that this behavior provides what we believe to be a new molecular explanation for the control of Ca2+ entry in these steroidogenic cells.

Aldosterone-producing zona glomerulosa (zG) cells of the adrenal gland arrange in distinct multi-cellular rosettes that provide a structural framework for adrenal cortex morphogenesis and plasticity. Whether this cyto-architecture also plays functional roles in signaling remains unexplored. To determine if structure informs function, we generated mice with zG-specific expression of GCaMP3 and imaged zG cells within their native rosette structure. Here we demonstrate that within the rosette, angiotensin II evokes periodic Ca v 3-dependent calcium events that form bursts that are stereotypic in form. Our data reveal a critical role for angiotensin II in regulating burst occurrence, and a multifunctional role for the rosette structure in activity-prolongation and coordination. Combined our data define the calcium burst as the fundamental unit of zG layer activity evoked by angiotensin II and highlight a novel role for the rosette as a facilitator of cell communication. Aldosterone-producing zona glomerulosa cells in the adrenal gland arrange into rosette structures known to be important for morphogenesis. Here the authors show that the cells in the rosettes produce coordinated calcium activity bursts in response to angiotensin II that correlate with aldosterone production level.

When inappropriate for salt status, the mineralocorticoid aldosterone induces cardiac and renal injury. Autonomous overproduction of aldosterone from the adrenal zona glomerulosa (ZG) is also the most frequent cause of secondary hypertension. Yet, the etiology of nontumorigenic primary hyperaldosteronism caused by bilateral idiopathic hyperaldosteronism remains unknown. Here, we show that genetic deletion of TWIK-related acid-sensitive K (TASK)-1 and TASK-3 channels removes an important background K current that results in a marked depolarization of ZG cell membrane potential. Although TASK channel deletion mice (TASK⁻/⁻) adjust urinary Na excretion and aldosterone production to match Na intake, they produce more aldosterone than control mice across the range of Na intake. Overproduction of aldosterone is not the result of enhanced activity of the renin-angiotensin system because circulating renin concentrations remain either unchanged or lower than those of control mice at each level of Na intake. In addition, TASK⁻/⁻ mice fail to suppress aldosterone production in response to dietary Na loading. Autonomous aldosterone production is also demonstrated by the failure of an angiotensin type 1 receptor blocker, candesartan, to normalize aldosterone production to control levels in TASK⁻/⁻ mice. Thus, TASK⁻/⁻ channel knockout mice exhibit the hallmarks of primary hyperaldosteronism. Our studies establish an animal model of nontumorigenic primary hyperaldosteronism and identify TASK channels as a possible therapeutic target for primary hyperaldosteronism.

The neurotransmitter acetylcholine (ACh) regulates a diverse array of physiological processes throughout the body. Despite its importance, cholinergic transmission in the majority of tissues and organs remains poorly understood owing primarily to the limitations of available ACh-monitoring techniques. We developed a family of ACh sensors (GACh) based on G-protein-coupled receptors that has the sensitivity, specificity, signal-to-noise ratio, kinetics and photostability suitable for monitoring ACh signals in vitro and in vivo . GACh sensors were validated with transfection, viral and/or transgenic expression in a dozen types of neuronal and non-neuronal cells prepared from multiple animal species. In all preparations, GACh sensors selectively responded to exogenous and/or endogenous ACh with robust fluorescence signals that were captured by epifluorescence, confocal, and/or two-photon microscopy. Moreover, analysis of endogenous ACh release revealed firing-pattern-dependent release and restricted volume transmission, resolving two long-standing questions about central cholinergic transmission. Thus, GACh sensors provide a user-friendly, broadly applicable tool for monitoring cholinergic transmission underlying diverse biological processes.

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.

Fibroblast growth factor receptors (FGFRs) are tyrosine kinase receptors critical for organogenesis and tissue maintenance, including in the adrenal gland. Here we delineate the role of FGFR2 in the morphogenesis, maintenance, and function of the adrenal cortex with a focus on the zona glomerulosa (zG). zG-specific Fgfr2 deletion (Fgfr2-cKO) resulted in impaired zG cell identity, proliferation, and transdifferentiation into zona fasciculata (zF) cells during postnatal development. In adult mice, induced deletion of Fgfr2 led to loss of mature zG cell identity, highlighting the importance of FGFR2 for the maintenance of a differentiated zG state. Strikingly, Fgfr2-cKO was sufficient to fully abrogate β-catenin-induced zG hyperplasia and to reduce aldosterone levels. Finally, short-term treatment with pan-FGFR small molecule inhibitors suppressed aldosterone production in both WT and β-catenin gain-of-function mice. These results demonstrate a critical role for FGFR signaling in adrenal morphogenesis, maintenance, and function and suggest that targeting FGFR signaling may benefit patients with aldosterone excess and/or adrenal hyperplasia.

Aldosterone, which plays a central role in the regulation of blood pressure, is produced by zona glomerulosa (ZG) cells of the adrenal gland. When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and renal disease. Although sustained production of aldosterone requires persistent [Ca.sup.2+] entry through low-voltage activated [Ca.sup.2+] channels, isolated ZG cells are considered nonexcitable, with recorded membrane voltages that are too hyperpolarized to permit [Ca.sup.2+] entry. Here, we show that mouse ZG cells within adrenal slices spontaneously generate membrane poten-tial oscillations of low periodicity. This innate electrical excitability of ZG cells provides a platform for the production of a recurrent [Ca.sup.2+] signal that can be controlled by Ang II and extracellular potassium, the 2 major regulators of aldosterone production. We conclude that native ZG cells are electrical oscillators, and that this behavior provides what we believe to be a new molecular explanation for the control of [Ca.sup.2+] entry in these steroidogenic cells.

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) constitutes a significant cause of cardiovascular morbidity, which has been 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 (αCat) complex and mediate aldosterone production. Whether βCat-GOF drives zG hyperplasia, a key feature of PA, via AJs is unknown. Here, we show that aldosterone secretagogues (K , AngII) and βCat-GOF mediate AJ enrichment via Rho-ROCK-actomyosin signaling. In addition, Rho-ROCK inhibition leads to altered zG rosette morphology and decreased aldosterone production. Mice with zG-specific βCat-GOF demonstrate increased AJ formation and zG hyperplasia, which was blunted by Rho-ROCK inhibition and deletion of αCat. Further, analysis of human aldosterone-producing adenomas (APAs) revealed high levels of βCat expression were associated with increased membranous expression of K-Cadherin. Together, our findings identify Rho-ROCK signaling and αCat as key mediators of AJ enrichment and β-Catenin-driven hyperplasia. This study demonstrates that β-Catenin-driven hyperplasia in the adrenal cortex, a key feature of primary aldosteronism, is mediated through Rho-ROCK signaling and α-Catenin-dependent stabilization of adherens junctions, with significant implications for patients with primary aldosteronism. Rho-ROCK signaling drives AJ enrichment in the adrenalROCK inhibition via fasudil blunts aldosterone productionβCat drives adrenal hyperplasia via enhanced AJ enrichmentROCK inhibition or ɑCat deletion block zG hyperplasia.

Juxtaglomerular (JG) cells are sensors that control blood pressure (BP) and fluid-electrolyte homeostasis. They are arranged as clusters at the tip of each afferent arteriole. In response to a decrease in BP or extracellular fluid volume, JG cells secrete renin, initiating an enzymatic cascade that culminates in the production of angiotensin II (AngII), a potent vasoconstrictor that restores BP and fluid-electrolyte homeostasis. In turn, AngII exerts negative feedback on renin release concomitantly with increased intracellular Ca , preventing excessive circulating renin and hypertension. However, within their native structural organization, the intricacies of intracellular Ca signaling dynamics and their sources remain uncharacterized. We generated mice expressing the JG cell-specific genetically encoded Ca indicator (GCaMP6f) to investigate Ca dynamics within JG cell clusters and . For Ca imaging, acutely prepared kidney slices were perfused continuously with a buffer containing variable Ca and AngII concentrations ± Ca channel inhibitors. For Ca image capture, native mouse kidneys were imaged using multi-photon microscopy with and without AngII administration. ELISA measurements of renin concentrations determined acute renin secretion and , respectively. Ca imaging revealed that JG cells exhibit robust and coordinated intracellular oscillatory signals with cell-cell propagation following AngII stimulation. AngII dose-dependently induced stereotypical burst patterns characterized by consecutive Ca spikes, which inversely correlated with renin secretion. Pharmacological channel inhibition identified key sources of these oscillations: endoplasmic reticulum Ca storage and release, extracellular Ca uptake via ORAI channels, and intercellular communication through gap junctions. Blocking ORAI channels and gap junctions reduced AngII inhibitory effect on renin secretion. Ca imaging demonstrated robust intracellular and intercellular Ca oscillations within JG cell clusters under physiological conditions, exhibiting spike patterns consistent with those measured in preparations. Administration of AngII enhanced the Ca oscillatory signals and suppressed acute renin secretion . AngII elicits coordinated intracellular and intercellular Ca oscillations within JG cell clusters, and . The effect is driven by endoplasmic reticulum-derived Ca release, ORAI channels, and gap junctions, leading to suppressed renin secretion.

The steroid hormone aldosterone, produced by the zona glomerulosa (zG) of the adrenal gland, is a master regulator of plasma electrolytes and blood pressure. While aldosterone control by the renin-angiotensin system is well understood, other key regulatory factors have remained elusive. Here, we replicated a prior association between a non-coding variant in and an increased risk of primary aldosteronism, a prevalent and debilitating disease caused by excessive aldosterone production. We further show that in both mice and humans, WNT2B is expressed in the mesenchymal capsule surrounding the adrenal cortex, in close proximity to the zG. Global loss of in the mouse results in a dysmorphic and hypocellular zG, with impaired aldosterone production. Similarly, humans harboring loss-of-function mutations develop a novel form of Familial Hyperreninemic Hypoaldosteronism, designated here as Type 4. Additionally, we demonstrate that WNT2B signals by activating the non-canonical Wnt/planar cell polarity pathway. Our findings identify WNT2B as a key regulator of zG function and aldosterone production with important clinical implications.