Biology subjects

Guagliardo, N. A.

Publications and source records attributed to Guagliardo, N. A..

4 recordsLinked to original sources

bioRxiv2025

Rho-ROCK signaling and α-Catenin mediate β-Catenin-driven hyperplasia in the adrenal via adherens junctions

How {beta}-Catenin ({beta}Cat) 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 {beta}Cat 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 {beta}Cat gain-of-function ({beta}Cat-GOF). Adherens junctions (AJs) connect the actin cytoskeletons of adjacent zona Glomerulosa (zG) cells via a cadherin/{beta}Cat/-Catenin (Cat) complex and mediate aldosterone production. Whether {beta}Cat-GOF drives zG hyperplasia, a key feature of PA, via AJs is unknown. Here, we show that aldosterone secretagogues (K+, AngII) and {beta}Cat-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 {beta}Cat-GOF demonstrate increased AJ formation and zG hyperplasia, which was blunted by Rho-ROCK inhibition and deletion of Cat. Further, analysis of human aldosterone-producing adenomas (APAs) revealed high levels of {beta}Cat expression were associated with increased membranous expression of K-Cadherin. Together, our findings identify Rho-ROCK signaling and Cat as key mediators of AJ enrichment and {beta}-Catenin-driven hyperplasia. One Sentence SummaryThis study demonstrates that {beta}-Catenin-driven hyperplasia in the adrenal cortex, a key feature of primary aldosteronism, is mediated through Rho-ROCK signaling and -Catenin-dependent stabilization of adherens junctions, with significant implications for patients with primary aldosteronism. HighlightsO_LIRho-ROCK signaling drives AJ enrichment in the adrenal C_LIO_LIROCK inhibition via fasudil blunts aldosterone production C_LIO_LI{beta}Cat drives adrenal hyperplasia via enhanced AJ enrichment C_LIO_LIROCK inhibition or [a]Cat deletion block zG hyperplasia C_LI

cell biology↗

bioRxiv2024

Angiotensin II elicits robust calcium oscillations coordinated within juxtaglomerular cell clusters to suppress renin secretion.

BACKGROUNDJuxtaglomerular (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 Ca2+, preventing excessive circulating renin and hypertension. However, within their native structural organization, the intricacies of intracellular Ca2+ signaling dynamics and their sources remain uncharacterized. METHODSWe generated mice expressing the JG cell-specific genetically encoded Ca2+ indicator (GCaMP6f) to investigate Ca2+ dynamics within JG cell clusters ex vivo and in vivo. For ex vivo Ca2+ imaging, acutely prepared kidney slices were perfused continuously with a buffer containing variable Ca2+ and AngII concentrations {+/-} Ca2+ channel inhibitors. For in vivo Ca2+ image capture, native mouse kidneys were imaged in situ using multi-photon microscopy with and without AngII administration. ELISA measurements of renin concentrations determined acute renin secretion ex vivo and in vivo, respectively. RESULTSEx vivo Ca2+ 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 Ca2+ spikes, which inversely correlated with renin secretion. Pharmacological channel inhibition identified key sources of these oscillations: endoplasmic reticulum Ca2+ storage and release, extracellular Ca2+ uptake via ORAI channels, and intercellular communication through gap junctions. Blocking ORAI channels and gap junctions reduced AngII inhibitory effect on renin secretion. In vivo Ca2+ imaging demonstrated robust intracellular and intercellular Ca2+ oscillations within JG cell clusters under physiological conditions, exhibiting spike patterns consistent with those measured in ex vivo preparations. Administration of AngII enhanced the Ca2+ oscillatory signals and suppressed acute renin secretion in vivo. CONCLUSIONAngII elicits coordinated intracellular and intercellular Ca2+ oscillations within JG cell clusters, ex vivo and in vivo. The effect is driven by endoplasmic reticulum-derived Ca2+ release, ORAI channels, and gap junctions, leading to suppressed renin secretion.

cell biology↗

bioRxiv2024

Non-canonical Wnt signaling triggered by WNT2B drives adrenal aldosterone production

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 WNT2B 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 Wnt2b in the mouse results in a dysmorphic and hypocellular zG, with impaired aldosterone production. Similarly, humans harboring WNT2B 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. HighlightsO_LIWNT2B variant is associated with increased risk for primary aldosteronism C_LIO_LIWnt2b knock-out mice show defects in adrenal morphology C_LIO_LIWnt2b knock-out mice have hyperreninemic hypoaldosteronism C_LIO_LIWNT2B activates non-canonical Wnt/planar cell polarity signaling C_LIO_LIWNT2B deficiency causes a new form of familial hyperreninemic hypoaldosteronism C_LI

genetics↗

bioRxiv2018

A genetically-encoded fluorescent acetylcholine indicator

Acetylcholine (ACh) regulates a diverse array of physiological processes throughout the body, yet cholinergic transmission in the majority of tissues/organs remains poorly understood due primarily to the limitations of available ACh-monitoring techniques. We developed a family of G-protein-coupled receptor activation-based ACh sensors (GACh) with 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 several animal species. In all preparations, GACh sensors selectively responded to exogenous and/or endogenous ACh with robust fluorescence signals that were captured by epifluorescent, 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 toolbox for monitoring cholinergic transmission underlying diverse biological processes.

neuroscience↗