Biology subjects

Rainey, W. E.

Publications and source records attributed to Rainey, W. E..

4 recordsLinked to original sources

bioRxiv2024

Somatic Mutations in MCOLN3 in Aldosterone-Producing Adenomas cause Primary Aldosteronism.

Primary aldosteronism is characterized by renin-independent hyperaldosteronism that originates from aldosterone-producing lesions in the adrenal glands. Under physiological conditions, aldosterone synthase (CYP11B2) expression is confined to the adrenal zona glomerulosa where it catalyzes the final reaction yielding aldosterone. The regulation of CYP11B2 transcription depends on the control of cellular membrane potential and cytosolic calcium activity. In primary aldosteronism, aldosterone-producing adenomas (APAs) are characterized by disrupted regulation of CYP11B2 expression resulting in autonomous biosynthesis of aldosterone. These lesions often harbor aldosterone-driver somatic mutations in genes encoding ion transporters/channels/pumps that increase cytosolic calcium activity causing increased CYP11B2 expression and aldosterone biosynthesis. We investigated APAs devoid of known somatic mutations and detected a missense mutation and a deletion-insertion variant in MCOLN3 which encodes for mucolipin-3 (TRPML3) -- a highly conserved inwardly-rectifying, cation-permeable channel. These MCOLN3 mutations were identified in three APAs derived from male patients with primary aldosteronism: p. Y391D and p.N411_V412delinsI. Both mutations are located near the ion pore and selectivity filter of TRPML3. This is the first report of disease-causing MCOLN3 mutations in humans. Functional studies suggest MCOLN3Y391D might directly or indirectly via membrane depolarization alter calcium influx of transfected adrenocortical cells, resulting in increased CYP11B2 transcription and aldosterone production. This study implicates mutated MCOLN3 as a driver of aldosterone excess in primary aldosteronism. Significance StatementPrimary aldosteronism is a common but under-diagnosed endocrine disease that contributes to global hypertension burden and cardiovascular mortality and morbidity. Hyperaldosteronism in primary aldosteronism is mainly caused by adrenal lesions harboring somatic mutations that disrupt intracellular calcium levels and consequently aldosterone synthase expression and aldosterone production. Majority of these mutations have been identified in genes encoding ion transporters/channels/pumps. Herein, we report the first disease-causing somatic mutations in human MCOLN3 in aldosterone-producing adenomas (APAs) devoid of known mutations. In vitro investigations showed the MCOLN3 variant (p.Y391D) caused an influx of cytosolic calcium in adrenocortical cells and the subsequent increase in aldosterone synthase and aldosterone biosynthesis.

genetics↗

bioRxiv2022

Zinc transporter somatic gene mutations cause primary aldosteronism

Primary aldosteronism (PA) is the most common form of endocrine hypertension and effects one in 50 adults. PA is characterized by inappropriately elevated aldosterone production via renin-independent mechanisms. Driver somatic mutations for aldosterone excess have been found in approximately 90% of aldosterone-producing adenomas (APAs). Using next-generation sequencing, we identified recurrent in-frame deletions in SLC30A1 in five APAs (p.L51_A57del, n=3; p.L49_L55del, n=2). SLC30A1 encodes the ubiquitous zinc efflux transporter ZnT1 (zinc transporter 1). The identified SLC30A1 variants are situated in close proximity of the zincbinding site (H43 and D47) in transmembrane domain II and likely cause abnormal ion transport. PA cases with the unique SLC30A1 mutations showed male dominance and demonstrated increased aldosterone and 18-oxo-cortisol concentrations. Functional studies of the mutant SLC30A151_57del variant in a doxycycline-inducible adrenal cell system revealed abnormal Na+ conductivity caused by the mutant, which in turn led to the depolarization of the resting membrane potential, and thus to the opening of voltage-gated calcium channels. This resulted in an increase in cytosolic Ca2+ activity, which stimulated CYP11B2 mRNA expression and aldosterone production. Collectively, these data implicate the first-in-field zinc transporter mutations as a dominant driver of aldosterone excess in PA.

genetics↗

bioRxiv2022

β-catenin programs a tissue-specific epigenetic vulnerability in aggressive adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare cancer in which tissue-specific differentiation is paradoxically associated with dismal outcomes. The differentiated ACC subtype CIMP-high is prevalent, incurable, and routinely fatal. CIMP-high ACC possess abnormal DNA methylation and frequent {beta}-catenin activating mutations. Here, we demonstrate that ACC differentiation is maintained by a balance between nuclear, tissue-specific {beta}-catenin-containing complexes and the epigenome. On chromatin, {beta}-catenin binds master adrenal transcription factor SF1 and hijacks the adrenocortical super-enhancer landscape to maintain differentiation. Off chromatin, {beta}-catenin binds histone methyltransferase EZH2, which is redistributed by the CIMP-high DNA methylation signature. SF1/{beta}-catenin and EZH2/{beta}-catenin complexes exist in normal adrenals and are selected for through all phases of ACC evolution. Pharmacologic EZH2 inhibition in CIMP-high ACC favors EZH2/{beta}-catenin assembly and purges SF1/{beta}-catenin from chromatin, erasing differentiation and restraining cancer growth in vitro and in vivo. Our studies illustrate how tissue-specific programs shape oncogene selection, surreptitiously encoding targetable therapeutic vulnerabilities.

cancer biology↗

bioRxiv2021

RNA-binding proteins regulate aldosterone homeostasis in human steroidogenic cells

Angiotensin II (AngII) binds to the type I angiotensin receptor in the adrenal cortex to initiate a cascade of events leading to the production of aldosterone, a master regulator of blood pressure. Despite extensive characterization of the transcriptional and enzymatic control of adrenocortical steroidogenesis, there are still major gaps in our knowledge related to precise regulation of AII-induced gene expression kinetics. Specifically, we do not know the regulatory contribution of RNA-binding proteins (RBPs) and RNA decay, which can control the timing of stimulus-induced gene expression. To investigate this question, we performed a high-resolution RNA-seq time course of the AngII stimulation response and 4-thiouridine pulse labeling in a steroidogenic human cell line (H295R). We identified twelve temporally distinct gene expression responses that contained mRNA encoding proteins known to be important for various steps of aldosterone production, such as cAMP signaling components and steroidogenic enzymes. AngII response kinetics for many of these mRNAs revealed a coordinated increase in both synthesis and decay. These findings were validated in primary human adrenocortical cells stimulated ex vivo with AngII. Using a candidate siRNA screen, we identified a subset of RNA-binding protein and RNA decay factors that activate or repress AngII-stimulated aldosterone production. Among the repressors of aldosterone were BTG2, which promotes deadenylation and global RNA decay. BTG2 was induced in response to AngII stimulation and promoted the repression of mRNAs encoding pro-steroidogenic factors indicating the existence of an incoherent feedforward loop controlling aldosterone homeostasis. Together, these data support a model in which coordinated increases in transcription and regulated RNA decay facilitates the major transcriptomic changes required to implement a pro-steroidogenic gene expression program that is temporally restricted to prevent aldosterone overproduction.

genomics↗