Aldosterone-Regulating Receptors and Aldosterone-Driver Somatic Mutations

BackgroundSomatic gene mutations that facilitate inappropriate intracellular calcium entrance have been identified in most aldosterone-producing adenomas (APAs). Studies suggest that angiotensin II and adrenocorticotropic hormone (ACTH) augment aldosterone production from APAs. Little is known, however, regarding possible variations in response to hormonal stimuli between APAs with different aldosterone-driver mutations.ObjectiveTo analyze the transcript expression of type 1 angiotensin II receptors (AGTR1), ACTH receptors (MC2R), and melanocortin 2 receptor accessory protein (MRAP) in APAs with known aldosterone-driver somatic mutations.MethodsRNA was isolated from APAs with mutations in: KCNJ5 (n = 14), ATP1A1 (n = 14), CACNA1D (n = 14), and ATP2B3 (n = 5), and from normal adjacent adrenal tissue (n = 45). Transcript expression of MC2R, MRAP, AGTR1, aldosterone synthase (CYP11B2), 17α-hydroxylase/17,20-lyase (CYP17A1), and 11β-hydroxylase (CYP11B1) were quantified using quantitative RT-PCR and normalized to β-actin.ResultsCompared to adjacent normal adrenal tissue, APAs had higher transcript levels of CYP11B2 (2,216.4 [1,112.0, 2,813.5]-fold, p < 0.001), MC2R (2.88 [2.00, 4.52]-fold, p < 0.001), and AGTR1 (1.80 [1.02, 2.80]-fold, p < 0.001]), and lower transcript levels of MRAP, CYP17A1, and CYP11B1 (0.28–0.36, p < 0.001 for all). MC2R and CYP11B2 transcripts were lower in APAs with KCNJ5 vs. other mutations (p < 0.01 for both). MC2R expression correlated positively with that of AGTR1 in APAs harboring KCNJ5 and CACNA1D mutations, and with MRAP expression in APAs harboring ATPase mutations.ConclusionsWhile MC2R and AGTR1 are expressed in all APAs, differences were observed based on the underlying aldosterone-driver somatic mutations. In tandem, our findings suggest that APAs with ATPase-mutations are more responsive to ACTH than KCNJ5-mutated APAs.

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Aldosterone-stimulating somatic gene mutations are common in normal adrenal glands

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1505529112 ◽

2015 ◽

Vol 112 (33) ◽

pp. E4591-E4599 ◽

Cited By ~ 139

Author(s):

Koshiro Nishimoto ◽

Scott A. Tomlins ◽

Rork Kuick ◽

Andi K. Cani ◽

Thomas J. Giordano ◽

...

Keyword(s):

Gene Mutations ◽

Secondary Hypertension ◽

Zona Glomerulosa ◽

Driver Mutations ◽

Molecular Characteristics ◽

Zona Fasciculata ◽

Adrenal Tissue ◽

Somatic Gene ◽

Aldosterone Production ◽

Normal Adrenal Tissue

Primary aldosteronism (PA) represents the most common cause of secondary hypertension, but little is known regarding its adrenal cellular origins. Recently, aldosterone-producing cell clusters (APCCs) with high expression of aldosterone synthase (CYP11B2) were found in both normal and PA adrenal tissue. PA-causing aldosterone-producing adenomas (APAs) harbor mutations in genes encoding ion channels/pumps that alter intracellular calcium homeostasis and cause renin-independent aldosterone production through increased CYP11B2 expression. Herein, we hypothesized that APCCs have APA-related aldosterone-stimulating somatic gene mutations. APCCs were studied in 42 normal adrenals from kidney donors. To clarify APCC molecular characteristics, we used microarrays to compare the APCC transcriptome with conventional adrenocortical zones [zona glomerulosa (ZG), zona fasciculata, and zona reticularis]. The APCC transcriptome was most similar to ZG but with an enhanced capacity to produce aldosterone. To determine if APCCs harbored APA-related mutations, we performed targeted next generation sequencing of DNA from 23 APCCs and adjacent normal adrenal tissue isolated from both formalin-fixed, paraffin-embedded, and frozen tissues. Known aldosterone driver mutations were identified in 8 of 23 (35%) APCCs, including mutations in calcium channel, voltage-dependent, L-type, α1D-subunit (CACNA1D; 6 of 23 APCCs) and ATPase, Na+/K+transporting, α1-polypeptide (ATP1A1; 2 of 23 APCCs), which were not observed in the adjacent normal adrenal tissue. Overall, we show three major findings: (i) APCCs are common in normal adrenals, (ii) APCCs harbor somatic mutations known to cause excess aldosterone production, and (iii) the mutation spectrum of aldosterone-driving mutations is different in APCCs from that seen in APA. These results provide molecular support for APCC as a precursor of PA.

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SAT-LB90 Angiotensin II and ACTH Receptor Expression in Aldosterone-Producing Adenomas

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.2318 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Jung Soo Lim ◽

Samuel Plaska ◽

Juilee Rege ◽

Adina F Turcu ◽

William E Rainey

Keyword(s):

Angiotensin Ii ◽

Somatic Mutations ◽

Gene Mutations ◽

Receptor Expression ◽

Driver Mutations ◽

Angiotensin Ii Receptor ◽

Gene Expressions ◽

Acth Receptor ◽

Aldosterone Production ◽

Active Research

Abstract Background: The mechanisms leading to elevated aldosterone synthesis in aldosterone-producing adenomas (APAs) remain an area of active research. Aldosterone-driver somatic gene mutations that allow inappropriate intracellular calcium entrance have been identified in most APAs. Cell-based studies of such mutations indicate that responses to physiologic stimuli, such as angiotensin II or ACTH, are increased. Little is known, however, regarding possible variations in response to hormonal stimuli between APAs with different aldosterone-driver mutations. Herein, we analyzed the transcript expression of the ACTH receptor (MC2R), the melanocortin 2 receptor accessory protein (MRAP) and the type 1 angiotensin II receptor (AGTR1) in APAs with known aldosterone-driver somatic mutations. Methods: RNA was isolated from normal adrenal glands (n=8), and from APAs with mutations in: KCNJ5 (n=14), ATP1A1 (n=14), CACNA1D (n=14), and ATP2B3 (n=5). The gene expressions of MC2R, MRAP, AGTR1 and aldosterone synthase (CYP11B2) were quantified using qPCR and normalized to β-actin. Results: All APA mutation groups had significantly higher transcript levels of CYP11B2, MC2R and AGTR1 as compared to whole normal adrenals. While MRAP and AGTR1 transcripts were comparable between tumor mutation groups, MC2R expression was significantly lower in KCNJ5-mutated APAs compared to other APAs. Overall, CYP11B2 expression demonstrated positive correlations with MC2R (R=0.728, p<0.0001) and AGTR1 (R=0.397, p=0.006) in APAs. These correlations were strongest in APAs harboring ATP1A1 mutations, and weakest in KCNJ5-mutated APAs. Conversely, CYP11B2 did not correlate with MC2R and AGTR1 in the normal adrenals. Conclusions: ACTH and angiotensin II receptors are expressed in all APAs, regardless of the underlying aldosterone-driver somatic mutations. Further research to clarify the effects of ACTH and posture on aldosterone production from APAs could provide additional insight into developing diagnostic and subtyping tools for primary aldosteronism.

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Abstract 56: Candesartan And Valsartan, Contrary To Irbesartan, Are Potent Biased Antagonists Of Adrenal (beta)arrestin-dependent, Angiotensin II Type 1 Receptor-induced Aldosterone Production And Improve Cardiac Function Post-myocardial Infarction

Circulation Research ◽

10.1161/res.115.suppl_1.56 ◽

2014 ◽

Vol 115 (suppl_1) ◽

Author(s):

Anastasios Lymperopoulos ◽

Karlee Walklett ◽

Samalia Dabul ◽

Ashley Siryk ◽

Emmanuel Sturchler ◽

...

Keyword(s):

Myocardial Infarction ◽

Angiotensin Ii ◽

Cardiac Function ◽

G Protein ◽

Plasma Aldosterone ◽

Post Myocardial Infarction ◽

Aldosterone Production

Introduction: The scaffolding protein βarrestin1 (βarr1) by the angiotensin II (AngII) type 1 receptor (AT 1 R) mediates AngII-induced aldosterone production in vitro and physiologically in vivo, thereby exacerbating heart failure (HF) progression post-myocardial infarction (MI). Herein, we sought to investigate the relative potency of various AT 1 R antagonist drugs (sartans) at inhibiting βarr vs. G protein activation and hence aldosterone production in vitro and in vivo. We also investigated the alterations in plasma aldosterone levels conferred by these agents and their impact on cardiac function of post-MI rats. Methods: For the in vitro tests, transfected CHO and adrenocortical H295R cells were used. For in vivo studies, post-MI rats overexpressing βarr1 in their adrenals received 7-day-long treatments with the drugs of interest. Results: Among the sartans tested, candesartan and valsartan were the most potent βarr activation and βarr-mediated aldosterone production inhibitors in vitro, as well as the most “biased” antagonists towards βarr vs. G-protein inhibition. Conversely, losartan and irbesartan were the least potent βarr inhibitors and the least “biased” antagonists towards βarr inhibition. These in vitro findings were corroborated in vivo, since candesartan and valsartan, contrary to irbesartan, caused significant plasma aldosterone reductions in post-MI rats. Accordingly, cardiac ejection fraction (EF) and contractility were significantly augmented in candesartan- and valsartan-treated rats (EF: 41.1±1% and 40±1% respectively, vs. 35±0.3% for saline-treated), but further deteriorated in irbesartan-treated post-MI rats (EF: 32±1%, n=7 rats/group). Conclusions: These findings provide important insights that might aid pharmacotherapeutic decisions (i.e. individual agent selections) involving this commonly prescribed cardiovascular drug class (sartans).

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Clonal haematopoiesis in chronic ischaemic heart failure: prognostic role of clone size for DNMT3A- and TET2-driver gene mutations

European Heart Journal ◽

10.1093/eurheartj/ehaa845 ◽

2020 ◽

Cited By ~ 1

Author(s):

Birgit Assmus ◽

Sebastian Cremer ◽

Klara Kirschbaum ◽

David Culmann ◽

Katharina Kiefer ◽

...

Keyword(s):

Heart Failure ◽

Somatic Mutations ◽

Prognostic Significance ◽

Gene Mutations ◽

Amplicon Sequencing ◽

Driver Mutations ◽

Driver Gene ◽

Roc Curve Analysis ◽

Driver Genes ◽

Clone Size

Abstract Aims Somatic mutations of the epigenetic regulators DNMT3A and TET2 causing clonal expansion of haematopoietic cells (clonal haematopoiesis; CH) were shown to be associated with poor prognosis in chronic ischaemic heart failure (CHF). The aim of our analysis was to define a threshold of variant allele frequency (VAF) for the prognostic significance of CH in CHF. Methods and results We analysed bone marrow and peripheral blood-derived cells from 419 patients with CHF by error-corrected amplicon sequencing. Cut-off VAFs were optimized by maximizing sensitivity plus specificity from a time-dependent receiver operating characteristic (ROC) curve analysis from censored data. 56.2% of patients were carriers of a DNMT3A- (N = 173) or a TET2- (N = 113) mutation with a VAF >0.5%, with 59 patients harbouring mutations in both genes. Survival ROC analyses revealed an optimized cut-off value of 0.73% for TET2- and 1.15% for DNMT3A-CH-driver mutations. Five-year-mortality was 18% in patients without any detected DNMT3A- or TET2 mutation (VAF < 0.5%), 29% with only one DNMT3A- or TET2-CH-driver mutations above the respective cut-off level and 42% in patients harbouring both DNMT3A- and TET2-CH-driver mutations above the respective cut-off levels. In carriers of a DNMT3A mutation with VAF ≥ 1.15%, 5-year mortality was 31%, compared with 18% mortality in those with VAF < 1.15% (P = 0.048). Likewise, in patients with TET2 mutations, 5-year mortality was 32% with VAF ≥ 0.73%, compared with 19% mortality with VAF < 0.73% (P = 0.029). Conclusion The present study defines novel threshold levels for clone size caused by acquired somatic mutations in the CH-driver genes DNMT3A and TET2 that are associated with worse outcome in patients with CHF.

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Absence of angiotensin II type 1 receptor gene mutations in human adrenal tumors

Acta Endocrinologica ◽

10.1530/eje.0.1370262 ◽

1997 ◽

pp. 262-266 ◽

Cited By ~ 16

Author(s):

R Sachse ◽

XJ Shao ◽

A Rico ◽

U Finckh ◽

A Rolfs ◽

...

Keyword(s):

Angiotensin Ii ◽

Receptor Gene ◽

Gene Mutations ◽

At1 Receptor ◽

Adrenal Tumors ◽

Base Substitution ◽

Coding Region ◽

Activating Mutations ◽

Activating Mutation

Regulatory actions of angiotensin II (AngII), which is involved in the pathophysiology of hypertension and also participates in cell proliferation and cell differentiation, are mainly mediated by AngII type 1 (AT1) receptor. Recently, activating mutations of receptors causing hyperfunctioning endocrine diseases have been described in the case of the TSH and LH receptors, implicating that such mutations might occur in other G-protein-coupled receptors. Furthermore it seems to be possible that genetic variations of AT1 receptor have an influence upon the action of AngII. Therefore, we searched by sequence analysis of the coding region of AT1 receptor gene for activating mutations and genetic polymorphisms in 56 human adrenal tumors (16 aldosterone-producing adenomas, 10 cortisol-producing adenomas, 1 aldosterone-producing carcinoma, and 29 incidentalomas). We were not able to identify any activating mutation in the coding region of AT1 receptor gene. We conclude that activating mutations of the AT1 receptor are not a major cause of the development of adrenal adenomas, if at all. In addition, polymorphic subtypes of AT1 receptor do not seem to play a major role in the pathogenesis of these tumors, even though a tendency towards a higher frequency of the polymorphic base substitution at position 573 (T573-->C) in cortisol-producing tumors needs to be further evaluated.

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Aldosterone Breakthrough Caused by Chronic Blockage of Angiotensin II Type 1 Receptors in Human Adrenocortical Cells: Possible Involvement of Bone Morphogenetic Protein-6 Actions

Endocrinology ◽

10.1210/en.2007-1476 ◽

2008 ◽

Vol 149 (6) ◽

pp. 2816-2825 ◽

Cited By ~ 25

Author(s):

Hiroyuki Otani ◽

Fumio Otsuka ◽

Kenichi Inagaki ◽

Jiro Suzuki ◽

Tomoko Miyoshi ◽

...

Keyword(s):

Angiotensin Ii ◽

Bone Morphogenetic Protein ◽

Ang Ii ◽

Adrenocortical Cells ◽

Activin Receptor ◽

Morphogenetic Protein ◽

Receptor Like Kinase ◽

Aldosterone Production ◽

Aldosterone Breakthrough

Circulating aldosterone concentrations occasionally increase after initial suppression with angiotensin II (Ang II) converting enzyme inhibitors or Ang II type 1 receptor blockers (ARBs), a phenomenon referred to as aldosterone breakthrough. However, the underlying mechanism causing the aldosterone breakthrough remains unknown. Here we investigated whether aldosterone breakthrough occurs in human adrenocortical H295R cells in vitro. We recently reported that bone morphogenetic protein (BMP)-6, which is expressed in adrenocortical cells, enhances Ang II- but not potassium-induced aldosterone production in human adrenocortical cells. Accordingly, we examined the roles of BMP-6 in aldosterone breakthrough induced by long-term treatment with ARB. Ang II stimulated aldosterone production by adrenocortical cells. This Ang II stimulation was blocked by an ARB, candesartan. Interestingly, the candesartan effects on Ang II-induced aldosterone synthesis and CYP11B2 expression were attenuated in a course of candesartan treatment for 15 d. The impairment of candesartan effects on Ang II-induced aldosterone production was also observed in Ang II- or candesartan-pretreated cells. Levels of Ang II type 1 receptor mRNA were not changed by chronic candesartan treatment. However, BMP-6 enhancement of Ang II-induced ERK1/2 signaling was resistant to candesartan. The BMP-6-induced Smad1, -5, and -8 phosphorylation, and BRE-Luc activity was augmented in the presence of Ang II and candesartan in the chronic phase. Chronic Ang II exposure decreased cellular expression levels of BMP-6 and its receptors activin receptor-like kinase-2 and activin type II receptor mRNAs. Cotreatment with candesartan reversed the inhibitory effects of Ang II on the expression levels of these mRNAs. The breakthrough phenomenon was attenuated by neutralization of endogenous BMP-6 and activin receptor-like kinase-2. Collectively, these data suggest that changes in BMP-6 availability and response may be involved in the occurrence of cellular escape from aldosterone suppression under chronic treatment with ARB.

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Targeted Mutational Analysis of Cortisol-Producing Adenomas

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/clinem/dgab682 ◽

2021 ◽

Author(s):

Juilee Rege ◽

Jessie Hoxie ◽

Chia-Jen Liu ◽

Morgan N Cash ◽

James M Luther ◽

...

Keyword(s):

Somatic Mutations ◽

Mutational Analysis ◽

Cushing Syndrome ◽

Gene Mutations ◽

Amplicon Sequencing ◽

Formalin Fixed Paraffin ◽

Mutation Profile ◽

Somatic Gene ◽

Formalin Fixed Paraffin Embedded ◽

Aldosterone Producing Adenoma

Abstract Background Somatic gene mutations have been identified in only about half of cortisol-producing adenomas (CPA). Affected genes include PRKACA, GNAS, PRKAR1A, and CTNNB1. Objective To expand our understanding of the prevalence of somatic mutations in CPA from patients with overt Cushing syndrome (OCS) and “subclinical” mild autonomous cortisol excess (MACE), with an immunohistochemistry (IHC)‒guided targeted amplicon sequencing approach using formalin-fixed paraffin-embedded (FFPE) tissue. Method We analyzed FFPE adrenal tissue from 77 patients (n=12 men, 65 women) with either OCS (n=32) or MACE (n=45). Using IHC for 17α-hydroxylase/17,20-lyase (CYP17A1) and 3β-hydroxysteroid dehydrogenase (HSD3B2), we identified 78 CPA (32 OCS-CPA and 46 MACE-CPA). Genomic DNA was isolated from the FFPE CPA and subjected to targeted amplicon sequencing for identification of somatic mutations. Results Somatic mutations were identified in 71.8% (56/78) of the CPA. While PRKACA was the most frequently mutated gene in OCS-CPA (14/32, 43.8%), somatic genetic aberrations in CTNNB1 occurred in 56.5% (26/46) of the MACE-CPA. Most GNAS mutations were observed in MACE-CPA (5/7,71.4%). No mutations were observed in PRKAR1A. In addition to the known mutations, we identified one previously unreported mutation in PRKACA. Two patients with MACE harbored two adjacent tumors within the same adrenal gland: one patient had two CPA, and the other patient had a CPA and an aldosterone-producing adenoma (identified by IHC for aldosterone synthase). Conclusion Comprehensive FFPE IHC-guided gene-targeted sequencing approach identified somatic mutations in 71.8% of the CPA. OCS-CPA demonstrated a distinct mutation profile compared to MACE-CPA.

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Characterization of Myelodysplastic Syndromes (MDS) with T-Cell Large Granular Lymphocyte Proliferations (LGL)

Blood ◽

10.1182/blood.v128.22.113.113 ◽

2016 ◽

Vol 128 (22) ◽

pp. 113-113 ◽

Cited By ~ 1

Author(s):

Christa Roe ◽

Najla Alali ◽

Eric Padron ◽

Pearlie K Burnette ◽

Kendra L. Sweet ◽

...

Keyword(s):

Flow Cytometry ◽

T Cell ◽

Peripheral Blood ◽

Scoring System ◽

Lower Risk ◽

Research Funding ◽

Somatic Mutations ◽

Gene Mutations ◽

Significant Difference ◽

Somatic Gene

Abstract Introduction: MDS include a spectrum of hematopoietic stem cell malignancies characterized by bone marrow failure and dysplastic morphology. LGL is a clonal proliferation of cytotoxic T cells, which manifest as neutropenia, anemia, and thrombocytopenia and is associated with autoimmune disorders. LGL in association with MDS has been previously reported. However, clinicopathological features, prognostic, and predictive factors in those patients diagnosed with both LGL and MDS is not well studied. Methods: We identified patients at Moffitt Cancer Center (MCC) diagnosed with MDS who were previously tested for the presence of LGL clonal populations by peripheral blood flow cytometry at time of first visit. An LGL population was defined by the standard flow cytometry immunophenotype and clonality confirmed by T-cell receptor gamma and beta gene rearrangement.. Next Generation sequencing data was available for 151 patients. Recurrent somatic gene mutations were compared between patients with an LGL clone and those without. Results: Of the 675 patients with MDS tested for LGL in the database, 206 (30.5%) had an LGL clonal population. The mean LGL absolute cell count in the peripheral blood was 335/µL. Table-1 summarizes the baseline characteristics of the two groups. There was no difference in response to azacitidine therapy. Among 50 patients with LGL clone who received azacitidine with available data on response, the rate of hematological improvement or better (HI+) was 38%. The (HI+) was 28% among 105 patients evaluable for response without LGL clone. P .14 The median overall survival (OS) was for patients with no LGL clone was 65 months (mo) compared to 46 mo (p .024). The median OS for lower risk MDS patients (low/int-1 by International Prognostic Scoring System [IPSS]) was 68 mo versus 97 mo for those with or without LGL proliferation, respectively (P .005). In higher risk MDS, there was no difference in median OS between those with or without LGL expansion, respectively (20 mo versus 16 mo, p .7). The median OS for patients with very low/ low Revised-Internatinal Prognostic Scoring System (R-IPSS) was 96 mo if LGL proliferation was detected compared to 128 mo if it was not, (p value .016). For intermediate R-IPSS the median OS was 65 mo and 41 mo with or without LGL proliferation (p .16). Finally, for high/very high R-IPSS the median OS was 18 and 16 mo with or without LGL proliferation, (p .84) In cox regression analysis the presence of an LGL clone was independently prognostic for OS after adjusting for age and R-IPSS, Hazard ratio 1.3, p = .05. Somatic gene mutation data were available for 151 patients; there was no statistically significant difference in the distribution of any mutation except IDH-2 (Table-2). The most common somatic mutations observed among patients with LGL clone were SF3B1 19%, TET-2 16%, U2AF1 13%, IDH-2 13%, RUNX-1 13%, and ASXL-1 10%. In patients without an LGL clone the most common somatic mutations were TET-2 26%, ASXL-1 20%, DNMT3A 16%, TP53 13%, SF3B1 12%. Conclusion: An LGL clone is demonstrable in approximately 30% of patients with MDS in association with advancing age. The presence of LGL proliferation was associated with worse OS in lower risk MDS pts. Although the spectrum of somatic gene mutations were similar, the presence of IDH-2 mutation and absence of DNMT3A or TP53 gene mutationscharacterized LGL+ cases. Table 1. Table 1. Table 2. Table 2. Disclosures Roe: Celgene: Speakers Bureau; Alexion: Speakers Bureau; Seattle Genetics: Speakers Bureau. Sweet:Pfizer: Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Ariad: Consultancy, Speakers Bureau; Incyte Corporation: Research Funding; Karyopharm: Honoraria, Research Funding. Sokol:Seattle Genetics: Consultancy; Spectrum: Consultancy. Komrokji:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Speakers Bureau; Incyte: Consultancy.

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The Potential Role of Aldosterone-Producing Cell Clusters in Adrenal Disease

Hormone and Metabolic Research ◽

10.1055/a-1128-0421 ◽

2020 ◽

Vol 52 (06) ◽

pp. 427-434

Author(s):

Jung Soo Lim ◽

William E. Rainey

Keyword(s):

Gene Mutations ◽

Normal Subjects ◽

Secondary Hypertension ◽

Cell Clusters ◽

Somatic Gene ◽

Aldosterone Production ◽

Next Generation Sequencing Ngs ◽

Generation Sequencing ◽

Made In

AbstractPrimary aldosteronism (PA) is the most common cause of secondary hypertension. The hallmark of PA is adrenal production of aldosterone under suppressed renin conditions. PA subtypes include adrenal unilateral and bilateral hyperaldosteronism. Considerable progress has been made in defining the role for somatic gene mutations in aldosterone-producing adenomas (APA) as the primary cause of unilateral PA. This includes the use of next-generation sequencing (NGS) to define recurrent somatic mutations in APA that disrupt calcium signaling, increase aldosterone synthase (CYP11B2) expression, and aldosterone production. The use of CYP11B2 immunohistochemistry on adrenal glands from normal subjects, patients with unilateral and bilateral PA has allowed the identification of CYP11B2-positive cell foci, termed aldosterone-producing cell clusters (APCC). APCC lie beneath the adrenal capsule and like APA, many APCC harbor somatic gene mutations known to increase aldosterone production. These findings suggest that APCC may play a role in pathologic progression of PA. Herein, we provide an update on recent research directed at characterizing APCC and also discuss the unanswered questions related to the role of APCC in PA.

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