Showing papers on "Adrenal cortex published in 2012"
Journal Article•
TL;DR: It has been shown, in this study, that only Dkk3 expression is significantly upregulated in adult female Task1-/- mice, which reinforces the evidence suggesting a key role for the Wnt signaling pathway in regulating the production of aldosterone in the adrenal cortex.
Abstract: The adrenal gland is composed of two ontogenetically and functionally distinct tissues, the medulla and the cortex. The cortex, the subject of the present article, forms the major part of the murine gland and is further organized into three concentric layers: the outer zona glomerulosa, the zona fasciculata and the innermost X-zone. Specific hormonal production is finely tuned in time and space, in relation with the structure and functional organization of the adrenal cortex. This tight, reciprocal regulation of adrenocortical steroid-synthesizing enzymes is termed functional zonation. Maintenance of adrenal gland structure and function is regulated through the integration of extra- and intracellular signals that have only recently started to be defined. To study specifically the role of Wnt signaling pathway in normal adrenocortical functional zonation, the TWIK-related acid-sensitive potassium channel 1 (Task1) knockout mice are likely to become a valuable tool as it is the first model for severe but reversible disorganization of the adrenal cortex. In the real-time polymerase chain reaction (RT-PCR) experiments, the relative mRNA expression levels of Wnt4, the two antagonists Dkk3 and Sfrp4 and the membrane receptor Ror2 in the adrenals of young (postnatal day 15) and adult (postnatal day 40) Task1 null mice of both sexes coordinately with the phenotype versus their corresponding wild-type mice were analyzed. It has been shown, in this study, that only Dkk3 expression is significantly upregulated in adult female Task1-/- mice. This finding reveals that Dkk3 plays a role in adrenocortical functional zonation and further reinforce the evidence suggesting a key role for the Wnt signaling pathway in regulating the production of aldosterone in the adrenal cortex.
250 citations
TL;DR: What is believed to be the first human mutation in minichromosome maintenance-deficient 4 (MCM4) is identified and shown that it is associated with adrenal insufficiency, short stature, and NK cell deficiency.
Abstract: An interesting variant of familial glucocorticoid deficiency (FGD), an autosomal recessive form of adrenal failure, exists in a genetically isolated Irish population. In addition to hypocortisolemia, affected children show signs of growth failure, increased chromosomal breakage, and NK cell deficiency. Targeted exome sequencing in 8 patients identified a variant (c.71-1insG) in minichromosome maintenance-deficient 4 (MCM4) that was predicted to result in a severely truncated protein (p.Pro24ArgfsX4). Western blotting of patient samples revealed that the major 96-kDa isoform present in unaffected human controls was absent, while the presence of the minor 85-kDa isoform was preserved. Interestingly, histological studies with Mcm4-depleted mice showed grossly abnormal adrenal morphology that was characterized by non-steroidogenic GATA4- and Gli1-positive cells within the steroidogenic cortex, which reduced the number of steroidogenic cells in the zona fasciculata of the adrenal cortex. Since MCM4 is one part of a MCM2-7 complex recently confirmed as the replicative helicase essential for normal DNA replication and genome stability in all eukaryotes, it is possible that our patients may have an increased risk of neoplastic change. In summary, we have identified what we believe to be the first human mutation in MCM4 and have shown that it is associated with adrenal insufficiency, short stature, and NK cell deficiency.
226 citations
TL;DR: It is demonstrated that lentiviral-mediated expression of a gene carrying the T158A mutation of the KCNJ5 in the HAC15 adrenal cortical carcinoma cell line causes a 5.3-fold increase in aldosterone secretion in unstimulated HAC 15-KCNJ5 cells and that forskolin-stimulated ald testosterone secretion was greater than that of angiotensin II.
Abstract: Primary aldosteronism is the most common cause of secondary hypertension, most frequently due to an aldosterone-producing adenoma or idiopathic hyperaldosteronism. Somatic mutations of the potassium channel KCNJ5 in the region of the selectivity filter have been found in a significant number of aldosterone-producing adenomas. There are also familial forms of primary aldosteronism, one of which, familial hyperaldosteronism type 3 which to date has been found in one family who presented with a severe abnormality in aldosterone and 18-oxocortisol production and hypertrophy and hyperplasia of the transitional zone of the adrenal cortex. In familial hyperaldosteronism type 3, there is a genomic mutation causing a T158A change of amino acids within the selectivity filter region of the KCNJ5 gene.
We are reporting our studies demonstrating that lentiviral-mediated expression of a gene carrying the T158A mutation of the KCNJ5 in the HAC15 adrenal cortical carcinoma cell line causes a 5.3-fold increase in aldosterone secretion in unstimulated HAC15-KCNJ5 cells and that forskolin-stimulated aldosterone secretion was greater than that of angiotensin II. Expression of the mutated KCNJ5 gene decreases plasma membrane polarization, allowing sodium and calcium influx into the cells. The calcium channel antagonist nifedipine and the calmodulin inhibitor W-7 variably inhibited the effect. Overexpression of the mutated KCNJ5 channel resulted in a modest decrease in HAC15 cell proliferation.
These studies demonstrate that the T158A mutation of the KCNJ5 gene produces a marked stimulation in aldosterone biosynthesis that is dependent on membrane depolarization and sodium and calcium influx into the HAC15 adrenal cortical carcinoma cells.
154 citations
TL;DR: KCNJ5 mutations are prevalent in APA, and the data suggest that these mutations increase expression of CYP11B2 and NR4A2, thus increasing aldosterone production.
Abstract: Context: Primary aldosteronism is a heterogeneous disease that includes both sporadic and familial forms. A point mutation in the KCNJ5 gene is responsible for familial hyperaldosteronism type III. Somatic mutations in KCNJ5 also occur in sporadic aldosterone producing adenomas (APA). Objective: The objective of the study was to define the effect of the KCNJ5 mutations on gene expression and aldosterone production using APA tissue and human adrenocortical cells. Methods: A microarray analysis was used to compare the transcriptome profiles of female-derived APA samples with and without KCNJ5 mutations and HAC15 adrenal cells overexpressing either mutated or wild-type KCNJ5. Real-time PCR validated a set of differentially expressed genes. Immunohistochemical staining localized the KCNJ5 expression in normal adrenals and APA. Results: We report a 38% (18 of 47) prevalence of KCNJ5 mutations in APA. KCNJ5 immunostaining was highest in the zona glomerulosa of NA and heterogeneous in APA tissue, and KCNJ5 mRNA ...
125 citations
TL;DR: Currently available human adrenocortical carcinoma cell lines are discussed and their use as model systems for adrenal studies are discussed.
123 citations
TL;DR: Testing IGF2 oncogenic properties by developing two distinct transgenic mouse models of Igf2 overexpression in the adrenal cortex suggests that the growth factor IGF2 is a mild contributor to malignant adrenocortical tumourigenesis.
Abstract: Adrenal cortical carcinomas (ACC) are rare but aggressive tumours associated with poor prognosis. The two most frequent alterations in ACC in patients are overexpression of the growth factor IGF2 and constitutive activation of Wnt/β-catenin signalling. Using a transgenic mouse model, we have previously shown that constitutive active β-catenin is a bona fide adrenal oncogene. However, although all these mice developed benign adrenal hyperplasia, malignant progression was infrequent, suggesting that secondary genetic events were required for aggressive tumour development. In the present paper, we have tested IGF2 oncogenic properties by developing two distinct transgenic mouse models of Igf2 overexpression in the adrenal cortex. Our analysis shows that despite overexpression levels ranging from 7 (basal) to 87 (ACTH-induced) fold, Igf2 has no tumour initiating potential in the adrenal cortex. However, it induces aberrant accumulation of Gli1 and Pod1-positive progenitor cells, in a hedgehog-independent manner. We have also tested the hypothesis that Igf2 may cooperate with Wnt signalling by mating Igf2 overexpressing lines with mice that express constitutive active β-catenin in the adrenal cortex. We show that the combination of both alterations has no effect on tumour phenotype at stages when β-catenin-induced tumours are benign. However, there is a mild promoting effect at later stages, characterised by increased Weiss score and proliferation. Formation of malignant tumours is nonetheless a rare event, even when Igf2 expression is further increased by ACTH treatment. Altogether these experiments suggest that the growth factor IGF2 is a mild contributor to malignant adrenocortical tumourigenesis.
69 citations
TL;DR: Genetic aberrations in various components of cAMP signalling pathway predispose to endocrine tumours and the phosphodiesterases (PDEs) are involved in the predisposition to adrenocortical neoplastic conditions.
Abstract: SummaryBackground
Genetic aberrations in various components of cAMP signalling pathway predispose to endocrine tumours. Mutations in the phosphodiesterases (PDEs) are involved in the predisposition to adrenocortical neoplastic conditions.
Objective
To screen for genetic variations in PDE8B among patients with different types of adrenocortical tumours.
Design and subjects
This is a case–control study followed by functional analyses. Two hundred and sixteen unrelated patients with different types of adrenocortical tumours and 192 healthy control individuals participated in the study.
Methods
Bidirectional Sanger sequencing, in vitro cell line transfection and in silico modelling are used in this study.
Results
Nine different PDE8B sequence changes, six novel and three previously reported, were identified in our patients and controls. Two of the variations, seen only in the patient group, showed significant potential to impair protein function, both in vitro and in silico.
Conclusion
PDE8B is another PDE gene in which variations may contribute to predisposition of adrenocortical tumours.
65 citations
TL;DR: Using genetic ablation of an intermediate filament protein in mice, results suggest that vimentin is involved in the movement of cholesterol from its storage in lipid droplets to mitochondria for steroidogenesis.
Abstract: In steroidogenic tissues, cholesterol must be transported to the inner mitochondrial membrane to be converted to pregnenolone as the first step of steroidogenesis. Whereas steroidogenic acute regulatory protein has been shown to be responsible for the transport of cholesterol from the outer to the inner mitochondrial membrane, the process of how cholesterol moves to mitochondria from the cytoplasm is not clearly defined. The involvement of the cytoskeleton has been suggested; however, no specific mechanism has been confirmed. In this paper, using genetic ablation of an intermediate filament protein in mice, we present data demonstrating a marked defect in adrenal and ovarian steroidogenesis in the absence of vimentin. Cosyntropin-stimulated corticosterone production is decreased 35 and 50% in male and female Vimentin null (Vim(-/-)) mice, respectively, whereas progesterone production is decreased 70% in female Vim(-/-) mice after pregnant mare's serum gonadotropin and human chorionic gonadotropin stimulation, but no abnormalities in human chorionic gonadotropin-stimulated testosterone production is observed in male Vim(-/-) mice. These defects in steroid production are also seen in isolated adrenal and granulosa cells in vitro. Further studies show a defect in the movement of cholesterol from the cytosol to mitochondria in Vim(-/-) cells. Because the mobilization of cholesterol from lipid droplets and its transport to mitochondria is a preferred pathway for the initiation of steroid production in the adrenal and ovary but not the testis and vimentin is a droplet-associated protein, our results suggest that vimentin is involved in the movement of cholesterol from its storage in lipid droplets to mitochondria for steroidogenesis.
64 citations
TL;DR: The prophylactic treatment of hypercortisolism in depression is associated with suppression of pituitary and adrenal responses to low glucocorticoid feedback, particularly in patients with a history of substance abuse.
Abstract: Carroll BJ, Iranmanesh A, Keenan DM, Cassidy F, Wilson WH, Veldhuis JD. Pathophysiology of hypercortisolism in depression: pituitary and adrenal responses to low glucocorticoid feedback.
Objective: To test three theories of hypercortisolemia in depression–hypothalamic overdrive, impaired glucocorticoid feedback, or autonomous cortisol production.
Method: We applied an overnight low-cortisol feedback strategy by administering metyrapone to hypercortisolemic depressed in-patients and control subjects.
Results: Under metyrapone, the increases of plasma adrenocorticotropic hormone (ACTH) concentrations and of basal and pulsatile ACTH secretion were not exaggerated in hypercortisolemic depressed patients compared with control subjects. ACTH approximate entropy (ApEn) did not differ at baseline or under metyrapone. Thus, neither hypothalamic overdrive nor irregular ACTH secretion was seen. We did not detect impaired cortisol feedback: the ACTH response was not reduced, and ApEn measures that are sensitive to feedback changes were comparable in both groups. Metyrapone disrupted cortisol secretory regularity in depressed and control subjects. On the baseline day, basal cortisol secretion was significantly increased and was highly irregular (high ApEn), and ACTH-cortisol cross-ApEn was markedly elevated in high-cortisol patients.
Conclusion: Classical feed-forward overdrive and impaired feedback theories of hypercortisolemia in depression were not supported. Depressive hypercortisolemia may result from alternative pathophysiological mechanisms involving irregular basal hypersecretion of cortisol, associated with adrenal enlargement, possibly through splanchnic sympathetic activation of the adrenal cortex.
63 citations
TL;DR: These results imply that stress levels of CORT (100–1000 nM) drive the spinogenesis via synaptic GR and multiple kinase pathways.
Abstract: Background
Modulation of dendritic spines under acute stress is attracting much attention. Exposure to acute stress induces corticosterone (CORT) secretion from the adrenal cortex, resulting in rapid increase of CORT levels in plasma and the hippocampus.
62 citations
TL;DR: The key findings are that Shh signals produced by a population of partially differentiated cortical cells located in the outer cortex/zona glomerulosa are received by non-cortical mesenchymal cells located predominantly in the overlying capsule, but not for cortical zonation or steroidogenic cell differentiation.
TL;DR: By inhibiting 11β-hydroxylase and 17-hydroxyylase activity, pharmacological concentrations of fluconazole dose dependently inhibit cortisol production in human adrenocortical cells in vitro, it might become an alternative for ketoconazole to control hypercortisolism in CS.
Abstract: The antifungal agent ketoconazole is often used to suppress cortisol production in patients with Cushing's syndrome (CS). However, ketoconazole has serious side effects and is hepatotoxic. Here, the in vitro effects of ketoconazole and fluconazole, which might be less toxic, on human adrenocortical steroidogenesis were compared. The effects on steroidogenesis were examined in primary cultures of nine human adrenocortical tissues and two human adrenocortical carcinoma cell lines. Moreover, the effects on mRNA expression levels of steroidogenic enzymes and cell growth were assessed. Ketoconazole significantly inhibited 11-deoxycortisol (H295R cells; maximum inhibition 99%; EC50 0.73 μM) and cortisol production (HAC15 cells; 81%; EC50 0.26 μM and primary cultures (mean EC50 0.75 μM)). In cultures of normal adrenal cells, ketoconazole increased pregnenolone, progesterone, and deoxycorticosterone levels, while concentrations of 17-hydroxypregnenolone, 17-hydroxyprogesterone, 11-deoxycortisol, DHEA, and androstenedione decreased. Fluconazole also inhibited 11-deoxycortisol production in H295R cells (47%; only at 1 μM) and cortisol production in HAC15 cells (maximum inhibition 55%; EC50 35 μM) and primary cultures (mean EC50 67.7 μM). In the cultures of normal adrenals, fluconazole suppressed corticosterone, 17-hydroxypregnenolone, and androstenedione levels, whereas concentrations of progesterone, deoxycorticosterone, and 11-deoxycortisol increased. Fluconazole (1 μM) slightly increased STAR mRNA expression in both cell lines. Neither compound affected mRNA levels of other steroidogenic enzymes or cell number. In conclusion, by inhibiting 11β-hydroxylase and 17-hydroxylase activity, pharmacological concentrations of fluconazole dose dependently inhibit cortisol production in human adrenocortical cells in vitro. Although fluconazole seems less potent than ketoconazole, it might become an alternative for ketoconazole to control hypercortisolism in CS. Furthermore, patients receiving fluconazole because of mycosis might be at risk for developing adrenocortical insufficiency.
TL;DR: An initial characterization of a malignancy among patients with Carney complex is reported, which has implications for disease surveillance and management of individuals with this genetic syndrome.
Abstract: Context: Carney complex is a genetically heterogenous multiple neoplasia syndrome. Adrenal cortical carcinoma is a rare malignancy with a poor prognosis that is not recognized to be associated with this syndrome. Objective: We report a 22-yr-old female presenting with Carney complex who developed adrenal carcinoma. The response to adjunctive therapy is also described. Methods: We performed a detailed pathology review of the adrenal tumor to examine morphologic changes, Ki-67 labeling, and p53 expression. We also performed genetic testing of candidate genes and describe the response to radiation and kinase inhibition therapy. Results: The patient presented with an 8.5-cm adrenal mass with a MIB-1 labeling index of 20% and unequivocal angioinvasion classified as a T3NXM0 carcinoma. The nontumorous adrenal cortex revealed characteristic features of primary pigmented nodular adrenocortical disease. Genetic analysis revealed a novel PRKAR1 frame shift mutation resulting in a premature stop codon and a heterozy...
TL;DR: WGEP analysis revealed that not all cAMP activation is the same: adrenal lesions harboring PRKAR1A or GNAS mutations share the downstream activation of certain oncogenic signals but differ substantially in their effects on others.
Abstract: Context: The overwhelming majority of benign lesions of the adrenal cortex leading to Cushing syndrome are linked to one or another abnormality of the cAMP or protein kinase pathway. PRKAR1A-inactivating mutations are responsible for primary pigmented nodular adrenocortical disease, whereas somatic GNAS activating mutations cause macronodular disease in the context of McCune-Albright syndrome, ACTH-independent macronodular hyperplasia, and, rarely, cortisol-producing adenomas. Objective and Design: The whole-genome expression profile (WGEP) of normal (pooled) adrenals, PRKAR1A- (3) and GNAS-mutant (3) was studied. Quantitative RT-PCR and Western blot were used to validate WGEP findings. Results: MAPK and p53 signaling pathways were highly overexpressed in all lesions against normal tissue. GNAS-mutant tissues were significantly enriched for extracellular matrix receptor interaction and focal adhesion pathways when compared with PRKAR1A-mutant (fold enrichment 3.5, P < 0.0001 and 2.1, P < 0.002, respective...
TL;DR: Classic CAH patients require chronic glucocorticoid treatment at the lowest dose that adequately suppresses adrenal androgens and maintains normal growth and weight gain, and most require mineralocortioid (fludrocortisone).
Abstract: The most frequent form of congenital adrenal hyperplasia (CAH) is steroid 21-hydroxylase deficiency, accounting for more than 90% of cases. Affected patients cannot synthesize cortisol efficiently. Thus the adrenal cortex is stimulated by corticotropin (ACTH) and overproduces cortisol precursors. Some precursors are diverted to sex hormone biosynthesis, causing signs of androgen excess including ambiguous genitalia in newborn females and rapid postnatal growth in both sexes. In the most severe "salt wasting" form of CAH (~75% of severe or "classic" cases), concomitant aldosterone deficiency may lead to salt wasting with consequent failure to thrive, hypovolemia, and shock. Newborn screening minimizes delays in diagnosis, especially in males, and reduces morbidity and mortality from adrenal crises. CAH is a recessive disorder caused by mutations in the CYP21 (CYP21A2) gene, most of which arise from recombination between CYP21 and a nearby pseudogene, CYP21P (CYP21A1P). Phenotype is generally correlated with genotype. Classic CAH patients require chronic glucocorticoid treatment at the lowest dose that adequately suppresses adrenal androgens and maintains normal growth and weight gain, and most require mineralocorticoid (fludrocortisone). Transition of care of older patients to adult physicians should be planned in advance as a structured, ongoing process.
TL;DR: In this article, the effect of glucocorticoids on the number of astrocytes and GR expression in vitro and in vivo was investigated. And the results suggest that glucoc corticoids decrease the number and expression of GR in both vitro and vivo.
TL;DR: The lists of transcripts obtained in the current study will be an invaluable tool for the elucidation of cellular mechanisms leading to zG and zF functional zonation.
Abstract: In mammals, aldosterone is produced in the zona glomerulosa (zG), the outermost layer of the adrenal cortex, whereas glucocorticoids are produced in adjacent zona fasciculata (zF). However, the cellular mechanisms controlling the zonal development and the differential hormone production (i.e. functional zonation) are poorly understood. To explore the mechanisms, we defined zone-specific transcripts in this study. Eleven-week-old male rats were used and adrenal tissues were collected from zG and zF using laser-capture microdissection. RNA was isolated, biotin labeled, amplified, and hybridized to Illumina microarray chips. The microarray data were compared by fold change calculations. In zG, 235 transcripts showed more than a 2-fold up-regulation compared to zF with statistical significance. Similarly, 231 transcripts showed up-regulation in zF. The microarray findings were validated using quantitative RT-PCR and immunohistochemical staining on selected transcripts, including Cyp11b2 (zG/zF: 214.2x), Rgs4 (68.4x), Smoc2 (49.3x), and Mia1 (43.1x) in zG as well as Ddah1 (zF/zG 16.2x), Cidea (15.5x), Frzb (9.5x), and Hsd11b2 (8.3x) in zF. The lists of transcripts obtained in the current study will be an invaluable tool for the elucidation of cellular mechanisms leading to zG and zF functional zonation.
TL;DR: A functional biological clock at the systemic and cellular levels is therefore necessary for steroid synthesis and secretion.
TL;DR: A comparison of the available human adrenal cell lines indicates that the H295R-S2 and the clonal cell lines, HAC13, Hac15 and HAC50 produced the highest levels of aldosterone and responded well to Ang II.
Abstract: Several human adrenocortical cell lines have been used as model systems for aldosterone production. However, these cell lines have not been directly compared with each other. Human adrenal cell lines SW13, CAR47, the NCI-H295 and its sub-strains and sub-clones were compared with regard to aldosterone production and aldosterone synthase (CYP11B2) expression. Culture media was collected 48 h after incubation, aldosterone secretion was measured and the data were normalized to the amount of cell protein. RNA was isolated for microarray analysis and quantitative RT-PCR (qPCR). The cell lines with the highest aldosterone production were further tested with regard to angiotensin II (Ang II) stimulation. Neither aldosterone nor CYP11B2 transcript were detected in SW13 or CAR47 cells. The aldosterone production by the NCI-H295, H295A, H295R-S1, H295R-S2, H295R-S3, HAC13, HAC15 and HAC50 were 119, 1, 6, 826, 18, 139, 412, and 1 334 (pmol/mg protein/48 h), respectively. H295A and H295R-S1 expressed less CYP11B2 than the commonly used H295R-S3 cells; while NCI-H295, H295R-S2, HAC13, HAC15 and HAC50 expressed 24-, 14-, 3-, 10-, and 35-fold higher CYP11B2 compared with the H295R-S3 cells. When treated with Ang II, NCI-H295, H295R-S2, HAC13, HAC15 and HAC50 showed significantly higher aldosterone production than the basal level (p<0.05). A comparison of the available human adrenal cell lines indicates that the H295R-S2 and the clonal cell lines, HAC13, HAC15 and HAC50 produced the highest levels of aldosterone and responded well to Ang II.
TL;DR: Evidence shall be presented that a local secretory RAS exists in the adrenal cortex that stimulates aldosterone production and serves as an amplification system for circulating angiotensin (ANG) II.
TL;DR: New-onset autoimmune Addisons disease should be considered as a potentially reversible condition in some patients, and future studies of immunomodulation in autoimmune Addison's disease may be warranted.
Abstract: Context: A diagnosis of Addison's disease means lifelong dependence on daily glucocorticoid and mineralocorticoid therapy and is associated with increased morbidity and mortality as well as a risk of unexpected adrenal crisis. Objective: The objective of the study was to determine whether immunomodulatory therapy at an early stage of autoimmune Addison's disease could lead to preservation or improvement in adrenal steroidogenesis. Design and Intervention: This was an open-label, pilot study of B lymphocyte depletion therapy in new-onset idiopathic primary adrenal failure. Doses of iv rituximab (1 g) were given on d 1 and 15, after pretreatment with 125 mg iv methylprednisolone. Patients and Main Outcome Measures: Six patients (aged 17–47 yr; four females) were treated within 4 wk of the first diagnosis of idiopathic primary adrenal failure. Dynamic testing of adrenal function was performed every 3 months for at least 12 months. Results: Serum cortisol levels declined rapidly and were less than 100 nmol/li...
TL;DR: VLDL can stimulate aldosterone synthesis in adrenocortical cells by increasing StAR and CYP11B2 expression, an event likely mediated by a calcium-initiated signaling cascade, suggesting that calcium is the main signal transduction pathway used by VLDL in adrenal cells.
Abstract: Very low-density lipoproteins (VLDL) are a class of large lipoprotein synthesized in the liver. The key function of VLDL, in vivo, is to carry triglyceride from the liver to adipose tissue. As a steroidogenic organ, the adrenal gland mainly uses lipoproteins as sources of cholesterol. Although VLDL receptors have been detected in the human adrenal, the function of VLDL in the adrenal gland remains unknown. Herein, we used primary cultures of human and bovine adrenal cells and the adrenocortical cell line H295R as models to determine the effects of VLDL on adrenal steroidogenesis. Our studies revealed that VLDL significantly increased aldosterone synthesis in all of the models tested. This increase was largely due to VLDL's stimulation of the expression of steroidogenic acute regulatory (StAR) protein and aldosterone synthase (CYP11B2). VLDL increased CYP11B2 mRNA expression in a concentration-dependent manner. Effects of VLDL on CYP11B2 transcript levels were not additive with angiotensin II or potassium but were additive with the cAMP pathway agonists ACTH and forskolin. Nifedipine completely inhibited the effects of VLDL on CYP11B2 mRNA, suggesting that calcium is the main signal transduction pathway used by VLDL in adrenal cells. Indeed, VLDL increased cytosolic free calcium levels. An in vivo study conducted in sucrose-fed rats showed a positive correlation between elevated triglyceride (VLDL) levels in plasma and CYP11B2 expression in the adrenal. In conclusion, we have shown that VLDL can stimulate aldosterone synthesis in adrenocortical cells by increasing StAR and CYP11B2 expression, an event likely mediated by a calcium-initiated signaling cascade.
TL;DR: The results suggest that Ang II facilitates CYP11B2 activity and the ensuing aldosterone production via activation of AT(1)R-Nox-H(2)O( 2) signaling pathway.
Abstract: Background: The Renin-Angiotensin-Aldosterone-System plays a pivotal role in hypertension. Angiotensin II (Ang II) is a major regulator of aldosterone synthesis and secretion, and it is known to facilitate reactive oxygen species (ROS) generation in many cell types. Aims: Here, we assessed the role of ROS signaling in Ang II-induced aldosterone synthesis by focusing on the regulation of aldosterone synthase (CYP11B2), a cytochrome P450 oxidase that catalyzes the final step in aldosterone biosynthetic pathway. Results: Ang II increased CYP11B2 activity, mRNA and protein with a concomitant elevation of 6-Carboxy- 2′,7′-dichlorodihydrofluorescein diacetate fluorescence, malondialdehyde and protein carbonyl levels (indices of ROS), NADPH oxidase (Nox) activity, and H2O2 levels in human and rat adrenal cortical cells. The expression of nuclear receptor related 1 protein, a transcription factor known to regulate CYP11B2 expression, was also augmented by Ang II. These Ang II-evoked effects were either a...
TL;DR: Although the GIPr is essential for adrenal steroidogenesis and links HF feeding to increased levels of corticosterone, reduced glucocorticoid levels do not significantly contribute to the enhanced metabolic phenotypes in HF-fed Gipr−/− mice.
Abstract: Glucose-dependent insulinotropic polypeptide (GIP) promotes glucose-dependent insulin secretion. However, GIP also enhances glucocorticoid secretion and promotes adiposity. Because obesity and diabetes are glucocorticoid dependent, we examined whether the effects of GIP on energy balance and glycemia are regulated by glucocorticoids using pharmacological activation of GIP receptor (GIPR) signaling with [d-Ala2]GIP in mice and in Y1 adrenocortical cells. Genetic elimination of GIPR activity was also studied in normal- and high-fat (HF)-fed Gipr-deficient (Gipr−/−) mice. [d-Ala2]GIP increased murine corticosterone levels in a GIPR-dependent manner. Conversely, basal corticosterone levels were reduced, whereas food deprivation resulted in significantly enhanced plasma corticosterone levels in Gipr−/− mice. [d-Ala2]GIP increased cAMP levels, activated extracellular signal\x{2013}related kinase (ERK)1/2, increased expression of steroidogenic genes, and increased neutral lipid storage in Y1GIPR cells. Gipr−/− adrenal glands demonstrated a twofold upregulation of the ACTH receptor mRNA and increased sensitivity to ACTH ex vivo. Although HF-fed Gipr−/− mice exhibited significantly lower plasma corticosterone, glucocorticoid-treated HF-fed Gipr−/− mice had similar energy balance and glycemia compared with Gipr+/+ controls. Hence, although the Gipr is essential for adrenal steroidogenesis and links HF feeding to increased levels of corticosterone, reduced glucocorticoid levels do not significantly contribute to the enhanced metabolic phenotypes in HF-fed Gipr−/− mice.
TL;DR: Pigs carrying this SNP could provide a new animal model to study neurobiological and physiological consequences of genetically based GR hypersensitivity and adrenal hypofunction, and provide compelling evidence that SNP c.1829C>T in porcine NR3C1 is a gain-of-function mutation with a major effect on the activity of the adrenal gland.
Abstract: Glucocorticoids produced in the adrenal cortex under the control of the hypothalamic-pituitary axis play a vital role in the maintenance of basal and stress-related homeostasis and influence health and well-being. To identify loci affecting regulation of the hypothalamic-pituitary-adrenal (HPA) axis in the pig we performed a genome-wide association study for two parameters of acute and long-term adrenal activity: plasma cortisol level and adrenal weight. We detected a major quantitative trait locus at the position of the glucocorticoid receptor gene (NR3C1) – a key regulator of HPA axis activity. To determine the causal variant(s), we resequenced the coding region of NR3C1 and found three missense single nucleotide polymorphisms (SNPs). SNP c.1829C>T, leading to a p.Ala610Val substitution in the ligand binding domain, showed large (about 0.6× and 1.2× phenotypic standard deviations for cortisol level and adrenal weight, respectively), and highly significant (2.1E-39≤log10(1/p)≤1.7E+0) negative effects on both traits. We were able to replicate the association in three commercial pig populations with different breed origins. We analyzed effects of the p.Ala610Val substitution on glucocorticoid-induced transcriptional activity of porcine glucocorticoid receptor (GR) in vitro and determined that the substitution introduced by SNP c.1829C>T increased sensitivity of GR by about two-fold. Finally, we found that non-coding polymorphisms in linkage disequilibrium with SNP c.1829C>T have only a minor effect on the expression of NR3C1 in tissues related to the HPA axis. Our findings provide compelling evidence that SNP c.1829C>T in porcine NR3C1 is a gain-of-function mutation with a major effect on the activity of the adrenal gland. Pigs carrying this SNP could provide a new animal model to study neurobiological and physiological consequences of genetically based GR hypersensitivity and adrenal hypofunction.
TL;DR: It is concluded that GATA4 is a key modifier of gonadectomy-induced adrenocortical neoplasia, postovariectomy obesity, and sex steroidogenic cell differentiation.
Abstract: In response to gonadectomy certain inbred mouse strains develop sex steroidogenic adrenocortical neoplasms. One of the hallmarks of neoplastic transformation is expression of GATA4, a transcription factor normally present in gonadal but not adrenal steroidogenic cells of the adult mouse. To show that GATA4 directly modulates adrenocortical tumorigenesis and is not merely a marker of gonadal-like differentiation in the neoplasms, we studied mice with germline or conditional loss-of-function mutations in the Gata4 gene. Germline Gata4 haploinsufficiency was associated with attenuated tumor growth and reduced expression of sex steroidogenic genes in the adrenal glands of ovariectomized B6D2F1 and B6AF1 mice. At 12 months after ovariectomy, wild-type B6D2F1 mice had biochemical and histological evidence of adrenocortical estrogen production, whereas Gata4+/− B6D2F1 mice did not. Germline Gata4 haploinsufficiency exacerbated the secondary phenotype of postovariectomy obesity in B6D2F1 mice, presumably by limiting ectopic estrogen production in the adrenal glands. Amhr2-cre-mediated deletion of floxed Gata4 (Gata4F) in nascent adrenocortical neoplasms of ovariectomized B6.129 mice reduced tumor growth and the expression of gonadal-like markers in a Gata4F dose-dependent manner. We conclude that GATA4 is a key modifier of gonadectomy-induced adrenocortical neoplasia, postovariectomy obesity, and sex steroidogenic cell differentiation.
TL;DR: In oncological patients, especially when the morphological imaging criteria indicate an adrenal metastasis, biopsy of the lesion should be considered after pheochromocytoma is ruled out biochemically, and functional imaging mainly by positron emission tomography (PET) is available using various tracers.
Abstract: Because of the more widespread and frequent use of cross-sectional techniques, mainly computed tomography (CT), an increasing number of adrenal tumors are detected as incidental findings ("incidentalomas"). These incidentaloma patients are much more frequent than those undergoing imaging because of symptoms related to adrenal disease. CT and magnetic resonance imaging (MRI) are in most patients sufficient for characterization and follow-up of the incidentaloma. In a minor portion of patients, biochemical screening reveals a functional tumor and further diagnostic work-up and therapy need to be performed according to the type of hormonal overproduction. In oncological patients, especially when the morphological imaging criteria indicate an adrenal metastasis, biopsy of the lesion should be considered after pheochromocytoma is ruled out biochemically. In the minority of patients in whom CT and MRI fail to characterize the tumor and when time is of essence, functional imaging mainly by positron emission tomography (PET) is available using various tracers. The most used PET tracer, [(18)F]fluoro-deoxy-glucose ((18)FDG), is able to differentiate benign from malignant adrenal tumors in many patients. (11)C-metomidate ((11)C-MTO) is a more specialized PET tracer that binds to the 11-beta-hydroxylase enzyme in the adrenal cortex and thus makes it possible to differ adrenal tumors (benign adrenocortical adenoma and adrenocortical cancer) from those of non-adrenocortical origin.
TL;DR: SF-1 and EMA may be helpful in the differentiation of adrenal tumors from renal tumors in difficult cases.
Abstract: Steroidogenic factor -1 (SF-1) is an orphan member of the nuclear hormone receptor superfamily, and is considered to play an important role in the differentiation of steroidogenic tissues. In this study, we compared the immunohistochemical stains of SF-1 and epithelial membrane antigen (EMA) in non-neoplastic adrenal tissue, and adrenal and renal tumors using tissue microarrays (TMAs). The adrenal tissue array included 19 cases of normal adrenal cortex, 22 cases of adrenal adenoma, and 20 cases of adrenal cortical carcinoma. The renal tissue array included 20 cases of each of the following types of renal cell carcinoma: clear cell, papillary, and chromophobe. In addition, 20 cases of renal oncocytoma were also included in the study. SF-1 showed positive staining in all cases (100%) of normal adrenal cortex and adrenal cortical adenoma, and in 18 (90%) cases of adrenocortical carcinoma. In renal tumors, SF-1 showed negative stains in all of oncocytoma, papillary, and chromophobe renal cell carcinoma. Only 3 out of 20 cases of clear cell renal cell carcinoma showed weak positivity in approximately 10% of tumor cells. EMA stained positively in 85%, 95%, 100%, and 95% of clear cell, papillary, chromophobe renal cell carcinomas, and oncocytomas, respectively. EMA was completely negative in the adrenal TMAs. In conclusion, SF-1 and EMA may be helpful in the differentiation of adrenal tumors from renal tumors in difficult cases.
TL;DR: TheSF-1 gene profile can be used to distinguish malignant from benign adrenocortical tumors, a finding that implicates SF-1 in the development of malignant adrenocortsical carcinoma.
Abstract: The orphan nuclear receptor Steroidogenic Factor-1 (SF-1, NR5A1) is a critical regulator of development and homeostasis of the adrenal cortex and gonads. We recently showed that a complex containing E3 ubiquitin ligase RNF31 and the known SF-1 corepressor DAX-1 (NR0B1) interacts with SF-1 on target promoters and represses transcription of steroidogenic acute regulatory protein (StAR) and aromatase (CYP19) genes. To further evaluate the role of SF-1 in the adrenal cortex and the involvement of RNF31 in SF-1-dependent pathways, we performed genome-wide gene-expression analysis of adrenocortical NCI-H295R cells where SF-1 or RNF31 had been knocked down using RNA interference. We find RNF31 to be deeply connected to cholesterol metabolism and steroid hormone synthesis, strengthening its role as an SF-1 coregulator. We also find intriguing evidence of negative crosstalk between SF-1 and both transforming growth factor (TGF) β and Wnt/β-catenin signaling. This crosstalk could be of importance for adrenogonadal development, maintenance of adrenocortical progenitor cells and the development of adrenocortical carcinoma. Finally, the SF-1 gene profile can be used to distinguish malignant from benign adrenocortical tumors, a finding that implicates SF-1 in the development of malignant adrenocortical carcinoma.
TL;DR: In a model of androgen-producing cells, under stimulated conditions, overexposure to saturated FAs significantly increases androgen production and reduces MEK/ERK activation, which strongly supports a central role of lipotoxicity in PCOS pathophysiology.