Adrenal changes associated with adrenarche

Adrenal androgen production in catarrhine primates and the evolution of adrenarche

Adrenarche is a developmental event involving differentiation of the adrenal gland and production of adrenal androgens, and has been hypothesized to play a role in the extension of the preadolescent phase of human ontogeny. It remains unclear whether any nonhuman primate species shows a similar suite of endocrine, biochemical, and morphological changes as are encompassed by human adrenarche. Here, we report serum concentrations of the adrenal androgens dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) measured in 698 cross-sectional and mixed longitudinal serum samples from catarrhine primates ranging from 0.6 to 47 years of age. DHEAS in Pan is most similar to that of humans in both age-related pattern and absolute levels, and a transient early increase appears to be present in Gorilla. DHEA levels are highest in Cercocebus, Cercopithecus, and Macaca. We also tested for evidence of adaptive evolution in six genes that code for proteins involved in DHEA/S synthesis. Our genetic analyses demonstrate the protein-coding regions of these genes are highly conserved among sampled primates. We describe a tandem gene duplication event probably mediated by a retrotransposon that resulted in two 3-β-hydroxysteroid dehydrogenase/Delta 5-Delta 4 genes (HSD3B1 and HSD3B2) with tissue specific functions in catarrhines. In humans, HSD3B2 is expressed primarily in the adrenals, ovary, and testis, while HSD3B1 is expressed in the placenta. Taken together, our findings suggest that while adrenarche has been suggested to be unique to hominoids, the evolutionary roots for this developmental stage are more ancient.

The syndrome of 17,20 lyase deficiency

CONTEXT

Disorders of steroidogenesis have been instrumental in delineating human steroidogenic pathways. Each genetic disorder seemed to correspond to a different steroidogenic activity, helping to identify several enzymes. Beginning in 1972, several patients have been reported as having "17,20 lyase deficiency," but there have been inconsistent genetic findings.

OBJECTIVE

This manuscript reviews the biochemistry, genetics, and clinical disorders of 17,20 lyase activity, which converts 21-carbon precursors of glucocorticoids to 19-carbon precursors of sex steroids.

FINDINGS

A single enzyme, cytochrome P450c17, catalyzes both 17α-hydroxylase activity and 17,20 lyase activity. The 17,20 lyase activity is especially sensitive to the activities of the accessory proteins P450 oxidoreductase and cytochrome b(5). The first cases of genetically and biochemically proven 17,20 lyase deficiency were reported in 1997, in which specific P450c17 mutations were identified that lost 17,20 lyase activity but not 17α-hydroxylase activity when assayed in vitro. Subsequent work identified other P450c17 mutations and mutations in the genes encoding P450 oxidoreductase and cytochrome b(5). Recently, the initially reported cases from 1972 were found to carry mutations in two aldo-keto reductases, AKR1C2 and AKR1C4. These AKR1C isozymes catalyze 3α-hydroxysteroid dehydrogenase activity in the so-called "backdoor pathway" by which the fetal testis produces dihydrotestosterone without the intermediacy of testosterone.

CONCLUSIONS

17,20 Lyase deficiency should be considered a syndrome with multiple causes, and not a single disease. Study of this very rare disorder has substantially advanced our understanding of the pathways, mechanisms, and control of androgen synthesis. Mutations in other, as-yet unidentified genes may also cause this phenotype.

Prenatal and early life exposure to polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls may influence dehydroepiandrosterone sulfate levels at prepubertal age: results from the Duisburg birth cohort study

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCB) are postulated to act as endocrine disrupters. In the ongoing Duisburg birth cohort study, started in 2000-2002, influence of persistent organic pollutants (POP) on child development was monitored. For the first time, associations were reported between prenatal and postnatal PCDD/F and PCB exposures and early endocrinological changes concerning adrenarchal development. PCDD/F and PCB concentrations were measured in blood samples taken in wk 32 of pregnancy and in breast milk using gas chromatography and high-resolution mass spectrometry (GC/HRMS). At the age of 6-7 and 8-9 yr, serum samples were collected from 111 children. The samples were assayed for the sex hormones testosterone, estradiol, dehydroepiandrosterone sulfate (DHEA-S), and 17-OH-progesterone (17-OHP) by using an automated chemiluminescence assay system. Analyses of repeated measurements of DHEA-S serum levels were performed by linear regression analysis using generalized estimating equations (GEE). Linear regression analysis showed a positive association between DHEA-S and breast milk levels of PCDD/F and PCB expressed as toxicity equivalents according to toxicity equivalent factors published by the World Health Organization (WHO) in 2005 (WHO(2005)-TEq) (increase of 29%, geometric mean ratio, GMR: 1.29, 95% CI 1.06-1. 58 per doubling of PCDD/F + PCB WHO(2005)-TEq levels). Results for the association with the WHO(2005)-TEq levels in blood of mothers were in the same direction (increase of 15%, GMR 1.15, 95% CI 0.93-1.42 per doubling of PCDD/F + PCB WHO(2005)-TEq levels), but not significant. Data indicate that PCDD/F and PCB exposure in infancy may influence DHEA-S serum levels in prepubertal children. Increased DHEA-S serum levels are considered to indicate acceleration of the adrenal maturation.

Premature adrenarche: novel lessons from early onset androgen excess

Adrenarche reflects the maturation of the adrenal zona reticularis resulting in increased secretion of the adrenal androgen precursor DHEA and its sulphate ester DHEAS. Premature adrenarche (PA) is defined by increased levels of DHEA and DHEAS before the age of 8 years in girls and 9 years in boys and the concurrent presence of signs of androgen action including adult-type body odour, oily skin and hair and pubic hair growth. PA is distinct from precocious puberty, which manifests with the development of secondary sexual characteristics including testicular growth and breast development. Idiopathic PA (IPA) has long been considered an extreme of normal variation, but emerging evidence links IPA to an increased risk of developing the metabolic syndrome (MS) and thus ultimately cardiovascular morbidity. Areas of controversy include the question whether IPA in girls is associated with a higher rate of progression to the polycystic ovary syndrome (PCOS) and whether low birth weight increases the risk of developing IPA. The recent discoveries of two novel monogenic causes of early onset androgen excess, apparent cortisone reductase deficiency and apparent DHEA sulphotransferase deficiency, support the notion that PA may represent a forerunner condition for PCOS. Future research including carefully designed longitudinal studies is required to address the apparent link between early onset androgen excess and the development of insulin resistance and the MS.

Approach to the girl with early onset of pubic hair

Premature pubarche, or the development of pubic hair before the age of 8 in girls or 9 in boys, is most commonly caused by premature adrenarche. Adrenarche is the maturation of the adrenal zona reticularis in both boys and girls, resulting in the development of pubic hair, axillary hair, and adult apocrine body odor. Although originally thought to be a benign variant of normal development, premature adrenarche has been associated with insulin resistance and the later development of metabolic syndrome and polycystic ovary syndrome. Although further studies are needed to confirm these relationships, the case presented herein argues for periodic assessment of children at risk. Indeed, recognition of these associations may allow for early preventive measures.

Clinical, biochemical, and molecular characterization of macronodular adrenocortical hyperplasia of the zona reticularis: a new syndrome

CONTEXT

Macronodular adrenocortical hyperplasia classically presents with progressive hypercortisolemia and Cushing syndrome. We describe a 29-yr-old man with massive macronodular adrenocortical hyperplasia without hypercortisolemia but rather markedly elevated and nonsuppressible production of dehydroepiandrosterone (DHEA) and its sulfate (DHEAS).

OBJECTIVE

To characterize the clinical and molecular features of this case and to determine whether the tissue biochemically resembles the zona reticularis or fetal adrenal.

SETTING

University clinic, hospital, and laboratories.

DESIGN

Static and dynamic blood and urine testing were performed preoperatively. Tissue was studied by light microscopy, immunoblot, RNA microarray, and enzyme assay.

PARTICIPANT

A 29-yr-old man with incidentally discovered bilateral adrenal enlargement.

INTERVENTION

Bilateral adrenalectomy.

MAIN OUTCOME MEASURES

Molecular studies compared with control samples.

RESULTS

Hypercortisolism and 21-hydroxylase deficiency were excluded. DHEA, DHEAS, and 17-hydroxypregnenolone were markedly elevated and did not suppress with dexamethasone 2 mg/d for 4 d. Homogenates of the adrenals demonstrated high 17-hydroxylase, good 17,20-lyase, and low or absent 21-hydroxylase and 3β-hydroxysteroid dehydrogenase activities. Immunoblots confirmed robust expression of cytochrome P450c17 and AKR1C3 but not P450c21. Microarray analysis demonstrated high CYP11A1 and CYP17A1 expression but low or absent HSD3B1, HSD3B2, and CYP21A2 expression. Expression of mRNA for cytochrome b(5) (CYB5A) and AKR1C3, markers of the zona reticularis, were markedly elevated.

CONCLUSION

This is the first case of macronodular hyperplasia of the adrenal zona reticularis confirmed with studies of enzyme activity, mRNA expression, and protein identification. We speculate that this condition can be clinically silent in men but might cause severe hyperandrogenemia in women.

Concomitant mutations in the P450 oxidoreductase and androgen receptor genes presenting with 46,XY disordered sex development and androgenization at adrenarche

CONTEXT

Undervirilization in males, i.e. 46,XY disordered sex development (46,XY DSD), is commonly caused by either lack of androgen action due to mutant androgen receptor (AR) or deficient androgen synthesis, e.g. due to mutations in 17alpha-hydroxylase (CYP17A1). Like all other microsomal cytochrome P450 (CYP) enzymes, CYP17A1 requires electron transfer from P450 oxidoreductase (POR).

OBJECTIVE

The objective of the study was to analyze the clinical and biochemical phenotype in a 46,XY individual carrying concomitant POR and AR mutations and to dissect their impact on phenotypic expression.

METHODS

We characterized the clinical and biochemical phenotype, genetic identification, and functional analysis of POR missense mutation by yeast micrososomal coexpression assays for CYP17A1, CYP21A2 and CYP19A1 activities.

RESULTS

The patient presented neonatally with 46,XY DSD and was diagnosed as partial androgen insensitivity syndrome carrying a disease causing AR mutation (p.Q798E). She was raised as a girl and gonadectomized at the age of 4 yr. At 9 yr progressive clitoral enlargement prompted reassessment. Urinary steroid analysis was indicative of POR deficiency, but surprisingly androgen production was normal. Genetic analysis identified compound heterozygous POR mutations (p.601fsX12/p.Y607C). In vitro analysis confirmed p.Y607C as a pathogenic mutation with differential inhibition of steroidogenic CYP enzymes.

CONCLUSION

Both mutant AR and POR are likely to contribute to the neonatal presentation with 46,XY DSD. Virilization at the time of adrenarche appears to suggest an age-dependent, diminishing disruptive effect of both mutant proteins. This case further highlights the importance to assess both gonadal and adrenal function in patients with 46,XY DSD.

Assessment of circulating sex steroid levels in prepubertal and pubertal boys and girls by a novel ultrasensitive gas chromatography-tandem mass spectrometry method

CONTEXT

Estrogens and androgens play key roles for pubertal onset and sexual maturation. Most currently used immunoassays are not sensitive enough to accurately measure the low circulating levels of sex steroids in children without any signs of puberty. However, this does not exclude that sex steroids have important biological roles in prepubertal children.

OBJECTIVES

To accurately determine levels of sex steroid hormones and their metabolites in serum of healthy children before any physical signs of puberty and to evaluate possible sex differences.

MAIN OUTCOME MEASURES

Total (unconjugated plus conjugated) serum levels of 17beta-testosterone, 17alpha-testosterone, 5alpha-dihydrotestosterone, 5beta-dihydrotestosterone, androsterone, etiocholanolone, estradiol, and estrone measured by an ultrasensitive method based on gas chromatography-tandem mass spectrometry in samples from 81 healthy schoolchildren (42 boys) without any signs of puberty. For comparison, 48 pubertal children were studied.

RESULTS

17beta-Estradiol levels in prepubertal boys were undetectable or extremely low (median < 3.7 pmol/liter), whereas levels in prepubertal girls were significantly higher (median 9.6 pmol/liter, P < 0.001). Among the older prepubertal children (>8 yr), girls had significantly higher androsterone (4.07 vs. 1.45 nmol/liter, P < 0.05), etiocholanolone (5.45 vs. 1.95 nmol/liter, P < 0.0001), 5alpha-dihydrotestosterone (0.11 vs. <0.10 nmol/liter, P < 0.01), and 17beta-testosterone concentrations (0.69 vs. 0.47 nmol/liter, P < 0.05) compared with similarly aged prepubertal boys.

CONCLUSION

Using an accurate and sensitive method, we found significantly higher levels of estrogens as well as androgen metabolites in prepubertal girls compared with age-matched boys. The higher prepubertal sex steroid levels in girls may contribute to their earlier onset of puberty including pubic hair development.

The mediator complex subunit 1 enhances transcription of genes needed for adrenal androgen production

There are three enzymes involved in the biosynthesis of the adrenal androgen dehydroepiandrosterone (DHEA) sulfate. Cholesterol side-chain cleavage (CYP11A1) and 17alpha-hydroxylase/17,20-lyase (CYP17) metabolize cholesterol into DHEA, whereas steroid sulfotransferase family 2A1 (SULT2A1) is responsible for conversion of DHEA to DHEA sulfate. We previously examined the mechanisms regulating CYP11A1, CYP17, and SULT2A1 transcription and found that each is regulated, in part, by the transcription factor GATA-6. Previous studies suggested that mediator complex subunit 1 (MED1, also called PPARBP or TRAP220) is a cofactor involved in not only the regulation of nuclear receptors but also the activation of GATA-6 transcription. Herein we demonstrated a role for MED1 in the regulation of CYP11A1, CYP17, and SULT2A1 transcription. Transient transfection assays with SULT2A1 deletion and mutation promoter constructs allowed the determination of specific the GATA-6 binding cis-regulatory elements necessary for transactivation of SULT2A1 transcription. Binding of MED1 and GATA-6 was confirmed by coimmunoprecipitation/Western analysis and chromatin immunoprecipitation assay. We demonstrated expression of MED1 mRNA and protein in the human adrenal and determined that knockdown of MED1 expression via specific small interfering RNA attenuated CYP11A1, CYP17, and SULT2A1 expression levels in H295R cells. In addition, we demonstrated that MED1 enhanced GATA-6 stimulated transcription of promoter constructs for each of these genes. Moreover, the activity of MED1 for SULT2A1 promoter was mediated by GATA-6 via the -190 GATA-binding site. These data support the hypothesis that MED1 and GATA-6 are key regulators of SULT2A1 expression, and they play important roles in adrenal androgen production.