Endocrine Abstracts

The characterization and measurement of steroids in health and disease has been a cornerstone of endocrinology since the 1930s. The first example of a diagnostic steroid for an endocrine disorder was the discovery of pregnanetriol in the urine of patients with the adrenogenital syndrome (CAH) by Guy Marrian in 1937. He went on to head the Clinical Endocrinology Research unit in Edinburgh for many years. For decades, paper and TLC dominated metabolomic (urinary steroid) approac...

Gas chromatography–mass spectrometry (GC–MS) has been used for urinary steroid analysis for over 50 years. The process of hydrolysis to release steroids from their conjugates is routinely performed using commercially available snail Helix-Pomatia sulfatase (HP). However, as this is a naturally occurring enzyme its production process results in batch variation and so each batch requires experimental validation to adjust for the difference in efficiency of the enzymati...

Mitochondrial steroidogenic cytochrome P450 (CYP) enzymes, such as P450 side-chain cleavage, rely on electron transfer from the redox partner ferredoxin (FDX1) for catalytic activity. Previous in vitro data suggest these cofactors are key regulators of CYP enzyme activity. This study aims to establish the role of redox regulation on steroidogenesis using zebrafish as a vertebrate in vivo model.In contrast to humans, zebrafish have two F...

In humans, androgen synthesis crucially depends on the enzyme CYP17A1 expressed in adrenals and gonads. The 17,20 lyase activity of CYP17A1 catalyses the key step in human androgen biosynthesis, the conversion of 17-hydroxypregnenolone to the universal sex steroid precursor dehydroepiandrosterone (DHEA). For its catalytic activity, CYP17A1 requires electron transfer from P450 oxidoreductase (POR). Mutations in CYP17A1 and POR are known to disrupt human androgen s...

Steroids present in human serum can be used to identify a number of conditions such as congenital adrenal hyperplasia, Addison’s disease and Cushing’s disorder. Historically this has been completed using immunoassays; currently there is a move towards mass spectrometry which reduces analysis time, cross reactivity and improves sensitivity. When mass spectrometers are coupled with liquid chromatography systems (LC–MS) it is possible to monitor a number of steroid...

Congenital adrenal hyperplasia (CAH) caused by mutations in the electron donor enzyme P450 oxidoreductase (POR) is unique amongst all CAH variants in that it can be associated with ambiguous genitalia (disordered sex differentiation, DSD) both in 46,XX and 46,XY individuals. POR has a pivotal role in facilitating electron transfer from NADPH to microsomal P450 enzymes, including CYP17, which catalyses a key step in human androgen synthesis, the conversion of 17-hydroxypregneno...

P450 oxidoreductase (POR) has a pivotal role as electron donor to all cytochrome P450 enzymes that are microsomally located, i.e. CYP type II enzymes. Importantly, those include key enzymes involved in glucocorticoid and sex steroid biosynthesis such as CYP17 and CYP21. In addition, the activity of hepatic CYP enzymes involved in drug metabolism and detoxification also crucially depend on the transfer of electrons from NADPH via POR. Recently, mutations in P450 oxidoreductase ...

Background: The urinary steroid metabolome is considered the fingerprint of adrenal gland function. Novel methods using mass spectrometry profiling have seen the advent of a new era for metabolomics with powerful implications for both diagnostics and discovery. Its interpretation is difficult and performed by few specialists with the expertise to do so. This makes it a relatively inaccessible tool for the majority of Clinical Endocrinologists.Objective: ...

Dysregulation of the enzymes that control local tissue steroid metabolism has been implicated in the pathogenesis of obesity and insulin resistant states, however longitudinal changes in glucocorticoid metabolism over time have not been investigated. This study was designed to evaluate the role of pre-receptor glucocorticoid metabolism in the development of insulin resistance and obesity. 24 h urinary glucocorticoid and mineralocorticoid metabolites were measured by gas chroma...

Zebrafish has emerged as an important vertebrate in vivo model to study human disease. Steroidogenesis in zebrafish is not well characterised. Human CYP11A1 (hCYP11A1) catalyses the first step of steroidogenesis, the conversion of cholesterol to pregnenolone. Zebrafish Cyp11a1 (zCyp11a1) is essential during embryogenesis. Published data suggest that zCyp11a1 facilitates steroidogenesis in the interrenal (equivalent to mammalian adrenal), gonad and brain. We identified...