Absence of testicular steroid sulphatase activity in a boy with recessive X-linked ichthyosis and testicular maldescent

Transporter for sulfated steroid hormones in the testis - expression pattern, biological significance and implications for fertility in men and rodents

In various tissues, steroid hormones may be sulfated, glucuronidated or otherwise modified. For a long time, these hydrophilic molecules have been considered to be merely inactive metabolites for excretion via bile or urine. Nevertheless, different organs such as the placenta and breast tissue produce large amounts of sulfated steroids. After the discovery of the enzyme steroid sulfatase, which is able to re-activate sulfated steroids, these precursor molecules entered the focus of interest again as a local supply for steroid hormone synthesis with a prolonged half-life compared to their unconjugated counterparts. The first descriptions of this so-called sulfatase pathway in the placenta and breast tissue (with special regards to hormone-dependent breast cancer) were quickly followed by studies of steroid sulfate production and function in the testis. These hydrophilic molecules may not permeate the cell membrane by diffusion in the way that unbound steroids can, but need to be transported through the plasma membrane by transport systems. In the testis, a functional sulfatase pathway requires the expression of specific uptake carrier and efflux transporters in testicular cells, i.e. Sertoli, Leydig and germ cells. Main focus has to be placed on Sertoli cells, as these cells build up the blood-testis barrier. In this review, an overview of carrier expression pattern in the human as well as rodent testis is provided with special interest towards implications on fertility.

The Regulation of Steroid Action by Sulfation and Desulfation

Steroid sulfation and desulfation are fundamental pathways vital for a functional vertebrate endocrine system. After biosynthesis, hydrophobic steroids are sulfated to expedite circulatory transit. Target cells express transmembrane organic anion-transporting polypeptides that facilitate cellular uptake of sulfated steroids. Once intracellular, sulfatases hydrolyze these steroid sulfate esters to their unconjugated, and usually active, forms. Because most steroids can be sulfated, including cholesterol, pregnenolone, dehydroepiandrosterone, and estrone, understanding the function, tissue distribution, and regulation of sulfation and desulfation processes provides significant insights into normal endocrine function. Not surprisingly, dysregulation of these pathways is associated with numerous pathologies, including steroid-dependent cancers, polycystic ovary syndrome, and X-linked ichthyosis. Here we provide a comprehensive examination of our current knowledge of endocrine-related sulfation and desulfation pathways. We describe the interplay between sulfatases and sulfotransferases, showing how their expression and regulation influences steroid action. Furthermore, we address the role that organic anion-transporting polypeptides play in regulating intracellular steroid concentrations and how their expression patterns influence many pathologies, especially cancer. Finally, the recent advances in pharmacologically targeting steroidogenic pathways will be examined.

Membrane transporters for sulfated steroids in the human testis--cellular localization, expression pattern and functional analysis

Sulfated steroid hormones are commonly considered to be biologically inactive metabolites, but may be reactivated by the steroid sulfatase into biologically active free steroids, thereby having regulatory function via nuclear androgen and estrogen receptors which are widespread in the testis. However, a prerequisite for this mode of action would be a carrier-mediated import of the hydrophilic steroid sulfate molecules into specific target cells in reproductive tissues such as the testis. In the present study we detected predominant expression of the Sodium-dependent Organic Anion Transporter (SOAT), the Organic Anion Transporting Polypeptide 6A1, and the Organic Solute Carrier Partner 1 in human testis biopsies. All of these showed significantly lower or even absent mRNA expression in severe disorders of spermatogenesis (arrest at the level of spermatocytes or spermatogonia, Sertoli cell only syndrome). Only SOAT was significantly lower expressed in biopsies showing hypospermatogenesis. By use of immunohistochemistry SOAT was localized to germ cells at various stages in human testis biopsies showing normal spermatogenesis. SOAT immunoreactivity was detected in zygotene primary spermatocytes of stage V, pachytene spermatocytes of all stages (I–V), secondary spermatocytes of stage VI, and round spermatids (step 1 and step 2) in stages I and II. Furthermore, SOAT transport function for steroid sulfates was analyzed with a novel liquid chromatography tandem mass spectrometry procedure capable of profiling steroid sulfate molecules from cell lysates. With this technique, the cellular inward-directed SOAT transport was verified for the established substrates dehydroepiandrosterone sulfate and estrone-3-sulfate. Additionally, β-estradiol-3-sulfate and androstenediol-3-sulfate were identified as novel SOAT substrates.

Steroid metabolism and profile of steroidogenic gene expression in Episkin: high similarity with human epidermis

The skin is a well-recognized site of steroid formation and metabolism. Episkin is a cultured human epidermis. In this report, we investigate whether Episkin possesses a steroidogenic machinery able to metabolize adrenal steroid precursors into active steroids. Episkin was incubated with [14C]-dehydroepiandrosterone (DHEA) and 4-androstenedione (4-dione) and their metabolites were analyzed by liquid chromatography/mass spectrometry (LC/MS/MS). The results show that the major product of DHEA metabolism in Episkin is DHEA sulfate (DHEAS) (88% of the metabolites) while the other metabolites are 7alpha-OH-DHEA (8.2%), 4-dione (1.3%), 5-androstenediol (1.3%), dihydrotestosterone (DHT) (1.4%) and androsterone (ADT) (2.3%). When 4-dione is used as substrate, much higher levels of C19-steroids are produced with ADT representing 77% of the metabolites. These data indicate that 5alpha-reductase, 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and 3alpha-hydroxysteroid dehdyrogenase (3alpha-HSD) activities are present at moderate levels in Episkin, while 3beta-HSD activity is low and represents a rate-limiting step in the conversion of DHEA into C19-steroids. Using realtime PCR, we have measured the level of mRNAs encoding the steroidogenic enzymes in Episkin. A good agreement is found between the mRNAs expression in Episkin and the metabolic profile. High expression levels of steroid sulfotransferase SULT2B1B and type 3 3alpha-HSD (AKR1C2) correspond to the high levels of DHEA sulfate (DHEAS) and ADT formed from DHEA and 4-dione, respectively. 3beta-HSD is almost undetectable while the other enzymes such as type 1 5alpha-reductase, types 2, 4, 5, 7, 8, and 10 17beta-HSD and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) (AKR1C1) are highly expressed. Except for UGT-glucuronosyl transferase, similar mRNA expression profiles between Episkin and human epidermis are observed.

Testis cancer. Ichthyosis constitutes a significant risk factor

Testis cancer and ichthyosis are both relatively rare diseases. Hence the finding of six individuals with both these conditions in a small population with testicular cancer is highly conspicuous and indicates some kind of connection among such persons. Despite the identical clinical appearances of their ichthyoses, three of the ichthyotic subjects had no measurable activity of the enzyme, steroid sulfatase (STS) in leucocytes, a distinct characteristic of recessive X-linked ichthyosis (RXLI). However, the remaining three subjects had normal STS activity, a strong indicator of autosomal dominant ichthyosis (ADI). The STS activity in patients with testicular cancer who do not have ichthyosis (N = 30) was also within the normal range. The patients with testicular cancer with no skin disease had elevated serum levels of 4-androstenedione (4-AD), follicle stimulating hormone (FSH), and luteinizing hormone (LH) but had reduced levels of estrone and estrone sulfate. The other serum parameters measured did not significantly differ from normal levels. In essence, the hormone levels obtained for the patients with ichthyotic testicular cancer followed the same pattern, although their dehydroepiandrosterone sulfate (DHEAS) and estrone sulfate levels tended to be slightly higher than normal. However, no conspicuous aberrations in any of the parameters examined were observed, and why men with ichthyosis are at high risk for testicular cancer remains an unresolved issue.

Steroid sulfatase activity in nails: screening for X-linked ichthyosis

X-linked ichthyosis is generally diagnosed by a deficiency of steroid sulfatase activity in fibroblasts or leukocytes. We established a method of assaying nail steroid sulfatase activity for diagnostic use. Nail samples were easy to collect and handle, and satisfied the screening criteria of accuracy, sensitivity, and stability. The detergents Tween 20 and Triton-X 100, which enhance nail STS activity, enabled us to assay the activity with small amounts of nails. The detergent-facilitated assay was also suitable for use with pediatric patients, from whom small amounts of nails were collected.

Cloning of a cDNA for steroid sulfatase: frequent occurrence of gene deletions in patients with recessive X chromosome-linked ichthyosis

A human steroid sulfatase (steryl-sulfatase; steryl-sulfate sulfohydrolase, EC 3.1.6.2) cDNA 2.4 kilobases long was isolated from a human placental lambda gt11 cDNA expression library. The library was screened with monospecific rabbit antibodies elicited by injection of steroid sulfatase protein purified from human placentas. Hybridization of the cDNA with EcoRI-digested genomic DNA indicated that patients from 14 of 15 apparently unrelated families have gross deletions of the gene for steroid sulfatase. One patient had genomic DNA fragments that were identical to those from normal individuals, indicating the absence of any major deletions as the cause of his lack of steroid sulfatase enzyme activity.

Steroid sulphatase deficiency disease

Seventy-six ichthyotic male patients with a biochemically confirmed diagnosis of steroid sulphatase deficiency are reported. Ascertainment was based on either a previous diagnosis of placental steroid sulphatase deficiency (21 probands and 15 secondary cases), or ichthyosis with steroid sulphatase deficiency (29 probands and 11 secondary cases). The ichthyotic phenotype of the first group was indistinguishable from that of the other group, and completely fitting the classic description of recessive X-linked ichthyosis. A prominent skin peeling in early infancy was found to be a characteristic feature of this syndrome. Maldescent of the testis was registered in 9 patients; and testis cancer had been diagnosed in 2 males with normally descended gonads. This high proportion of patients with gonadal abnormalities strongly indicates a relation with the steroid sulphatase deficiency. Corneal opacities, not affecting visual acuity, were seen in 14 out of 28 males by slit-lamp examination.