Steroid sulphatase deficiency

The hormonal control of parturition

Parturition is a complex physiological process that must occur in a reliable manner and at an appropriate gestation stage to ensure a healthy newborn and mother. To this end, hormones that affect the function of the gravid uterus, especially progesterone (P4), 17β-estradiol (E2), oxytocin (OT), and prostaglandins (PGs), play pivotal roles. P4 via the nuclear P4 receptor (PR) promotes uterine quiescence and for most of pregnancy exerts a dominant block to labor. Loss of the P4 block to parturition in association with a gain in prolabor actions of E2 are key transitions in the hormonal cascade leading to parturition. P4 withdrawal can occur through various mechanisms depending on species and physiological context. Parturition in most species involves inflammation within the uterine tissues and especially at the maternal-fetal interface. Local PGs and other inflammatory mediators may initiate parturition by inducing P4 withdrawal. Withdrawal of the P4 block is coordinated with increased E2 actions to enhance uterotonic signals mediated by OT and PGs to promote uterine contractions, cervix softening, and membrane rupture, i.e., labor. This review examines recent advances in research to understand the hormonal control of parturition, with focus on the roles of P4, E2, PGs, OT, inflammatory cytokines, and placental peptide hormones together with evolutionary biology of and implications for clinical management of human parturition.

Tissue physiology and pathology of aromatase

Aromatase is expressed in multiple tissues, indicating a crucial role for locally produced oestrogens in the differentiation, regulation and normal function of several organs and processes. This review is an overview of the role of aromatase in different tissues under normal physiological conditions and its contribution to the development of some oestrogen-related pathologies.

Cholesterol sulphate sulphohydrolase from human placenta microsomes--purification and properties of the dephosphorylated form of enzyme

The procedure for purification of cholesterol sulphate sulphohydrolase (ChS-ase) from human placenta microsomes was elaborated. The highly purified enzyme preparation (specific activity 2000 nmol x min(-1) x mg protein(-1)) exhibited optimal activity at pH 9.0. The K(m) value was established to be 1.5+/-0.85 x 10(-5) M. The high molecular weight form (200 kDa) and the low molecular weight form (20 kDa) of the enzyme were separated. The interconversion of the high molecular weight variant into the low one occurs under the influence of dephosphorylation. Both forms exhibited typical Michaelis-Menten saturation kinetics. The effect of different compounds on the enzyme activity was tested.

The role of estrogen in the maintenance of primate pregnancy

OBJECTIVE

The aim of this study was to determine the role of estrogen in pregnancy maintenance in baboons by suppressing estrogen synthesis through administration of a highly specific nonsteroidal aromatase inhibitor, CGS 20267.

STUDY DESIGN

CGS 20267 was administered subcutaneously at maximal dosages of 2.0 mg/d to pregnant baboons (n = 24) daily beginning on either day 30 (n = 8), day 60 (n = 8), or day 100 (n = 8) of gestation (normal length of gestation is 184 days) until animals miscarried or were delivered abdominally on days 160 through 168 of gestation. CGS 20267 and estradiol (n = 9), each at maximal dosages of 2 mg/d, were administered at the same intervals of gestation. Twenty baboons served as untreated control animals. Serum estradiol and progesterone levels were determined by radioimmunoassay from serum samples obtained at 1- to 3-day intervals from a maternal peripheral vein.

RESULTS

Within 1 to 3 days of the initiation of CGS 20267 administration, maternal serum estradiol concentration decreased to and remained at a level that was substantially lower (mean +/- SE, 0. 096 +/- 0.003 ng/mL) than in the untreated control animals throughout gestation (0.35-4.0 ng/mL; P <.001). Although pregnancy was maintained in 19 of the 20 untreated control baboons (95%), only 12 of the 24 animals that received CGS 20267 (50%) maintained pregnancy. In contrast, all the baboons treated concomitantly with estradiol and CGS 20267 (9/9) maintained pregnancy. Thus estradiol alone prevented the high rate of miscarriage induced by the antiestrogenic agent CGS 20267. Serum progesterone concentrations were not significantly different throughout the experimental period between the CGS 20267-treated baboons that maintained pregnancy (12. 9 +/- 1.4 ng/mL) and those that miscarried (13.6 +/- 1.6 ng/mL) and were not lower in antiestrogen-treated baboons than in untreated control baboons (10.6 +/- 0.8 ng/mL).

CONCLUSION

Estrogen, acting directly, indirectly, or both through a factor or factors other than the level of progesterone, plays a critically important physiologic role in the maintenance of primate pregnancy.

X-linked ichthyosis: an update

X-linked ichthyosis is a genetic disorder of keratinization characterized by a generalized desquamation of large, adherent, dark brown scales. Extracutaneous manifestations include corneal opacity and cryptorchidism. Since 1978 it has been known that a deficit in steroid sulphatase enzyme (STS) is responsible for the abnormal cutaneous scaling, although the exact physiological mechanism remains uncertain. The STS gene has been mapped to the distal part of the short arm of the X chromosome. Interestingly, this region escapes X chromosome inactivation and has the highest ratio of chromosomal deletions among all genetic disorders, complete deletions having been found in up to 90% of patients. Diagnosis of patients with X-linked ichthyosis and female carriers is based on biochemical and genetic analysis. The latter currently seems to be the most accurate method in the majority of cases.

Higher levels of plasma cholesterol sulfate in patients with liver cirrhosis and hypercholesterolemia

An analytical method for the determination of cholesterol sulfate (CS) in plasma using gas-liquid chromatography was developed. We measured plasma CS concentrations in patients with liver cirrhosis and hypercholesterolemia as examples of disorders that involve aberrations in cholesterol metabolism. Patients with liver cirrhosis had plasma CS concentrations that were significantly higher than those of control subjects (444.6 +/- 51.7 vs. 253.0 +/- 24.6 micrograms/dL, mean +/- SE). The levels of other lipids were lower in cirrhotics, although the differences were not significant. There was no correlation between the levels of CS and sulfated bile acids in cirrhotic patients. CS levels in plasma were also higher in subjects with hypercholesterolemia (413.7 +/- 44.5 micrograms/dL); however, the ratio of CS to total cholesterol (TC) clearly differed between cirrhotics and hypercholesterolemic subjects (1.44 +/- 0.11 x 10(-3) vs. 3.31 +/- 0.63 x 10(-3); P < 0.05). Both in subjects with hypercholesterolemia and in healthy controls, the CS/TC ratio was similar and CS accounted for roughly 0.14% of the TC concentration.

Partial characterization of the steroidsulfatases in Peptococcus niger H4

The strictly anaerobic intestinal Peptococcus niger H4 synthesizes three different steroidsulfatase enzymes: a constitutive arylsulfatase and two inducible alkylsteroidsulfatases. The arylsulfatase desulfates estrogen-3-sulfates and phenylsulfates. The two alkylsteroidsulfatases desulfate, respectively, 3 alpha-sulfates and 3 beta-sulfates of delta 5, 5 alpha, and 5 beta androstanes, pregnanes, and bile acids. Cholesterol-3 beta-sulfate was not desulfated by the alkylsteroidsulfatases nor were steroids or bile acids that were sulfated in positions other than the 3 position. The alkylsteroidsulfatases were induced by their substrates; bile acid sulfates, however, were poor inducers of the 3 beta-sulfatase and did not induce the 3 alpha-sulfatase activity. In intact bacterial cells, taurine and sulfite suppressed the induction of the alkylsteroidsulfatases and inhibited the activity of the arylsulfatase and alkylsteroidsulfatases. In cell homogenates, the arylsulfatase and alkylsteroidsulfatases activities were inhibited by sulfite and sulfate but not by taurine. Our results support the hypothesis that the main function of the steroidsulfatases in P. niger H4 is to provide the bacteria with sulfur for dissimilatory purposes.

Determination of cholesteryl sulphate by isotope dilution-mass spectrometry for diagnosis of steroid sulphatase deficiency

A specific and accurate method for determination of cholesteryl sulphate in serum based on isotope dilution-mass spectrometry has been developed. 2H-labelled cholesteryl sulphate was synthesized and used as internal standard. After addition of the internal standard to serum, the cholesteryl sulphate is extracted with butanol and purified by thin-layer chromatography. The material is then solvolysed, converted into trimethylsilyl ether, and analysed by combined gas chromatography-mass spectrometry. The ratio between unlabelled and labelled cholesterol is determined by selected ion monitoring of the ions at m/e 458 (corresponding to the molecular ion of derivative of unlabelled cholesterol) and m/e 465 (corresponding to the molecular ion of derivative of 2H7-labelled cholesterol). The concentration of cholesteryl sulphate is calculated with use of a standard curve. The coefficient of variation of the method was found to vary between 4% and 9% in different concentration ranges. Nine healthy male infants (age range, 1-3 yr) had concentrations of cholesteryl sulphate varying between 0.2 and 11 mumol/l (mean, 3.8 mumol/l). A boy with suspected steroid sulphatase deficiency had a concentration of cholesteryl sulphate of 69 and 64 mumol/l at the age of 12 and 18 months, respectively.

Plasma cholesteryl sulfate in Friedreich's ataxia

Alteration of membrane fluidity and anomalies of membrane structural proteins have been suspected in Friedreich's ataxia. Plasma lecithin:cholesterol acyltransferase (LCAT) activity is also lowered in this disease, presumably because of a substrate effect. The membrane-stabilizing effect of cholesteryl sulfate (CS) and its inhibitory effect on LCAT activity prompted us to measure this substance in the plasma of Friedreich's ataxia patients as well as in normal subjects and in patients with Charlevoix-Saguenay disease. Plasma cholesteryl sulfate concentrations were significantly higher in Friedreich's ataxia, with levels above the upper limit of normal in nearly half of the cases. This increase was unrelated to age, sex or plasma cholesterol levels, but closely associated with the severity of the disease and thus considered to be secondary. A similar phenomenon (except the association with severity) was observed in Charlevoix-Saguenay ataxia. Levels also tended to be higher in first-degree relatives of Friedreich cases. The significance of these findings is discussed in the light of recent knowledge and experimental data obtained in this laboratory on rats made deficient in essential fatty acids. The highest concentrations of CS observed in Friedreich's ataxia (1097 micrograms/dL, 6 times the normal mean) was only 25% as high as the concentrations reported to inhibit LCAT activity.

Human placental steroid sulphatase--purification and monospecific antibody production in rabbits

Human steroid sulphatase was purified 43-fold from placental microsomes using a four step procedure: solubilization with Miranol H2M, Bio-Gel A 1.5 m chromatography, column chromatofocusing and Sephadex G-75 chromatography. The purified enzyme that appeared electrophoretically homogeneous was used to immunize rabbits. Protein blotting demonstrated that the resulting antiserum mainly reacted with a polypeptide of 63 000 dalton, which is about the size of placental steroid sulphatase. The antiserum was freed from minor impurities by absorbing it to Sepharose 4B with immobilized antigens prepared from a steroid sulphatase deficient placenta.

The nature of placental steroid sulphatase deficiency in man

Human placental steroid sulphatase was partially purified from microsome suspensions of control and steroid sulphatase deficient placentae. After polyacrylamidegel electrophoresis, staining for protein and enzymatic activity revealed that steroid sulphatase from control placenta migrates at Rf = 0.44. In steroid sulphatase deficient microsomes no protein band and only a very faint sulphatase activity band could be detected at Rf = 0.44. Immunoelectrophoresis employing antisera raised against both steroid sulphatase preparations, only gave a protein precipitation line with sulphatase activity when using control placenta microsomes and the antiserum against steroid sulphatase from control placenta. All other placental microsomes-antisera combinations appeared to be negative. Our results strongly suggest that the nature of X-linked steroid sulphatase deficiency is a decreased amount of steroid sulphatase protein.

Human placental steroid sulfatase: purification and properties

Steroid sulfatase is recovered quantitatively from the 105,000 g h supernatant of human placental microsomes extracted with Triton X-100. The solubilized enzyme has been purified using conventional techniques. Throughout the purification procedure, steroid sulfatase appears to be heterogeneous as evidenced by certain, but not all, criteria. Following polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the final preparation exhibits a major component and varying amounts of two minor ones. Antibodies raised in rabbits with the heterogeneous immunogen give rise to a single precipitation line when the native enzyme is analyzed by double immunodiffusion or by immunoelectrophoresis. In addition, using aged preparations of microsomes and immunoaffinity techniques, steroid sulfatase activity was found to be associated with the fastest migrating minor component. This finding would suggest that the apparent heterogeneity of purified steroid sulfatase is linked to degradation processes occurring within the microsomal preparations. Steroid sulfatase has a Stokes radius of 56 A, a sedimentation coefficient of 4.85 +/- 0.15S (in Triton-containing buffers) and binds 1.3 g of Triton X-100-per g of protein. The molecular weight of the Triton-protein complex was calculated to be 166,000 in which the glycoprotein portion contribution is about 43% (72,000). In contrast, the apparent molecular weight of the major polypeptide determined on calibrated SDS-gels is 62,000. The purified enzyme exhibits two pH optima with cholesterol sulfate as substrate, an acidic one at pH 5.0 and a second one at pH 7.5. The Km values for cholesterol sulfate, dehydroandrosterone sulfate and p-nitrophenylsulfate were 5.26, 14 and 1,320 microM, respectively.

The ichthyoses--pathogenesis and prenatal diagnosis: a review of recent advances

Disturbances in the process of normal cornification leading to pathologic scaling provide the pathophysiologic basis for the ichthyoses. These disturbances may result from either abnormalities in protein metabolism (keratinization) (i.e., the "bricks") or in lipid metabolism (i.e., the "mortar") (Fig. 1). The evidence linking the various ichthyoses to defects in protein or lipid metabolism have been reviewed. It is likely that future advances will lead not only to a more complete understanding of the pathogenesis of these disorders, but also will shed significant light on the normal stratum corneum functions of barrier formation and desquamation, as well as lead the way to more rational and effective therapies. In recent years, prenatal diagnosis has been successfully performed in several of the ichthyoses. It is likely that improvements in our ability to prenatally diagnose those disorders will advance hand-in-hand with further progress in unraveling their underlying causes.

Antenatal diagnosis of steroid sulphatase deficiency: case report and literature survey

Steroid sulphatase deficiency is a recently recognised genetically determined inborn error of metabolism. Originally identified as an enzyme disorder of the placenta (commonly termed placental sulphatase deficiency), it is now known that the progeny of affected pregnancies have a generalised steroid sulphatase deficiency and that the enzyme defect persists throughout life. The disorder is characterised clinically by markedly low maternal oestrogen excretion in the presence of normal fetal growth and development. The importance of antenatal diagnosis lies in the differentiation of this disorder from the more ominous fetal defects that result in low oestrogen concentrations. This paper summarises the relevant literature and describes a case in which biochemical tests were used for the antenatal diagnosis of steroid sulphatase deficiency. The pregnancy resulted in a healthy baby boy delivered vaginally after a spontaneous labour.

Review: genetics of steroid sulphatase deficiency and X-linked ichthyosis

Steroid sulphatase deficiency which started out as a curious placental microsomal enzyme deficiency associated with low maternal urinary oestrogen excretion and difficulties in delivery, first described only twelve years ago, has now become a generalized enzyme deficiency associated also with a common skin disease. It turns out not only to be inherited in an X-linked recessive manner, but to be part of a gene cluster which includes the Xg blood group gene and which has been precisely assigned to the distal tip of the short arm of the X-chromosome. This cluster is unique for genes on the X-chromosome in escaping X-inactivation. It remains to be unequivocally demonstrated whether steroid sulphatase is identical to arylsulphatase C or whether these are two enzymes sharing a common polypeptide chain determined by a single gene. However, Rose (1982) presents evidence that one steroid sulphatase is probably identical with arylsulphatase C. It also remains to be conclusively demonstrated whether the gene for the enzyme deficiency is also that for ichthyosis or whether they are two very closely linked genes. If the former is true the role of steroid sulphatase in the abnormal keratinization of ichthyosis is still to be elucidated. Above all the special nature of the DNA in this unique region awaits description.

Antenatal diagnosis of placental sulphatase deficiency

A dynamic test for the antenatal diagnosis of placenta sulphatase deficiency was examined in ten patients, selected on the basis of low urinary oestrogen levels (i.e. below the 10th centile at between 30 and 40 weeks gestation). The test consisted of measurement of plasma oestradiol levels over a period of 120 min after an i.v. injection of dehydroepiandrosterone sulphate. The oestradiol response was vigorous in seven patients, absent in two and small, but significant, in one. The three patients with reduced oestradiol response were also found to have raised levels of urinary steroid monosulphates and thus were probably placental sulphatase deficient. The overall clinical importance of placental sulphatase deficiency and the value of the dehydroepiandrosterone sulphate loading test in antenatal diagnosis are discussed.

Steroid sulfatase of human leukocytes and epidermis and the diagnosis of recessive X-linked ichthyosis

Patients with recessive X-linked ichthyosis, one of the inherited types of excessive stratum corneum cohesion, have deficient steroid sulfatase in fibroblasts grown from their dermis. Because of the expense and long period required to grow such cells, we have assayed this enzyme in peripheral blood leukocytes and found it to be undetectable in those from patients with this type of ichthyosis, but normal in those from patients with other hereditary or acquired types of ichthyosis. In addition, steroid sulfatase activity is less in leukocytes from women who are carriers of this disease than normal women, and this assay can be used to detect such carriers. Despite previous studies demonstrating that the gene for this enzyme escapes the inactivation of other x-chromosome genes, normal women have leukocyte steroid sulfatase activity only 1.3 times that of normal men, suggesting that some gene dosage compensation occurs. Normal human epidermis, the tissue most affected clinically, also expresses steroid sulfatase activity. The epidermal enzyme is similar in its subcellular localization, its molecular size, and kinetically to that of placenta, leukocytes, and fibroblasts.

The causes of low oestrogen excretion in pregnancy: assessment of the fetal contribution by steroid measurements post partum

Oestrogen levels in urine from 21 normotensive and 13 hypertensive pregnant women were moderately correlated (r = 0.48) with levels of 3 beta-hydroxy-5-ene steroids (oestrogen precursors) in urine from their infants. In five infants from otherwise normal pregnancies in which oestrogen excretion was very low, levels of 3 beta-hydroxy-5-ene steroids were significantly lower than normal while there was no difference between hypertensives and normals. Levels of urinary cortisol metabolites in the infants were moderately correlated with 3 beta-hydroxy-5-ene steroids (r = 0.55) and were especially low in 2 out of 5 infants in the series suffering from distress during delivery. We conclude that subnormal fetal steroidogenesis rather than reduced placental metabolism is the most common cause of low oestrogen excretion of unknown aetiology. A factor in the increased perinatal risk in this group may be an associated insufficient cortisol synthesis by the fetus.