A sensitive HPLC method for the assessment of metabolic conversion of estrogens

Disorders of estrogen-responsive tissues are frequently associated with aberrations in steroid metabolism due to altered expression of synthesizing and metabolizing enzymes. For instance, overexposure to unopposed 17beta-estradiol has been associated with the pathogenesis of endometrial proliferative disorders, such as endometriosis. Investigations into the metabolic conversion in tissues and cells have been rather limited. This is mostly due to fact that such studies have to make use of radioactive steroid hormones and expensive equipment to obtain sufficient sensitivity. We adapted a sensitive non-radioactive HPLC method to study estrogen metabolism in more detail. This HPLC method is based on the solid phase extraction of estrogens and the derivatization of the steroids with 2-(4-carboxy-phenyl)-5,6-dimethylbenzimidazole. The technique is sensitive, robust and is useful for the detection of aromatase, 17beta-HSD types 1 and 2 and sulfatase activities in lysates of placenta and endometrium.

Induction of endometriosis in the marmoset monkey (Callithrix jacchus)

Endometriosis is an estrogen-dependent gynaecological disease associated with pain and infertility, which occurs in humans and menstruating primates. In this study, the marmoset monkey (Callithrix jacchus), which is a non-menstruating primate with high circulating estrogen levels, was used to test firstly the hypothesis that endometriosis is based on uterine shedding into the peritoneal cavity, secondly to study the pathogenesis of endometriosis due to its estrogenic situation. Female marmoset monkeys (n = 29) were exposed to two different experimental procedures (non-invasive versus invasive) for intrapelvic placement of endometrial cells by uterine flushing over an experimental period of 2-3 years. First endometriotic foci were detected by colour Doppler ultrasound at the bladder, the uterus and the ovaries at the earliest after 4 months of either treatments. However, invasive induction was more effective in terms of the time-course of induction and the number of resulting endometriotic foci. The analysis of the endometriotic foci by histology, immunohistochemistry and molecular techniques allowed a division into two distinct groups: an initial developing stage occurred, which under further treatment led to the second stage of established endometriosis. Both procedures showed a treatment-dependent increase of vascular supply to the endometriotic foci over the experimental period. The invasive method induced the final established stage of endometriosis more rapidly, with the expression of steroid receptors, aromatase, 17betaHSD1 and CD10. Altogether, 72% of the treated marmoset monkeys developed endometriosis under our endometrial reflux protocols. Our data support the theory that endometriosis can be induced artificially in a non-menstruating primate (C. jacchus) by endometrial shedding into the peritoneal cavity. Because the marmoset is a primate with very high peripheral estrogen levels, this offers an interesting model for studying the pathogenesis of this estrogen-dependent disease, as well as for therapeutic impacts on enzymes involved in steroid metabolism.

Evaluation of inhibitors for 17beta-hydroxysteroid dehydrogenase type 1 in vivo in immunodeficient mice inoculated with MCF-7 cells stably expressing the recombinant human enzyme

17Beta-hydroxysteroid dehydrogenase (17HSD1) is an enzyme activating estrone (E1) to estradiol (E2). In the present study, a mechanistic animal model was set up for evaluating putative inhibitors for the human enzyme in vivo. Estrogen-dependent MCF-7 human breast carcinoma cells were stably transfected with a plasmid expressing human 17HSD1. These cells formed estrogen-dependent tumors in immunodeficient mice. In the optimized model, tumor sizes were decreased in both ovariectomized and intact vehicle-treated mice, whereas they were maintained or slightly increased in mice supplemented 2 weeks with an appropriate dose of the 17HSD1-substrate E1. Tumor sizes in mice treated with 0.1 micromol/kg/d of E1 were reduced by administering 5 micromol/kg/d of different 17HSD1-inhibitors and a 86% reduction in size was detected with the most potent inhibitor. A dose-response relationship in the inhibitory effect of this compound further confirmed the validity of the model for testing the drug candidates in vivo.

Characterization of 17beta-hydroxysteroid dehydrogenase type 7 in reproductive tissues of the marmoset monkey

In contrast to the known rodent enzymes, the physiological significance of 17beta-hydroxysteroid dehydrogenase type 7 (17HSD7) and its presumed function in reproductive biology is not well understood in primates. As a first step, we recently cloned the complete coding regions of human and marmoset monkey (Callithrix jacchus) 17HSD7 (cj17HSD7). In the present work the complete cDNA of marmoset 17HSD1 (cj17HSD1), including the proximal promoter region, and a partial sequence of marmoset aromatase (cjARO) were sequenced in order to compare the expression of these estradiol synthesizing enzymes with that of 17HSD7 in a primate model and to identify tissues where 17HSD7 might participate in the pathway of estradiol synthesis. The gene structures of cj17HSD1 and cj17HSD7 were determined and proved to be very similar to the human orthologues. Northern hybridization showed that cjARO mRNA seems to be coexpressed preferably with cj17HSD1 in placenta, whereas in other tissues it is expressed in parallel only with cj17HSD7. Especially in corpora lutea, the cj17HSD7 transcript is detectable throughout the luteal phase of the ovarian cycle and increases during pregnancy, in parallel with the transcript of aromatase. Results were confirmed by immunoblots and immunohistochemistry using new polyclonal antisera directed against cj17HSD7 and cjARO protein. The enzymatic conversion of estrone to estradiol was assessed in marmoset corpora lutea. The pattern of coexpression with aromatase supports the hypothesis that luteal 17HSD7 complements placental 17HSD1, ensuring continued estradiol synthesis throughout pregnancy in primates.

Relaxin enhances in-vitro invasiveness of breast cancer cell lines by up-regulation of matrix metalloproteases

Until recently, relaxin (RLX) has been known predominantly for its effects on the reproductive system, where it induces remodelling of the extracellular matrix and up-regulation of matrix metalloproteases (MMPs). In solid cancers, tissue remodelling and MMP activation are essential for invasion and metastasis. We therefore investigated the effect of RLX on invasiveness and MMP expression of human breast cancer cell lines. Upon incubation with porcine RLX, the invasiveness of SK-BR3 cells was significantly increased. Similar effects could be achieved in MCF-7 cells, especially when RLX was combined with epidermal growth factor. Enhanced invasiveness was accompanied by up-regulation of MMP production and could be almost completely blocked by the MMP inhibitor FN 439. Zymography revealed increased secretion of MMP-2, -7 and -9, associated with up-regulated mRNA concentrations of MMP-2, -9, -13 and -14. mRNA expression levels of MMP-1, -3, -7, -8, -10, -11, -12 and of tissue inhibitors of metalloproteases-1, -2, -3 and -4 were either very low or not detectably influenced by RLX. Taken together, RLX enhances in-vitro invasiveness of breast cancer cell lines by induction of MMP expression. It remains to be clarified whether RLX might play a similar role in vivo and promote tumour progression.

Mechanisms of estradiol inactivation in primate endometrium

In uterine endometrium, the level of estradiol is controlled by oxidative 17beta-hydroxysteroid dehydrogenase (17HSD) activity which converts the bioactive hormone to the less active compound estrone. At least three different types of 17HSD (types 2, 4 and 8) use estradiol as their preferred substrate and may contribute to the overall rate of estradiol-inactivation in the uterus. In this study the marmoset monkey (Callithrix jacchus) was used for the investigation of the particular contribution of each type of 17HSD. Northern Blots revealed essentially the same tissue distribution as in the human. Likewise, uterine 17HSD enzyme activity increases in the secretory phase of the reproductive cycle, in parallel to the rise in circulating progesterone levels. Northern analysis of uteri from defined time points of the reproductive cycle showed that only the level of 17HSD2 expression is strongly upregulated in the secretory phase, whereas 17HSD4 and 17HSD8 seem to be expressed constitutively.

Expression of the estradiol-synthesizing 17beta-hydroxysteroid dehydrogenases type 1 and type 7 in the nonhuman primate Callithrix jacchus

The common marmoset monkey (Callithrix jacchus) was used as a primate model for the study of the expression of the estradiol synthesizing enzymes 17beta-hydroxysteroid dehydrogenase type 1 and type 7 (17HSD1 and 17HSD7). The tissue-specific expression of 17HSD1 and 17HSD7 mRNA in Callithrix jacchus and human as shown by Northern Blot analysis revealed strong similarities between the two species. After cloning of the marmoset-specific coding cDNA sequence of 17HSD7 a similarity of 95% to the known human sequences was found. To elucidate the physiological function of 17HSD7 which is thought to be different to that of the well-known 17HSD1, the regulation of 17HSD7 expression in the corpus luteum was investigated. It was shown to be upregulated during the luteal phase of the reproductive cycle and during early pregnancy, when the primate corpus luteum is most active in estradiol synthesis, whereas 17HSD1 was not detectable in this tissue at any time.

Differential expression of 17beta-hydroxysteroid dehydrogenases types 2 and 4 in human endometrial epithelial cell lines

In the endometrium two enzymes are known to convert estradiol to its inactive metabolite estrone: microsomal 17beta-hydroxysteroid dehydrogenase type 2 (17beta-HSD2) and peroxisomal 17beta-HSD4. In order to elucidate the particular function of each of these two different enzymes, the human endometrial epithelial cell lines HEC-1-A and RL95-2 were examined with respect to the expression of 17betaHSD isozymes. They were compared with human endometrium in vivo. Non-radioactive in situ hybridization revealed both enzymes in glandular epithelial cells of human endometrium. The two cell lines were screened for mRNA expression of 17beta-HSD 1-4 by RT-PCR and Northern blot. 17beta-HSD2 and 4 could be detected by either method, 17beta-HSD1 only by RT-PCR, 17beta-HSD3 not at all. Both cell lines were proven to have no receptor for progesterone which is known as a physiological inducer of several 17beta-HSD isozymes. To study the regulation of 17beta-HSD2 and 17betaHSD4, the concentration of fetal calf serum in the cell culture media was reduced stepwise to 0.3% by dilution with a defined serum replacement. This treatment led to an inhibition of 17beta-HSD2 mRNA expression and an increase in the mRNA expression of 17beta-HSD4. Concomitantly, distinct morphological changes were observed, such as a decrease in the number and length of microvilli and a decrease in the formation of domes on top of the monolayers. The endometrial epithelial cell lines HEC-1-A and RL95-2 represent a suitable in vitro model for further studies of the differential expression of the major endometrial HSD isozymes, independent of the effect of progesterone.

Expression of the integrin subunits alpha 5, alpha 6 and beta 1 in the testes of the common marmoset

Integrin subunits alpha 5, alpha 6 and beta 1 were localized in the testis of pre-pubertal or adult non-human primates (Callithrix jacchus) by immunofluorescence staining and in situ hybridization. In animals of all ages subunits alpha 5 and beta 1 were localized in cells of the lamina propria of the seminiferous epithelium. In prepubertal animals, the integrin subunits alpha 5, alpha 6, as well as beta 1, were distributed all over the plasma membrane of Sertoli cells. In adult animals the integrin subunits were confined to those plasma membrane regions of Sertoli cells which are assigned to the basal compartment, including the basement membrane of the seminiferous tubules. Protein expression of integrin subunits alpha 6 and beta 1 was most pronounced in tubular stages in which elongated spermatids were not yet present in the adluminal compartment of the epithelium, suggesting that these integrin subunits are particularly essential at certain developmental stages of spermatogenesis. Non-radioactive in situ hybridization revealed that the mRNA for integrin subunits alpha 5, alpha 6 and beta 1 was expressed by Sertoli cells. In situ hybridization, together with immunofluorescence data, shows that these integrin subunits were exclusively synthesized in Sertoli cells. As to functional aspects, it is concluded that during primate spermatogenesis. Sertoli cell integrins may be involved in both cell matrix as well as cell-cell interactions, particularly during early spermatogenesis.

Chemical micropatterning of polymeric cell culture substrates using low-pressure hydrogen gas discharge plasmas

Micropatterned cell cultures will allow a new quality of bioartificial systems. Here, an approach to chemical micropatterning of polymer substrates is presented, which is completely based on low pressure gas discharge processes. Well expressed micropatterned cell cultures on polystyrene and poly (ether ether ketone) were obtained with many different cell types. No impairment of typical cell behavior was observed.

Glycodelin mRNA is expressed in the genital tract of male and female rats (Rattus norvegicus)

In the present study we demonstrate for the first time the expression of glycodelin mRNA in the female and male genital tracts of rats using non-radioactive in situ hybridisation. Glycodelin fragment 1 (+41 to +141) shares 100% homology with the human gene sequence. In the ovary, glycodelin mRNA was restricted to granulosa cells. In the uterus, glycodelin mRNA was expressed in all epithelial cells of the endometrium. In the male reproductive tract, glycodelin mRNA was distributed in all epithelial cells of the epididymis, the prostate and the seminal vesicle. However, in the testis, glycodelin mRNA was predominantly found in spermatogonia and in spermatocytes of the seminiferous epithelium. The expression in several reproductive organs of rats offers an excellent tool to study further the physiological role of glycodelin, which is so far thought to act as an immunosuppressive factor.

Characterization of the HSD17B4 gene: D-specific multifunctional protein 2/17beta-hydroxysteroid dehydrogenase IV

The HSD17B4 gene codes for a 80 kDa multifunctional enzyme containing three distinct functional domains and is localized in peroxisomes. The N-terminal part exhibits 3-hydroxyacyl-CoA dehydrogenase and 17beta-hydroxysteroid dehydrogenase activity whereas the central part shows enoyl-CoA hydratase activity. The carboxy-terminal part of the protein has sterol-carrier-protein activity. The protein is widely expressed, however in several tissues like brain, uterus and lung its expression is limited to specific cells like Purkinje cells or luminal epithelium. The HSD17B4 gene consist of 24 exons and 23 introns with classical intron-exon junctions spanning more than 100 kbp. The importance of the HSD17B4 protein is stressed by the identification of patients with severe clinical abnormalities due to mutations in the HSD17B4 gene. We have now checked the consequences of one frequent mutation, G16 S, which results in inactivation of the enzyme due to loss of interaction with NAD+.

Peroxisome targeting of porcine 17beta-hydroxysteroid dehydrogenase type IV/D-specific multifunctional protein 2 is mediated by its C-terminal tripeptide AKI

The product of the porcine HSD17B4 gene is a peroxisomal 80 kDa polypeptide containing three functionally distinct domains. The N-terminal part reveals activities of 17beta-estradiol dehydrogenase type IV and D-specific 3-hydroxyacyl CoA dehydrogenase, the central part shows D-specific hydratase activity with straight and 2-methyl-branched 2-enoyl-CoAs. The C-terminal part is similar to sterol carrier protein 2. The 80 kDa polypeptide chain ends with the tripeptide AKI, which resembles the motif SKL, the first identified peroxisome targeting signal PTS1. So far AKI, although being similar to the consensus sequence PTS1, has neither been reported to be present in mammalian peroxisomal proteins, nor has it been shown to be functional. We investigated whether the HSD17B4 gene product is targeted to peroxisomes by this C-terminal motif. Recombinant human PTS1 binding protein Pex5p interacted with the bacterially expressed C-terminal domain of the HSD17B4 gene product. Binding was competitively blocked by a SKL-containing peptide. Recombinant deletion mutants of the C-terminal domain lacking 3, 6, and 14 amino acids and presenting KDY, MIL, and IML, respectively, at their C-termini did not interact with Pex5p. The wild-type protein and mutants were also transiently expressed in the HEK 293 cells. Immunofluorescence analysis with polyclonal antibodies against the C-terminal domain showed a typical punctate peroxisomal staining pattern upon wild-type transfection, whereas all mutant proteins localized in the cytoplasm. Therefore, AKI is a functional PTS1 signal in mammals and the peroxisome targeting of the HSD17B4 gene product is mediated by Pex5p.

The expression of sf-1/Ad4BP is related to the process of luteinization in the marmoset (Callithrix jacchus) ovary

Expression of the nuclear receptor, steroidogenic factor-1 (SF-1/Ad4BP), was studied in a primate (marmoset) ovary using immunohistochemical, RT-PCR, and immunoblot techniques. The periovulatory phase was compared with the luteal phase. With PCR we found a marmoset homolog of SF-1/Ad4BP to be expressed in ovarian and other steroidogenic tissues. Characteristically, the periovulatory ovaries consisted of growing (non-luteinized) small follicles together with large luteinizing follicles and many corpora lutea accessoria (Clas), which had developed from atretic large follicles. During the luteal phase, true corpora lutea (Cls) were additionally found. In general, we found that small follicles were devoid of any immunoreactivity of SF-1/Ad4BP. In large follicles, the luteinizing theca and granulosa cells express SF-1/Ad4BP. All luteal cells of Clas showed a nuclear staining in both ovary types. In Cls, only a few luteal cells were positive. Large follicles of different sizes showed no differences in expression level, as evidenced by immunoblot analysis. Our results indicate that SF-1/ Ad4BP participates in the activation of genc transcription during the onset of luteinization and that Clas are essential for ovarian luteal function.

Steroids, fatty acyl-CoA, and sterols are substrates of 80-kDa multifunctional protein

The 2.9-kb mRNA of 17 beta-hydroxysteroid dehydrogenase IV codes for an 80-kDa (737 amino acids) protein featuring domains that are not present in the other human 17 beta-hydroxysteroid dehydrogenases. The N-terminal part reveals conserved motifs of the short-chain alcohol dehydrogenase family. The central- and C-terminal domains are similar to peroxisomal enzymes for beta-oxidation of fatty acids and to sterol carrier protein 2. The 80-kDa protein is N-terminally cleaved to a 32-kDa fragment (amino acids 1-323). Both the 80-kDa and the N-terminal 32-kDa peptides are able to catalyze the dehydrogenation with steroids at the C17 position and with 3-hydroxyacyl-CoA. The central part of the 80-kDa protein (amino acids 324-596) catalyzes the 2-enoyl-acyl-CoA hydratase reaction with high efficiency. The C-terminal part of the 80-kDa protein (amino acids 597-737) facilitates the transfer of 7-dehydrocholesterol and phosphaidylcholine between membranes in vitro. The unique multidomain structure of the 80-kDa protein permits the catalysis of several reactions previously thought to be performed by complexes of different enzymes.

Characterization of 17 beta-hydroxysteroid dehydrogenase IV

17 beta-Hydroxysteroid dehydrogenase (17 beta-HSD) IV is coded by 2.9 kb mRNA translated to an 80 kDa protein which is N-terminally cleaved to a 32 kDa enzyme. The 17 beta-HSD IV is dedicated to steroid inactivation and reveals only 25% amino acid similarity with 17 beta-HSD I-III enzymes. Despite five Asn-Xaa-Ser/Thr (Xaa = unspecified amino acid) sites in the 80 kDa protein the enzyme is not glycosylated. The porcine 32 kDa 17 beta-HSD IV forms dimers of 75 kDa. The highest 17 beta-HSD IV mRNA expression and specific activities are found in liver and kidney followed by ovary and testes. In porcine gonads the immunofluorescence assigned the 17 beta-HSD IV to granulosa cells and to Leydig and Sertoli cells. As shown by the treatment with phorbol-myristate-acetate in vitamin D-differentiated monocytic leukemia THP1 cells, steroid synthesis and inactivation are regulated differentially by the protein kinase C pathway: an increase in aromatase is accompanied by a decrease in 17 beta-HSD IV mRNA levels.

Molecular characterization of mouse 17 beta-hydroxysteroid dehydrogenase IV

17 beta-hydroxysteroid dehydrogenases (17 beta-HSD) catalyze the conversion of estrogens and androgens at the C17 position. The 17 beta-HSD type I, II, III and IV share less than 25% amino acid similarity. The human and porcine 17 beta-HSD IV reveal a three-domain structure unknown among other dehydrogenases. The N-terminal domains resemble the short chain alcohol dehydrogenase family while the central parts are related to the C-terminal parts of enzymes involved in peroxisomal beta-oxidation of fatty acids and the C-terminal domains are similar to sterol carrier protein 2. We describe the cloning of the mouse 17 beta-HSD IV cDNA and the expression of its mRNA. A probe derived from the human 17 beta-HSD IV was used to isolate a 2.5 kb mouse cDNA encoding for a protein of 735 amino acids showing 85 and 81% similarity with human and porcine 17 beta-HSD IV, respectively. The calculated molecular mass of the mouse enzyme amounts to 79,524 Da. The mRNA for 17 beta-HSD IV is a single species of about 3 kb, present in a multitude of tissues and expressed at high levels in liver and kidney, and at low levels in brain and spleen. The cloning and molecular characterization of murine, human and porcine 17 beta-HSD IV adds to the complexity of steroid synthesis and metabolism. The multitude of enzymes acting at C17 might be necessary for a precise control of hormone levels.

The subcellular localization of 17 beta-hydroxysteroid dehydrogenase type 4 and its interaction with actin

The porcine 17 beta-hydroxysteroid dehydrogenase type 4 is the key enzyme for the inactivation of estradiol. Its localization in peroxisomes was proven by immunogold electron microscopy. Interactions of the 17 beta-hydroxysteroid dehydrogenase with cytoskeletal proteins might be mandatory for a topical assignment of enzymatic activity to defined subcellular compartments.

The tissue distribution of porcine 17 beta-estradiol dehydrogenase and its induction by progesterone

Porcine 17 beta-estradiol dehydrogenase (EDH) was recently purified and cloned. It catalyzes the NAD(+)-dependent oxidation of estradiol to estrone 360-fold more efficiently than the back reaction with NADPH. The 32 kDa EDH is cut from an 80 kDa primary translation product with a multidomain structure unknown for other hydroxysteroid dehydrogenases. The highest EDH activities and strongest immunoreactions are found in liver (hepatocytes) and kidney (proximal tubuli) followed by uterus (luminal and glandular epithelium), lung (bronchial epithelium). Progesterone treatment of ovariectomized gilts stimulates oxidative EDH activity in uterus, anterior pituitary, skeletal muscle (diaphragm) and kidney. Constitutive levels of EDH activity were seen in the adrenals, the lung and the liver.

The organelles containing porcine 17 beta-estradiol dehydrogenase are peroxisomes

Porcine 17 beta-estradiol dehydrogenase was recently purified and cloned. It catalyzes the NAD(+)-dependent oxidation of estradiol to estrone 360-fold more efficiently than the reverse reaction with NADPH. Immunogold electron microscopy localizes 17 beta-estradiol dehydrogenase in organelles of 120 to 500 nm with moderate electron-dense matrices bounded by single membranes. Antibodies against the peroxisomal markers catalase and acyl-CoA oxidase recognize the same organelles in double-labeling studies. This is the first report on the participation of peroxisomes in the metabolism of estradiol.

Alterations in the subcellular distribution of 17 beta-estradiol dehydrogenase in porcine endometrial cells over the course of the estrous cycle

The uteri of German landrace gilts slaughtered at different days of the cycle were processed for immunocytochemistry and biochemical analyses. Plasma was collected for hormone assays. The monoclonal antibody F1 against the structure-bound 17 beta-estradiol dehydrogenase of porcine endometrial epithelium was applied to rehydrated paraffin sections either as a direct, peroxidase-linked probe or in combination with a fluorescing secondary antibody. The oxidation of estradiol was measured in homogenates of tissue powdered in liquid nitrogen. Immunoreactivity was restricted to endometrial epithelium. In the glandular epithelium, faint dots of fluorescence became visible at day 4, which apparently coalesced to spherical structures of 2-4 microns diameter at the cell basis between days 11 through 17 before disappearing by day 18. A similar distribution was observed for the oxidation products of diaminobenzidine beginning with a faint uniform staining and followed by the appearance of intensely stained basal bodies persisting until day 17. Essentially the same time course was seen in the luminal epithelium but with a different distribution. Immunoreactive material amassed in the apical region of the cells, but the conspicuous aggregations were absent. Time course and intensities of the immunological responses are matched by the enzymatic activity measured in parallel. Both correlate with the plasma progesterone levels, suggesting an induction of the enzyme by the hormone. An involvement of the cytoskeleton in the sequence of subcellular distribution patterns is discussed.

The sequence of porcine 80 kDa 17 beta-estradiol dehydrogenase reveals similarities to the short chain alcohol dehydrogenase family, to actin binding motifs and to sterol carrier protein 2

The cDNA of porcine 17 beta-estradiol dehydrogenase codes for a polypeptide of 737 amino acids. The dehydrogenase activity of the 80 kDa translation product is located in its N-terminal 32 kDa fragment, which is the major form isolated from endometrial epithelium. beta-Actin co-purifies with some of the 32 kDa enzyme, which contains actin-binding motifs and is homologous to hydratase-dehydrogenase-epimerase of Candida tropicalis. The microbody-targeting signal AKI and sequences resembling sterol carrier protein 2 are present in the C-terminal part of the 80 kDa protein. The N- and C-terminal parts are connected by a sequence containing the putative protease recognition signal AAP.

Molecular cloning and amino acid sequence of the porcine 17 beta-estradiol dehydrogenase

We describe the cloning and sequencing of porcine 17 beta-estradiol dehydrogenase. The enzyme performs oxidation 360-fold more efficiently than reduction, both measured under optimal conditions. It is localized in specialized vesicles of epithelial cells. The cDNA clones were isolated from a lambda UNI ZAP XR library of porcine kidney and polymerase-chain-reaction-amplified from templates of uterus epithelium. In both tissues, the same enzyme is coded by a transcript of 2.9 kb. It contains a 69-b 5'-noncoding region, an open reading frame of 2211 b and a 3'-noncoding region of 624 b. The open reading frame of 737 amino acids with a predicted molecular mass 79,973 Da was confirmed by amino acid sequencing of peptides. The 80-kDa translation product is processed to the N-terminal 32-kDa enzyme, part of which is then covalently linked to actin. The estradiol dehydrogenase/actin complex and the 80-kDa translation product comigrate in SDS/PAGE.

Linkage of 17 beta-oestradiol dehydrogenase to actin by epsilon-(gamma-glutamyl)-lysine in porcine endometrial cells

We report on the discovery of interactions of porcine endometrial 17 beta-oestradiol dehydrogenase with actin. The 17 beta-oestradiol dehydrogenase of porcine uteri is an essentially unidirectional enzyme compounded in specialized organelles. The enzyme activity in Brij 35 extracts of the particulate fraction of epithelial cells sedimenting between 1800 and 11,000 g(av). was collected by immunoadsorption and eluted at low pH. The eluate contained three proteins of 32, 45 and 80 kDa as shown by SDS/PAGE and silver staining. They were identified by amino acid sequencing and immunotyping as oestradiol dehydrogenase (32 kDa), actin (45 kDa) and a covalent dehydrogenase-actin complex (80 kDa). Disulphides, aldimines, periodate-degradable bonds and hydrophobic interactions were excluded as linkages in the 80 kDa protein. The epsilon-(gamma-glutamyl)-lysine nature of the covalent cross-link was recognized by narrow-bore h.p.l.c. analysis of enzymic digests of electro-eluted 80 kDa material. An involvement of the actin anchor in positioning of the oestradiol dehydrogenase-containing organelles according to metabolic requirements is discussed.

The 17 beta-oestradiol dehydrogenase of pig endometrial cells is localized in specialized vesicles

Two monoclonal antibodies against the 17 beta-oestradiol dehydrogenase of pig endometrial cells have been used in localization studies with immunogold electron microscopy. The antibodies attach both to a fraction of dehydrogenase-rich cytoplasmic vesicles isolated from homogenates and to vesicles of similar appearance in cells. The vesicles are filled with electron-dense material. Their tagging intensity indicates a high degree of specialization. Endometrial cells from mature animals contain a host of dehydrogenase vesicles, and cells from prepubertal animals only a few. Functional aspects of the novel organelle are discussed.

The membrane-bound 17β-estradiol dehydrogenase of porcine endometrial cells: purification, characterization and subcellular localization

The membrane-bound 17β-estradiol dehydrogenase of porcine endometrial cells was purified to homogeneity as judged by SDS-PAGE and silver staining of a single 32 kD band. A second, more hydrophobic product of the purification protocol contained additional bands at 45 and 80 kD. The 17β-estradiol dehydrogenase activities of both products exceeded those for 17-one reduction by more than 260-fold. Activities of 3α-, 3β- and 20α-dehydrogenases were absent in either fraction. Polyclonal and monoclonal antibodies raised against the 32 kD protein and the more hydrophobic product precipitated the enzymatic activity and reacted with the 32 and 80 kD bands, but not with the 45 kD band in Western blots. The subcellular localization of the enzyme was studied in sections of intact cells and of isolated organelles using gold sol coated with F(ab')₂ fragments of monoclonal antibody F1. Gold particles were found exclusively over cytoplasmic vesicles of 120-150 nm diameter with electron-dense contents.

Purification and properties of oestradiol 17 beta-dehydrogenase extracted from cytoplasmic vesicles of porcine endometrial cells

Porcine endometrial oestradiol-17 beta dehydrogenase was solubilized from the particulate fraction of homogenates sedimenting between 1200 g and 10,000 g by treatment with 0.4% Brij 35 in neutral buffers. The extracts were processed by successive passage through DEAE-Sepharose, Amberlyte XAD-2 and Blue-Sepharose, and the enzyme was collected from the washed affinity matrix at 0.8 M of a 0-2 M-KCl gradient. A genuine oestrone reductase was eluted at 1.9 M-KCl. The dehydrogenase pool was resolved by butyl-Sepharose chromatography into a major (80%) peak (EDHM) eluted at 0.8 M-(NH4)2SO4 and a very hydrophobic fraction (VHF) recovered at 0.1 M. EDHM was further purified by filtration through Sephadex G-200 and cation-exchange chromatography on Mono S. Sephacryl 300 was used for VHF followed by Mono S. Enrichments from the homogenate amounted to 1074-fold for EDHM and 632-fold for VHF. A single silver-stained band at 32 kDa is seen on SDS/PAGE of EDHM, and VHF contains additional bands at 45 and 80 kDa. Polyclonal antibodies (G436) raised against EDHM and the monoclonal antibody F1 raised against VHF recognize the single 32 kDa band in EDHM and both the 32 kDa and 80 kDa bands in composite VHF. The 45 kDa band of VHF reacts with neither. Monoclonal antibody W1 raised against EDHM only recognizes the 32 kDa peptide of EDHM and VHF. The specific activity for oestradiol oxidation amounts to 4081 mu-units/mg for EDHM and to 2402 mu-units/mg for VHF. Both possess a minimal (1/260) endogenous reductase activity and are devoid of 3 beta, 3 alpha- and 20 alpha-dehydrogenases. We consider EDHM to be authentic oestradiol-17 beta dehydrogenase of porcine endometrium. The composite VHF could reflect the situation of the enzyme in vivo or result from aggregations occurring during processing.