Functional ovarian and placental isoforms of porcine aromatase

Corbin, C. J.; Khalil, M. W.; Conley, Alan J

doi:10.1016/0303-7207(95)03607-9

Cited by 78 publications

(67 citation statements)

References 24 publications

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“…It has been shown that etomidate is an inhibitor of the porcine ovarian aromatase [10]. We have found that the blastocyst form behaves like the placental form and the human enzyme in that they are less sensitive to etomidate than the ovarian form ( Fig.…”

Section: Inhibitor Studiesmentioning

confidence: 70%

“…[4][5][6][7][8][9][10][11][12][13][14] C]Testosterone was incubated separately with the porcine placental form, the porcine blastocyst form, or the human wild-type aromatase in the presence of bovine liver NADPH-cytochrome P450 reductase and NADPH. The major products were found, by TLC, to be 17b-estradiol (E2) and 19-nortestosterone (19-norT).…”

Section: R E S U L T Smentioning

confidence: 99%

“…In addition, the same group has identified a variant cDNA form in blastocysts in which exons encoding for amino-acid residues 100±248 are deleted [9]. Corbin et al [10] isolated an aromatase cDNA clone from term placenta. The translated amino-acid sequences of the placental isoform of Choi et al and that of Corbin et al differ by seven amino acids among a total of 503 amino acids.…”

mentioning

confidence: 99%

“…The translated amino-acid sequences of the placental isoform of Choi et al and that of Corbin et al differ by seven amino acids among a total of 503 amino acids. Finally, Corbin et al [10] cloned an ovarian form of aromatase which shares 88% aminoacid sequence identity with the blastocyst form. The ovarian form also differs from the blastocyst form and the placenta form by being comprised of 501 instead of 503 amino acids.…”

mentioning

confidence: 99%

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Catalytic differences between porcine blastocyst and placental aromatase isozymes

Kao

Higashiyama

Sun

et al. 2000

European Journal of Biochemistry

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Two isozymes of porcine aromatase, the placental and the blastocyst forms, were expressed in CHO cells using the mammalian cell transfection method. Using an`in-cell' assay (a 3 H-water release method), catalytic parameters of the porcine placental aromatase were found to be very similar to those of the human enzyme; however, the activity of the blastocyst isozyme was found to be one-thirtieth that of the placental isozyme. Product isolation assay (using testosterone as the substrate) revealed that the major steroid products were 17b-estradiol and 19-nortestosterone. The product ratio of estradiol/19-nortestosterone was found to be 94 : 6 for the porcine placental form, 6 : 94 for the porcine blastocyst form, and 92 : 8 for the human wild-type aromatase. Therefore, the porcine blastocyst aromatase isozyme catalyzes mainly androgen 19-desmethylation rather than aromatization. In addition, inhibition profile analyses on the placental and blastocyst isozymes were performed using three steroidal inhibitors [4-hydroxyandro-stenedione (4-OHA), 7a-(4 H -amino)phenylthio-1,4-androstandiene-3,17-dione (7a-APTADD), and bridge (2,19-methyleneoxy) androstene-3,17-dione (MDL 101,003)], and four nonsteroidal inhibitors [aminoglutethimide (AG), CGS 20267, ICI D1033, and vorozole (R83842)]. While the two isozymes of porcine aromatase share 93% amino-acid sequence identity, our results indicate that the two porcine aromatase isozymes have distinct responses to various aromatase inhibitors.

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Section: Inhibitor Studiesmentioning

confidence: 70%

Section: R E S U L T Smentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Catalytic differences between porcine blastocyst and placental aromatase isozymes

Kao

Higashiyama

Sun

et al. 2000

European Journal of Biochemistry

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“…Most species investigated express Cyp19 in the gonads and the brain (Harada et al 1992, Lephart et al 1992, Nitta et al 1993. However, in rabbits, primates and several ungulate species Cyp19 transcripts were also found in the placenta (Simpson et al 1994, Corbin et al 1995, Hinshelwood et al 1995, Fürbass et al 1997, Delarue et al 1998, Vanselow et al 1999. The expression of Cyp19 is regulated by several promoter regions with tissue-specific preferences.…”

Section: Introductionmentioning

confidence: 99%

Cis-acting elements regulating the placenta-specific promoter of the bovine Cyp19 gene

Kalbe

Fürbaß²,

Schwerin³

et al. 2000

Journal of Molecular Endocrinology

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Cyp19 encodes aromatase cytochrome P450, the key enzyme of oestrogen biosynthesis. In the bovine placenta, the majority of Cyp19 transcripts include a 5 untranslated region which is encoded by exon 1.1; this suggests that its 5 -flanking region is the predominant placental promoter. The aim of the present investigation was to examine the promoter activity of this region and to map cis-acting regulatory elements in order to improve our understanding of the complex regulation of this gene within the placenta. As an initial approach, human JEG-3 choriocarcinoma cells were transiently transfected with reporter-gene constructs consisting of different 5 -flanking sequences of exon 1.1 fused to the luciferase gene as a reporter. To localise and further characterise functional cisacting elements, targeted point mutations and electrophoretic mobility-shift experiments were used. The data demonstrate, for the first time, (1) that the bovine exon 1.1 5 -flanking sequence is an active promoter, (2) that 404 bp of this region are sufficient for constitutive reporter-gene expression in JEG-3 cells and (3) that the region includes at least two different enhancer elements; the data also suggest (4) that one of these elements consists of the E-box motif CATGTG and that the second enhancer element includes the half-site hexameric sequence AGGTCA and additional nucleotides flanking this element upstream.

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5?-reductase isozymes and aromatase are differentially expressed and active in the androgen-independent human prostate cancer cell lines DU145 and PC3

et al. 1999

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BACKGROUND The presence and possible role of androgen‐metabolizing enzymes in androgen‐independent prostate carcinoma (CaP) are still unclear. The aim of the present study was: 1) to evaluate the pattern of androgen metabolism (relative production of 5α‐reduced vs. 17‐keto androgens); and 2) to analyze whether one or both the two known 5α‐reductase isoforms (5α‐R1 and 5α‐R2) and the aromatase (Aro) are expressed and active in this pathology. METHODS Two different cell lines (DU145 and PC3) were used as a model of androgen‐independent human CaP. In these cells, the expression of the two 5α‐Rs and of Aro were evaluated by reverse transcription‐polymerase chain reaction (RT‐PCR) and Southern blot, using specific sets of oligoprimers and of [32P]‐labeled oligoprobes; the enzymatic activities of 5α‐R and of Aro were evaluated by radioenzymatic methods. The pH optimum for the activity of the two 5α‐Rs was assessed in cell homogenates at different pH (from 3.5–8), using substrate concentrations similar either to 5α‐R1 or to 5α‐R2 Kms. RESULTS The two CaP cell lines DU145 and PC3, although unresponsive to androgens, possess the enzymatic machinery involved in the metabolism of this class of hormonal steroids: 5α‐Rs, which allow their transformation into 5α‐reduced steroids (5α‐dihydrotestosterone, DHT, and 5α‐androstandione, 5α‐A), and 17β‐hydroxysteroid‐oxidoreductase (17β‐HSD), which interconverts testosterone (T) and androstenedione (ADIONE); however, the two cell lines show differences in the rate of formation of these metabolites. Furthermore, two cell lines expressed the type 1 isoform of 5α‐R, but only DU145 cells also possess 5α‐R2. Aro is expressed and active in DU145 as well as in PC3 cells. CONCLUSIONS The present findings suggest that T might still be indirectly active in androgen‐unresponsive CaP through its local conversion into estrogens by the action of Aro; the biological role played by the two 5α‐Rs in androgen‐independent CaP deserves further investigation. Prostate 41:224–232, 1999. © 1999 Wiley‐Liss, Inc.

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Functional ovarian and placental isoforms of porcine aromatase

Cited by 78 publications

References 24 publications

Catalytic differences between porcine blastocyst and placental aromatase isozymes

Catalytic differences between porcine blastocyst and placental aromatase isozymes

Cis-acting elements regulating the placenta-specific promoter of the bovine Cyp19 gene

5?-reductase isozymes and aromatase are differentially expressed and active in the androgen-independent human prostate cancer cell lines DU145 and PC3

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