Expression of 17 beta-hydroxysteroid dehydrogenase in human granulosa cells: correlation with follicular size, cytochrome P450 aromatase activity and oestradiol production.
The aim of this study was to examine the expression and regulation of type 1 17 beta-hydroxysteroid dehydrogenase (type 1 17-HSD) enzyme protein and mRNA, and 17-HSD activity in human granulosa cells. The cells were obtained from patients taking part in an in vitro fertilization programme. The cells from each patient were divided into two groups: cells obtained from preovulatory follicles (LGC = granulosa cells from large follicles > or = 18 mm in diameter), and cells from other visible follicles (SGC = granulosa cells from small follicles, less than 15 mm in diameter). The identity of 17-HSD enzyme protein expressed in human granulosa cells with placental cytosolic 17-HSD (type 1 17-HSD) was assessed by immunoblot analysis using polyclonal antibodies, and the enzyme was immunolocalized in the cytoplasm of granulosa cells. Type 1 17-HSD protein concentration, 17-HSD and cytochrome P450 aromatase (P450arom) activities and oestradiol (OE2) production in cells from LGC were significantly lower than the corresponding values obtained in SGC in the same patient (paired t-test). The type 1 17-HSD protein concentration, 17-HSD activity and P450arom activity were 140 +/- 16% (mean +/- S.E.M.), 121 +/- 22% and 113 +/- 26% higher in cells from SGC, which was also reflected in a 70 +/- 12% higher OE2 production in these cells. In freshly isolated cells from LGC or SGC, a high correlation between 17-HSD and P450arom activities was observed (r = 0.93, P < 0.001). In long-term cultured cells, type 1 17-HSD was stably expressed at least until day 9, while P450arom expression decreased. In addition, treatments with gonadotrophins did not affect type 1 17-HSD protein concentration and 17-HSD activity. In contrast to this, both P450arom activity and OE2 production were significantly increased (P < 0.05). The data, therefore, suggest that type 1 17-HSD and P450arom are expressed in parallel during the latest stages of follicular maturation but, in cultured granulosa-luteal cells, the enzymes are regulated by distinct mechanisms.
Ghersevich
S A
SA
Biocenter, University of Oulu, Finland.
Poutanen
M H
MH
Martikainen
H K
HK
Vihko
R K
RK
D015067:17-Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D001141:Aromatase / Q000378:metabolism*; D015152:Blotting, Northern; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D006107:Granulosa Cells / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D006080:Ovarian Follicle / Q000033:anatomy & histology*; D012313:RNA / Q000032:analysis
D004958:Estradiol; D012313:RNA; D015067:17-Hydroxysteroid Dehydrogenases; D001141:Aromatase