essentially a splice-variant of promoter II. Both of these are regulated by cAMP, therefore in the ovary they are regulated by follicle-stimulating hormone (FSH), but in the case of adipose tissue, by PGE2. For the purposes of this discussion, we will consider
Evan R Simpson and Kristy A Brown
Kazuya Kusama, Mikihiro Yoshie, Kazuhiro Tamura, Kazuhiko Imakawa, and Eiichi Tachikawa
leukemia inhibitory factor (LIF), cyclooxygenase 2 (COX2, PTGS2), and prostaglandin E2 (PGE2), which are essential for embryo development and endometrial stromal cell differentiation ( Stewart et al . 1992 , Lim et al . 1999 ). LIF expression and PTGS2
Rong Wan, Yunxin Liu, Li Li, Chao Zhu, Lai Jin, and Shengnan Li
cPLA2, which exhibits a specific preference for arachidonic acid (AA; Clark et al . 1990 ). Subsequently, AA could be oxidized to prostaglandins, such as prostaglandin E 2 (PGE 2 ) by the cyclooxygenase enzymes cyclooxygenase 1 (COX1) and COX2
J. R. Hodam, M. C. Snabes, T. J. Kuehl, M. A. Jones, and M. J. K. Harper
Membrane preparations (100 000 g pellet) of rabbit, baboon and tree shrew (Tupaia belangeri) uteri were studied for binding of [3H]prostaglandin E2 ([3H]PGE2). Unbound [3H]PGE2 was separated by filtration through Whatman GF/F filters. Nonspecific binding was determined by the amount of radioactivity associated with the filters in the presence of a 100-fold excess of radioinert PGE2. PGE2 bound to membranes could be displaced by some other prostaglandin (PG) molecules: PGE1, 16,16-dimethyl-PGE2, PGA1 and PGF2α, but not by 6-keto-PGF1α, PGD2 or arachidonic acid. No PGE2 binding was detected using either membrane ghosts from red blood cells or liposomes. Apparent equilibrium of the binding was reached by 60 min. There was no difference in dissociation constant (K d) values between rabbits of different reproductive stages (mean range±s.e.m. was from 4·6±0·3 to 5·5 ± 1·0 nm), but pregnant baboons showed a significantly lower value (3·3±0·4 nm) than did cyclic animals (12·0 ± 2·0 nm). Binding capacity (Bmax) values, in contrast, were different only between oestrous rabbits and other reproductive stages. The small amounts of [ill] tissue only permitted estimates of the K d and Bmax values to be made; these were 3·8 nm and 499 fmol/mg protein for oestrous animals and 5·4 nm and 674 fmol/mg protein for animals on day 7 of pregnancy, assuming only one class of sites. The present results demonstrate the presence of specific binding sites for PGE2 in uteri from several species.
SE Bulun, KM Zeitoun, K Takayama, and H Sasano
Conversion of C(19) steroids to estrogens is catalyzed by aromatase in human ovary, placenta and extraglandular tissues such as adipose tissue, skin and the brain. Aromatase activity is not detectable in normal endometrium. In contrast, aromatase is expressed aberrantly in endometriosis and is stimulated by prostaglandin E(2) (PGE(2)).( )This results in local production of estrogen, which induces PGE(2) formation and establishes a positive feedback cycle. Another abnormality in endometriosis, i.e. deficient hydroxysteroid dehydrogenase (17beta-HSD) type 2 expression, impairs the inactivation of estradiol to estrone. These molecular aberrations collectively favor accumulation of increasing quantities of estradiol and PGE(2 )in endometriosis. The clinical relevance of these findings was exemplified by the successful treatment of an unusually aggressive case of postmenopausal endometriosis using an aromatase inhibitor.
JS Gilmour, WR Hansen, HC Miller, JA Keelan, TA Sato, and MD Mitchell
Increased prostaglandin biosynthesis during intrauterine infection may be a possible mechanism by which preterm labour is initiated. Inflammatory cytokines and growth factors are known to stimulate prostaglandin production through an increase in prostaglandin endoperoxide H synthase (PGHS)-2 synthesis and activity. Interleukin-4 (IL-4), an anti-inflammatory cytokine, can downregulate PGHS-2 expression and inhibit prostaglandin production. Therefore, the aims of the current study were to determine the effects of IL-4 on PGHS-1 and PGHS-2 expression in amion-derived WISH cells treated with inflammatory cytokines and growth factors. In WISH cells, near-maximal production of the PGHS-2 mRNA occurred using 5 ng/ml EGF, 1 ng/ml IL-1beta or 50 ng/ml TNF-alpha. Time-course experiments determined that the PGHS-2 mRNA was induced maximally by these stimuli by 1 h. Pretreatment of WISH cells with IL-4 reduced PGHS-2 mRNA levels at 1 h by 67% in cells treated with EGF, 62% in cells treated with IL-1beta and 54% in cells treated with TNF-alpha. Pretreatment with IL-4 more effectively inhibited PGHS-2 expression than simultaneous addition with EGF or IL-1beta but not TNF-alpha. Immunoblot analysis showed a correlation between inhibition of mRNA levels and levels of PGHS-2 protein, although stimulation of PGHS-2 protein production by EGF was undetectable. Levels of PGHS-1 protein and mRNA remained unchanged in all experiments. Increased production of prostaglandin E2 (PGE2) in response to TNF-alpha and IL-1beta treatment was attenuated by IL-4 pretreatment, by 52% and 72%, respectively. No attenuation of EGF-stimulated PGE2 levels was seen. We conclude that IL-4 inhibits PGHS-2 mRNA and protein production in cytokine-stimulated WISH cells, but does not affect EGF-stimulated PGE2 production, suggesting that EGF can induce prostaglandin biosynthesis by a mechanism other than through increased PGHS-2 expression.
WR Hansen, T Sato, and MD Mitchell
We have evaluated the mechanism by which tumour necrosis factor-alpha (TNF-alpha) induces increased prostaglandin (PG) biosynthesis in amnion-derived WISH cells. WISH cells were treated with 50 ng/ml TNF-alpha or vehicle for 0-24 h. PGE2 production was stimulated by TNF-alpha within 2 h and continued to accumulate for at least 24 h. Increased prostaglandin endoperoxide H synthase (PGHS)-2 mRNA expression was evident within 30 min and was highest by 1 h, returning to unstimulated levels by 2 h. The PGHS-2 mRNA was re-induced at 8 h and was also elevated at 16 h. Immunoreactive PGHS-2 protein was nearly undetectable in control cells. However, within 30 min of TNF-alpha treatment, PGHS-2 protein was elevated and was induced for at least 16 h suggesting rapid production of both the PGHS-2 mRNA and protein. Transcription run-on assays indicated that the initial increase in the PGHS-2 mRNA was due to a 20-fold increase in the rate of transcription. The PGHS-2 mRNA decayed with an apparent half-life of 1 h in TNF-alpha-stimulated WISH cells. Induction of PGHS-2 expression proceeded in the presence of 10 microg/ml cycloheximide which agrees with the classification of PGHS-2 as an immediate early gene. These results indicate that a bi-phasic induction of the PGHS-2 mRNA is due, in part, to an initial transcriptional activation which results in rapid and continued synthesis of the PGHS-2 protein. This may be a unique characteristic of amnion cells which may be partially responsible for increased PG concentrations in the amniotic fluid during infection-associated preterm labour.
S Sivagurunathan, C N Pagel, L H Loh, L C Wijeyewickrema, R N Pike, and E J Mackie
osteoclast differentiation, including parathyroid hormone (PTH), prostaglandin E 2 (PGE 2 ), 1,25-dihydroxyvitamin D 3 (1,25D) and interleukin 6 (IL6), do so by stimulating an increase in the expression of RANKL relative to that of its soluble decoy
Hong Zhao, Ling Zhou, Anna Junjie Shangguan, and Serdar E Bulun
aromatase transcript is increased in breast cancer tissue ( Harada 1997 ). More importantly, malignant breast epithelial cells secrete prostaglandin E2 (PGE2) and other unknown factors to cause aromatase promoter switching from I.4 to the more potent I.3 and
Mary S Erclik and Jane Mitchell
transfected along with cDNA encoding β-galactosidase to assess transfection efficiency. This region of the IGFBP-5 gene has previously been shown to respond to various factors including cAMP, PGE 2 and OP-1. Luciferase activity associated with the pGL2 vector