Genes Dev. 2003 Dec 1;17(23):2864-9.
Proplatelet formation of megakaryocytes is triggered by autocrine-synthesized estradiol.

Nagata Y, Yoshikawa J, Hashimoto A, Yamamoto M, Payne AH, Todokoro K.

Recognition and Formation, Precursory Research for Embryonic Science and Technology, Japan Science and Technology Corporation, Japan. y-nagatostman.riken.go.jp

A matured megakaryocyte releases thousands of platelets through a drastic morphological change, proplatelet formation (PPF). The megakaryocyte/erythrocyte-specific transcription factor, p45 NF-E2, is essential for initiating PPF, but the factor regulating PPF has not been identified. Here we report that estradiol synthesized in megakaryocytes triggers PPF. We demonstrate that a key enzyme for steroid hormone biosynthesis, 3beta-hydroxysteroid dehydrogenase (3beta-HSD), is a target of p45 NF-E2, and rescues PPF of p45 NF-E2-deficient megakaryocytes. We also show that estradiol is synthesized within megakaryocytes, and that extracellular estradiol stimulates PPF, inhibition of 3beta-HSD activity blocks PPF, and estrogen receptor antagonists inhibit platelet production in vivo. We conclude that autocrine estradiol action regulates platelet production by triggering PPF.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14665668&dopt=Abstract estradiol



Reprod Biol. 2001 Jul;1(1):33-41.
Different action of ovine GH on porcine theca and granulosa cells proliferation and insulin-like growth factors I- and II-stimulated estradiol production.

Kolodziejczyk J, Gregoraszczuk EL, Leibovich H, Gertler A.

Laboratory of Domestic Animal Physiology and Toxicology, Department of Animal Physiology, Institute of Zoology, Jagiellonian University, ul. Ingardena 6, 30-060 Krakow, Poland.

Growth hormone (GH) and insulin-like growth factors (IGFs) are recognized as regulators of ovarian function. This study was designed to compare the effect of GH and IGFs added alone or together on porcine theca interna and granulosa cells proliferation and steroidogenesis. Moreover, the effect of GH on IGF-I secretion was examined. Cells were isolated from medium size follicles and cultured in vitro for 48 h in serum free medium. Estradiol and IGF-I medium concentrations were determined by radioimmunoassays. Proliferation was evaluated by alamar blue assay and by radiolabelled thymidine incorporation. GH increased IGF secretion by granulosa cells while decreased its secretion by theca cells. Proliferation of both cell types was stimulated by IGF-I and IGF-II (30 ng/ml) and modestly inhibited by GH (100 ng/ml). Insulin-like growth factor II increased, in a statistically significant manner, estradiol secretion by both cell types, while IGF-I stimulated estradiol secretion to a greater extent by granulosa then by theca cells. The synergistic action of GH and IGFs on estradiol secretion was stimulatory in theca cells and inhibitory in granulosa cells. These data demonstrate that despite its direct action on estradiol secretion by granulosa and theca cells, GH also modulated estradiol secretion induced by IGFs. Differences in the estradiol production in response to GH alone and the effect of the synergistic action of GH and IGFs suggest that different cellular mechanisms for these hormones are triggered in each cell type.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14666173&dopt=Abstract estradiol [PubMed - indexed for MEDLINE




Angiology. 2003 Nov-Dec;54(6):701-9.
Effect of intracoronary estradiol on postischemic microvascular damage in a porcine model: a myocardial contrast echocardiographic study.

Nishino M, Youn HJ, Gheorghevici D, Zellner C, Chou TM, Sudhir K, Redberg RF.

Division of Cardiology, University of California, San Francisco, CA 94143-0124, USA.

Coronary microvascular damage can occur in the presence of myocardial ischemia even if epicardial vessels are patent, a phenomenon known as "no-reflow." Estrogens have favorable effects on coronary conductance and resistance arteries, and may have therapeutic value in ischemic syndromes. Myocardial contrast echocardiography (MCE) is a promising method for evaluating microvascular damage. In this study, the authors hypothesized that acute intracoronary 17beta-estradiol administration can reduce postischemic microvascular damage, which is evaluated by MCE, in a porcine model. Sixteen male pigs were randomized into 2 groups: the treatment group (n = 9) received intracoronary estradiol in increasing doses, and the control group (n = 7) received intracoronary vehicle (dimethylsulfoxide, DMSO). Microvascular damage was induced by balloon catheter occlusion followed by reperfusion of the left circumflex coronary artery (LCX). MCE using Levovist with harmonic imaging was performed before and during 15-minute balloon occlusion of the proximal LCX to determine perfusion areas of the left anterior descending artery (LAD) and LCX. MCE was performed immediately postocclusion and after each injection of estradiol (1, 10, and 100 nmol/L) or DMSO. Videodensitometry measurements were performed as a quantitative marker for myocardial microvascular damage. Videodensitometry results were expressed as peak intensity ratios. Intracoronary estradiol induced a significant reduction in myocardial microvascular damage after ischemic episode by videodensitometry measurements when compared to intracoronary DMSO. The authors conclude that intracoronary injection of estradiol




Genomics. 2004 Jan;83(1):34-44.
Identification of genes involved in estrogenic action in the human prostate using microarray analysis.

Bektic J, Wrulich OA, Dobler G, Kofler K, Ueberall F, Culig Z, Bartsch G, Klocker H.

Department of Urology, University of Innsbruck, Austria.

Estrogens have profound effects on the developing prostate and are suspected to contribute to the development of benign prostatic hyperplasia, but the mechanism by which this hormone elicits its regulatory function still remains largely unknown. Using complementary RNA microarrays comprising approximately 10,000 oligonucleotide gene targets we compared differences in mRNA expression of estradiol-treated and untreated prostatic stromal cells in vitro. Based on a threshold of greater than twofold change, 228, 241, and 464 of the expressed genes were found to be regulated by estradiol after 10, 24, and 48 h of treatment, respectively. The secondary analysis of one estradiol-activated transcript, namely lipopolysaccharide-binding protein, and four estradiol-repressed genes, namely ras homolog gene family member E (RhoE/Rnd3), ubiquitin thiolesterase, interleukin 6, and interleukin 8 (IL-8), by real-time quantitative PCR confirmed the results of the microarray analysis. Moreover, IL-8 and RhoE were found to be down-regulated by estradiol at the protein level as well. We identified a set of genes involved in a wide range of cellular functions that are potentially important for understanding the molecular basis of estradiol action in the prostate.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14667807&dopt=Abstract estradiol




Endocrinology. 2004 Mar;145(3):1473-80. Epub 2003 Dec 11.
Folliculostellate cells determine the susceptibility of lactotropes to estradiol's mitogenic action.

Oomizu S, Chaturvedi K, Sarkar DK.

Endocrinology Program, Rutgers, Biomedical Divison of the Center for Alcohol Studies, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA.

Estradiol is known to increase lactotropic cell proliferation, but estradiol susceptibility varies among human populations and among various strains of rats. We had reported that folliculostellate (FS) cells regulate estradiol's mitogenic action on lactotropes; therefore, we studied their role in determining the susceptibility to estradiol in a high estradiol-responsive rat strain, Fischer 344 (F344), and in a low-responsive strain, Sprague Dawley (SD). Determination of total S-100-positive FS cells in the pituitary revealed that F344 rats have significantly more FS cells than do SD rats. Estradiol treatment did not change the number of FS cells in both F344 and SD rats. When cotransplanted with F344 pituitaries under the kidney capsule or cocultured with F344-derived lactotropes in vitro, FS cells derived from F344 rats increased estradiol's mitogenic action. They also increased estradiol's mitogenic action on SD-derived lactotropes in primary cultures. However, SD-derived FS cells failed to increase estrogen's action on F344- or SD-derived lactotropes. The levels of basic fibroblast growth factor production and secretion by TGF-beta 3 and estradiol were much higher in F344-derived FS cells than in SD-derived FS cells. However, the lactotropes' growth response to basic fibroblast growth factor was similar in both strains. These data suggest that cell-cell interaction between FS cells and lactotropes regulates estradiol's mitogenic action on lactotropes and also determines lactotrope susceptibility to the steroid.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14670997&dopt=Abstract estradiol




J Neurosci. 2003 Dec 10;23(36):11420-6.
Estradiol attenuates programmed cell death after stroke-like injury.

Rau SW, Dubal DB, Bottner M, Gerhold LM, Wise PM.

Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA.

Estradiol is a known neurotrophic and neuroprotective factor. Our previous work demonstrated that replacement with physiological concentrations of estradiol protects the cortex against middle cerebral artery occlusion (MCAO)-induced cell death. The cerebral cortex exhibits caspase-dependent programmed cell death (PCD) in many models of focal cerebral ischemia. We hypothesized that estradiol attenuates PCD during stroke injury. The current study explored the temporospatial pattern of markers of PCD, their relationship to the evolution of injury, and their modulation by estradiol. Rats were ovariectomized and treated with either estradiol or vehicle. One week later, rats underwent MCAO, and brains were collected at 1, 4, 8, 16, and 24 hr. We assessed the temporospatial evolution of infarction volume, DNA fragmentation, and levels of spectrin cleavage products in ischemic cortex. Estradiol led to a delay and attenuation of injury-mediated DNA fragmentation as early as 8 hr after MCAO. Estradiol also dramatically reduced the level of the 120 kDa caspase-mediated spectrin breakdown product (SBDP120) at 4 hr but not at 8 or 16 hr. The SBDP150, produced by caspase and calpain, showed peak levels at 16 hr but was not altered by estradiol. These results strongly suggest that estradiol protects the ischemic cortex by attenuating PCD, thereby reducing caspase activity, DNA fragmentation, and subsequently, overall cell death. These studies deepen our understanding of the mechanisms underlying estrogen-mediated neuroprotection.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14673006&dopt=Abstract estradiol




J Invest Dermatol. 2003 Dec;121(6):1500-9.
17beta-estradiol inhibits oxidative stress-induced apoptosis in keratinocytes by promoting Bcl-2 expression.

Kanda N, Watanabe S.

Teikyo University, Tokyo, Japan. nmed.teikyo-u.ac.jp

We examined in vitro effects of 17beta-estradiol on H2O2-induced apoptosis in human keratinocytes. 17beta-estradiol prevented the H2O2-induced apoptosis. H2O2 decreased, whereas 17beta-estradiol increased Bcl-2 protein and mRNA levels in keratinocytes, and H2O2 plus 17beta-estradiol led to basal levels. Overexpression of Bcl-2 protected keratinocytes against H2O2-induced apoptosis, indicating the anti-apoptotic effect of Bcl-2. H2O2 suppressed, whereas 17beta-estradiol enhanced bcl-2 promoter activity, and H2O2 plus 17beta-estradiol led to basal activity. Cyclic adenosine monophosphate (cAMP) response element on bcl-2 promoter was responsible for the effects of 17beta-estradiol and H2O2. Bcl-2 expression was enhanced by membrane-impermeable bovine serum albumin-conjugated 17beta-estradiol, indicating the effects via membrane 17beta-estradiol-binding sites. H2O2 decreased, whereas 17beta-estradiol increased the amount of phosphorylated cAMP response element-binding protein and cAMP response element-dependent transcriptional activity, and H2O2 plus 17beta-estradiol led to basal levels. H-89, an inhibitor of cAMP-dependent protein kinase A, suppressed basal and 17beta-estradiol-induced cAMP response element-binding protein phosphorylation, cAMP response element-dependent transcriptional activity, Bcl-2 expression, and apoptosis resistance. The cAMP analog, dibutyryl cAMP, enhanced cAMP response element-binding protein phosphorylation, cAMP response element-dependent transcriptional activity, Bcl-2 expression, and apoptosis resistance. 17Beta-estradiol increased intracellular cAMP level and protein kinase A activity, whereas these were not altered by H2O2. Keratinocytes expressed mRNA for estrogen receptor beta and guanine nucleotide-binding protein-coupled receptor, GPR30




Gynecol Oncol. 2003 Dec;91(3):651-6.
Steroids and adrenomedullin growth patterns in human ovarian cancer cells: estrogenic-regulation assay.

Giacalone PL, Daures JP, Ouafik L, Martin PM, Laffargue F, Maudelonde T.

Department of Obstetrics and Gynecology (Pr F Laffargue), Hopital Arnaud de Villeneuve, University of Montpellier, Montpellier, France. pl.giacalonanadoo.fr

OBJECTIVE: Adrenomedullin is a multifunctional regulatory peptide with mitogenic and angiogenic capabilities. Objectives in this study were: (1) to describe the effects of adrenomedullin and anti-adrenomedullin antibodies on ovarian carcinoma cell proliferation, and (2) to assess the estradiol regulation of adrenomedullin metabolism. METHODS: We assessed the effects of estradiol, adrenomedullin, and anti-adrenomedullin antibodies on cell growth in three human ovarian cell lines. RT-PCR was used to assess mRNA expression and Western blots to determine protein levels. RESULTS: Estradiol stimulates BG-1 and PEO4 cells growth but not PEO14 cells. Adrenomedullin mRNA expression and secretion were not under estrogen control. Adrenomedullin and anti-adrenomedullin antibodies had no growth effects in vitro. Adjunction of anti-adrenomedullin antibodies to estradiol-stimulated cells significantly inhibited their growth. CONCLUSION: Adrenomedullin metabolism is not under estradiol control. Anti-adrenomedullin antibodies display inhibitory effects on cells having high mitogenic activity. This opens the need for additional search toward in vivo specific immunotherapy.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14675694&dopt=Abstract estradiol




Clin Exp Pharmacol Physiol. 2003 Sep;30(9):643-8.
Oestrogen improves glucose metabolism and insulin signal transduction in HepG2 cells.

Xie P, Liu ML, Gu YP, Lu J, Xu X, Zeng WM, Song HP.

Department of Biochemistry, Xiangya School of Medicine, Central South University, Changsha, Hunan 410-078, People's Republic of China.

1. Many clinical studies have suggested a relationship between oestrogen and insulin sensitivity. In the present study, HepG2 cells were divided into four groups: (i) control, incubated with 1 nmol/L insulin; (ii) the HI group, which was incubated with 100 nmol/L insulin to induce insulin resistance; (iii) the E2 group, in which control cells were incubated with 1 nmol/L insulin plus 1 nmol/L oestradiol; and (iv) the HI + E2 group, in which insulin-resistant cells were incubated with 100 nmol/L insulin + 1 nmol/L oestradiol. 2. A high concentration of insulin decreased the activity of phosphofructo-1-kinase (PFK), pyruvate dehydrogenase (PDH) and glycogen synthase (GS), as well as decreasing the expression of insulin receptor (IR) and insulin receptor substrate-2 (IRS-2). High insulin had no effect on glucose transport or the expression of insulin receptor-1 (IRS-1). 3. The addition of oestradiol to control cells increased glucose transport, the activity of PFK, PDH and GS and the expression of IRS-1 and IRS-2, but had no effect on the expression of IR. 4. Treatment of insulin-resistant HepG2 cells with oestradiol attenuated HI-induced decreases, except for IR, and the expression of IRS-1 was significantly higher than control, attaining levels seen in group 3. The expression of IRS-2 was significant higher than in insulin-resistant cells, but did not reach control levels. Changes in the activity of PFK, PDH and GS were the same as the changes seen in the expression of IRS-2. 5. These results suggest that high concentrations of insulin induce insulin resistance in HepG2 cells, whereas oestradiol improves glucose metabolism and insulin signal transduction of cells by enhancing the acti