1
|
Vanderschueren D, Laurent MR, Claessens F, Gielen E, Lagerquist MK, Vandenput L, Börjesson AE, Ohlsson C. Sex steroid actions in male bone. Endocr Rev 2014; 35:906-60. [PMID: 25202834 PMCID: PMC4234776 DOI: 10.1210/er.2014-1024] [Citation(s) in RCA: 185] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Sex steroids are chief regulators of gender differences in the skeleton, and male gender is one of the strongest protective factors against osteoporotic fractures. This advantage in bone strength relies mainly on greater cortical bone expansion during pubertal peak bone mass acquisition and superior skeletal maintenance during aging. During both these phases, estrogens acting via estrogen receptor-α in osteoblast lineage cells are crucial for male cortical and trabecular bone, as evident from conditional genetic mouse models, epidemiological studies, rare genetic conditions, genome-wide meta-analyses, and recent interventional trials. Genetic mouse models have also demonstrated a direct role for androgens independent of aromatization on trabecular bone via the androgen receptor in osteoblasts and osteocytes, although the target cell for their key effects on periosteal bone formation remains elusive. Low serum estradiol predicts incident fractures, but the highest risk occurs in men with additionally low T and high SHBG. Still, the possible clinical utility of serum sex steroids for fracture prediction is unknown. It is likely that sex steroid actions on male bone metabolism rely also on extraskeletal mechanisms and cross talk with other signaling pathways. We propose that estrogens influence fracture risk in aging men via direct effects on bone, whereas androgens exert an additional antifracture effect mainly via extraskeletal parameters such as muscle mass and propensity to fall. Given the demographic trends of increased longevity and consequent rise of osteoporosis, an increased understanding of how sex steroids influence male bone health remains a high research priority.
Collapse
Affiliation(s)
- Dirk Vanderschueren
- Clinical and Experimental Endocrinology (D.V.) and Gerontology and Geriatrics (M.R.L., E.G.), Department of Clinical and Experimental Medicine; Laboratory of Molecular Endocrinology, Department of Cellular and Molecular Medicine (M.R.L., F.C.); and Centre for Metabolic Bone Diseases (D.V., M.R.L., E.G.), KU Leuven, B-3000 Leuven, Belgium; and Center for Bone and Arthritis Research (M.K.L., L.V., A.E.B., C.O.), Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden
| | | | | | | | | | | | | | | |
Collapse
|
2
|
Gao QG, Chan HY, Man CWY, Wong MS. Differential ERα-mediated rapid estrogenic actions of ginsenoside Rg1 and estren in human breast cancer MCF-7 cells. J Steroid Biochem Mol Biol 2014; 141:104-12. [PMID: 24508513 DOI: 10.1016/j.jsbmb.2014.01.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/17/2014] [Accepted: 01/28/2014] [Indexed: 12/16/2022]
Abstract
Recent studies indicated that both estren and Rg1 appear to be able to activate mitogen-activated protein kinase (MAPK) pathway in estrogen responsive cells. Rg1 could lead to MAPK activation through ligand-independent activation of estrogen receptor (ER), while estren could activate the Src-MAPK pathway in an ERE-independent manner. Thus, it is important to understand the mechanistic insights on the difference in transcriptional activation between estren and Rg1. The present study also addressed the differential abilities of Rg1 and estren in terms of the ability to activate ER and the ability to induce ER translocation in MCF-7 cells. Our data indicated that Rg1 could increase pS2 gene expression, and could recruit the co-activator steroid receptor co-activator-1 (SRC-1) to the pS2 promoter. Rg1 could also induce ERα nuclear translocation as well as ERα phosphorylation at Ser118 principally in the cytoplasm in MCF-7 cells. We deduced that estren induced ERE-dependent transcriptional activity and activated ERα at Ser118 occurred in the nucleus of MCF-7 cells. However, it was found to decrease pS2 gene expression and failed to induce the recruitment of SRC-1 to the pS2 promoter in MCF-7 cells. Our results suggest that the abilities of Rg1 and estren to regulate pS2 gene expression, to recruit co-activators as well as to induce sub-cellular distribution of ERα are dramatically different.
Collapse
Affiliation(s)
- Quan-Gui Gao
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region
| | - Hoi-Yi Chan
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region
| | - Cornelia Wing-Yin Man
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region
| | - Man-Sau Wong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region; State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen 518057, China.
| |
Collapse
|
3
|
Murata T, Narita K, Ichimaru T. Rat uterine oxytocin receptor and estrogen receptor α and β mRNA levels are regulated by estrogen through multiple estrogen receptors. J Reprod Dev 2013; 60:55-61. [PMID: 24334513 PMCID: PMC3963296 DOI: 10.1262/jrd.2012-139] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Estrogen action is mediated through several types of receptors (ERs), such as ERα, ERβ
and putative membrane ERs. Oxytocin receptor (OTR) and ER expression levels in the rat
uterus are regulated by estrogen; however, which types of ERs are involved has not been
elucidated. This study examined OTR, ERα and ERβ levels in ovariectomized rats treated
with 17β-estradiol (E2), an ERα agonist (PPT), an ERβ agonist (DPN) or estren (Es). E2 and
PPT increased OTR mRNA levels and decreased ERα and ERβ mRNA levels 3 and 6 h
posttreatment. DPN decreased ERα and ERβ mRNA levels at 3 and 6 h, while OTR mRNA levels
increased at 3 h and decreased at 6 h. OTR mRNA levels increased 3 h after the Es
treatment and then declined until 6 h. ERα and ERβ mRNA levels decreased by 3 h and
remained low until 6 h posttreatment with Es. The ER antagonist ICI182,780 (ICI)
suppressed the increases in OTR mRNA levels induced 3 h after the Es treatment. However,
ICI and tamoxifen (Tam) had no significant effect on ERα and ERβ mRNA levels in the
Es-treated or vehicle-treated group. In intact rats, proestrus-associated increases in OTR
mRNA levels were antagonized by both ICI and Tam. However, decreases in ERα and ERβ mRNA
levels were not antagonized by Tam and ICI, respectively. Therefore, uterine OTR gene
expression is upregulated by estrogen through the classical nuclear (or non-nuclear) ERs,
ERα and ERβ, while the levels of these ERs are downregulated by estrogen through multiple
pathways including Es-sensitive nonclassical ERs.
Collapse
Affiliation(s)
- Takuya Murata
- Department of Integrative Physiology, Faculty of Medical Science, University of Fukui, Fukui 910-1193, Japan
| | | | | |
Collapse
|
4
|
Koszegi Z, Szego ÉM, Cheong RY, Tolod-Kemp E, Ábrahám IM. Postlesion estradiol treatment increases cortical cholinergic innervations via estrogen receptor-α dependent nonclassical estrogen signaling in vivo. Endocrinology 2011; 152:3471-82. [PMID: 21791565 DOI: 10.1210/en.2011-1017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
17β-Estradiol (E2) treatment exerts rapid, nonclassical actions via intracellular signal transduction system in basal forebrain cholinergic (BFC) neurons in vivo. Here we examined the effect of E2 treatment on lesioned BFC neurons in ovariectomized mice and the role of E2-induced nonclassical action in this treatment. Mice given an N-methyl-d-aspartic acid (NMDA) injection into the substantia innominata-nucleus basalis magnocellularis complex (SI-NBM) exhibited cholinergic cell loss in the SI-NBM and ipsilateral cholinergic fiber loss in the cortex. A single injection of E2 after NMDA lesion did not have an effect on cholinergic cell loss in the SI-NBM, but it restored the ipsilateral cholinergic fiber density in the cortex in a time- and dose-dependent manner. The most effective cholinergic fiber restoration was observed with 33 ng/g E2 treatment at 1 h after NMDA lesion. The E2-induced cholinergic fiber restoration was absent in neuron-specific estrogen receptor-α knockout mice in vivo. Selective activation of nonclassical estrogen signaling in vivo by estren induced E2-like restorative actions. Selective blockade of the MAPK or protein kinase A pathway in vivo prevented E2's ability to restore cholinergic fiber loss. Finally, studies in intact female mice revealed an E2-induced restorative effect that was similar to that of E2-treated ovariectomized mice. These observations demonstrate that a single E2 treatment restores the BFC fiber loss in the cortex, regardless of endogenous E2 levels. They also reveal the critical role of nonclassical estrogen signaling via estrogen receptor-α and protein kinase A-MAPK pathways in E2-induced restorative action in the cholinergic system in vivo.
Collapse
Affiliation(s)
- Zsombor Koszegi
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | | | | | | | | |
Collapse
|
5
|
Zárate S, Jaita G, Zaldivar V, Radl DB, Eijo G, Ferraris J, Pisera D, Seilicovich A. Estrogens exert a rapid apoptotic action in anterior pituitary cells. Am J Physiol Endocrinol Metab 2009; 296:E664-71. [PMID: 19158323 DOI: 10.1152/ajpendo.90785.2008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It is now accepted that estrogens not only stimulate lactotrope proliferation but also sensitize anterior pituitary cells to proapoptotic stimuli. In addition to their classical mechanism of action through binding to intracellular estrogen receptors (ERs), there is increasing evidence that estrogens exert rapid actions mediated by cell membrane-localized ERs (mERs). In the present study, we examined the involvement of membrane-initiated steroid signaling in the proapoptotic action of estradiol in primary cultures of anterior pituitary cells from ovariectomized rats by using estren, a synthetic estrogen with no effect on classical transcription and a cell-impermeable 17beta-estradiol conjugate (E2-BSA). Both compounds induced cell death of anterior pituitary cells after 60 min of incubation as assessed by flow cytometry and the [3-(4,5-dimethylthiazol-2-yl)]-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Estren, E2, and E2-BSA induced apoptosis of lactotropes and somatotropes as evaluated by the deoxynucleotidyltransferase-mediated dUTP nick end-labeling assay and immunodetection of prolactin (PRL) and growth hormone (GH). The proapoptotic effect of E2-BSA was abrogated by ICI-182,780, an antagonist of ERs. The expression of membrane-associated ERalpha was observed in PRL- and GH-bearing cells. Our results indicate that estradiol is able to exert a rapid apoptotic action in anterior pituitary cells, especially lactotropes and somatotropes, by a mechanism triggered by mERs. This mechanism could be involved in anterior pituitary cell turnover.
Collapse
Affiliation(s)
- S Zárate
- Instituto de Investigaciones en Reproducción, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, piso 10, Buenos Aires, Argentina
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Venken K, Callewaert F, Boonen S, Vanderschueren D. Sex hormones, their receptors and bone health. Osteoporos Int 2008; 19:1517-25. [PMID: 18392663 DOI: 10.1007/s00198-008-0609-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
Sex steroids regulate skeletal maturation and preservation in both men and women, as already recognized in the 1940s by Albright and Reifenstein. The impact of gonadal insufficiency on skeletal integrity has been widely recognized in adult men and women ever since. In the context of their skeletal actions, androgens and estrogens are no longer considered as just male and female hormones, respectively. Androgens can be converted into estrogens within the gonads and peripheral tissues and both are present in men and women, albeit in different concentrations. In the late 1980s, sex steroid receptors were discovered in bone cells. However, the understanding of sex steroid receptor activation and translation into biological skeletal actions is still incomplete. Due to the complex metabolism, sex steroids may have not only endocrine but also paracrine and/or autocrine actions. Also, circulating sex steroid concentrations do not necessarily reflect their biological activity due to strong binding to sex hormone binding globulin (SHBG). Finally, sex steroid signaling may include genomic and non-genomic effects in bone and non-bone cells. This review will focus on our current understanding of gonadal steroid metabolism, receptor activation, and their most relevant cellular and biological actions on bone.
Collapse
Affiliation(s)
- K Venken
- Bone Research Unit, Laboratory for Experimental Medicine and Endocrinology, Department of Experimental Medicine, Katholieke Universiteit Leuven, Herestraat 49, Box 902, B-3000, Leuven, Belgium
| | | | | | | |
Collapse
|
7
|
Carlsten H. Interaction with estrogen receptors as treatment of arthritis and osteoporosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 602:83-92. [PMID: 17966392 DOI: 10.1007/978-0-387-72009-8_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Affiliation(s)
- Hans Carlsten
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, Göteborg Academy, Göteborg, Sweden
| |
Collapse
|
8
|
Manolagas SC, Jilka RL, Kousteni S, Bellido T, Weinstein RS, O'Brien CA, Plotkin L, Han L. Response to Windahl et al. J Clin Invest 2006; 116:2834. [PMID: 17080186 PMCID: PMC1626133 DOI: 10.1172/jci30535] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
9
|
Kousteni S, Almeida M, Han L, Bellido T, Jilka RL, Manolagas SC. Induction of osteoblast differentiation by selective activation of kinase-mediated actions of the estrogen receptor. Mol Cell Biol 2006; 27:1516-30. [PMID: 17158928 PMCID: PMC1800724 DOI: 10.1128/mcb.01550-06] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Estrogens control gene transcription by cis or trans interactions of the estrogen receptor (ER) with target DNA or via the activation of cytoplasmic kinases. We report that selective activation of kinase-mediated actions of the ER with 4-estren-3alpha,17beta-diol (estren) or an estradiol-dendrimer conjugate, each a synthetic compound that stimulates kinase-mediated ER actions 1,000 to 10,000 times more potently than direct DNA interactions, induced osteoblastic differentiation in established cell lines of uncommitted osteoblast precursors and primary cultures of osteoblast progenitors by stimulating Wnt and BMP-2 signaling in a kinase-dependent manner. In sharp contrast, 17beta-estradiol (E(2)) suppressed BMP-2-induced osteoblast progenitor commitment and differentiation. Consistent with the in vitro findings, estren, but not E(2), stimulated Wnt/beta-catenin-mediated transcription in T-cell factor-lacZ transgenic mice. Moreover, E(2) stimulated BMP signaling in mice in which ERalpha lacks DNA binding activity and classical estrogen response element-mediated transcription (ERalpha(NERKI/-)) but not in wild-type controls. This evidence reveals for the first time the existence of a large signalosome in which inputs from the ER, kinases, bone morphogenetic proteins, and Wnt signaling converge to induce differentiation of osteoblast precursors. ER can either induce it or repress it, depending on whether the activating ligand (and presumably the resulting conformation of the receptor protein) precludes or accommodates ERE-mediated transcription.
Collapse
Affiliation(s)
- Stavroula Kousteni
- Division of Endocrinology and Metabolism, University of Arkansas for Medical Sciences, 4301 West Markham, Little Rock, AR 72205, USA
| | | | | | | | | | | |
Collapse
|
10
|
Windahl SH, Galien R, Chiusaroli R, Clément-Lacroix P, Morvan F, Lepescheux L, Nique F, Horne WC, Resche-Rigon M, Baron R. Bone protection by estrens occurs through non-tissue-selective activation of the androgen receptor. J Clin Invest 2006; 116:2500-9. [PMID: 16955145 PMCID: PMC1555662 DOI: 10.1172/jci28809] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Accepted: 06/20/2006] [Indexed: 11/17/2022] Open
Abstract
The use of estrogens and androgens to prevent bone loss is limited by their unwanted side effects, especially in reproductive organs and breast. Selective estrogen receptor modulators (SERMs) partially avoid such unwanted effects, but their efficacy on bone is only moderate compared with that of estradiol or androgens. Estrens have been suggested to not only prevent bone loss but also exert anabolic effects on bone while avoiding unwanted effects on reproductive organs. In this study, we compared the effects of a SERM (PSK3471) and 2 estrens (estren-alpha and estren-beta) on bone and reproductive organs to determine whether estrens are safe and act via the estrogen receptors and/or the androgen receptor (AR). Estrens and PSK3471 prevented gonadectomy-induced bone loss in male and female mice, but none showed true anabolic effects. Unlike SERMs, the estrens induced reproductive organ hypertrophy in both male and female mice and enhanced MCF-7 cell proliferation in vitro. Estrens directly activated transcription in several cell lines, albeit at much higher concentrations than estradiol or the SERM, and acted for the most part through the AR. We conclude that the estrens act mostly through the AR and, in mice, do not fulfill the preclinical efficacy or safety criteria required for the treatment or prevention of osteoporosis.
Collapse
Affiliation(s)
- Sara H. Windahl
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - René Galien
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Riccardo Chiusaroli
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Philippe Clément-Lacroix
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Frederic Morvan
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Liên Lepescheux
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - François Nique
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - William C. Horne
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Michèle Resche-Rigon
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Roland Baron
- Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut, USA.
ProStrakan Pharmaceuticals, Romainville, France.
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
| |
Collapse
|
11
|
Abstract
Estrogens and androgens play a key role in regulating bone mass. However, their clinical use as bone anabolic agents is limited due to unwanted side effects, particularly in reproductive organs. In 2002, the synthetic ligand estren was described to reproduce the bone anabolic, nongenotropic effects of sex steroids while having no effect on the uterus or seminal vesicles. But in the current issue of the JCI, Windahl et al. provide data showing that estrens are not as suitable a replacement for estrogen as was initially reported (see the related article beginning on page 2500). Though not catabolic, estrens triggered only minor, nonsignificant increases in bone mass in gonadectomized mice, all the while inducing hypertrophy of reproductive organs. Does this mean estrens should not be pursued as a therapy for osteoporosis?
Collapse
Affiliation(s)
- Ushma S Neill
- Journal of Clinical Investigation, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
| |
Collapse
|
12
|
Hewitt SC, Collins J, Grissom S, Hamilton K, Korach KS. Estren behaves as a weak estrogen rather than a nongenomic selective activator in the mouse uterus. Endocrinology 2006; 147:2203-14. [PMID: 16469803 DOI: 10.1210/en.2005-1292] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A proposed membrane-mediated mechanism of rapid nongenomic response to estrogen has been the intense focus of recent research. Estren, a synthetic steroid, is reported to act selectively through a rapid membrane-mediated pathway, rather than through the classical nuclear estrogen receptor (ER)-mediated pathway, to maintain bone density in ovariectomized mice without uterotropic effects. To evaluate the mechanism and physiological effects of estren, we studied responses in adult ovariectomized mice. In a 3-d uterine bioassay, we found that 300 microg estren significantly increased uterine weight; in comparison, a more maximal response was seen with 1 mug estradiol (E2). The estren response was partly ERalpha independent, because ERalpha knockout (alphaERKO) uteri also exhibited a more moderate weight increase. Estren induced epithelial cell proliferation in wild-type, but not alphaERKO, mice, indicating ERalpha dependence of the epithelial growth response. Examination of estren-regulated uterine genes by microarray indicated that early (2 h) changes in gene expression are similar to the early responses to E2. These gene responses are ERalpha dependent, because they are not seen in alphaERKO mice. Later estren-induced changes in gene expression (24 h) are blunted compared with those seen 24 h after E2. In contrast to early genes, these later estren responses are independent of ERalpha, because the alphaERKO shows a similar response to estren at 24 h. We found that E2 or estren treatments lead to depletion of ERalpha in the uterine cytosol fraction and accumulation in the nuclear fraction within 30-60 min, consistent with the ability of estren to regulate genes through a nuclear ERalpha rather than a nongenomic mechanism. Interestingly, estren, but not E2, induces accumulation of androgen receptor (AR) in the nuclear fraction of both wild-type and alphaERKO samples, suggesting that AR might be involved in the later ERalpha-independent genomic responses to estren. In conclusion, our studies suggest that estren is weakly estrogenic in the mouse uterus and might induce nuclear ERalpha- and AR-mediated responses. Given its activity in our uterine model, the use of estren as a bone-selective clinical compound needs to be reconsidered.
Collapse
Affiliation(s)
- Sylvia C Hewitt
- Receptor Biology Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, North Carolina 27709, USA
| | | | | | | | | |
Collapse
|
13
|
Abstract
In addition to its effects on sexual differentiation and reproduction, estrogen has important impact on the immune system and on bone. It has also been evident that the effects of estrogen on bone to a large extent are mediated via its action on immune cells. Estrogen has a dichotomous impact on the immune system by downregulation of inflammatory immune responses but simultaneous upregulation of immunoglobulin production. Consequently, immune-mediated diseases in humans and in animal models are modulated by estrogen. Estrogen deficiency after ovariectomy in mice and after menopause in women is associated with significant bone loss. In rheumatic diseases such as rheumatoid arthritis (RA), osteoporosis is frequent, and in patients with postmenopausal RA, the degree of bone loss is dramatically increased. Hormone replacement therapy (HRT) in murine and human arthritis has beneficial effects on bone loss, as expected, but it also ameliorates inflammation and inflammation-triggered joint destruction. Long-term use of HRT has been associated with increased risk of breast cancer, thrombosis, and possibly also stroke. Accordingly, there is great need for new activators of estrogen receptors (ERs) selectively reproducing only the beneficial effects of estrogen. To achieve this aim, better knowledge of the mechanisms of how activation of ER-alpha and ER-beta modulates the immune system and bone at the cellular and molecular levels is necessary.
Collapse
Affiliation(s)
- Hans Carlsten
- Department of Rheumatology and Inflammation Research, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden.
| |
Collapse
|
14
|
Islander U, Hasséus B, Erlandsson MC, Jochems C, Skrtic SM, Lindberg M, Gustafsson JÅ, Ohlsson C, Carlsten H. Estren promotes androgen phenotypes in primary lymphoid organs and submandibular glands. BMC Immunol 2005; 6:16. [PMID: 16011795 PMCID: PMC1187889 DOI: 10.1186/1471-2172-6-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 07/12/2005] [Indexed: 11/15/2022] Open
Abstract
Background Estrogens and androgens have extensive effects on the immune system, for example they suppress both T and B lymphopoiesis in thymus and bone marrow. Submandibular glands are sexually dimorphic in rodents, resulting in larger granular convoluted tubules in males compared to females. The aim of the present experiments was to investigate the estrogenic and androgenic effects of 4-estren-3α,17β-diol (estren) on thymus, bone marrow and submandibular glands, and compare the effects to those of 17β-estradiol (E2) and 5α-dihydrotestosterone (DHT), respectively. Estrogen receptors (ERs) were blocked by treatment of mice with the ER-antagonist ICI 182,780; also, knock-out mice lacking one or both ERs were used. Results As expected, the presence of functional ERs was mandatory for all the effects of E2. Similar to DHT-treatment, estren-treatment resulted in decreased thymus weight, as well as decreased frequency of bone marrow B cells. Treatment with estren or DHT also resulted in a shift in submandibular glands towards an androgen phenotype. All the effects of estren and DHT were independent of ERs. Conclusion Our study is the first to show that estren has similar effects as the androgen DHT on lymphopoiesis in thymus and bone marrow, and on submandibular glands, and that these effects are independent of estrogen receptors. This supports the hypothesis of estren being able to signal through the androgen receptor.
Collapse
Affiliation(s)
- Ulrika Islander
- Department of Rheumatology and Inflammation Research at the Sahlgrenska Academy, Göteborg University, Sweden
| | - Bengt Hasséus
- Institute of Odontology, Sahlgrenska Academy, Göteborg University, Sweden
| | - Malin C Erlandsson
- Department of Rheumatology and Inflammation Research at the Sahlgrenska Academy, Göteborg University, Sweden
| | - Caroline Jochems
- Department of Rheumatology and Inflammation Research at the Sahlgrenska Academy, Göteborg University, Sweden
| | - Sofia Movérare Skrtic
- Center for Bone Research at the Sahlgrenska Academy (CBS), Göteborg University, Sweden
| | - Marie Lindberg
- Center for Bone Research at the Sahlgrenska Academy (CBS), Göteborg University, Sweden
| | - Jan-Åke Gustafsson
- Center for Biotechnology and Department of Medical Nutrition, Karolinska Institute, NOVUM, Huddinge, Sweden
| | - Claes Ohlsson
- Center for Bone Research at the Sahlgrenska Academy (CBS), Göteborg University, Sweden
| | - Hans Carlsten
- Department of Rheumatology and Inflammation Research at the Sahlgrenska Academy, Göteborg University, Sweden
| |
Collapse
|
15
|
Cordey M, Gundimeda U, Gopalakrishna R, Pike CJ. The synthetic estrogen 4-estren-3α,17β-diol (estren) induces estrogen-like neuroprotection. Neurobiol Dis 2005; 19:331-9. [PMID: 15837589 DOI: 10.1016/j.nbd.2005.01.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 01/10/2005] [Accepted: 01/12/2005] [Indexed: 11/24/2022] Open
Abstract
Estrogen has demonstrated neuroprotective properties, which may underlie the observed preventive effect of estrogen-based hormone therapy (HT) against the development of neurodegenerative disorders such as Alzheimer's disease. Deleterious side effects of HT have increased efforts to develop safer compounds that selectively reproduce beneficial estrogen actions. Recently, 4-estren-3 alpha,17 beta-diol (estren) was identified as having estrogen agonist properties in bone, without significantly stimulating growth of reproductive tissues. Here, we examined whether estren parallels the neuroprotective actions of estrogen against beta-amyloid (A beta) in cultured cerebrocortical neurons. Estren increased neuronal viability to a similar extent to that observed with 17 beta-estradiol (E2) and 17 alpha-estradiol. As we previously reported for E2, estren rapidly increased PKC activity, and PKC inhibition prevented estren neuroprotection. In contrast, the estrogen receptor antagonist ICI 182,780 blocked E2, but not estren neuroprotection. Our results indicate that estren-induced activation of rapid cell signaling pathways protects cultured neurons from A beta toxicity.
Collapse
Affiliation(s)
- Myriam Cordey
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089-0191, USA
| | | | | | | |
Collapse
|
16
|
Islander U, Erlandsson MC, Chavoshi T, Jochems C, Movérare S, Nilsson S, Ohlsson C, Gustafsson JA, Carlsten H. Estren-mediated inhibition of T lymphopoiesis is estrogen receptor-independent whereas its suppression of T cell-mediated inflammation is estrogen receptor-dependent. Clin Exp Immunol 2005; 139:210-5. [PMID: 15654819 PMCID: PMC1809293 DOI: 10.1111/j.1365-2249.2005.02698.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Estrogen has extensive effects on the immune system. The aim of the present experiments was to compare the effects of 17beta-estradiol (E2) and 4-estren-3alpha,17beta-diol (estren) on T lymphopoiesis and T cell-dependent inflammation. In order to investigate the role of estrogen receptors (ER) in the effects of E2 and estren on the immune system, ER knock-out mice lacking both ERalpha and ERbeta (DERKO) were used. T lymphopoiesis and T cell-dependent inflammation were studied by investigating thymus cellularity, the delayed-type hypersensitivity (DTH) reaction, CD4(+) T cells in spleen and serum levels of interleukin (IL)-6. As expected, the presence of ERs was mandatory for all the effects of E2. In contrast, treatment with estren reduced thymus cellularity in ER knock-out mice, indicating an effect through ER-independent pathways. Interestingly, estren suppressed only DTH, the frequency of CD4(+) T cells in spleen and serum levels of IL-6 in wild-type (WT) mice, but not in mice lacking ERs. Thus, our study is the first to show that estren inhibits T lymphopoiesis via ER-independent pathways, whereas its suppressive effects on inflammation are ER-dependent.
Collapse
Affiliation(s)
- U Islander
- Department of Rheumatology and Inflammation Research at the Sahlgrenska Academy, Göteborg, Sweden.
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Björnström L, Sjöberg M. Mechanisms of estrogen receptor signaling: convergence of genomic and nongenomic actions on target genes. Mol Endocrinol 2005; 19:833-42. [PMID: 15695368 DOI: 10.1210/me.2004-0486] [Citation(s) in RCA: 964] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Estrogen receptors (ERs) act by regulating transcriptional processes. The classical mechanism of ER action involves estrogen binding to receptors in the nucleus, after which the receptors dimerize and bind to specific response elements known as estrogen response elements (EREs) located in the promoters of target genes. However, ERs can also regulate gene expression without directly binding to DNA. This occurs through protein-protein interactions with other DNA-binding transcription factors in the nucleus. In addition, membrane-associated ERs mediate nongenomic actions of estrogens, which can lead both to altered functions of proteins in the cytoplasm and to regulation of gene expression. The latter two mechanisms of ER action enable a broader range of genes to be regulated than the range that can be regulated by the classical mechanism of ER action alone. This review surveys our knowledge about the molecular mechanism by which ERs regulate the expression of genes that do not contain EREs, and it gives examples of the ways in which the genomic and nongenomic actions of ERs on target genes converge. Genomic and nongenomic actions of ERs that do not depend on EREs influence the physiology of many target tissues, and thus, increasing our understanding of the molecular mechanisms behind these actions is highly relevant for the development of novel drugs that target specific receptor actions.
Collapse
Affiliation(s)
- Linda Björnström
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | | |
Collapse
|
18
|
Centrella M, Christakos S, McCarthy TL. Skeletal hormones and the C/EBP and Runx transcription factors: interactions that integrate and redefine gene expression. Gene 2005; 342:13-24. [PMID: 15527960 DOI: 10.1016/j.gene.2004.06.036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 05/27/2004] [Accepted: 06/17/2004] [Indexed: 11/27/2022]
Abstract
Systemic hormones and local growth factors have significant and often complex roles in normal tissue development, growth, remodeling, and repair. Early efforts in skeletal tissue attempted to define active panels of these agents and their direct effects on cell proliferation, matrix production, and secretion of other soluble mediators of differentiated cell function. Initial results resolved many of these questions and began to unveil functional interactions between specific hormones and growth factors. More recent evidence suggests that interactions between individual hormone systems also occur in less anticipated but probably not less meaningful ways. In some cases, these interactions may help to define a spectrum of effects on gene expression by focusing, refocusing, or integrating the activity of previously recognized transcription regulators. Other studies in isolated osteoblasts predict that certain steroid hormones have distinctive effects on specific transcription factors with important roles in bone growth and repair. In this review, we focus on studies that define functional and physical interactions between molecular mediators of hormone activity that could directly effect skeletal growth factor biology.
Collapse
Affiliation(s)
- Michael Centrella
- Department of Surgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8041, USA.
| | | | | |
Collapse
|