| 1. |
- Börjesson, Anna E, et al.
(författare)
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The role of estrogen receptor-alpha and its activation function-1 for growth plate closure in female mice
- 2012
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Ingår i: American Journal of Physiology-Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 302:11
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Tidskriftsartikel (refereegranskat)abstract
- Borjesson AE, Windahl SH, Karimian E, Eriksson EE, Lagerquist MK, Engdahl C, Antal MC, Krust A, Chambon P, Savendahl L, Ohlsson C. The role of estrogen receptor-alpha and its activation function-1 for growth plate closure in female mice. Am J Physiol Endocrinol Metab 302: E1381-E1389, 2012. First published March 13, 2012; doi:10.1152/ajpendo.00646.2011.-High estradiol levels in late puberty induce growth plate closure and thereby cessation of growth in humans. In mice, the growth plates do not fuse after sexual maturation, but old mice display reduced longitudinal bone growth and high-dose estradiol treatment induces growth plate closure. Estrogen receptor (ER)-alpha stimulates gene transcription via two activation functions (AFs), AF-1 and AF-2. To evaluate the role of ER alpha and its AF-1 for age-dependent reduction in longitudinal bone growth and growth plate closure, female mice with inactivation of ER alpha (ER alpha(-/-)) or ER alpha AF-1 (ER alpha AF-1(0)) were evaluated. Old (16- to 19-mo-old) female ER alpha(-/-) mice showed continued substantial longitudinal bone growth, resulting in longer bones (tibia: +8.3%, P < 0.01) associated with increased growth plate height (+18%, P < 0.05) compared with wild-type (WT) mice. In contrast, the longitudinal bone growth ceased in old ER alpha AF-1(0) mice (tibia: -4.9%, P < 0.01). Importantly, the proximal tibial growth plates were closed in all old ER alpha AF-1(0) mice while they were open in all WT mice. Growth plate closure was associated with a significantly altered balance between chondrocyte proliferation and apoptosis in the growth plate. In conclusion, old female ER alpha(-/-) mice display a prolonged and enhanced longitudinal bone growth associated with increased growth plate height, resembling the growth phenotype of patients with inactivating mutations in ER alpha or aromatase. In contrast, ER alpha AF-1 deletion results in a hyperactive ER alpha, altering the chondrocyte proliferation/apoptosis balance, leading to growth plate closure. This suggests that growth plate closure is induced by functions of ER alpha that do not require AF-1 and that ER alpha AF-1 opposes growth plate closure.
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| 2. |
- Nilsson, Maria E., et al.
(författare)
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Measurement of a comprehensive sex steroid profile in rodent serum by high-sensitive gas chromatography-tandem mass spectrometry.
- 2015
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Ingår i: Endocrinology. - : The Endocrine Society. - 1945-7170 .- 0013-7227. ; 156:7, s. 2492-502
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Tidskriftsartikel (refereegranskat)abstract
- Accurate measurement of sex steroid concentrations in rodent serum is essential to evaluate mouse and rat models for sex steroid-related disorders. The aim of the present study was to develop a sensitive and specific gas chromatography-tandem mass spectrometry (GC-MS/MS) method to assess a comprehensive sex steroid profile in rodent serum. A major effort was invested in reaching an exceptionally high sensitivity for measuring serum estradiol concentrations. We established a GC-MS/MS assay with a lower limit of detection for estradiol, estrone, testosterone, dihydrotestosterone, progesterone, androstenedione and dehydroepiandrosterone of 0.3, 0.5, 4, 1.6, 8, 4 and 50 pg/ml, respectively, while the corresponding values for the lower limit of quantification were 0.5, 0.5, 8, 2.5, 74, 12 and 400 pg/ml, respectively. Calibration curves were linear, intra- and inter-assay CVs were low and accuracy was excellent for all analytes. The established assay was used to accurately measure a comprehensive sex steroid profile in female rats and mice according to estrus cycle phase. In addition, we characterized the impact of age, sex, gonadectomy, and estradiol treatment on serum concentrations of these sex hormones in mice. In conclusion, we have established a highly sensitive and specific GC-MS/MS method to assess a comprehensive sex steroid profile in rodent serum in a single run. This GC-MS/MS assay has, to the best of our knowledge, the best detectability reported for estradiol. Our method therefore represents an ideal tool to characterize sex steroid metabolism in a variety of sex steroid-related rodent models and in human samples with low estradiol levels.
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| 3. |
- Windahl, Sara H, 1971, et al.
(författare)
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Estrogen Receptor-alpha is required for the Osteogenic Response to mechanical loading in a Ligand-Independent manner involving its activation function 1 but Not 2
- 2013
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 28:2, s. 291-301
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen receptor-alpha (ER alpha) is crucial for the adaptive response of bone to loading but the role of endogenous estradiol (E2) for this response is unclear. To determine in vivo the ligand dependency and relative roles of different ERa domains for the osteogenic response to mechanical loading, gene-targeted mouse models with (1) a complete ERa inactivation (ER alpha(-/-)), (2) specific inactivation of activation function 1 (AF-1) in ER alpha (ER alpha AF-1(0)), or (3) specific inactivation of ER alpha AF-2 (ER alpha AF- 2(0)) were subjected to axial loading of tibia, in the presence or absence (ovariectomy [ovx]) of endogenous E2. Loading increased the cortical bone area in the tibia mainly as a result of an increased periosteal bone formation rate (BFR) and this osteogenic response was similar in gonadal intact and ovx mice, demonstrating that E2 (ligand) is not required for this response. Female ER alpha(-/-) mice displayed a severely reduced osteogenic response to loading with changes in cortical area (-78% +/- 15%, p < 0.01) and periosteal BFR (-81% +/- 9%, p < 0.01) being significantly lower than in wild-type (WT) mice. ER alpha AF-1(0) mice also displayed a reduced response to mechanical loading compared with WT mice (cortical area -40% +/- 11%, p < 0.05 and periosteal BFR -41% +/- 8%, p < 0.01), whereas the periosteal osteogenic response to loading was unaffected in ER alpha AF-2(0) mice. Mechanical loading of transgenic estrogen response element (ERE)-luciferase reporter mice did not increase luciferase expression in cortical bone, suggesting that the loading response does not involve classical genomic ERE-mediated pathways. In conclusion, ERa is required for the osteogenic response to mechanical loading in a ligand-independent manner involving AF-1 but not AF-2. (C) 2013 American Society for Bone and Mineral Research.
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| 4. |
- Börjesson, Anna E, et al.
(författare)
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Roles of transactivating functions 1 and 2 of estrogen receptor-alpha in bone.
- 2011
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 108:15, s. 6288-6293
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Tidskriftsartikel (refereegranskat)abstract
- The bone-sparing effect of estrogen is primarily mediated via estrogen receptor-α (ERα), which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand binding domain. To evaluate the role of ERα AF-1 and ERα AF-2 for the effects of estrogen in bone in vivo, we analyzed mouse models lacking the entire ERα protein (ERα(-/-)), ERα AF-1 (ERαAF-1(0)), or ERα AF-2 (ERαAF-2(0)). Estradiol (E2) treatment increased the amount of both trabecular and cortical bone in ovariectomized (OVX) WT mice. Neither the trabecular nor the cortical bone responded to E2 treatment in OVX ERα(-/-) or OVX ERαAF-2(0) mice. OVX ERαAF-1(0) mice displayed a normal E2 response in cortical bone but no E2 response in trabecular bone. Although E2 treatment increased the uterine and liver weights and reduced the thymus weight in OVX WT mice, no effect was seen on these parameters in OVX ERα(-/-) or OVX ERαAF-2(0) mice. The effect of E2 in OVX ERαAF-1(0) mice was tissue-dependent, with no or weak E2 response on thymus and uterine weights but a normal response on liver weight. In conclusion, ERα AF-2 is required for the estrogenic effects on all parameters evaluated, whereas the role of ERα AF-1 is tissue-specific, with a crucial role in trabecular bone and uterus but not cortical bone. Selective ER modulators stimulating ERα with minimal activation of ERα AF-1 could retain beneficial actions in cortical bone, constituting 80% of the skeleton, while minimizing effects on reproductive organs.
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| 5. |
- Börjesson, Anna E, et al.
(författare)
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SERMs have substance-specific effects on bone, and these effects are mediated via ER alpha AF-1 in female mice
- 2016
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Ingår i: American Journal of Physiology-Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 310:11
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Tidskriftsartikel (refereegranskat)abstract
- The bone-sparing effect of estrogens is mediated primarily via estrogen receptor (ER)alpha, which stimulates gene transcription through activation function (AF)-1 and AF-2. The role of ER alpha AF-1 for the estradiol (E-2) effects is tissue specific. The selective ER modulators (SERMs) raloxifene (Ral), lasofoxifene (Las), and bazedoxifene (Bza) can be used to treat postmenopausal osteoporosis. They all reduce the risk for vertebral fractures, whereas Las and partly Bza, but not Ral, reduce the risk for nonvertebral fractures. Here, we have compared the tissue specificity of Ral, Las, and Bza and evaluated the role of ER alpha AF-1 for the effects of these SERMs, with an emphasis on bone parameters. We treated ovariectomized (OVX) wild-type (WT) mice and OVX mice lacking ER alpha AF-1 (ER alpha AF-1(0)) with E-2, Ral, Las, or Bza. All three SERMs increased trabecular bone mass in the axial skeleton. In the appendicular skeleton, only Las increased the trabecular bone volume/tissue volume and trabecular number, whereas both Ral and Las increased the cortical bone thickness and strength. However, Ral also increased cortical porosity. The three SERMs had only a minor effect on uterine weight. Notably, all evaluated effects of these SERMs were absent in ovx ER alpha AF-1(0) mice. In conclusion, all SERMs had similar effects on axial bone mass. However, the SERMs had slightly different effects on the appendicular skeleton since only Las increased the trabecular bone mass and only Ral increased the cortical porosity. Importantly, all SERM effects require a functional ER alpha AF-1 in female mice. These results could lead to development of more specific treatments for osteoporosis.
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| 6. |
- Börjesson, Anna E, et al.
(författare)
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The role of activation functions 1 and 2 of estrogen receptor-alpha for the effects of estradiol and selective estrogen receptor modulators in male mice
- 2013
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 28:5, s. 1117-1126
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Tidskriftsartikel (refereegranskat)abstract
- Estradiol (E2) is important for male skeletal health and the effect of E2 is mediated via estrogen receptor (ER)-. This was demonstrated by the findings that men with an inactivating mutation in aromatase or a nonfunctional ER had osteopenia and continued longitudinal growth after sexual maturation. The aim of the present study was to evaluate the role of different domains of ER for the effects of E2 and selective estrogen receptor modulators (SERMs) on bone mass in males. Three mouse models lacking either ERAF-1 (ERAF-10), ERAF-2 (ERAF-20), or the total ER (ER/) were orchidectomized (orx) and treated with E2 or placebo. E2 treatment increased the trabecular and cortical bone mass and bone strength, whereas it reduced the thymus weight and bone marrow cellularity in orx wild type (WT) mice. These parameters did not respond to E2 treatment in orx ER/ or ERAF-20 mirx ERAF-10 mice were tissue-dependent, with a clear response in cortical bone parameters and bone marrow cellularity, but no response in trabecular bone. To determine the role of ERAF-1 for the effects of SERMs, we treated orx WT and ERAF-10 mice with raloxifene (Ral), lasofoxifene (Las), bazedoxifene (Bza), or vehicle. These SERMs increased total body areal bone mineral density (BMD) and trabecular volumetric BMD to a similar extent in orx WT mice. Furthermore, only Las increased cortical thickness significantly and only Bza increased bone strength significantly. However, all SERMs showed a tendency toward increased cortical bone parameters. Importantly, all SERM effects were absent in the orx ERAF-10 mice. In conclusion, ERAF-2 is required for the estrogenic effects on all evaluated parameters, whereas the role of ERAF-1 is tissue-specific. All evaluated effects of Ral, Las and Bza are dependent on a functional ERAF-1. Our findings might contribute to the development of bone-specific SERMs in males. (c) 2013 American Society for Bone and Mineral Research.
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| 7. |
- Börjesson, Anna E, et al.
(författare)
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The role of estrogen receptor-alpha in growth plate cartilage for longitudinal bone growth.
- 2010
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Ingår i: Journal of bone and mineral research. - : Wiley. - 1523-4681 .- 0884-0431. ; 25:12, s. 2414-24
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Tidskriftsartikel (refereegranskat)abstract
- Estrogens enhance skeletal growth during early sexual maturation while high estradiol levels during late puberty result in growth plate fusion in humans. Although the growth plates do not fuse directly after sexual maturation in rodents, a reduction in growth plate height is seen by treatment with a high dose of estradiol. It is unknown whether the effects of estrogens on skeletal growth are mediated directly via estrogen receptors (ERs) in growth plate cartilage and/or indirectly via other mechanisms such as the GH/IGF-I axis. To determine the role of ERalpha in growth plate cartilage for skeletal growth, we developed a mouse model with cartilage-specific inactivation of ERalpha. Although mice with total ERalpha inactivation displayed affected longitudinal bone growth associated with alterations in the GH/IGF-I axis, the skeletal growth was normal during sexual maturation in mice with cartilage-specific ERalpha inactivation. High dose estradiol treatment of adult mice reduced the growth plate height as a consequence of attenuated proliferation of growth plate chondrocytes in control mice but not in cartilage-specific ERalpha(-/-) mice. Adult cartilage-specific ERalpha(-/-) mice continued to grow after four months of age while growth was limited in control mice, resulting in increased femur length in one-year-old cartilage-specific ERalpha(-/-) mice compared with control mice. We conclude that during early sexual maturation ERalpha in growth plate cartilage is not important for skeletal growth. In contrast, it is essential for high dose estradiol to reduce the growth plate height in adult mice and for reduction of longitudinal bone growth in elderly mice. (c) 2010 American Society for Bone and Mineral Research.
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| 8. |
- Börjesson, Anna E, et al.
(författare)
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The role of estrogen receptor α in the regulation of bone and growth plate cartilage.
- 2013
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Ingår i: Cellular and molecular life sciences : CMLS. - : Springer Science and Business Media LLC. - 1420-9071 .- 1420-682X.
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Tidskriftsartikel (refereegranskat)abstract
- Estrogens are important endocrine regulators of skeletal growth and maintenance in both females and males. Studies have demonstrated that the estrogen receptor (ER)-α is the main mediator of these estrogenic effects in bone. Therefore, estrogen signaling via ERα is a target both for affecting longitudinal bone growth and bone remodeling. However, treatment with estradiol (E2) leads to an increased risk of side effects such as venous thromboembolism and breast cancer. Thus, an improved understanding of the signaling pathways of ERα will be essential in order to find better bone specific treatments with minimal adverse effects for different estrogen-related bone disorders. This review summarizes the recent data regarding the intracellular signaling mechanisms, in vivo, mediated by the ERα activation functions (AFs), AF-1 and AF-2, and the effect on bone, growth plate and other estrogen responsive tissues. In addition, we review the recent cell-specific ERα-deleted mouse models lacking ERα specifically in neuronal cells or growth plate cartilage. The newly characterized signaling pathways of estrogen, described in this review, provide a better understanding of the ERα signaling pathways, which may facilitate the design of new, bone-specific treatment strategies with minimal adverse effects.
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| 9. |
- Colldén, Hannah, et al.
(författare)
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Dehydroepiandrosterone Supplementation Results in Varying Tissue-specific Levels of Dihydrotestosterone in Male Mice
- 2022
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 163:12
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Tidskriftsartikel (refereegranskat)abstract
- Dehydroepiandrosterone (DHEA), an adrenal androgen precursor, can be metabolized in target tissues into active sex steroids. It has been proposed that DHEA supplementation might result in restoration of physiological local sex steroid levels, but knowledge on the effect of DHEA treatment on local sex steroid levels in multiple tissues is lacking. To determine the effects of DHEA on tissue-specific levels of sex steroids, we treated orchiectomized (ORX) male mice with DHEA for 3 weeks and compared them with vehicle-treated ORX mice and gonadal intact mice. Intra-tissue levels of sex steroids were analyzed in reproductive organs (seminal vesicles, prostate, m. levator ani), major body compartments (white adipose tissue, skeletal muscle, and brain), adrenals, liver, and serum using a sensitive and validated gas chromatography-mass spectrometry method. DHEA treatment restored levels of both testosterone (T) and dihydrotestosterone (DHT) to approximately physiological levels in male reproductive organs. In contrast, this treatment did not increase DHT levels in skeletal muscle or brain. In the liver, DHEA treatment substantially increased levels of T (at least 4-fold) and DHT (+536%, P < 0.01) compared with vehicle-treated ORX mice. In conclusion, we provide a comprehensive map of the effect of DHEA treatment on intra-tissue sex steroid levels in ORX mice with a restoration of physiological levels of androgens in male reproductive organs while DHT levels were not restored in the skeletal muscle or brain. This, and the unexpected supraphysiological androgen levels in the liver, may be a cause for concern considering the uncontrolled use of DHEA.
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| 10. |
- Engdahl, Cecilia, 1983, et al.
(författare)
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Amelioration of collagen-induced arthritis and immune-associated bone loss through signaling via estrogen receptor alpha, and not estrogen receptor beta or G protein-coupled receptor 30.
- 2010
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Ingår i: Arthritis and rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 62:2, s. 524-33
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The effects of estrogen may be exerted via the nuclear estrogen receptors (ERs) ERalpha or ERbeta or via the recently proposed transmembrane estrogen receptor G protein-coupled receptor 30 (GPR-30). The purpose of this study was to elucidate the ER specificity for the ameliorating effects of estrogen on arthritis and bone loss in a model of postmenopausal rheumatoid arthritis (RA). METHODS: Female DBA/1 mice underwent ovariectomy or sham operation, and type II collagen-induced arthritis was induced. Mice were treated subcutaneously 5 days/week with the specific agonists propylpyrazoletriol (PPT; for ERalpha), diarylpropionitrile (DPN; for ERbeta), G1 (for GPR-30), or with a physiologic dose of estradiol. Clinical arthritis scores were determined continuously. At termination of the study, bone mineral density (BMD) was analyzed, paws were collected for histologic assessment, serum was analyzed for cytokines and markers of bone and cartilage turnover, and bone marrow was subjected to fluorescence-activated cell sorting. RESULTS: Treatment with PPT as well as estradiol dramatically decreased the frequency and severity of arthritis. Furthermore, estradiol and PPT treatment resulted in preservation of bone and cartilage, as demonstrated by increased BMD and decreased serum levels of bone resorption markers and cartilage degradation markers, whereas no effect was seen after DPN or G1 treatment. CONCLUSION: In a well-established model of postmenopausal RA, ERalpha, but not ERbeta or GPR-30 signaling, was shown to ameliorate the disease and the associated development of osteoporosis. Since long-term treatment with estrogen has been associated with significant side effects, increased knowledge about the mechanisms behind the beneficial effects of estrogen is useful in the search for novel treatments of postmenopausal RA.
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