| 1. |
- Svensson, Johan, 1964, et al.
(författare)
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Liver-derived igf-I regulates mean life span in mice
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:7
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Tidskriftsartikel (refereegranskat)abstract
- Transgenic mice with low levels of global insulin-like growth factor-I (IGF-I) throughout their life span, including pre- and postnatal development, have increased longevity. This study investigated whether specific deficiency of liver-derived, endocrine IGF-I is of importance for life span.
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| 2. |
- Windahl, Sara H, 1971, et al.
(författare)
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Reduced bone mass and muscle strength in male 5α-reductase type 1 inactivated mice.
- 2011
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 6:6
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Tidskriftsartikel (refereegranskat)abstract
- Androgens are important regulators of bone mass but the relative importance of testosterone (T) versus dihydrotestosterone (DHT) for the activation of the androgen receptor (AR) in bone is unknown. 5α-reductase is responsible for the irreversible conversion of T to the more potent AR activator DHT. There are two well established isoenzymes of 5α-reductase (type 1 and type 2), encoded by separate genes (Srd5a1 and Srd5a2). 5α-reductase type 2 is predominantly expressed in male reproductive tissues whereas 5α-reductase type 1 is highly expressed in liver and moderately expressed in several other tissues including bone. The aim of the present study was to investigate the role of 5α-reductase type 1 for bone mass using Srd5a1⁻/⁻ mice. Four-month-old male Srd5a1⁻/⁻ mice had reduced trabecular bone mineral density (-36%, p<0.05) and cortical bone mineral content (-15%, p<0.05) but unchanged serum androgen levels compared with wild type (WT) mice. The cortical bone dimensions were reduced in the male Srd5a1⁻/⁻ mice as a result of a reduced cortical periosteal circumference compared with WT mice. T treatment increased the cortical periosteal circumference (p<0.05) in orchidectomized WT mice but not in orchidectomized Srd5a1⁻/⁻ mice. Male Srd5a1⁻/⁻ mice demonstrated a reduced forelimb muscle grip strength compared with WT mice (p<0.05). Female Srd5a1⁻/⁻ mice had slightly increased cortical bone mass associated with elevated circulating levels of androgens. In conclusion, 5α-reductase type 1 inactivated male mice have reduced bone mass and forelimb muscle grip strength and we propose that these effects are due to lack of 5α-reductase type 1 expression in bone and muscle. In contrast, the increased cortical bone mass in female Srd5a1⁻/⁻ mice, is an indirect effect mediated by elevated circulating androgen levels.
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| 3. |
- 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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| 4. |
- 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
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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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| 5. |
- 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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| 6. |
- Movérare-Skrtic, Sofia, et al.
(författare)
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Osteoblast-derived WNT16 represses osteoclastogenesis and prevents cortical bone fragility fractures.
- 2014
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 20:11, s. 1279-88
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Tidskriftsartikel (refereegranskat)abstract
- The WNT16 locus is a major determinant of cortical bone thickness and nonvertebral fracture risk in humans. The disability, mortality and costs caused by osteoporosis-induced nonvertebral fractures are enormous. We demonstrate here that Wnt16-deficient mice develop spontaneous fractures as a result of low cortical thickness and high cortical porosity. In contrast, trabecular bone volume is not altered in these mice. Mechanistic studies revealed that WNT16 is osteoblast derived and inhibits human and mouse osteoclastogenesis both directly by acting on osteoclast progenitors and indirectly by increasing expression of osteoprotegerin (Opg) in osteoblasts. The signaling pathway activated by WNT16 in osteoclast progenitors is noncanonical, whereas the pathway activated in osteoblasts is both canonical and noncanonical. Conditional Wnt16 inactivation revealed that osteoblast-lineage cells are the principal source of WNT16, and its targeted deletion in osteoblasts increases fracture susceptibility. Thus, osteoblast-derived WNT16 is a previously unreported key regulator of osteoclastogenesis and fracture susceptibility. These findings open new avenues for the specific prevention or treatment of nonvertebral fractures, a substantial unmet medical need.
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| 7. |
- Movérare-Skrtic, Sofia, et al.
(författare)
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The estrogen receptor antagonist ICI 182,780 can act both as an agonist and an inverse agonist when estrogen receptor α AF-2 is modified.
- 2014
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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. - 1091-6490. ; 111:3
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Tidskriftsartikel (refereegranskat)abstract
- The bone-sparing effect of estrogen is primarily mediated via estrogen receptor (ER) α, which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand-binding domain. It was recently demonstrated that the ER antagonist ICI 182,780 (ICI) acts as an ER agonist in uterus of mice with mutations in the ERα AF-2. To evaluate the estrogen-like effects of ICI in different tissues, ovariectomized wild-type mice and mice with mutations in the ERα AF-2 (ERαAF-2(0)) were treated with ICI, estradiol, or vehicle for 3 wk. Estradiol increased the trabecular and cortical bone mass as well as the uterine weight, whereas it reduced fat mass, thymus weight, and the growth plate height in wild-type but not in ERαAF-2(0) mice. Although ICI had no effect in wild-type mice, it exerted tissue-specific effects in ERαAF-2(0) mice. It acted as an ERα agonist on trabecular bone mass and uterine weight, whereas no effect was seen on cortical bone mass, fat mass, or thymus weight. Surprisingly, a pronounced inverse agonistic activity was seen on the growth plate height, resulting in enhanced longitudinal bone growth. In conclusion, ICI uses ERα AF-1 in a tissue-dependent manner in mice lacking ERαAF-2, resulting in no effect, agonistic activity, or inverse agonistic activity. We propose that ERα lacking AF-2 is constitutively active in the absence of ligand in the growth plate, enabling ICI to act as an inverse agonist.
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| 8. |
- Ohlsson, Claes, 1965, et al.
(författare)
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Probiotics protect mice from ovariectomy-induced cortical bone loss.
- 2014
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- The gut microbiota (GM) modulates the hosts metabolism and immune system. Probiotic bacteria are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host and can alter the composition of the GM. Germ-free mice have increased bone mass associated with reduced bone resorption indicating that the GM also regulates bone mass. Ovariectomy (ovx) results in bone loss associated with altered immune status. The purpose of this study was to determine if probiotic treatment protects mice from ovx-induced bone loss. Mice were treated with either a single Lactobacillus (L) strain, L. paracasei DSM13434 (L. para) or a mixture of three strains, L. paracasei DSM13434, L. plantarum DSM 15312 and DSM 15313 (L. mix) given in the drinking water during 6 weeks, starting two weeks before ovx. Both the L. para and the L. mix treatment protected mice from ovx-induced cortical bone loss and bone resorption. Cortical bone mineral content was higher in both L. para and L. mix treated ovx mice compared to vehicle (veh) treated ovx mice. Serum levels of the resorption marker C-terminal telopeptides and the urinary fractional excretion of calcium were increased by ovx in the veh treated but not in the L. para or the L. mix treated mice. Probiotic treatment reduced the expression of the two inflammatory cytokines, TNFα and IL-1β, and increased the expression of OPG, a potent inhibitor of osteoclastogenesis, in cortical bone of ovx mice. In addition, ovx decreased the frequency of regulatory T cells in bone marrow of veh treated but not probiotic treated mice. In conclusion, treatment with L. para or the L. mix prevents ovx-induced cortical bone loss. Our findings indicate that these probiotic treatments alter the immune status in bone resulting in attenuated bone resorption in ovx mice.
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| 9. |
- Sjögren, Klara, 1970, et al.
(författare)
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The gut microbiota regulates bone mass in mice
- 2012
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 27:6, s. 1357-1367
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Tidskriftsartikel (refereegranskat)abstract
- The gut microbiota modulates host metabolism and development of immune status. Here we show that the gut microbiota is also a major regulator of bone mass in mice. Germ-free (GF) mice exhibit increased bone mass associated with reduced number of osteoclasts per bone surface compared with conventionally raised (CONV-R) mice. Colonization of GF mice with a normal gut microbiota normalizes bone mass. Furthermore, GF mice have decreased frequency of CD4+ T cells and CD11b+/GR 1 osteoclast precursor cells in bone marrow, which could be normalized by colonization. GF mice exhibited reduced expression of inflammatory cytokines in bone and bone marrow compared with CONV-R mice. In summary, the gut microbiota regulates bone mass in mice, and we provide evidence for a mechanism involving altered immune status in bone and thereby affected osteoclast-mediated bone resorption. Further studies are required to evaluate the gut microbiota as a novel therapeutic target for osteoporosis. (C) 2012 American Society for Bone and Mineral Research.
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| 10. |
- Strauss, Leena, et al.
(författare)
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Seminal vesicles and urinary bladder as sites of aromatization of androgens in men, evidenced by a CYP19A1-driven luciferase reporter mouse and human tissue specimens.
- 2013
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 27:4, s. 1342-50
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Tidskriftsartikel (refereegranskat)abstract
- The human CYP19A1 gene is expressed in various tissues by the use of tissue-specific promoters, whereas the rodent cyp19a1 gene is expressed mainly in the gonads and brain. We generated a transgenic mouse model containing a >100-kb 5' region of human CYP19A1 gene connected to a luciferase reporter gene. The luciferase activity in mouse tissues mimicked the CYP19A1 gene expression pattern in humans. Interestingly, the reporter gene activity was 16 and 160 times higher in the urinary bladder and seminal vesicles, respectively, as compared with the activity in the testis. Accordingly, CYP19A1 gene and P450arom protein expression was detected in those human tissues. Moreover, the data revealed that the expression of CYP19A1 gene is driven by promoters PII, I.4, and I.3 in the seminal vesicles, and by promoters PII and I.4 in the urinary bladder. Furthermore, the reporter gene expression in the seminal vesicles was androgen dependent: Castration decreased the expression ∼20 times, and testosterone treatment restored it to the level of an intact mouse. This reporter mouse model facilitates studies of tissue-specific regulation of the human CYP19A1 gene, and our data provide evidence for seminal vesicles as important sites for estrogen production in males.-Strauss, L., Rantakari, P., Sjögren, K., Salminen, A., Lauren, E., Kallio, J., Damdimopoulou, P., Boström, M., Boström, P. J., Pakarinen, P., Zhang, F. P., Kujala, P., Ohlsson, C., Mäkelä, S., Poutanen, M. Seminal vesicles and urinary bladder as sites of aromatization of androgens in men, evidenced by a CYP19A1-driven luciferase reporter mouse and human tissue specimens.
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