1
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Fu Q, Bustamante-Gomez NC, Reyes-Pardo H, Gubrij I, Escalona-Vargas D, Thostenson JD, Palmieri M, Goellner JJ, Nookaew I, Barnes CL, Stambough JB, Ambrogini E, O’Brien CA. Reduced osteoprotegerin expression by osteocytes may contribute to rebound resorption after denosumab discontinuation. JCI Insight 2023; 8:e167790. [PMID: 37581932 PMCID: PMC10561722 DOI: 10.1172/jci.insight.167790] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 08/03/2023] [Indexed: 08/17/2023] Open
Abstract
Denosumab is an anti-RANKL Ab that potently suppresses bone resorption, increases bone mass, and reduces fracture risk. Discontinuation of denosumab causes rapid rebound bone resorption and bone loss, but the molecular mechanisms are unclear. We generated humanized RANKL mice and treated them with denosumab to examine the cellular and molecular conditions associated with rebound resorption. Denosumab potently suppressed both osteoclast and osteoblast numbers in cancellous bone in humanized RANKL mice. The decrease in osteoclast number was not associated with changes in osteoclast progenitors in bone marrow. Long-term, but not short-term, denosumab administration reduced osteoprotegerin (OPG) mRNA in bone. Localization of OPG expression revealed that OPG mRNA is produced by a subpopulation of osteocytes. Long-term denosumab administration reduced osteocyte OPG mRNA, suggesting that OPG expression declines as osteocytes age. Consistent with this, osteocyte expression of OPG was more prevalent near the surface of cortical bone in humans and mice. These results suggest that new osteocytes are an important source of OPG in remodeling bone and that suppression of remodeling reduces OPG abundance by reducing new osteocyte formation. The lack of new osteocytes and the OPG they produce may contribute to rebound resorption after denosumab discontinuation.
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Affiliation(s)
- Qiang Fu
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
| | | | - Humberto Reyes-Pardo
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
| | - Igor Gubrij
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
| | | | | | - Michela Palmieri
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
| | - Joseph J. Goellner
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
| | - Intawat Nookaew
- Center for Musculoskeletal Disease Research
- Department of Biomedical Informatics, and
| | - C. Lowry Barnes
- Center for Musculoskeletal Disease Research
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jeffrey B. Stambough
- Center for Musculoskeletal Disease Research
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Elena Ambrogini
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, USA
| | - Charles A. O’Brien
- Center for Musculoskeletal Disease Research
- Division of Endocrinology and Metabolism
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, USA
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2
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Xiong J, Cawley K, Piemontese M, Fujiwara Y, Zhao H, Goellner JJ, O'Brien CA. Soluble RANKL contributes to osteoclast formation in adult mice but not ovariectomy-induced bone loss. Nat Commun 2018; 9:2909. [PMID: 30046091 PMCID: PMC6060116 DOI: 10.1038/s41467-018-05244-y] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/15/2018] [Indexed: 11/30/2022] Open
Abstract
Receptor activator of NFkB ligand (RANKL) is a TNF-family cytokine required for osteoclast formation, as well as immune cell and mammary gland development. It is produced as a membrane-bound protein that can be shed to form a soluble protein. We created mice harboring a sheddase-resistant form of RANKL, in which soluble RANKL is undetectable in the circulation. Lack of soluble RANKL does not affect bone mass or structure in growing mice but reduces osteoclast number and increases cancellous bone mass in adult mice. Nonetheless, the bone loss caused by estrogen deficiency is unaffected by the lack of soluble RANKL. Lymphocyte number, lymph node development, and mammary gland development are also unaffected by the absence of soluble RANKL. These results demonstrate that the membrane-bound form of RANKL is sufficient for most functions of this protein but that the soluble form does contribute to physiological bone remodeling in adult mice. RANKL is a cytokine produced as a membrane-bound and a secreted protein. Here, using mice lacking soluble RANKL, the authors show that the secreted protein is important for osteoclast function, but not for mammary gland and lymphocyte development.
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Affiliation(s)
- Jinhu Xiong
- Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA.,Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA
| | - Keisha Cawley
- Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA.,Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA
| | - Marilina Piemontese
- Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA
| | - Yuko Fujiwara
- Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA
| | - Haibo Zhao
- Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA
| | - Joseph J Goellner
- Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA.,Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA.,Central Arkansas Veterans Healthcare System, Little Rock, 72205, AR, USA
| | - Charles A O'Brien
- Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA. .,Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA. .,Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, 72205, AR, USA. .,Central Arkansas Veterans Healthcare System, Little Rock, 72205, AR, USA.
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3
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Fil D, DeLoach A, Yadav S, Alkam D, MacNicol M, Singh A, Compadre CM, Goellner JJ, O’Brien CA, Fahmi T, Basnakian AG, Calingasan NY, Klessner JL, Beal FM, Peters OM, Metterville J, Brown RH, Ling KK, Rigo F, Ozdinler PH, Kiaei M. Mutant Profilin1 transgenic mice recapitulate cardinal features of motor neuron disease. Hum Mol Genet 2017; 26:686-701. [PMID: 28040732 PMCID: PMC5968635 DOI: 10.1093/hmg/ddw429] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/08/2016] [Accepted: 12/16/2016] [Indexed: 12/11/2022] Open
Abstract
The recent identification of profilin1 mutations in 25 familial ALS cases has linked altered function of this cytoskeleton-regulating protein to the pathogenesis of motor neuron disease. To investigate the pathological role of mutant profilin1 in motor neuron disease, we generated transgenic lines of mice expressing human profilin1 with a mutation at position 118 (hPFN1G118V). One of the mouse lines expressing high levels of mutant human PFN1 protein in the brain and spinal cord exhibited many key clinical and pathological features consistent with human ALS disease. These include loss of lower (ventral horn) and upper motor neurons (corticospinal motor neurons in layer V), mutant profilin1 aggregation, abnormally ubiquitinated proteins, reduced choline acetyltransferase (ChAT) enzyme expression, fragmented mitochondria, glial cell activation, muscle atrophy, weight loss, and reduced survival. Our investigations of actin dynamics and axonal integrity suggest that mutant PFN1 protein is associated with an abnormally low filamentous/globular (F/G)-actin ratio that may be the underlying cause of severe damage to ventral root axons resulting in a Wallerian-like degeneration. These observations indicate that our novel profilin1 mutant mouse line may provide a new ALS model with the opportunity to gain unique perspectives into mechanisms of neurodegeneration that contribute to ALS pathogenesis.
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Affiliation(s)
- Daniel Fil
- Department of Pharmacology and Toxicology
| | | | | | - Duah Alkam
- Department of Pharmacology and Toxicology
| | | | | | | | - Joseph J. Goellner
- Division of Endocrinology, University of Arkansas for Medical Sciences, AR,
USA
| | - Charles A. O’Brien
- Division of Endocrinology, University of Arkansas for Medical Sciences, AR,
USA
| | | | - Alexei G. Basnakian
- Department of Pharmacology and Toxicology
- Central Arkansas Veterans Healthcare System, Little Rock, AR 72205, USA
| | - Noel Y. Calingasan
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New
York, NY 10065, USA
| | - Jodi L. Klessner
- Department of Neurology, Northwestern University, Feinberg School of
Medicine, 303 E. Chicago Ave, Chicago, IL 6011, USA
| | - Flint M. Beal
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New
York, NY 10065, USA
| | - Owen M. Peters
- Department of Neurology, University of Massachusetts Medical School,
Worcester, MA 01605, USA
| | - Jake Metterville
- Department of Neurology, University of Massachusetts Medical School,
Worcester, MA 01605, USA
| | - Robert H. Brown
- Department of Neurology, University of Massachusetts Medical School,
Worcester, MA 01605, USA
| | - Karen K.Y. Ling
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New
York, NY, 10065, USA
| | - Frank Rigo
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New
York, NY, 10065, USA
| | - P. Hande Ozdinler
- Department of Neurology, Northwestern University, Feinberg School of
Medicine, 303 E. Chicago Ave, Chicago, IL 6011, USA
| | - Mahmoud Kiaei
- Department of Pharmacology and Toxicology
- Physiology and Biophysics
- Center for Translational Neuroscience
- Department of Neurology
- Department of Geriatrics, The University of Arkansas for Medical Sciences,
AR, USA
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4
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Xiong J, Piemontese M, Onal M, Campbell J, Goellner JJ, Dusevich V, Bonewald L, Manolagas SC, O’Brien CA. Osteocytes, not Osteoblasts or Lining Cells, are the Main Source of the RANKL Required for Osteoclast Formation in Remodeling Bone. PLoS One 2015; 10:e0138189. [PMID: 26393791 PMCID: PMC4578942 DOI: 10.1371/journal.pone.0138189] [Citation(s) in RCA: 206] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/26/2015] [Indexed: 01/17/2023] Open
Abstract
The cytokine receptor activator of nuclear factor kappa B ligand (RANKL), encoded by the Tnfsf11 gene, is essential for osteoclastogenesis and previous studies have shown that deletion of the Tnfsf11 gene using a Dmp1-Cre transgene reduces osteoclast formation in cancellous bone by more than 70%. However, the Dmp1-Cre transgene used in those studies leads to recombination in osteocytes, osteoblasts, and lining cells making it unclear whether one or more of these cell types produce the RANKL required for osteoclast formation in cancellous bone. Because osteoblasts, osteocytes, and lining cells have distinct locations and functions, distinguishing which of these cell types are sources of RANKL is essential for understanding the orchestration of bone remodeling. To distinguish between these possibilities, we have now created transgenic mice expressing the Cre recombinase under the control of regulatory elements of the Sost gene, which is expressed in osteocytes but not osteoblasts or lining cells in murine bone. Activity of the Sost-Cre transgene in osteocytes, but not osteoblast or lining cells, was confirmed by crossing Sost-Cre transgenic mice with tdTomato and R26R Cre-reporter mice, which express tdTomato fluorescent protein or LacZ, respectively, only in cells expressing the Cre recombinase or their descendants. Deletion of the Tnfsf11 gene in Sost-Cre mice led to a threefold decrease in osteoclast number in cancellous bone and increased cancellous bone mass, mimicking the skeletal phenotype of mice in which the Tnfsf11 gene was deleted using the Dmp1-Cre transgene. These results demonstrate that osteocytes, not osteoblasts or lining cells, are the main source of the RANKL required for osteoclast formation in remodeling cancellous bone.
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Affiliation(s)
- Jinhu Xiong
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | - Marilina Piemontese
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | - Melda Onal
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | - Josh Campbell
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | - Joseph J. Goellner
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | - Vladimir Dusevich
- Department of Oral Biology, University of Missouri-Kansas City School of Dentistry, Kansas City, Missouri, United States of America
| | - Lynda Bonewald
- Department of Oral Biology, University of Missouri-Kansas City School of Dentistry, Kansas City, Missouri, United States of America
| | - Stavros C. Manolagas
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | - Charles A. O’Brien
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- The Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
- * E-mail:
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5
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Onal M, Bishop KA, St John HC, Danielson AL, Riley EM, Piemontese M, Xiong J, Goellner JJ, O'Brien CA, Pike JW. A DNA segment spanning the mouse Tnfsf11 transcription unit and its upstream regulatory domain rescues the pleiotropic biologic phenotype of the RANKL null mouse. J Bone Miner Res 2015; 30:855-68. [PMID: 25431114 PMCID: PMC5240630 DOI: 10.1002/jbmr.2417] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 11/15/2014] [Accepted: 11/24/2014] [Indexed: 12/26/2022]
Abstract
Receptor activator of NF-κB ligand (RANKL) is a TNFα-like cytokine that is produced by a diverse set of lineage-specific cells and is involved in a wide variety of physiological processes that include skeletal remodeling, lymph node organogenesis, mammary gland development, and thermal regulation. Consistent with these diverse functions, control of RANKL expression is accomplished in a cell-specific fashion via a set of at least 10 regulatory enhancers that are located up to 170 kb upstream of the gene's transcriptional start site. Here we examined the in vivo consequence of introducing a contiguous DNA segment containing these components into a genetically deleted RANKL null mouse strain. In contrast to RANKL null littermates, null mice containing the transgene exhibited normalized body size, skeletal development, and bone mass as well as normal bone marrow cavities, normalized spleen weights, and the presence of developed lymph nodes. These mice also manifested normalized reproductive capacity, including the ability to lactate and to produce normal healthy litters. Consistent with this, the transgene restored endogenous-like RANKL transcript levels in several RANKL-expressing tissues. Most importantly, restoration of RANKL expression from this segment of DNA was fully capable of rescuing the complex aberrant skeletal and immune phenotype of the RANKL null mouse. RANKL also restored appropriate levels of B220+ IgM+ and B220+ IgD+ B cells in spleen. Finally, we found that RANKL expression from this transgene was regulated by exogenously administered 1,25(OH)2 D3 , parathyroid hormone (PTH), and lipopolysaccharide (LPS), thus recapitulating the ability of these same factors to regulate the endogenous gene. These findings fully highlight the properties of the Tnfsf11 gene locus predicted through previous in vitro dissection. We conclude that the mouse Tnfsf11 gene locus identified originally through unbiased chromatin immunoprecipitation with DNA microarray (ChIP-chip) analysis contains the necessary genetic information to direct appropriate tissue-specific and factor-regulated RANKL expression in vivo.
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Affiliation(s)
- Melda Onal
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
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6
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Abstract
The syndrome of hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR) is a genetic disease of altered mineral homeostasis due to mutations in the vitamin D receptor (VDR) gene. It is frequently, but not always, accompanied by the presence of alopecia. Mouse models that recapitulate this syndrome have been prepared through genetic deletion of the Vdr gene and are characterized by the presence of rickets and alopecia. Subsequent studies have revealed that VDR expression in hair follicle keratinocytes protects against alopecia and that this activity is independent of the protein's ability to bind 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. In the present study, we introduced into VDR-null mice a human VDR (hVDR) bacterial artificial chromosome minigene containing a mutation that converts leucine to serine at amino acid 233 in the hVDR protein, which prevents 1,25(OH)2D3 binding. We then assessed whether this transgene recreated features of the HVDRR syndrome without alopecia. RT-PCR and Western blot analysis in one strain showed an appropriate level of mutant hVDR expression in all tissues examined including skin. The hVDR-L233S mutant failed to rescue the aberrant systemic and skeletal phenotype characteristic of the VDR null mouse due to the inability of the mutant receptor to activate transcription after treatment with 1,25(OH)2D3. Importantly, however, neither alopecia nor the dermal cysts characteristic of VDR-null mice were observed in the skin of these hVDR-L233S mutant mice. This study confirms that we have created a humanized mouse model of HVDRR without alopecia that will be useful in defining additional features of this syndrome and in identifying potential novel functions of the unoccupied VDR.
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Affiliation(s)
- Seong Min Lee
- Department of Biochemistry (S.M.L., J.W.P.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and University of Arkansas for Medical Sciences (J.J.G., C.A.O.), Little Rock, Arkansas 72205
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7
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Lee SM, Bishop KA, Goellner JJ, O'Brien CA, Pike JW. Mouse and human BAC transgenes recapitulate tissue-specific expression of the vitamin D receptor in mice and rescue the VDR-null phenotype. Endocrinology 2014; 155:2064-76. [PMID: 24693968 PMCID: PMC4020932 DOI: 10.1210/en.2014-1107] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The biological actions of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) are mediated by the vitamin D receptor (VDR), which is expressed in numerous target tissues in a cell type-selective manner. Recent studies using genomic analyses and recombineered bacterial artificial chromosomes (BACs) have defined the specific features of mouse and human VDR gene loci in vitro. In the current study, we introduced recombineered mouse and human VDR BACs as transgenes into mice and explored their expression capabilities in vivo. Individual transgenic mouse strains selectively expressed BAC-derived mouse or human VDR proteins in appropriate vitamin D target tissues, thereby recapitulating the tissue-specific expression of endogenous mouse VDR. The mouse VDR transgene was also regulated by 1,25(OH)2D3 and dibutyryl-cAMP. When crossed into a VDR-null mouse background, both transgenes restored wild-type basal as well as 1,25(OH)2D3-inducible gene expression patterns in the appropriate tissues. This maneuver resulted in the complete rescue of the aberrant phenotype noted in the VDR-null mouse, including systemic features associated with altered calcium and phosphorus homeostasis and disrupted production of parathyroid hormone and fibroblast growth factor 23, and abnormalities associated with the skeleton, kidney, parathyroid gland, and the skin. This study suggests that both mouse and human VDR transgenes are capable of recapitulating basal and regulated expression of the VDR in the appropriate mouse tissues and restore 1,25(OH)2D3 function. These results provide a baseline for further dissection of mechanisms integral to mouse and human VDR gene expression and offer the potential to explore the consequence of selective mutations in VDR proteins in vivo.
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Affiliation(s)
- Seong Min Lee
- Department of Biochemistry (S.M.L., K.A.B., J.W.P.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and University of Arkansas for Medical Sciences (J.J.G., C.A.O.), Little Rock, Arkansas 72205
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8
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O'Brien CA, Plotkin LI, Galli C, Goellner JJ, Gortazar AR, Allen MR, Robling AG, Bouxsein M, Schipani E, Turner CH, Jilka RL, Weinstein RS, Manolagas SC, Bellido T. Control of bone mass and remodeling by PTH receptor signaling in osteocytes. PLoS One 2008; 3:e2942. [PMID: 18698360 PMCID: PMC2491588 DOI: 10.1371/journal.pone.0002942] [Citation(s) in RCA: 257] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 07/21/2008] [Indexed: 11/30/2022] Open
Abstract
Osteocytes, former osteoblasts buried within bone, are thought to orchestrate skeletal adaptation to mechanical stimuli. However, it remains unknown whether hormones control skeletal homeostasis through actions on osteocytes. Parathyroid hormone (PTH) stimulates bone remodeling and may cause bone loss or bone gain depending on the balance between bone resorption and formation. Herein, we demonstrate that transgenic mice expressing a constitutively active PTH receptor exclusively in osteocytes exhibit increased bone mass and bone remodeling, as well as reduced expression of the osteocyte-derived Wnt antagonist sclerostin, increased Wnt signaling, increased osteoclast and osteoblast number, and decreased osteoblast apoptosis. Deletion of the Wnt co-receptor LDL related receptor 5 (LRP5) attenuates the high bone mass phenotype but not the increase in bone remodeling induced by the transgene. These findings demonstrate that PTH receptor signaling in osteocytes increases bone mass and the rate of bone remodeling through LRP5-dependent and -independent mechanisms, respectively.
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Affiliation(s)
- Charles A. O'Brien
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail: (CO); (TB)
| | - Lilian I. Plotkin
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Carlo Galli
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Joseph J. Goellner
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Arancha R. Gortazar
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Matthew R. Allen
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Alexander G. Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Mary Bouxsein
- Department of Orthopedic Surgery, Harvard Medical School, Orthopedic Biomechanics Laboratory, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Ernestina Schipani
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Charles H. Turner
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Robert L. Jilka
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Robert S. Weinstein
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Stavros C. Manolagas
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Teresita Bellido
- Division of Endocrinology, Center for Osteoporosis and Metabolic Bone Diseases, Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail: (CO); (TB)
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9
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Abstract
Aldosterone classically promotes unidirectional transepithelial sodium transport, thereby regulating blood volume and blood pressure. Recently, both clinical and experimental studies have suggested additional, direct roles for aldosterone in the cardiovascular system. To evaluate aldosterone activation of cardiomyocyte mineralocorticoid receptors, transgenic mice overexpressing 11beta-hydroxysteroid dehydrogenase type 2 in cardiomyocytes were generated using the mouse alpha-myosin heavy chain promoter. This enzyme converts glucocorticoids to receptor-inactive metabolites, allowing aldosterone occupancy of cardiomyocyte mineralocorticoid receptors. Transgenic mice were normotensive but spontaneously developed cardiac hypertrophy, fibrosis, and heart failure and died prematurely on a normal salt diet. Eplerenone, a selective aldosterone blocker, ameliorated this phenotype. These studies confirm the deleterious consequences of inappropriate activation of cardiomyocyte mineralocorticoid receptors by aldosterone and reveal a tonic inhibitory role of glucocorticoids in preventing such outcomes under physiological conditions. In addition, these data support the hypothesis that aldosterone blockade may provide additional therapeutic benefit in the treatment of heart failure.
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MESH Headings
- 11-beta-Hydroxysteroid Dehydrogenase Type 2
- Aldosterone/physiology
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Cardiomegaly/genetics
- Cardiomegaly/physiopathology
- Disease Models, Animal
- Echocardiography
- Eplerenone
- Female
- Fibrosis/genetics
- Fibrosis/physiopathology
- Gene Expression Regulation/drug effects
- Gene Expression Regulation, Enzymologic/drug effects
- Heart Failure/genetics
- Heart Failure/physiopathology
- Hydroxysteroid Dehydrogenases/genetics
- Hydroxysteroid Dehydrogenases/metabolism
- Kidney/metabolism
- Kidney/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mineralocorticoid Receptor Antagonists
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Spironolactone/analogs & derivatives
- Spironolactone/pharmacology
- Up-Regulation
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Dysfunction, Left/prevention & control
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Affiliation(s)
- Wenning Qin
- Department of Genomics Sciences, Pfizer, Inc, St Louis, Mo 63167, USA
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10
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Andreasson KI, Savonenko A, Vidensky S, Goellner JJ, Zhang Y, Shaffer A, Kaufmann WE, Worley PF, Isakson P, Markowska AL. Age-dependent cognitive deficits and neuronal apoptosis in cyclooxygenase-2 transgenic mice. J Neurosci 2001; 21:8198-209. [PMID: 11588192 PMCID: PMC6763862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
The cyclooxygenases catalyze the rate-limiting step in the formation of prostaglandins from arachidonic acid and are the pharmacological targets of (NSAIDs). In brain, cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase, is selectively expressed in neurons of the cerebral cortex, hippocampus, and amygdala. As an immediate-early gene, COX-2 is dramatically and transiently induced in these neurons in response to NMDA receptor activation. In models of acute excitotoxic neuronal injury, elevated and sustained levels of COX-2 have been shown to promote neuronal apoptosis, indicating that upregulated COX-2 activity is injurious to neurons. COX-2 may also contribute to the development of Alzheimer's disease, for which early administration of NSAIDs is protective against development of the disease. To test the effect of constitutively elevated neuronal COX-2, transgenic mice were generated that overexpressed COX-2 in neurons and produced elevated levels of prostaglandins in brain. In cross-sectional behavioral studies, COX-2 transgenic mice developed an age-dependent deficit in spatial memory at 12 and 20 months but not at 7 months and a deficit in aversive behavior at 20 months of age. These behavioral changes were associated with a parallel age-dependent increase in neuronal apoptosis occurring at 14 and 22 months but not at 8 months of age and astrocytic activation at 24 months of age. These findings suggest that neuronal COX-2 may contribute to the pathophysiology of age-related diseases such as Alzheimer's disease by promoting memory dysfunction, neuronal apoptosis, and astrocytic activation in an age-dependent manner.
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Affiliation(s)
- K I Andreasson
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Markham RB, Pier GB, Goellner JJ, Mizel SB. In vitro T cell-mediated killing of Pseudomonas aeruginosa. II. The role of macrophages and T cell subsets in T cell killing. The Journal of Immunology 1985. [DOI: 10.4049/jimmunol.134.6.4112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
T lymphocytes from immune mice can adoptively transfer protection against infection with the extra-cellular Gram-negative bacterium Pseudomonas aeruginosa to nonimmune recipients, and in vitro, immune T cells are able to kill these bacteria. Earlier studies indicated that this killing is mediated by a bactericidal lymphokine. Those studies also showed that macrophages enhance this in vitro T cell killing but do not directly participate in the bacterial killing, nor do macrophages function to present antigen to T cells. The current studies demonstrate that the ability of macrophages to enhance T cell killing can be replaced by macrophage culture supernatants or by purified recombinant interleukin 1 (IL 1). In addition, the macrophage supernatant-induced enhancement can also be blocked by antibody to purified IL 1. These studies also demonstrate that the T cell subset that serves as the final effector cell in the killing process is the Lyt-1-, 2,3+, I-J+ phenotype.
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Markham RB, Pier GB, Goellner JJ, Mizel SB. In vitro T cell-mediated killing of Pseudomonas aeruginosa. II. The role of macrophages and T cell subsets in T cell killing. J Immunol 1985; 134:4112-7. [PMID: 3921618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
T lymphocytes from immune mice can adoptively transfer protection against infection with the extra-cellular Gram-negative bacterium Pseudomonas aeruginosa to nonimmune recipients, and in vitro, immune T cells are able to kill these bacteria. Earlier studies indicated that this killing is mediated by a bactericidal lymphokine. Those studies also showed that macrophages enhance this in vitro T cell killing but do not directly participate in the bacterial killing, nor do macrophages function to present antigen to T cells. The current studies demonstrate that the ability of macrophages to enhance T cell killing can be replaced by macrophage culture supernatants or by purified recombinant interleukin 1 (IL 1). In addition, the macrophage supernatant-induced enhancement can also be blocked by antibody to purified IL 1. These studies also demonstrate that the T cell subset that serves as the final effector cell in the killing process is the Lyt-1-, 2,3+, I-J+ phenotype.
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