scholarly journals Estrogen Stimulation of Pleiotrophin Enhances Osteoblast Differentiation and Maintains Bone Mass in IGFBP-2 Null Mice

Endocrinology ◽  
2020 ◽  
Vol 161 (4) ◽  
Author(s):  
Gang Xi ◽  
Victoria E Demambro ◽  
Susan D’Costa ◽  
Shalier K Xia ◽  
Zach C Cox ◽  
...  
Keyword(s):  
Bone Mass ◽  
Osteoblast Differentiation ◽  
Volume Fraction ◽  
Tyrosine Phosphatase ◽  
Areal Bone Mineral Density ◽  
Wild Type ◽  
Mineral Density ◽  
Bone Volume Fraction ◽  
Skeletal Phenotype

Abstract Insulin-like growth factor binding protein-2 (IGFBP-2) stimulates osteoblast differentiation but only male Igfbp2 null mice have a skeletal phenotype. The trophic actions of IGFBP-2 in bone are mediated through its binding to receptor tyrosine phosphatase beta (RPTPβ). Another important ligand for RPTPβ is pleiotrophin (PTN), which also stimulates osteoblast differentiation. We determined the change in PTN and RPTPβ in Igfbp2–/– mice. Analysis of whole bone mRNA in wild-type and knockout mice revealed increased expression of Ptn. Rptpβ increased in gene-deleted animals with females having greater expression than males. Knockdown of PTN expression in osteoblasts in vitro inhibited differentiation, and addition of PTN to the incubation medium rescued the response. Estradiol stimulated PTN secretion and PTN knockdown blocked estradiol-stimulated differentiation. PTN addition to IGFBP-2 silenced osteoblast stimulated differentiation, and an anti-fibronectin-3 antibody, which inhibits PTN binding to RPTPβ, inhibited this response. Estrogen stimulated PTN secretion and downstream signaling in the IGFBP-2 silenced osteoblasts and these effects were inhibited with anti-fibronectin-3. Administration of estrogen to wild-type and Igfbp2–/– male mice stimulated an increase in both areal bone mineral density and trabecular bone volume fraction but the increase was significantly greater in the Igfbp2–/– animals. Estrogen also stimulated RPTPβ expression in the null mice. We conclude that loss of IGFBP-2 expression is accompanied by upregulation of PTN and RPTPβ expression in osteoblasts, that the degree of increase is greater in females due to estrogen secretion, and that this compensatory change may account for some component of the maintenance of normal bone mass in female mice.

scholarly journals Early-Onset Type 2 Diabetes Impairs Skeletal Acquisition in the Male TALLYHO/JngJ Mouse

Endocrinology ◽  
2014 ◽  
Vol 155 (10) ◽  
pp. 3806-3816 ◽  
Author(s):  
M. J. Devlin ◽  
M. Van Vliet ◽  
K. Motyl ◽  
L. Karim ◽  
D. J. Brooks ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Bone Marrow ◽  
Bone Mass ◽  
Early Onset ◽  
Volume Fraction ◽  
Mineral Density ◽  
Bone Volume Fraction ◽  
Skeletal Acquisition

Abstract Type 2 diabetes (T2D) incidence in adolescents is rising and may interfere with peak bone mass acquisition. We tested the effects of early-onset T2D on bone mass, microarchitecture, and strength in the TALLYHO/JngJ mouse, which develops T2D by 8 weeks of age. We assessed metabolism and skeletal acquisition in male TALLYHO/JngJ and SWR/J controls (n = 8–10/group) from 4 weeks to 8 and 17 weeks of age. Tallyho mice were obese; had an approximately 2-fold higher leptin and percentage body fat; and had lower bone mineral density vs SWR at all time points (P < .03 for all). Tallyho had severe deficits in distal femur trabecular bone volume fraction (−54%), trabecular number (−27%), and connectivity density (−82%) (P < .01 for all). Bone formation was higher in Tallyho mice at 8 weeks but lower by 17 weeks of age vs SWR despite similar numbers of osteoblasts. Bone marrow adiposity was 7- to 50-fold higher in Tallyho vs SWR. In vitro, primary bone marrow stromal cell differentiation into osteoblast and adipocyte lineages was similar in SWR and Tallyho, suggesting skeletal deficits were not due to intrinsic defects in Tallyho bone-forming cells. These data suggest the Tallyho mouse might be a useful model to study the skeletal effects of adolescent T2D.

scholarly journals Kindlin-2 regulates skeletal homeostasis by modulating PTH1R in mice

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Xuekun Fu ◽  
Bo Zhou ◽  
Qinnan Yan ◽  
Chu Tao ◽  
Lei Qin ◽  
...  
Keyword(s):  
Bone Mass ◽  
Volume Fraction ◽  
Bone Marrow Cells ◽  
Bone Matrix ◽  
Osteoblastic Cells ◽  
Mineral Density ◽  
Bone Volume Fraction ◽  
Ovariectomized Mice

AbstractIn vertebrates, the type 1 parathyroid hormone receptor (PTH1R) is a critical regulator of skeletal development and homeostasis; however, how it is modulated is incompletely understood. Here we report that deleting Kindlin-2 in osteoblastic cells using the mouse 10-kb Dmp1-Cre largely neutralizes the intermittent PTH-stimulated increasing of bone volume fraction and bone mineral density by impairing both osteoblast and osteoclast formation in murine adult bone. Single-cell profiling reveals that Kindlin-2 loss increases the proportion of osteoblasts, but not mesenchymal stem cells, chondrocytes and fibroblasts, in non-hematopoietic bone marrow cells, with concomitant depletion of osteoblasts on the bone surfaces, especially those stimulated by PTH. Furthermore, haploinsufficiency of Kindlin-2 and Pth1r genes, but not that of either gene, in mice significantly decreases basal and, to a larger extent, PTH-stimulated bone mass, supporting the notion that both factors function in the same genetic pathway. Mechanistically, Kindlin-2 interacts with the C-terminal cytoplasmic domain of PTH1R via aa 474–475 and Gsα. Kindlin-2 loss suppresses PTH induction of cAMP production and CREB phosphorylation in cultured osteoblasts and in bone. Interestingly, PTH promotes Kindlin-2 expression in vitro and in vivo, thus creating a positive feedback regulatory loop. Finally, estrogen deficiency induced by ovariectomy drastically decreases expression of Kindlin-2 protein in osteocytes embedded in the bone matrix and Kindlin-2 loss essentially abolishes the PTH anabolic activity in bone in ovariectomized mice. Thus, we demonstrate that Kindlin-2 functions as an intrinsic component of the PTH1R signaling pathway in osteoblastic cells to regulate bone mass accrual and homeostasis.

scholarly journals Osteopontin Deficiency Induces Parathyroid Hormone Enhancement of Cortical Bone Formation

Endocrinology ◽  
2003 ◽  
Vol 144 (5) ◽  
pp. 2132-2140 ◽  
Author(s):  
Keiichiro Kitahara ◽  
Muneaki Ishijima ◽  
Susan R. Rittling ◽  
Kunikazu Tsuji ◽  
Hisashi Kurosawa ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Bone Formation ◽  
Bone Mass ◽  
Cortical Bone ◽  
Cancellous Bone ◽  
Wild Type ◽  
Mineral Density ◽  
Cortical Bone Mass ◽  
Intermittent Pth

Intermittent PTH treatment increases cancellous bone mass in osteoporosis patients; however, it reveals diverse effects on cortical bone mass. Underlying molecular mechanisms for anabolic PTH actions are largely unknown. Because PTH regulates expression of osteopontin (OPN) in osteoblasts, OPN could be one of the targets of PTH in bone. Therefore, we examined the role of OPN in the PTH actions in bone. Intermittent PTH treatment neither altered whole long-bone bone mineral density nor changed cortical bone mass in wild-type 129 mice, although it enhanced cancellous bone volume as reported previously. In contrast, OPN deficiency induced PTH enhancement of whole-bone bone mineral density as well as cortical bone mass. Strikingly, although PTH suppressed periosteal bone formation rate (BFR) and mineral apposition rate (MAR) in cortical bone in wild type, OPN deficiency induced PTH activation of periosteal BFR and MAR. In cancellous bone, OPN deficiency further enhanced PTH increase in BFR and MAR. Analysis on the cellular bases for these phenomena indicated that OPN deficiency augmented PTH enhancement in the increase in mineralized nodule formation in vitro. OPN deficiency did not alter the levels of PTH enhancement of the excretion of deoxypyridinoline in urine, the osteoclast number in vivo, and tartrate-resistant acid phosphatase-positive cell development in vitro. These observations indicated that OPN deficiency specifically induces PTH activation of periosteal bone formation in the cortical bone envelope.

Healing Cranial Defects with AdRunx2-transduced Marrow Stromal Cells

2007 ◽  
Vol 86 (12) ◽  
pp. 1207-1211 ◽  
Author(s):  
Z. Zhao ◽  
Z. Wang ◽  
C. Ge ◽  
P. Krebsbach ◽  
R.T. Franceschi
Keyword(s):  
Stromal Cells ◽  
Volume Fraction ◽  
Marrow Stromal Cells ◽  
Osteogenic Potential ◽  
Specific Gene ◽  
Mineral Density ◽  
Bone Volume Fraction ◽  
Calvarial Defects

Marrow stromal cells (MSCs) include stem cells capable of forming all mesenchymal tissues, including bone. However, before MSCs can be successfully used in regeneration procedures, methods must be developed to stimulate their differentiation selectively to osteoblasts. Runx2, a bone-specific transcription factor, is known to stimulate osteoblast differentiation. In the present study, we tested the hypothesis that Runx2 gene therapy can be used to heal a critical-sized defect in mouse calvaria. Runx2-engineered MSCs displayed enhanced osteogenic potential and osteoblast-specific gene expression in vitro and in vivo. Runx2-expressing cells also dramatically enhanced the healing of critical-sized calvarial defects and increased both bone volume fraction and bone mineral density. These studies provide a novel route for enhancing osteogenesis that may have future therapeutic applications for craniofacial bone regeneration.

scholarly journals The Type 2 Cannabinoid Receptor Regulates Bone Mass and Ovariectomy-Induced Bone Loss by Affecting Osteoblast Differentiation and Bone Formation

Endocrinology ◽  
2011 ◽  
Vol 152 (6) ◽  
pp. 2141-2149 ◽  
Author(s):  
Antonia Sophocleous ◽  
Euphemie Landao-Bassonga ◽  
Robert J. van‘t Hof ◽  
Aymen I. Idris ◽  
Stuart H. Ralston
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Bone Mass ◽  
Osteoblast Differentiation ◽  
Cannabinoid Receptor ◽  
Nodule Formation ◽  
Wild Type

The type 2 cannabinoid receptor (CB2) has been reported to regulate bone mass and bone turnover but the mechanisms responsible are incompletely understood. In this study we investigated the role that the CB2 pathway plays in bone metabolism using a combination of genetic and pharmacological approaches. Bone mass and turnover were normal in young mice with targeted inactivation of CB2 receptor (CB2−/−), but by 12 months of age, they had developed high-turnover osteoporosis with relative uncoupling of bone resorption from bone formation. Primary osteoblasts from CB2−/− mice had a reduced capacity to form bone nodules in vitro when compared with cells from wild-type littermates and also had impaired PTH-induced alkaline phosphatase (ALP) activity. The CB2-selective agonist HU308 stimulated bone nodule formation in wild-type osteoblasts but had no effect in CB2−/− osteoblasts. Further studies in MC3T3-E1 osteoblast like cells showed that HU308 promoted cell migration and activated ERK phosphorylation, and these effects were blocked by the CB2 selective inverse agonist AM630. Finally, HU308 partially protected against ovariectomy induced bone loss in wild-type mice in vivo, primarily by stimulating bone formation, whereas no protective effects were observed in ovariectomized CB2−/− mice. These studies indicate that the CB2 regulates osteoblast differentiation in vitro and bone formation in vivo.

scholarly journals Semaphorin 3A Shifts Adipose Mesenchymal Stem Cells towards Osteogenic Phenotype and Promotes Bone Regeneration In Vivo

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Xiangwei Liu ◽  
Naiwen Tan ◽  
Yuchao Zhou ◽  
Xueying Zhou ◽  
Hui Chen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Bone Regeneration ◽  
Volume Fraction ◽  
Calcium Deposition ◽  
Mineral Density ◽  
Bone Volume Fraction ◽  
Adipose Mesenchymal Stem Cells

Adipose mesenchymal stem cells (ASCs) are considered as the promising seed cells for bone regeneration. However, the lower osteogenic differentiation capacity limits its therapeutic efficacy. Identification of the key molecules governing the differences between ASCs and BMSCs would shed light on manipulation of ASCs towards osteogenic phenotype. In this study, we screened semaphorin family members in ASCs and BMSCs and identified Sema3A as an osteogenic semaphorin that was significantly and predominantly expressed in BMSCs. The analyses in vitro showed that the overexpression of Sema3A in ASCs significantly enhanced the expression of bone-related genes and extracellular matrix calcium deposition, while decreasing the expression of adipose-related genes and thus lipid droplet formation, resembling a BMSCs phenotype. Furthermore, Sema3A modified ASCs were then engrafted into poly(lactic-co-glycolic acid) (PLGA) scaffolds to repair the critical-sized calvarial defects in rat model. As expected, Sema3A modified ASCs encapsulation significantly promoted new bone formation with higher bone volume fraction and bone mineral density. Additionally, Sema3A was found to simultaneously increase multiple Wnt related genes and thus activating Wnt pathway. Taken together, our study here identifies Sema3A as a critical gene for osteogenic phenotype and reveals that Sema3A-modified ASCs would serve as a promising candidate for bettering bone defect repair.

scholarly journals Absence of Dap12 and the αvβ3 integrin causes severe osteopetrosis

2014 ◽  
Vol 208 (1) ◽  
pp. 125-136 ◽  
Author(s):  
Wei Zou ◽  
Steven L. Teitelbaum
Keyword(s):  
Bone Mass ◽  
Αvβ3 Integrin ◽  
Skeletal Phenotype ◽  
Osteoclast Function ◽  
Deficient Mice

In vitro, ligand occupancy of αvβ3 integrin induces phosphorylation of Dap12, which is essential for osteoclast function. Like mice deleted of only αvβ3, Dap12−/− mice exhibited a slight increase in bone mass, but Dap12−/− mice, lacking another ITAM protein, FcRγ, were severely osteopetrotic. The mechanism by which FcRγ compensates for Dap12 deficiency is unknown. We find that co-deletion of FcRγ did not exacerbate the skeletal phenotype of β3−/− mice. In contrast, β3/Dap12 double-deficient (DAP/β3−/−) mice (but not β1/Dap12 double-deficient mice) were profoundly osteopetrotic, reflecting severe osteoclast dysfunction relative to those lacking αvβ3 or Dap12 alone. Activation of OSCAR, the FcRγ co-receptor, rescued Dap12−/− but not DAP/β3−/−osteoclasts. Thus, the absence of αvβ3 precluded compensation for Dap12 deficiency by FcRγ. In keeping with this, Syk phosphorylation did not occur in OSCAR-activated DAP/β3−/− osteoclasts. Thus, FcRγ requires the osteoclast αvβ3 integrin to normalize the Dap12-deficient skeleton.

scholarly journals Adiponectin inhibits leptin signalling via multiple mechanisms to exert protective effects against hepatic fibrosis

2011 ◽  
Vol 440 (3) ◽  
pp. 385-395 ◽  
Author(s):  
Jeffrey A. Handy ◽  
Ping P. Fu ◽  
Pradeep Kumar ◽  
Jamie E. Mells ◽  
Shvetank Sharma ◽  
...  
Keyword(s):  
Hepatic Fibrosis ◽  
Leptin Receptor ◽  
Tyrosine Phosphatase ◽  
Janus Kinase ◽  
Protective Effects ◽  
Wild Type ◽  
Matrix Deposition ◽  
Matrix Metalloproteinase 1 ◽  
Expression And Activity

Adiponectin is protective against hepatic fibrosis, whereas leptin promotes fibrosis. In HSCs (hepatic stellate cells), leptin signals via a JAK2 (Janus kinase 2)/STAT3 (signal transducer and activator of transcription 3) pathway, producing effects that enhance ECM (extracellular matrix) deposition. SOCS-3 (suppressor of cytokine signalling-3) and PTP1B (protein tyrosine phosphatase 1B) are both negative regulators of JAK/STAT signalling, and recent studies have demonstrated a role for adiponectin in regulating SOCS-3 expression. In the present study we investigate mechanisms whereby adiponectin dampens leptin signalling and prevents excess ECM production. We treated culture-activated rat HSCs with recombinant adiponectin, leptin, both or neither, and also treated adiponectin knockout (Ad−/−) and wild-type mice with leptin and/or carbon tetrachloride (CCl4) or saline. We analyse JAK2 and Ob-Rb (long form of the leptin receptor) phosphorylation, and PTP1B expression and activity. We also explore potential mechanisms through which adiponectin regulates SOCS-3–Ob-Rb association. Adiponectin inhibits leptin-stimulated JAK2 activation and Ob-Rb phosphorylation in HSCs, whereas both were increased in Ad−/− mice. Adiponectin stimulates PTP1B expression and activity in vitro, whereas PTP1B expression was lower in Ad−/−mice than in wild-type mice. Adiponectin also promotes SOCS-3–Ob-R association and blocks leptin-stimulated formation of extracellular TIMP-1 (tissue inhibitor of metalloproteinases-1)–MMP-1 (matrix metalloproteinase-1) complexes in vitro. These results suggest two novel mechanisms whereby adiponectin inhibits hepatic fibrosis: (i) by promoting binding of SOCS-3 to Ob-Rb, and (ii) by stimulating PTP1B expression and activity, thus inhibiting JAK2/STAT3 signalling at multiple points.

scholarly journals Risedronate Effects on the In Vivo Bioactive Glass Behavior: Nuclear Magnetic Resonance and Histopathological Studies

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Siwar Mosbahi ◽  
Hassane Oudadesse ◽  
Claire Roiland ◽  
Bertrand Lefeuvre ◽  
Lotfi Slimani ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Bioactive Glass ◽  
Volume Fraction ◽  
Chemical Reactivity ◽  
Femoral Condyle ◽  
Mineral Density ◽  
Nuclear Magnetic

The present study aimed to enhance the anti-osteoporotic performance of bioactive glass (46S6) through its association with bisphosphonate such as risedronate with amounts of 8, 12, and 20%. Obtained composites have been called 46S6-8RIS, 46S6-12RIS, and 46S6-20RIS, respectively. In vitro and in vivo explorations have been carried out. Bioactive glass and risedronate association has been performed by adsorption process. Structure analyses have been carried out to evaluate and to understand their chemical interactions. Solid Nuclear Magnetic Resonance (NMR) has been employed to study the structural properties of obtained biocomposite. The spectra deconvolution showed the appearance of a species (Q4) in the biocomposites 46S6-8RIS, 46S6-12RIS, and 46S6-20RIS indicating their successful chemical association. In vitro experiments showed the enhancement of the chemical reactivity of the composites 46S6-xRIS compared to the pure bioactive glass. In fact, the silicon liberation after 30 days of immersion was 50 ppm for pure bioactive glass 46S6, and 41, 64, and 62 from 46S6-8RIS, 46S6-12RIS, and 46S6-20RIS, respectively. Based on the in vitro results, 46S6-8RIS was implanted in the femoral condyle of an ovariectomized rat and compared with implanted pure glass in the goal to highlight its anti-osteoporotic performance. After 60 days, implanted group with 46S6-8RIS showed the increase in bone mineral density (BMD with 10%) and bone volume fraction (BV/TV with 80%) and the decrease in trabecular separation (Tb/Sp with 74%) when compared to that of 46S6 group. These results are confirmed by the histopathological analyses, which showed the bone trabeculae reconnection after the 46S6-8RIS implantation. Chemical analyses showed the reduction in silicon (Si) and sodium (Na) ion concentrations, and the rise in calcium (Ca) and phosphorus (P) ion levels, which was explained by the dissolution of biocomposite matrix and the deposition of hydroxyapatite layer. Histomorphometric results highlighted the risedronate effect on the antiosteoporotic phenomenon. Obtained results showed good behavior with only 8% of introduced risedronate in the glass matrix.

scholarly journals Adiposity, Insulin Resistance, and Bone Mass in Children and Adolescents

2018 ◽  
Vol 104 (3) ◽  
pp. 892-899 ◽  
Author(s):  
Joseph M Kindler ◽  
Andrea J Lobene ◽  
Kara A Vogel ◽  
Berdine R Martin ◽  
Linda D McCabe ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Insulin Resistance ◽  
Waist Circumference ◽  
Bone Mass ◽  
Bone Mineral ◽  
Fat Mass ◽  
Areal Bone Mineral Density ◽  
Mineral Density ◽  
Total Body ◽  
The Relationship

Abstract Context Insulin resistance is an adverse health outcome that accompanies obesity. Fat mass is negatively associated with the bone mass after adjustment for confounders. Insulin resistance might be an intermediary in this relationship. Objective To determine whether insulin resistance is an intermediary in the relationship between adiposity and bone mass in adolescents. Design Cross-sectional secondary analysis of baseline data from a previous randomized trial. Setting University research facility. Participants A total of 240 adolescents (68% female), aged 7 to 15 years. Main Outcome Measures Using dual energy x-ray absorptiometry, bone mineral content (BMC), areal bone mineral density, lean mass, and fat mass were measured. Skeletal sites of interest included the total body and lumbar spine (LS). Waist circumference was measured using an anthropometric tape measure. Insulin and glucose were measured in fasting sera, and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Path analysis was performed to determine whether the relationship between adiposity and bone was mediated through insulin resistance. Results Fat mass (r = 0.467; P < 0.001) and waist circumference (r = 0.487; P < 0.001) correlated positively with HOMA-IR. Controlling for race, sex, maturation, lean mass, and height, fat mass, waist circumference, and HOMA-IR were negatively associated with LS BMC and total body areal bone mineral density (P < 0.05 for all). Additionally, path models for fat mass (95% CI, −5.893 to −0.956) and waist circumference (95% CI, −15.473 to −2.124) showed a negative relationship with LS BMC via HOMA-IR. Conclusions These results support an intermediary role of insulin resistance in the relationship between adiposity and LS bone mass.

Sign in / Sign up

Export Citation Format

Share Document