scholarly journals Functions of vasopressin and oxytocin in bone mass regulation

2015 ◽  
Vol 113 (1) ◽  
pp. 164-169 ◽  
Author(s):  
Li Sun ◽  
Roberto Tamma ◽  
Tony Yuen ◽  
Graziana Colaianni ◽  
Yaoting Ji ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Formation ◽  
Bone Mass ◽  
High Bone Mass ◽  
Nuclear Extracts ◽  
High Bone ◽  
High Bone Mass Phenotype ◽  
Opposing Effects ◽  
G Protein Coupled

Prior studies show that oxytocin (Oxt) and vasopressin (Avp) have opposing actions on the skeleton exerted through high-affinity G protein-coupled receptors. We explored whether Avp and Oxtr can share their receptors in the regulation of bone formation by osteoblasts. We show that the Avp receptor 1α (Avpr1α) and the Oxt receptor (Oxtr) have opposing effects on bone mass: Oxtr−/− mice have osteopenia, and Avpr1α−/− mice display a high bone mass phenotype. More notably, this high bone mass phenotype is reversed by the deletion of Oxtr in Oxtr−/−:Avpr1α−/− double-mutant mice. However, although Oxtr is not indispensable for Avp action in inhibiting osteoblastogenesis and gene expression, Avp-stimulated gene expression is inhibited when the Oxtr is deleted in Avpr1α−/− cells. In contrast, Oxt does not interact with Avprs in vivo in a model of lactation-induced bone loss in which Oxt levels are high. Immunofluorescence microscopy of isolated nucleoplasts and Western blotting and MALDI-TOF of nuclear extracts show that Avp triggers Avpr1α localization to the nucleus. Finally, a specific Avpr2 inhibitor, tolvaptan, does not affect bone formation or bone mass, suggesting that Avpr2, which primarily functions in the kidney, does not have a significant role in bone remodeling.

Homozygous Dkk1 Knockout Mice Exhibit High Bone Mass Phenotype Due to Increased Bone Formation

2017 ◽  
Vol 102 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Michelle M. McDonald ◽  
Alyson Morse ◽  
Aaron Schindeler ◽  
Kathy Mikulec ◽  
Lauren Peacock ◽  
...  
Keyword(s):  
Bone Formation ◽  
Bone Mass ◽  
Knockout Mice ◽  
High Bone Mass ◽  
High Bone ◽  
High Bone Mass Phenotype

scholarly journals Amylin inhibits bone resorption while the calcitonin receptor controls bone formation in vivo

2004 ◽  
Vol 164 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Romain Dacquin ◽  
Rachel A. Davey ◽  
Catherine Laplace ◽  
Régis Levasseur ◽  
Howard A. Morris ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Bone Mass ◽  
Dependent Manner ◽  
Calcitonin Receptor ◽  
Low Bone Mass ◽  
High Bone Mass ◽  
High Bone

Amylin is a member of the calcitonin family of hormones cosecreted with insulin by pancreatic β cells. Cell culture assays suggest that amylin could affect bone formation and bone resorption, this latter function after its binding to the calcitonin receptor (CALCR). Here we show that Amylin inactivation leads to a low bone mass due to an increase in bone resorption, whereas bone formation is unaffected. In vitro, amylin inhibits fusion of mononucleated osteoclast precursors into multinucleated osteoclasts in an ERK1/2-dependent manner. Although Amylin +/− mice like Amylin-deficient mice display a low bone mass phenotype and increased bone resorption, Calcr +/− mice display a high bone mass due to an increase in bone formation. Moreover, compound heterozygote mice for Calcr and Amylin inactivation displayed bone abnormalities observed in both Calcr +/− and Amylin +/− mice, thereby ruling out that amylin uses CALCR to inhibit osteoclastogenesis in vivo. Thus, amylin is a physiological regulator of bone resorption that acts through an unidentified receptor.

scholarly journals Monosodium Glutamate-Sensitive Hypothalamic Neurons Contribute to the Control of Bone Mass

Endocrinology ◽  
2003 ◽  
Vol 144 (9) ◽  
pp. 3842-3847 ◽  
Author(s):  
Florent Elefteriou ◽  
Shu Takeda ◽  
Xiuyun Liu ◽  
Dawna Armstrong ◽  
Gerard Karsenty
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Bone Mass ◽  
Monosodium Glutamate ◽  
Hypothalamic Neurons ◽  
High Bone Mass ◽  
Independent Manner ◽  
Normal Bone ◽  
High Bone ◽  
High Bone Mass Phenotype

Abstract Using chemical lesioning we previously identified hypothalamic neurons that are required for leptin antiosteogenic function. In the course of these studies we observed that destruction of neurons sensitive to monosodium glutamate (MSG) in arcuate nuclei did not affect bone mass. However MSG treatment leads to hypogonadism, a condition inducing bone loss. Therefore the normal bone mass of MSG-treated mice suggested that MSG-sensitive neurons may be implicated in the control of bone mass. To test this hypothesis we assessed bone resorption and bone formation parameters in MSG-treated mice. We show here that MSG-treated mice display the expected increase in bone resorption and that their normal bone mass is due to a concomitant increase in bone formation. Correction of MSG-induced hypogonadism by physiological doses of estradiol corrected the abnormal bone resorptive activity in MSG-treated mice and uncovered their high bone mass phenotype. Because neuropeptide Y (NPY) is highly expressed in MSG-sensitive neurons we tested whether NPY regulates bone formation. Surprisingly, NPY-deficient mice had a normal bone mass. This study reveals that distinct populations of hypothalamic neurons are involved in the control of bone mass and demonstrates that MSG-sensitive neurons control bone formation in a leptin-independent manner. It also indicates that NPY deficiency does not affect bone mass.

scholarly journals Maf1, a repressor of RNA polymerase III-dependent transcription, regulates bone mass

2021 ◽  
Author(s):  
Ellen Busschers ◽  
Naseer Ahmad ◽  
Li Sun ◽  
James R Iben ◽  
Christopher J. Walkey ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Mass ◽  
Rna Polymerase ◽  
Osteoblast Differentiation ◽  
Rna Polymerase Iii ◽  
High Bone Mass ◽  
Polymerase Iii ◽  
High Bone ◽  
High Bone Mass Phenotype ◽  
Pol Iii

Maf1, a key repressor of RNA polymerase III-mediated transcription, has been shown to promote mesoderm formation in vitro. Here, we show for the first time that Maf1 plays a critical role in the regulation of osteoblast differentiation and bone mass. A high bone mass phenotype was noted in mice with global deletion of Maf1 (Maf1-/- mice), as well as paradoxically, in mice that overexpressed MAF1 in cells of the osteoblast lineage (Prx-Cre;LSL-Maf1 mice). Osteoblasts isolated from Maf1-/- mice unexpectedly showed reduced osteoblastogenesis ex vivo. Prx-Cre;LSL-Maf1 mice showed enhanced osteoblastogenesis concordant with their high bone mass phenotype. Thus, the high bone mass phenotype in Maf1-/- mice is likely due to the confounding effects of the global absence of MAF1 in Maf1-/- mice. Expectedly, MAF1 overexpression promoted osteoblast differentiation and shRNA-mediated Maf1 downregulation inhibited differentiation of ST2 cells, indicating an overall positive action of Maf1 on osteoblast formation. We also found that, in contrast to MAF1 overexpression, other perturbations that repress RNA pol III transcription, including Brf1 knockdown and the chemical inhibition of RNA pol III by ML-60218, paradoxically inhibited osteoblast differentiation. RNA-seq was used to determine the basis for these opposing actions. The three modalities used to perturb RNA pol III transcription resulted in distinct changes gene expression, indicating that this transcription process is highly sensitive and triggers diverse gene expression programs and phenotypic outcomes. Specifically, MAF1 overexpression in ST2 cells induced genes known to promote osteoblast differentiation. A subset of these genes was altered in an opposite manner with Brf1 downregulation or treatment with ML-60218, both of which also inhibit RNA pol III-mediated transcription. All these perturbations, however, enhanced adipogenesis in ST2 cell cultures. Furthermore, codon bias was observed in a subset of genes expressed during osteoblast differentiation. Together, these results reveal a novel role for Maf1 and RNA pol III-mediated transcription in osteoblast fate determination and differentiation and bone mass regulation.

scholarly journals Sex dimorphic regulation of osteoprogenitor progesterone in bone stromal cells

2017 ◽  
Vol 59 (4) ◽  
pp. 351-363 ◽  
Author(s):  
Alexander Kot ◽  
Zhendong A Zhong ◽  
Hongliang Zhang ◽  
Yu-An Evan Lay ◽  
Nancy E Lane ◽  
...  
Keyword(s):  
Mouse Model ◽  
Bone Mass ◽  
Gene Transcription ◽  
Conditional Knockout ◽  
Sequencing Analysis ◽  
Wild Type ◽  
High Bone Mass ◽  
Matrix Interaction ◽  
High Bone ◽  
High Bone Mass Phenotype

Increasing peak bone mass is a promising strategy to prevent osteoporosis. A mouse model of global progesterone receptor (PR) ablation showed increased bone mass through a sex-dependent mechanism. Cre-Lox recombination was used to generate a mouse model of osteoprogenitor-specific PR inactivation, which recapitulated the high bone mass phenotype seen in the PR global knockout mouse mode. In this work, we employed RNA sequencing analysis to evaluate sex-independent and sex-dependent differences in gene transcription of osteoprogenitors of wild-type and PR conditional knockout mice. PR deletion caused marked sex hormone-dependent changes in gene transcription in male mice as compared to wild-type controls. These transcriptional differences revealed dysregulation in pathways involving immunomodulation, osteoclasts, bone anabolism, extracellular matrix interaction and matrix interaction. These results identified many potential mechanisms that may explain our observed high bone mass phenotype with sex differences when PR was selectively deleted in the MSCs.

scholarly journals Novel LRP5 Missense Mutation in a Patient With a High Bone Mass Phenotype Results in Decreased DKK1-Mediated Inhibition of Wnt Signaling*

2007 ◽  
Vol 22 (5) ◽  
pp. 708-716 ◽  
Author(s):  
Wendy Balemans ◽  
Jean-Pierre Devogelaer ◽  
Erna Cleiren ◽  
Elke Piters ◽  
Emanuelle Caussin ◽  
...  
Keyword(s):  
Bone Mass ◽  
Wnt Signaling ◽  
Missense Mutation ◽  
High Bone Mass ◽  
High Bone ◽  
High Bone Mass Phenotype
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