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4-PBA Treatment Improves Bone Phenotypes in the Aga2 Mouse Model of Osteogenesis Imperfecta.

ABSTRACT: Osteogenesis imperfecta (OI) is a genetically heterogenous disorder most often due to heterozygosity for mutations in the type I procollagen genes, COL1A1 or COL1A2. The disorder is characterized by bone fragility leading to increased fracture incidence and long-bone deformities. Although multiple mechanisms underlie OI, endoplasmic reticulum (ER) stress as a cellular response to defective collagen trafficking is emerging as a contributor to OI pathogenesis. Herein, we used 4-phenylbutiric acid (4-PBA), an established chemical chaperone, to determine if treatment of Aga2^+/- mice, a model for moderately severe OI due to a Col1a1 structural mutation, could attenuate the phenotype. In vitro, Aga2^+/- osteoblasts show increased protein kinase RNA-like endoplasmic reticulum kinase (PERK) activation protein levels, which improved upon treatment with 4-PBA. The in vivo data demonstrate that a postweaning 5-week 4-PBA treatment increased total body length and weight, decreased fracture incidence, increased femoral bone volume fraction (BV/TV), and increased cortical thickness. These findings were associated with in vivo evidence of decreased bone-derived protein levels of the ER stress markers binding immunoglobulin protein (BiP), CCAAT/-enhancer-binding protein homologous protein (CHOP), and activating transcription factor 4 (ATF4) as well as increased levels of the autophagosome marker light chain 3A/B (LC3A/B). Genetic ablation of CHOP in Aga2^+/- mice resulted in increased severity of the Aga2^+/- phenotype, suggesting that the reduction in CHOP observed in vitro after treatment is a consequence rather than a cause of reduced ER stress. These findings suggest the potential use of chemical chaperones as an adjunct treatment for forms of OI associated with ER stress. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

SUBMITTER: Duran I

PROVIDER: S-EPMC9018561 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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4-PBA Treatment Improves Bone Phenotypes in the Aga2 Mouse Model of Osteogenesis Imperfecta.

Duran Ivan I Zieba Jennifer J Csukasi Fabiana F Martin Jorge H JH Wachtell Davis D Barad Maya M Dawson Brian B Fafilek Bohumil B Jacobsen Christina M CM Ambrose Catherine G CG Cohn Daniel H DH Krejci Pavel P Lee Brendan H BH Krakow Deborah D

Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 20220128 4

Osteogenesis imperfecta (OI) is a genetically heterogenous disorder most often due to heterozygosity for mutations in the type I procollagen genes, COL1A1 or COL1A2. The disorder is characterized by bone fragility leading to increased fracture incidence and long-bone deformities. Although multiple mechanisms underlie OI, endoplasmic reticulum (ER) stress as a cellular response to defective collagen trafficking is emerging as a contributor to OI pathogenesis. Herein, we used 4-phenylbutiric acid ...[more]

PMID: 34997935

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Project description:Osteogenesis imperfecta (OI) is a collagen-related bone disorder characterized by fragile osteopenic bone and muscle weakness. We have previously shown that the soluble activin receptor type IIB decoy (sActRIIB) molecule increases muscle mass and improves bone strength in the mild to moderate G610C mouse model of OI. The sActRIIB molecule binds multiple transforming growth factor-β (TGF-β) ligands, including myostatin and activin A. Here, we investigate the musculoskeletal effects of inhibiting activin A alone, myostatin alone, or both myostatin and activin A in wild-type (Wt) and heterozygous G610C (+/G610C) mice using specific monoclonal antibodies. Male and female Wt and +/G610C mice were treated twice weekly with intraperitoneal injections of monoclonal control antibody (Ctrl-Ab, Regn1945), anti-activin A antibody (ActA-Ab, Regn2476), anti-myostatin antibody (Mstn-Ab, Regn647), or both ActA-Ab and Mstn-Ab (Combo, Regn2476, and Regn647) from 5 to 16 weeks of age. Prior to euthanasia, whole body composition, metabolism and muscle force generation assessments were performed. Post euthanasia, hindlimb muscles were evaluated for mass, and femurs were evaluated for changes in microarchitecture and biomechanical strength using micro-computed tomography (μCT) and three-point bend analyses. ActA-Ab treatment minimally impacted the +/G610C musculoskeleton, and was detrimental to bone strength in male +/G610C mice. Mstn-Ab treatment, as previously reported, resulted in substantial increases in hindlimb muscle weights and overall body weights in Wt and male +/G610C mice, but had minimal skeletal impact in +/G610C mice. Conversely, the Combo treatment outperformed ActA-Ab alone or Mstn-Ab alone, consistently increasing hindlimb muscle and body weights regardless of sex or genotype and improving bone microarchitecture and strength in both male and female +/G610C and Wt mice. Combinatorial inhibition of activin A and myostatin more potently increased muscle mass and bone microarchitecture and strength than either antibody alone, recapturing most of the observed benefits of sActRIIB treatment in +/G610C mice. © 2022 American Society for Bone and Mineral Research (ASBMR).

Project description:Osteogenesis imperfecta (OI), is a genetic disorder of bone fragility caused by mutations in collagen I or proteins involved in collagen processing. Previous studies in mice and human OI bones have shown that excessive activation of TGF-β signaling plays an important role in dominant and recessive OI disease progression. Inhibition of TGF-β signaling with a murine pan-specific TGF-β neutralizing antibody (1D11) was shown to significantly increase trabecular bone volume and long bone strength in mouse models of OI. To investigate the frequency of dosing and dose options of TGF-β neutralizing antibody therapy, we assessed the effect of 1D11 on disease progression in a dominant OI mouse model (col1a2 gene mutation at G610C). In comparison with OI mice treated with a control antibody, we attempted to define mechanistic effects of 1D11 measured via μCT, biomechanical, dynamic histomorphometry, and serum biomarkers of bone turnover. In addition, osteoblast and osteoclast numbers in histological bone sections were assessed to better understand the mechanism of action of the 1D11 antibody in OI. Here we show that 1D11 treatment resulted in both dose and frequency dependency, increases in trabecular bone volume fraction and ultimate force in lumbar bone, and ultimate force, bending strength, yield force, and yield strength in the femur (p ≤ 0.05). Suppression of serum biomarkers of osteoblast differentiation, osteocalcin, resorption, CTx-1, and bone formation were observed after 1D11 treatment of OI mice. Immunohistochemical analysis showed dose and frequency dependent decreases in runt-related transcription factor, and increase in alkaline phosphatase in lumbar bone sections. In addition, a significant decrease in TRACP and the number of osteoclasts to bone surface area was observed with 1D11 treatment. Our results show that inhibition of the TGF-β pathway corrects the high-turnover aspects of bone disease and improves biomechanical properties of OI mice. These results highlight the potential for a novel treatment for osteogenesis imperfecta. © 2021 Sanofi-Genzyme. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Project description:ObjectiveOsteogenesis imperfecta (OI) is a congenital disorder characterized by muscle defect and skeletal fragility, and no cure is yet available. Crosstalk between bone and muscle has become a new coming focus of therapeutic strategy in OI. Irisin, a secreted myokine, was found to be involved in regulating bone metabolism, and may be beneficial for the treatment of OI. However, its effects in OI have yet to be determined. This study sought to determine whether Irisin therapy is capable of reducing fracture risk in OI and to investigate the potential mechanisms of action.MethodsFibronectin type III domain containing 5 (FNDC5)/Irisin expression was assessed by enzyme-linked immunosorbent assay (ELISA) and immunohistochemical staining. In vivo, X-ray was used for fracture counting and micro-CT, dynamic histomorphometry analysis, immunohistochemistry, histomorphometry, and biomechanical test were used to evaluate the effects of Irisin on fracture frequency and bone quality in OI mouse model, oim/oim mouse. In vitro, osteogenesis-related gene expressions were determined by quantitative real-time PCR (qRT-PCR), western blot, and osteoblastogenesis assay were assessed by alkaline phosphatase (ALP) staining and alizarin red S (ARS) staining. Mechanistically, cell immunofluorescence staining, co-immunoprecipitation (co-IP) (Co-IP), molecular docking, western blot, luciferase reporter assay, and chromatin immunoprecipitation (ChIP) assay were used for elucidating the mechanisms of how Irisin antagonized transforming growth factor-β (TGF-β)/Smad signaling in oim/oim osteoblasts and further attenuated the inhibitory effect of TGF-β1 on osteogenic differentiation.ResultsMusculoskeletal system-related FNDC5/Irisin was decreased in the serum, muscle, and bone in oim/oim mice. Irisin administration reduced bone fracture and attenuated bone abnormalities by improving bone mass and strength and facilitating the expression of osteogenic differentiation markers. In vivo study and in vitro experiments showed that Irisin antagonized TGF-β/Smad signaling by interfering with TGF-β1-TGF-β receptor II (TβRII) binding. In oim/oim osteoblasts, Irisin alleviated TGF-β1-induced suppression of osteogenic differentiation through both integrin-dependent and integrin-independent mechanisms. Independent of integrin receptors, Irisin affected osteogenesis by activating ERK/p38 signaling and counteracting TGF-β/Smad2/3 signaling. In particular, Irisin alleviated TGF-β1-induced inhibition of Runx2 function at the osteocalcin promoter through decreasing Smad2/3 signaling and inducing HADC4/5 degeneration.ConclusionsCollectively, Irisin could effectively reduce bone fracture in oim/oim mice through promoting osteogenesis and counteracting TGF-β/Smad signaling.Translational potential statementFindings from this study provided evidence for using Irisin as a potential therapeutic reagent to prevent the progression of OI.

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4-PBA Treatment Improves Bone Phenotypes in the Aga2 Mouse Model of Osteogenesis Imperfecta.

Publications

4-PBA Treatment Improves Bone Phenotypes in the Aga2 Mouse Model of Osteogenesis Imperfecta.

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