Browsing by Subject "Wnt signaling pathway"

Now showing 1 - 8 of 8
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    Doubling Down on Wnt Signaling to Overcome Myeloma Bone Disease
    (Oxford University Press, 2023) Delgado-Calle, Jesus; Roodman, G. David; Medicine, School of Medicine
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    GSK3β Inhibitors Inhibit TGFβ Signaling in the Human Trabecular Meshwork
    (Association for Research in Vision and Ophthalmology, 2024) Sugali, Chenna Kesavulu; Rayana, Naga Pradeep; Dai, Jiannong; Harvey, Devon H.; Dhamodaran, Kamesh; Mao, Weiming; Ophthalmology, School of Medicine
    Purpose: Primary open-angle glaucoma (POAG) is a leading cause of blindness, and its primary risk factor is elevated intraocular pressure (IOP) due to pathologic changes in the trabecular meshwork (TM). We previously showed that there is a cross-inhibition between TGFβ and Wnt signaling pathways in the TM. In this study, we determined if activation of the Wnt signaling pathway using small-molecule Wnt activators can inhibit TGFβ2-induced TM changes and ocular hypertension (OHT). Methods: Primary human TM (pHTM) cells and transduced SBE-GTM3 cells were treated with or without Wnt and/or TGFβ signaling activators and used for luciferase assays; for the extraction of whole-cell lysate, conditioned medium, cytosolic proteins, and nuclear proteins for Western immunoblotting (WB); or for immunofluorescent staining. Human donor eyes were perfusion cultured to study the effect of Wnt activators on IOP. Results: We found that the small-molecule Wnt activators (GSK3β inhibitors) (BIO, SB216763, and CHIR99021) activated canonical Wnt signaling in pHTM cells without toxicity at tested concentrations. This activation inhibited TGFβ signaling as well as TGFβ2-induced extracellular matrix deposition and formation of cross-linked actin networks in pHTM cells or SBE-GTM3 cells. We also observed nuclear translocation of both Smad4 and β-catenin in pHTM cells, which suggested that the cross-inhibition between the TGFβ and Wnt signaling pathways may occur in the nucleus. Using our ex vivo model, we found that CHIR99021 inhibited TGFβ2-induced OHT in perfusion-cultured human eyes. Conclusions: Our results showed that small-molecule Wnt activators have the potential for treating TGFβ signaling-induced OHT in patients with POAG.
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    Molecular Basis for Craniofacial Phenotypes Caused by Sclerostin Deletion
    (Sage, 2021) Chen, J.; Yuan, X.; Pilawski, I.; Liu, X.; Delgado-Calle, J.; Bellido, T.; Turkkahraman, H.; Helms, J.A.; Medicine, School of Medicine
    Some genetic disorders are associated with distinctive facial features, which can aid in diagnosis. While considerable advances have been made in identifying causal genes, relatively little progress has been made toward understanding how a particular genotype results in a characteristic craniofacial phenotype. An example is sclerosteosis/van Buchem disease, which is caused by mutations in the Wnt inhibitor sclerostin (SOST). Affected patients have a high bone mass coupled with a distinctive appearance where the mandible is enlarged and the maxilla is foreshortened. Here, mice carrying a null mutation in Sost were analyzed using quantitative micro-computed tomographic (µCT) imaging and histomorphometric analyses to determine the extent to which the size and shape of craniofacial skeleton were altered. Sost-/- mice exhibited a significant increase in appositional bone growth, which increased the height and width of the mandible and reduced the diameters of foramina. In vivo fluorochrome labeling, histology, and immunohistochemical analyses indicated that excessive bone deposition in the premaxillary suture mesenchyme curtailed overall growth, leading to midfacial hypoplasia. The amount of bone extracellular matrix produced by Sost-/- cells was significantly increased; as a consequence, osteoid seams were evident throughout the facial skeleton. Collectively, these analyses revealed a remarkable fidelity between human characteristics of sclerosteosis/van Buchem disease and the Sost-/- phenotype and provide clues into the conserved role for sclerostin signaling in modulating craniofacial morphology.
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    New Insights Into the Local and Systemic Functions of Sclerostin: Regulation of Quiescent Bone Lining Cells and Beige Adipogenesis in Peripheral Fat Depots
    (Wiley, 2017-05) Delgado-Calle, Jesus; Bellido, Teresita; Anatomy and Cell Biology, School of Medicine
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    Protection From Glucocorticoid-Induced Osteoporosis by Anti-Catabolic Signaling in the Absence of Sost/Sclerostin
    (Wiley, 2016-10) Sato, Amy Y.; Cregor, Meloney; Delgado-Calle, Jesus; Condon, Keith W.; Allen, Matthew R.; Peacock, Munro; Plotkin, Lilian I.; Bellido, Teresita; Anatomy, Cell Biology and Physiology, School of Medicine
    Excess of glucocorticoids, either due to disease or iatrogenic, increases bone resorption and decreases bone formation and is a leading cause of osteoporosis and bone fractures worldwide. Improved therapeutic strategies are sorely needed. We investigated whether activating Wnt/β-catenin signaling protects against the skeletal actions of glucocorticoids, using female mice lacking the Wnt/β-catenin antagonist and bone formation inhibitor Sost. Glucocorticoids decreased the mass, deteriorated the microarchitecture, and reduced the structural and material strength of bone in wild-type (WT), but not in Sost-/- mice. The high bone mass exhibited by Sost-/- mice is due to increased bone formation with unchanged resorption. However, unexpectedly, preservation of bone mass and strength in Sost-/- mice was due to prevention of glucocorticoid-induced bone resorption and not to restoration of bone formation. In WT mice, glucocorticoids increased the expression of Sost and the number of sclerostin-positive osteocytes, and altered the molecular signature of the Wnt/β-catenin pathway by decreasing the expression of genes associated with both anti-catabolism, including osteoprotegerin (OPG), and anabolism/survival, such as cyclin D1. In contrast in Sost-/- mice, glucocorticoids did not decrease OPG but still reduced cyclin D1. Thus, in the context of glucocorticoid excess, activation of Wnt/β-catenin signaling by Sost/sclerostin deficiency sustains bone integrity by opposing bone catabolism despite markedly reduced bone formation and increased apoptosis. This crosstalk between glucocorticoids and Wnt/β-catenin signaling could be exploited therapeutically to halt resorption and bone loss induced by glucocorticoids and to inhibit the exaggerated bone formation in diseases of unwanted hyperactivation of Wnt/β-catenin signaling.
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    Targeted inhibition of Wnt signaling with a Clostridioides difficile toxin B fragment suppresses breast cancer tumor growth
    (Public Library of Science, 2023-11-09) He, Aina; Tian, Songhai; Kopper, Oded; Horan, Daniel J.; Chen, Peng; Bronson, Roderick T.; Sheng, Ren; Wu, Hao; Sui, Lufei; Zhou, Kun; Tao, Liang; Wu, Quan; Huang, Yujing; Shen, Zan; Han, Sen; Chen, Xueqing; Chen, Hong; He, Xi; Robling, Alexander G.; Jin, Rongsheng; Clevers, Hans; Xiang, Dongxi; Li, Zhe; Dong, Min; Anatomy, Cell Biology and Physiology, School of Medicine
    Wnt signaling pathways are transmitted via 10 homologous frizzled receptors (FZD1-10) in humans. Reagents broadly inhibiting Wnt signaling pathways reduce growth and metastasis of many tumors, but their therapeutic development has been hampered by the side effect. Inhibitors targeting specific Wnt-FZD pair(s) enriched in cancer cells may reduce side effect, but the therapeutic effect of narrow-spectrum Wnt-FZD inhibitors remains to be established in vivo. Here, we developed a fragment of C. difficile toxin B (TcdBFBD), which recognizes and inhibits a subclass of FZDs, FZD1/2/7, and examined whether targeting this FZD subgroup may offer therapeutic benefits for treating breast cancer models in mice. Utilizing 2 basal-like and 1 luminal-like breast cancer models, we found that TcdBFBD reduces tumor-initiating cells and attenuates growth of basal-like mammary tumor organoids and xenografted tumors, without damaging Wnt-sensitive tissues such as bones in vivo. Furthermore, FZD1/2/7-positive cells are enriched in chemotherapy-resistant cells in both basal-like and luminal mammary tumors treated with cisplatin, and TcdBFBD synergizes strongly with cisplatin in inhibiting both tumor types. These data demonstrate the therapeutic value of narrow-spectrum Wnt signaling inhibitor in treating breast cancers.
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    The LRP5 high-bone-mass mutation causes alveolar bone accrual with minor craniofacial alteration
    (Wiley, 2023) Turkkahrama, Hakan; Flanagan, Shannan; Zhu, Tianli; Bellido, Teresita M.; Yuan, Xue; Orthodontics and Oral Facial Genetics, School of Dentistry
    Background and Objective Mutations in low-density lipoprotein receptor-related protein 5 (LRP5) cause various bone diseases. Several mouse models were generated to study the role of LRP5 in bone development. But most of the studies were confined to the appendicular skeleton. The role of LRP5 in the axial skeleton, especially in the craniofacial skeleton, is largely unknown. The aim of this study was to investigate the craniofacial phenotype with the LRP5G171V mutation. Methods To understand how LRP5 affects craniofacial bone properties, we analyzed LRP5 high-bone-mass mutant mice carrying the G171V missense mutation (LRP5HBM). Quantitative microcomputed tomographic imaging and histomorphometric analyses were used to study craniofacial phenotypes and bone density. Histology, immunohistochemistry, and in vivo fluorochrome labeling were used to study molecular mechanisms. Results LRP5HBM mice showed overall minor changes in the craniofacial bone development but with increased bone mass in the interradicular alveolar bone, edentulous ridge, palatine bone, and premaxillary suture. Elevated osteocyte density was observed in LRP5HBM mice, along with increased Runx2 expression and unmineralized bone surrounding osteocytes. Meanwhile, LRP5HBM mice exhibited increased osteoprogenitors, but no significant changes were observed in osteoclasts. This led to a high-bone-mass phenotype, and an increased osteocyte density in the alveolar bone and edentulous ridge. Conclusion LRP5HBM mice display increased bone mass in the alveolar bone with minor changes in the craniofacial morphology. Collectively, these data elucidated the important role of LRP5 in axial bone development and homeostasis and provided clues into the therapeutical potential of LRP5 signaling in treating alveolar bone loss.
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    Wnt/β-catenin Signaling Controls Maxillofacial Hyperostosis
    (Sage, 2022) Chen, J.; Cuevas, P. L.; Dworan, J. S.; Dawid, I.; Turkkahraman, H.; Tran, K.; Delgado-Calle, J.; Bellido, T.; Gorski, J. P.; Liu, B.; Brunski, J. B.; Helms, J. A.; Orthodontics and Oral Facial Genetics, School of Dentistry
    The roles of Wnt/β-catenin signaling in regulating the morphology and microstructure of craniomaxillofacial (CMF) bones was explored using mice carrying a constitutively active form of β-catenin in activating Dmp1-expressing cells (e.g., daβcatOt mice). By postnatal day 24, daβcatOt mice exhibited midfacial truncations coupled with maxillary and mandibular hyperostosis that progressively worsened with age. Mechanistic insights into the basis for the hyperostotic facial phenotype were gained through molecular and cellular analyses, which revealed that constitutively activated β-catenin in Dmp1-expressing cells resulted in an increase in osteoblast number and an increased rate of mineral apposition. An increase in osteoblasts was accompanied by an increase in osteocytes, but they failed to mature. The resulting CMF bone matrix also had an abundance of osteoid, and in locations where compact lamellar bone typically forms, it was replaced by porous, woven bone. The hyperostotic facial phenotype was progressive. These findings identify for the first time a ligand-independent positive feedback loop whereby unrestrained Wnt/β-catenin signaling results in a CMF phenotype of progressive hyperostosis combined with architecturally abnormal, poorly mineralized matrix that is reminiscent of craniotubular disorders in humans.