Benzofuran pyran hybrid prevents glucocorticoid induced osteoporosis in mice via modulation of canonical Wnt/β-catenin signaling.
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ABSTRACT:
SUBMITTER: Tripathi AK
PROVIDER: S-EPMC8808472 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Wnt proteins modulate cell proliferation and differentiation and the self-renewal of stem cells by inducing ?-catenin-dependent signalling through the Wnt receptor frizzled (FZD) and the co-receptors LRP5 and LRP6 to regulate cell fate decisions and the growth and repair of several tissues. The 19 mammalian Wnt proteins are cross-reactive with the 10 FZD receptors, and this has complicated the attribution of distinct biological functions to specific FZD and Wnt subtype interactions. Furthermore, Wnt proteins are modified post-translationally by palmitoylation, which is essential for their secretion, function and interaction with FZD receptors. As a result of their acylation, Wnt proteins are very hydrophobic and require detergents for purification, which presents major obstacles to the preparation and application of recombinant Wnt proteins. This hydrophobicity has hindered the determination of the molecular mechanisms of Wnt signalling activation and the functional importance of FZD subtypes, and the use of Wnt proteins as therapeutic agents. Here we develop surrogate Wnt agonists, water-soluble FZD-LRP5/LRP6 heterodimerizers, with FZD5/FZD8-specific and broadly FZD-reactive binding domains. Similar to WNT3A, these Wnt agonists elicit a characteristic ?-catenin signalling response in a FZD-selective fashion, enhance the osteogenic lineage commitment of primary mouse and human mesenchymal stem cells, and support the growth of a broad range of primary human organoid cultures. In addition, the surrogates can be systemically expressed and exhibit Wnt activity in vivo in the mouse liver, regulating metabolic liver zonation and promoting hepatocyte proliferation, resulting in hepatomegaly. These surrogates demonstrate that canonical Wnt signalling can be activated by bi-specific ligands that induce receptor heterodimerization. Furthermore, these easily produced, non-lipidated Wnt surrogate agonists facilitate functional studies of Wnt signalling and the exploration of Wnt agonists for translational applications in regenerative medicine.
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Project description:Accumulating evidence strongly implicates iron in the pathogenesis of aging and disease. Iron levels have been found to increase with age in both the human and mouse retinas. We and others have shown that retinal diseases such as age-related macular degeneration and diabetic retinopathy are associated with disrupted iron homeostasis, resulting in retinal iron accumulation. In addition, hereditary disorders due to mutation in one of the iron regulatory genes lead to age dependent retinal iron overload and degeneration. However, our knowledge on whether iron toxicity contributes to the retinopathy is limited. Recently, we reported that iron accumulation is associated with the upregulation of retinal and renal renin-angiotensin system (RAS). Evidences indicate that multiple genes/components of the RAS are targets of Wnt/β-catenin signaling. Interestingly, aberrant activation of Wnt/β-catenin signaling is observed in several degenerative diseases. In the present study, we explored whether iron accumulation regulates canonical Wnt signaling in the retina. We found that in vitro and in vivo iron treatment resulted in the upregulation of Wnt/β-catenin signaling and its downstream target genes including renin-angiotensin system in the retina. We confirmed further that iron activates canonical Wnt signaling in the retina using TOPFlash T-cell factor/lymphoid enhancer factor promoter assay and Axin2-LacZ reporter mouse. The presence of an iron chelator or an antioxidant reversed the iron-mediated upregulation of Wnt/β-catenin signaling in retinal pigment epithelial (RPE) cells. In addition, treatment of RPE cells with peroxisome proliferator-activated receptor (PPAR) α-agonist fenofibrate prevented iron-induced activation of oxidative stress and Wnt/β-catenin signaling by chelating the iron. The role of fenofibrate, an FDA-approved drug for hyperlipidemia, as an iron chelator has potentially significant therapeutic impact on iron associated degenerative diseases.
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Project description:Canonical WNT/?-catenin signaling is involved in most of the mechanisms that lead to the formation and development of cancer cells. It plays a central role in three cyclic processes, which are the cell division cycle, the immune cycle, and circadian rhythms. When the canonical WNT pathway is upregulated as in cancers, the increase in ?-catenin in the nucleus leads to activation of the expression of numerous genes, in particular CYCLIN D1 and cMYC, where the former influences the G1 phase of the cell division cycle, and the latter, the S phase. Every stage of the immune cycle is disrupted by the canonical WNT signaling. In numerous cancers, the dysfunction of the canonical WNT pathway is accompanied by alterations of the circadian genes (CLOCK, BMAL1, PER). Induction of these cyclic phenomena leads to the genesis of thermodynamic mechanisms that operate far from equilibrium, and that have been called "dissipative structures." Moreover, upregulation of the canonical WNT/?-catenin signaling is important in the myofibroblasts of the cancer stroma. Their differentiation is controlled by the canonical WNT /TGF-?1 signaling. Myofibroblasts present ultraslow contractile properties due to the presence of the non-muscle myosin IIA. Myofibroblats also play a role in the inflammatory processes, often found in cancers and fibrosis processes. Finally, upregulated canonical WNT deviates mitochondrial oxidative phosphorylation toward the Warburg glycolysis metabolism, which is characteristic of cancers. Among all these cancer-generating mechanisms, the upregulated canonical WNT pathway would appear to offer the best hope as a therapeutic target, particularly in the field of immunotherapy.
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Project description:A multitude of signalling pathways are involved in the process of forming an eye. Here we demonstrate that ?-catenin is essential for eye development as inactivation of ?-catenin prior to cellular specification in the optic vesicle caused anophthalmia in mice. By achieving this early and tissue-specific ?-catenin inactivation we find that retinal pigment epithelium (RPE) commitment was blocked and eye development was arrested prior to optic cup formation due to a loss of canonical Wnt signalling in the dorsal optic vesicle. Thus, these results show that Wnt/?-catenin signalling is required earlier and play a more central role in eye development than previous studies have indicated. In our genetic model system a few RPE cells could escape ?-catenin inactivation leading to the formation of a small optic rudiment. The optic rudiment contained several neural retinal cell classes surrounded by an RPE. Unlike the RPE cells, the neural retinal cells could be ?-catenin-negative revealing that differentiation of the neural retinal cell classes is ?-catenin-independent. Moreover, although dorsoventral patterning is initiated in the mutant optic vesicle, the neural retinal cells in the optic rudiment displayed almost exclusively ventral identity. Thus, ?-catenin is required for optic cup formation, commitment to RPE cells and maintenance of dorsal identity of the retina.
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Project description:Wnt/?-catenin signalling is central to development and its regulation is essential in preventing cancer. Using phosphorylation of Dishevelled as readout of pathway activation, we identified Drosophila Wnk kinase as a new regulator of canonical Wnt/?-catenin signalling. WNK kinases are known for regulating ion co-transporters associated with hypertension disorders. We demonstrate that wnk loss-of-function phenotypes resemble canonical Wnt pathway mutants, while Wnk overexpression causes gain-of-function canonical Wnt-signalling phenotypes. Importantly, knockdown of human WNK1 and WNK2 also results in decreased Wnt signalling in mammalian cell culture, suggesting that Wnk kinases have a conserved function in ensuring peak levels of canonical Wnt signalling.
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Project description:The development of skeletal muscle from immature precursors is partially driven by canonical WNT/?-catenin signaling. Rhabdomyosarcomas (RMS) are immature skeletal muscle-like, highly lethal cancers with a variably pronounced blockade of muscle differentiation. To investigate whether canonical ?-catenin signaling in RMS is involved in differentiation and aggressiveness of RMS, we analyzed the effects of WNT3A and of a siRNA-mediated or pharmacologically induced ?-catenin knock-down on proliferation, apoptosis and differentiation of embryonal and alveolar RMS cell lines. While the canonical WNT pathway was maintained in all cell lines as shown by WNT3A induced AXIN expression, more distal steps including transcriptional activation of its key target genes were consistently impaired. In addition, activation or inhibition of canonical WNT/?-catenin only moderately affected proliferation, apoptosis or myodifferentiation of the RMS tumor cells and a conditional knockout of ?-catenin in RMS of Ptch del/+ mice did not alter RMS incidence or multiplicity. Together our data indicates a subordinary role of the canonical WNT/?-catenin signaling for RMS proliferation, apoptosis or differentiation and thus aggressiveness of this malignant childhood tumor.
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Project description:The canonical Wnt/β-catenin pathway plays an important role in different developmental processes through the regulation of stem cell functions. In the activation of the canonical Wnt/β-catenin pathway, β-catenin protein is imported into the nucleus and activates transcription of target genes including cyclin D1 and c-myc. Aberrant activation of the Wnt/β-catenin pathway contributes to carcinogenesis and malignant behaviors, and Wnt signaling is essential for the maintenance of cancer stem cells. The canonical Wnt/β-catenin pathway has been investigated extensively as a target in cancer treatment and several specific inhibitors of this signaling pathway have been identified through high-throughput screening. In this review, the significance of the canonical Wnt/β-catenin pathway in hematological carcinogenesis and screening methods for specific inhibitors are discussed.
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Project description:Unlabelled: Gene-modified mesenchymal stem cell (MSC)-like cells with enhanced bone marrow homing and osteogenesis have been used in treating glucocorticoid-induced murine osteoporosis (GIOP). Recent preclinical studies have further demonstrated the immunomodulatory and anticatabolic potential of allogeneic MSCs in treating osteoporosis under inflammatory and autoimmune conditions. In this study, we investigated whether systemic infusion of allogeneic MSCs without genetic manipulation could prevent GIOP, whether anabolic and anticatabolic effects existed, and whether homing or immunomodulation underlay the putative therapeutic effects. Allogeneic bone marrow-derived MSCs (BMMSCs) were isolated, identified, and systemically infused into mice treated with excessive dexamethasone. We revealed that allogeneic MSC transplantation prevented the reduction of bone mass and strength in GIOP. Bone histomorphometric analyses of bone remodeling demonstrated the maintenance of bone formation and osteoblast survival after MSC therapy. Using green fluorescent protein (GFP)-labeled BMMSCs, we showed that donor BMMSCs(GFP) homed and inhabited recipient bone marrow for at least 4 weeks and prevented recipient bone marrow cell apoptosis, as shown by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. Furthermore, donor BMMSCs(GFP) committed to Osterix (Osx)(+) osteoblast progenitors and induced recipient osteoblastogenesis, as exhibited by GFP-Osx double-labeling immunofluorescence analysis. No anticatabolic effects or systemic immunomodulatory effects of infused BMMSCs were detected. These findings demonstrated that allogeneic MSC therapy prevented GIOP by inhabiting and functioning in recipient bone marrow, which promoted osteoblastogenesis, which in turn maintained bone formation. Our findings provide important information regarding cell-based anabolic therapy for GIOP and uncover MSC behaviors following the homing event.SignificanceThis study revealed the therapeutic potential of systemically infused, genetically unmodified allogeneic MSCs in glucocorticoid-induced osteoporosis. The donor MSCs inhabited recipient bone marrow and promoted osteoblastogenesis. The therapeutic effects were based on maintenance of bone formation. These results provide important information regarding cell-based anabolic therapy for glucocorticoid-induced osteoporosis and uncover previously unrecognized mesenchymal stem cell behaviors following a homing event. The current study also indicates that minimizing the time of cell culture confers an advantage for increasing transplanted mesenchymal stem cells to the targeted organ to promote therapeutic effects.
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Project description:The canonical Wnt signaling pathway controls normal embryonic development, cellular proliferation and growth, and its aberrant activity results in human carcinogenesis. The core component in regulation of this pathway is β-catenin, but molecular regulation mechanisms of β-catenin stability are not completely known. Here, our recent studies have shown that KCTD1 strongly inhibits TCF/LEF reporter activity. Moreover, KCTD1 interacted with β-catenin both in vivo by co-immunoprecipitation as well as in vitro through GST pull-down assays. We further mapped the interaction regions to the 1-9 armadillo repeats of β-catenin and the BTB domain of KCTD1, especially Position Ala-30 and His-33. Immunofluorescence analysis indicated that KCTD1 promotes the cytoplasmic accumulation of β-catenin. Furthermore, protein stability assays revealed that KCTD1 enhances the ubiquitination/degradation of β-catenin in a concentration-dependent manner in HeLa cells. And the degradation of β-catenin mediated by KCTD1 was alleviated by the proteasome inhibitor, MG132. In addition, KCTD1-mediated β-catenin degradation was dependent on casein kinase 1 (CK1)- and glycogen synthase kinase-3β (GSK-3β)-mediated phosphorylation and enhanced by the E3 ubiquitin ligase β-transducin repeat-containing protein (β-TrCP). Moreover, KCTD1 suppressed the expression of endogenous Wnt downstream genes and transcription factor AP-2α. Finally, we found that Wnt pathway member APC and tumor suppressor p53 influence KCTD1-mediated downregulation of β-catenin. These results suggest that KCTD1 functions as a novel inhibitor of Wnt signaling pathway.
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