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We investigated whether the WNT/β-catenin signalling pathway is involved in paediatric Kashin–Beck disease (KBD) and T-2-toxin-induced cartilage injury in rats to better understand the mechanism of KBD. One hundred twenty-two children were selected and assigned to the case (31), internal control (41), and external control (50) groups. The serum β-catenin and bone morphogenetic protein 2（BMP2）levels in each group were measured and compared. Thirty-six rats were randomly assigned to three groups, which received no intervention, T-2 toxin, or solvent. After 18 weeks, the expression of LDL receptor related proteins 5 (LRP5), β-catenin, BMP2, BAX, BCL2, APAF1, and caspase 9 was measured and compared. The serum BMP2 levels were significantly elevated in the children with KBD and in the rats treated with T-2 toxin. In the T-2 toxin group, LRP5 and β-catenin expression was reduced, whereas BAX, APAF1, and caspase 9 expression was increased. In conclusion, the WNT/β-catenin signalling pathway is suppressed in KBD, which induces chondrocyte apoptosis, leading to cartilage injury. Therefore, BMP2 may play a role in the pathogenesis of KBD.

Canonical Wnt signaling plays an important role in skeletal development, homeostasis, and both endochondral and intramembranous repair. While studies have demonstrated that the inhibition of Wnt signaling impairs intramembranous bone regeneration, how its activation affects intramembranous bone regeneration has been underexplored. Therefore, we sought to determine the effects of activation of canonical Wnt signaling on intramembranous bone regeneration by using the well-established marrow ablation model. We hypothesized that mice with a mutation in the Wnt ligand coreceptor gene Lrp5 would have accelerated intramembranous bone regeneration. Male and female wild-type and Lrp5-mutant mice underwent unilateral femoral bone marrow ablation surgery in the right femur at 4 weeks of age. Both the left intact and right operated femurs were assessed at Days 3, 5, 7, 10, and 14. The intact femur of Lrp5 mutant mice of both sexes had higher bone mass than wild-type littermates, although to a greater degree in males than females. Overall, the regenerated bone volume in Lrp5 mutant male mice was 1.8-fold higher than that of littermate controls, whereas no changes were observed between female Lrp5 mutant and littermate control mice. In addition, the rate of intramembranous bone regeneration (from Day 3 to Day 7) was higher in Lrp5 mutant male mice compared to their same-sex littermate controls with no difference in the females. Thus, activation of canonical Wnt signaling increases bone mass in intact bones of both sexes, but accelerates intramembranous bone regeneration following an injury challenge only in male mice.

Masaki Nakano,1,* Haruka Yui,1,* Shingo Kikugawa,2 Ryosuke Tokida,3 Noriko Sakai,4 Naoki Kondo,5 Naoto Endo,5 Hirotaka Haro,6 Hiroki Shimodaira,1 Takako Suzuki,1,7 Hiroyuki Kato,1 Jun Takahashi,1 Yukio Nakamura1 1Department of Orthopaedic Surgery, Shinshu University School of Medicine, Matsumoto, Nagano, 390-8621, Japan; 2DNA Chip Research Inc., Minato-ku, Tokyo, 105-0022, Japan; 3Rehabilitation Center, Shinshu University Hospital, Matsumoto, Nagano, 390-8621, Japan; 4Department of Orthopaedic Surgery, New Life Hospital, Obuse, Nagano, 381-0295, Japan; 5Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, 951-8510, Japan; 6Department of Orthopaedic Surgery, University of Yamanashi Graduate School of Medicine, Chuo, Yamanashi, 409-3898, Japan; 7Department of Human Nutrition, Faculty of Human Nutrition, Tokyo Kasei Gakuin University, Chiyoda-ku, Tokyo, 102-8341, Japan*These authors contributed equally to this workCorrespondence: Yukio NakamuraDepartment of Orthopaedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, JapanTel +81-263-37-2659Fax +81-263-35-8844Email yxn14@aol.jpObjective: Osteoarthritis (OA) is a common and degenerative joint disorder in the elderly. A greater importance of understanding the relationship between genetic factors and OA prevalence has emerged with population aging. We therefore investigated the associations of several bone disease-related genetic variants with the prevalence of OA and osteoporosis in Japanese elderly women from the Obuse study cohort, which was randomly sampled from a basic town resident registry.Methods and Results: In total, 206 female participants (mean ± standard deviation age: 69.7 ± 11.0 years) who completed OA, bone mineral density, and genotype assessments were included. The number of patients diagnosed as having knee/hip OA and osteoporosis was 59 (28.6%) and 30 (14.6%), respectively. Fisher’s exact testing revealed significant relationships between the minor T allele of LDL receptor related protein 5 (LRP5) rs3736228 and the prevalence of knee/hip OA and osteoporosis. The respective odds ratios (ORs) of the TT genotype for knee/hip OA and osteoporosis were 7.28 (95% confidence interval [CI] 2.22– 28.08) and 5.24 (95% CI 0.95– 26.98). An additional subgroup analysis for knee OA revealed that the frequency of the common C allele of methylenetetrahydrofolate reductase (MTHFR) rs1801133 had a statistically significant protective association with the prevalence of knee OA (OR 0.58, 95% CI 0.35– 0.97).Conclusion: In sum, the present study demonstrated significant associations of LRP5 rs3736228 and MTHFR rs1801133 with knee/hip OA and osteoporosis prevalences and knee OA prevalence, respectively, in Japanese elderly women. These results will help further the understanding of OA pathogenesis and related genetic risk factors.Keywords: genetic variant, LRP5, MTHFR, osteoarthritis, osteoporosis

Objectives Childhood osteoporosis is an uncommon condition that usually develops secondary to underlying disease states. Idiopathic juvenile osteoporosis or early onset osteoporosis is a rare cause of primary osteoporosis in childhood associated with mutations in “bone fragility” genes. Case presentation The index case presented with upper back pain and was detected to have multiple vertebral fractures. Further workup for the cause revealed a homozygous benign mutation in low-density lipoprotein receptor-related protein 5, which was also detected in the mother who remained asymptomatic till presentation. The child was successfully treated with intravenous zoledronate. Conclusions The case report describes the management approach and four-year follow-up of the child.

Altres ajuts: Fundación Investigación Cardiovascular-Fundación Jesus Serra Altres ajuts: Sociedad Española de Cardiología FEC2019 Microvesicles (MV) contribute to cell-to-cell communication through their transported proteins and nucleic acids. MV, released into the extracellular space, exert paracrine regulation by modulating cellular responses after interaction with near and far target cells. MV are released at high concentrations by activated inflammatory cells. Different subtypes of human macrophages have been characterized based on surface epitopes being CD16 macrophages associated with anti-inflammatory phenotypes. We have previously shown that low-density lipoprotein receptor-related protein 5 (LRP5), a member of the LDLR family that participates in lipid homeostasis, is expressed in macrophage CD16 with repair and survival functions. The goal of our study was to characterize the cargo and tentative function of macrophage-derived MV, whether LRP5 is delivered into MV and whether these MV are able to induce inflammatory cell differentiation to a specific CD16 or CD16 phenotype. We show, for the first time, that lipid-loaded macrophages release MV containing LRP5. LDL loading induces increased expression of macrophage pro-inflammatory markers and increased release of MV containing pro-inflammatory markers. Conditioning of fresh macrophages with MV released by Lrp5-silenced macrophages induced the transcription of inflammatory genes and reduced the transcription of anti-inflammatory genes. Thus, MV containing LRP5 induce anti-inflammatory phenotypes in macrophages.

BACKGROUND The WNT signaling pathway is involved in the regulation of bone homeostasis, and the effect of WNT signaling pathway-related gene (WNT16 and LRP5) polymorphisms on osteoporosis risk among Chinese postmenopausal women is still unknown. Hence, we performed a case-control study to assess the association of WNT signaling pathway-related gene polymorphisms and osteoporosis risk. METHODS A total of 1026 women (515 osteoporosis patients and 511 controls) of postmenopausal age who were randomly sampled from Xi'an 630 Hospital (Shaanxi Province, China) were involved in this study. Seven genetic polymorphisms in WNT16 (rs3779381, rs3801387, rs917727 and rs7776725) and LRP5 (rs2291467, rs11228240 and rs12272917) were selected and genotyped using the Agena MassARRAY iPLEX system. The association of the genetic polymorphisms and osteoporosis risk was assessed by odds ratios and 95% confidence intervals. The multifactor dimensionality reduction (MDR) method was conducted to analyze single nucleotide polymorphism (SNP)-SNP interaction. RESULTS We found that LRP5 polymorphisms (rs2291467, rs11228240 and rs12272917) were significantly associated with a decreased risk of osteoporosis in homozygote, recessive and additive models (p 24 (p

In this study, fucoidans were extracted from the sea cucumber Thelenota ananas (Ta-FUCs) by enzymatic degradation. Four products with molecular weights of 1380.3, 524.0, 182.4, and 110.3 kDa were obtained, and the Ta-FUC showing optimal anti-adipogenic activities was determined. Results of MTT and Oil red O staining analyses showed that the Ta-FUCs inhibited the proliferation and differentiation of 3T3-L1 adipocytes. Futhermore, Ta-FUCs significantly downregulated the key transcriptional factors, such as SREBP-1c, PPARγ, and C/EBPα of adipocytes. The Ta-FUCs also activated Wnt/β-catenin pathway-related genes, such as β-catenin, LRP5, and FrZ. The Ta-FUCs suppressed lipid accumulation in 3T3-L1 adipocytes possibly by decreasing the expression of genes ACC, FAS, ME, GPAT, DGAT, and PILN, which are important in the synthesis of fatty acids and triglycerides; and by increasing the expression of genes PPARα, CPT-1α, and ACOX, which are crucial in fatty acid β-oxidation. The anti-adipogenic activities initially increased and then declined with decreasing molecular weight. Among the Ta-FUCs, the 182.4 kDa Ta-FUC exhibited optimal bioactivities. This study reports for the first time that Ta-FUCs can prevent obesity by regulating the differentiation and lipid accumulation of adipocytes.

Melittin is a major active peptide component of bee venom that has been demonstrated to show anti-tumor effects. Osteosarcoma is a type of bone tumor with a high degree of malignancy, and metastasis is the main challenge of osteosarcoma therapy. This study aimed to investigate the role of melittin in the lung metastasis of osteosarcoma. 143 B cells were treated with different concentrations of melittin in vitro. Wound-healing and transwell assays were performed to determine the cell migration and invasion potential. Quantitative real-time PCR and Western blot experiments were performed to evaluate the expression levels of Wnt/β-catenin signaling pathway-related factors after treatment with melittin. The orthotopic implantation model and hematoxylin-eosin staining were used to investigate the effect of melittin treatment on tumor formation and lung metastasis. Immunohistochemical staining and Western blot experiments were performed to indicate the melittin-mediated expression changes in Wnt/β-catenin signaling pathway-related factors. The cell migration and invasion potential were observed to be inhibited in a dose-dependent manner upon treatment with melittin. Treatment with medium and high concentrations of melittin attenuated the mRNA and protein expression of LRP5, β-catenin, MMP-2, cyclin D, c-Myc, survivin, MMP-9, and VEGF genes in vitro. Melittin significantly inhibited the growth of tibia xenografts in nude mice and decreased the number of lung metastatic nodules. Consistent with the results observed in vitro, treatment with melittin at medium and high concentrations attenuated the expression of Wnt/β-catenin signaling pathway-related factors in vivo. In vitro, Wnt/β-catenin signaling pathway was involved in Melittin-mediated -migration and invasion potential of 143 B cells. Similarly, as observed in the in vivo experiments, Wnt/β-catenin signaling pathway was also associated with the role of melittin on lung metastasis of osteosarcomas.

Wingless-integrated/β-catenin (Wnt/β-catenin) signaling pathway is an evolutionarily conserved signaling which is not only important for regulation of embryogenesis and organ development, but also for injury repair, homeostasis and tissue remodeling. Dysregulation of this pathway either by upregulation or even downregulation is highly implicated in various diseases such as; liver diseases, kidney diseases, lung fibrosis, heart failure, vascular calcification, osteoporosis, cellular senescence, neurodegeneration, Alzheimer's disease and cancers. Thus, targeting Wnt/β-catenin signaling has attracted scientific research as a good strategy ameliorating several diseases. In this review we discussed Wnt/β-catenin components, the Wnt-on state and the Wnt-off state. Furthermore, we summarized the effects of Wnt/β-catenin signaling in several distinct organs including brain, bone, liver, heart, lung and kidney. We also discussed various molecules that act as modulators of Wnt/β-catenin signaling pathway via targeting its components (Wnt, Frizzled, LRP5/6, Porcupine, Disheveled, β-catenin destruction complex and β-catenin activity) aiming to show their possible therapeutic potential in several diseases.

The LRP5 gene encodes a Wnt signaling receptor to which Wnt binds directly. In humans, pathogenic monoallelic variants in LRP5 have been associated with increased bone density and exudative vitreoretinopathy. In mice, LRP5 plays a role in tooth development, including periodontal tissue stability and cementum formation. Here, we report a 14-year-old patient with a de novo non-synonymous variant, p.(Val1245Met), in LRP5 who exhibited mildly reduced bone density and mild exudative vitreoretinopathy together with a previously unreported phenotype consisting of dental abnormalities that included fork-like small incisors with short roots and an anterior open bite, molars with a single root, and severe taurodontism. In that exudative vitreoretinopathy has been reported to be associated with heterozygous loss-of-function variants of LRP5 and that our patient reported here with the p.(Val1245Met) variant had mild exudative vitreoretinopathy, the variant can be considered as an incomplete loss-of-function variant. Alternatively, the p.(Val1245Met) variant can be considered as exerting a dominant-negative effect, as no patients with truncating LRP5 variants and exudative vitreoretinopathy have been reported to exhibit dental anomalies. The documentation of dental anomalies in the presently reported patient strongly supports the notion that LRP5 plays a critical role in odontogenesis in humans, similar to its role in mice.

Fractures are the most common large-organ, traumatic injury in humans. The fracture healing stage includes the inflammatory stage (0-5d), cartilage callus stage (5-14d) and hard callus stage (14-21d). All mice underwent open tibial fracture surgery and were treated with saline, Glu or SCII for 21d. Calluses were harvested 5d, 10d and 21d after fracture. Compared with the model group, SCII significantly decreased TNF-α and increased aggrecan serum levels by 5d. H&E results showed that fibrous calluses were already formed in the SCII group and that chondrocytes had begun to proliferate. By 10d, the chondrocytes in the SCII group became hypertrophic and mineralized, and the serum TGF-β and Col-Iα levels were significantly increased, which indicated that the mice with SCII treatment rapidly passed the cartilage repair period and new bone formation was accelerated. Skeletal muscle repaired bones through muscle paracrine factors. IGF-1 and irisin are the two major secretory cytokines. The results showed that the content of muscle homogenate IGF-1 in the SCII group reached the peak at 10d, followed by the up-regulation of Ihh, Patched, Gli1 and Col10α in the callus through the bone surface receptor IGF-1R. Besides, SCII also significantly elevated the muscle irisin level (10 and 21d), and then increased Wnt10b, LRP5, β-catenin and Runx2 expression in the callus by receptor αVβ5. These results suggest that SCII can accelerate the process of endochondral osteogenesis and promote fracture healing through activating the Ihh/PThrp and Wnt/β-catenin pathways by regulating muscle paracrine factors. To our knowledge, this is the first study to investigate the effect of marine-derived collagen on fracture healing. This study may provide a theoretical basis for the high-value application of the laryngeal cartilage of squid in the future.

A loss-of-function mutation in the Lrp5 gene in mice leads to a low bone mass disorder due to the inhibition of the canonical Wnt signaling pathway; however, the role of bone marrow microenvironment in mice with this mutation remains unclear. In this study, we evaluated proliferation and osteogenic potential of mouse osteoblasts using the MTT assay and Alizarin red staining. The levels of alkaline phosphatase, tartrate-resistant acid phosphatase, and adiponectin in culture supernatants were measured using the enzyme-linked immunosorbent assay. Osteoclast bone resorbing activity was evaluated by toluidine staining and the number and area of bone resorption pits were determined. We observed increased osteogenesis in osteoblasts co-cultured with the BM-derived myeloid cells compared to the osteoblasts cultured alone. Mice with global Lrp5 deletion had a relatively higher bone density compared to the mice carrying osteoblast/osteocyte-specific Lrp5 deletion. An increased frequency of M2 macrophages and reduced expression of inflammatory cytokines were detected in the myeloid cells derived from the bone marrow of mice with global Lrp5 deletion. Higher adipogenic potential and elevated levels of adiponectin in the global Lrp5 deletion mice contributed to the preferential M2 macrophage polarization. Here, we identified a novel systemic regulatory mechanism of bone formation and degradation in mice with global Lrp5 deletion. This mechanism depends on a crosstalk between the adipocytes and M2 macrophages in the bone marrow and is responsible for partly rescuing osteopenia developed as a result of decreased Wnt signaling.

Objective The temporomandibular joint (TMJ) is a unique fibrocartilaginous joint that adapts to mechanical loading through cell signaling pathways such as the Wnt pathway. Increased expression of low-density lipoprotein receptor-related protein 5 (Lrp5), a co-receptor of the Wnt pathway, is associated with a high bone mass (HBM) phenotype. The objective of this study was to analyze the effect of overexpression of Lrp5 on the subchondral bone and cartilage of the TMJ in mice exhibiting the HBM phenotype. Design Sixteen-week-old Lrp5 knock-in transgenic mice carrying either the A214V (EXP-A) or G171V (EXP-G) missense mutations, and wildtype controls (CTRL) were included in this study. Fluorescent bone labels, calcein, alizarin complexone, and demeclocycline were injected at 3.5, 7.5, and 11.5 weeks of age, respectively. The left mandibular condyle was used to compare the subchondral bone micro-computed tomography parameters and the right TMJ was used for histological analyses. Cartilage thickness, matrix proteoglycan accumulation, and immunohistochemical localization of Lrp5 and sclerostin were compared between the groups. Results Subchondral bone volume (BV) and percent bone volume (BV/TV) were significantly increased in both EXP-A and EXP-G compared with CTRL ( P < 0.05) whereas trabecular spacing (Tb.Sp) was decreased. Cartilage thickness, extracellular matrix production, and expression of Lrp5 and Sost were all increased in the experimental groups. The separation between the fluorescent bone labels indicated increased endochondral maturation between 3.5 and 7.5 weeks. Conclusions These data demonstrate that Lrp5 overexpression leads to adaptation changes in the mandibular condylar cartilage of the TMJ to prevent cartilage degradation.

The clearance of low-density lipoprotein (LDL) particles from the circulation is regulated by the LDL receptor (LDLR) and proprotein convertase subtilisin/kexin 9 (PCSK9) interaction. Its disruption reduces blood cholesterol levels and delays atherosclerosis progression. Whether other members of the LDLR superfamily are in vivo targets of PCSK9 has been poorly explored. The aim of this work was to study the interaction between PCSK9 and members of the LDLR superfamily in the regulation of liver cholesterol homeostasis in an in vivo low-density lipoprotein receptor related protein 5 (LRP5) deficient mice model challenged with high-fat diet. Our results show that Wt and Lrp5(-/-) mice fed a hypercholesterolemic diet (HC) have increased cholesterol ester accumulation and decreased liver LDLR and LRP5 gene and protein expression. Very low-density lipoprotein receptor (VLDLR), LRP6, LRP2, and LRP1 expression levels were analyzed in liver samples and show that they do not participate in Lrp5(-/-) liver cholesterol uptake. Immunoprecipitation experiments show that LRP5 forms a complex with PCSK9 in liver-specific fat-storing stellate cells but not in structural HepG2 cells. Hepatic stellate cells silenced for LRP5 and/or PCSK9 expression and challenged with lipids show reduced cholesterol ester accumulation, indicating that both proteins are involved in lipid processing in the liver. Our results indicate that cholesterol esters accumulate in livers of Wt mice in a LDLR-family-members dependent manner as VLDLR, LRP2, and LRP6 show increased expression in HC mice. However, this increase is lost in livers of Lrp5(-/-) mice, where scavenger receptors are involved in cholesterol uptake. PCSK9 expression is strongly downregulated in mice livers after HC feeding. However PCSK9 and LRP5 bind in the cytoplasm of fat storing liver cells, indicating that this PCSK9-LRP5 interaction is cell-type specific and that both proteins contribute to lipid uptake.

Background Apert syndrome is an autosomal, dominant inherited disorder characterized by craniosynostosis and syndactyly caused by gain‐of‐function mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. Wnt/β‐catenin signaling plays critical roles in regulating the skeletal development. Here, we analyzed the role of this pathway in the developing coronal sutures (CS) of a murine Apert syndrome model (Fgfr2S252W/+). Results We observed aberrantly increased mRNA expression of Lrp5 and Lrp6 in CS of Fgfr2S252W/+ mice, whereas both wild type (WT) and Fgfr2S252W/+ mice showed similar expression of other Wnt/β‐catenin‐related genes, such as Wnt3, Wnt3a, Fzd4, Fzd6, Axin2, and Dkk1 as evidenced by in situ hybridization. Significantly increased Lrp5 and Lrp6 mRNA expression was observed by quantitative PCR analysis of cultured cells isolated from CS of Fgfr2S252W/+ mice. Phospho‐LRP5, phospho‐LRP6, and non‐phospho‐β‐catenin were upregulated in Fgfr2S252W/+ CS compared with that in WT CS. Short‐interfering RNA targeting Lrp5 and Lrp6 significantly reduced runt‐related transcription factor 2, collagen type 1 alpha 1, and osteocalcin mRNA expression, and alkaline phosphatase activity in cultured cells. Conclusions The Wnt/β‐catenin pathway was activated in the CS of Fgfr2S252W/+ mice during craniofacial development, suggesting the involvement of the Wnt/β‐catenin pathway in the pathogenesis of CS synostosis in Fgfr2S252W/+ mice. This article is protected by copyright. All rights reserved.

Long noncoding RNAs (lncRNAs) have been implicated in a range of developmental processes and diseases, but the roles and mechanisms by which they act in adipogenic differentiation and adipose tissue biology are still unknown. By comparing the different expression patterns of lncRNAs before and after the adipocyte differentiation of human adipose-derived mesenchymal stem cells (hADSCs), we characterized a novel lncRNA, AC092834.1, which is significantly increased in preadipocytes. By gain- and loss-of-function experiments, we demonstrated that lncRNA AC092834.1 potentiated adipogenic differentiation through directly increasing the level of expression of DKK1, which competitively binds with LRP5 to inhibit the Wnt-β-catenin pathway and reduce the inhibition of adipogenesis by Wnt signaling. This finding provides novel mechanistic insights into a critical role for lncRNA AC092834.1 as a regulator of adipogenic differentiation, which expands our knowledge about the molecular mechanisms of obesity and other adipogenic differentiation-related disorders.

Wnt/β-catenin signaling pathway modulates miscellaneous biological events in cells including gene expression, cell growth, apoptosis, metabolism and transition. The aim of this study was to investigate the effect of endostatin on Wnt signaling pathway of stem-like cells in bladder cancer in tumor microenvironment. The qRT-PCR assay and western blot were conducted to evaluate related factors expressions of Wnt signaling pathway in both bladder cancer 5637 cells and stem cells. Loss of function assays were carried out to detect the influence of endostatin on the proliferation, migration, cell proliferation and apoptosis of bladder cancer cells. We demonstrated that endostatin triggered the degradation of β-catenin, a key mediator of Wnt signaling. The activation of the endostatin blocked β-catenin function and inhibited cell growth and migration of bladder cancer. In order to verify that the Wnt/β-catenin signaling pathway was inhibited by endostain in 5637 bladder cancer cells and stem cells, the Wnt/β-catenin signaling pathway-associated molecules, including DKK1, LRP5, TCF4, β-catenin, cyclin D1, and c-Myc, were evaluated in 5637 bladder cancer cells and stem cells. The western blotting results showed that expressions of these molecules were remarkably increased in the 5637 bladder cancer cells and stem cells compared to the control group. In summary, our study demonstrated that endostatin inhibited angiogenesis. The downregulation of the Wnt/β-catenin pathway may be engaged in the suppression of angiogenesis by endostatin in bladder cancer cells and cancer stem cells.

Bone erosion is a debilitating pathological process of osteopathic disorder like rheumatoid arthritis (RA). Current treatment strategies render low disease activity but with disease recurrence. To find an alternative, we designed this study with an aim to explore the underlying therapeutic effect of PEGylated liposomal BBR (PEG-BBR) against Wnt1/β-catenin mediated bone erosion in adjuvant-induced arthritic (AA) rat model and fibroblast-like synoviocytes (FLS) with reference to microRNA-23a (miR-23a) activity. Our initial studies using confocal microscopy and Near-Infrared Imaging (NIR) showed successful internalization of PEG-BBR and PEG-miR-23a in vitro and in vivo respectively and was retained till 48 h. The preferential internalization of PEG-BBR into the inflamed joint region significantly reduced the gene and protein level expression of major Wnt1 signaling mediators and reduced bone erosion in rats. Moreover, PEG-BBR treatment in FLS cells attenuated the gene and protein expression levels of FZD4, LRP5, β-catenin, and Dvl-1 through the induction of CYLD. Furthermore, inhibition of these factors resulted in reduced bone loss and increased calcium retainability by altering the RANKL/OPG axis. PEG-BBR treatment markedly inhibited the expression of LRP5 protein on par with the DKK-1 (LRP5/Wnt signaling inhibitor) and suppressed the transcriptional activation of β-catenin inside the cells. We further witnessed that miR-23a altered the expression levels of LRP5 through RNA interference. Overall, our findings endorsed that miR-23a possesses a multifaceted therapeutic efficiency like berberine in RA pathogenesis and can be considered as a potential candidate for therapeutic targeting of Wnt1/β-catenin signaling in RA disease condition.

Aberrant activation of the Wnt signaling pathway is associated with tumorigenesis, relapse/chemoresistance, and distance metastasis in TNBC. SM08502 is a novel, oral, small-molecule pan-CLK inhibitor that has been shown to potently inhibit the Wnt signaling pathway in several preclinical cancer models. The purpose of these studies was to examine the antitumor activity of SM08502 as monotherapy and in combination with standard chemotherapy in preclinical models of TNBC. The effect of SM08502 on cell proliferation was tested 13 BC cell lines, 7 of which were TNBC derived. Cell proliferation was strongly impaired by SM08502 across all lines (average EC50=0.170 µM [0.055-0.510]). SM08502 demonstrated similar potency between HR+ and TNBC cell lines with average EC50 values of 0.202 µM (0.058-0.510) and 0.142 µM (0.055-0.240), respectively. Relative to DMSO, SM08502 (1 μM) potently inhibited Wnt pathway-related gene and protein expression (TCF7, DVL2, LRP5, and ERBB2) in TNBC cell lines. Notably, SM08502 showed little inhibitory effect on cell proliferation in normal breast cells (Hs578Bst) compared with their paired TNBC cells (Hs578T) with an EC50 of 1.517 μM and 0.080 μM, respectively. Wnt pathway-related proteins were also overexpressed in Hs578T cells relative to Hs578Bst, and SM08502 (1 µM) strongly reduced their expression. In vivo antitumor effects and tolerability of oral SM08502 (25 mg/kg QD for 20 days) were assessed in mice bearing orthotopically implanted, luciferase-expressing, TNBC (MDA-MB231)-derived xenografts (n=5 mice per group). Significant tumor growth inhibition (TGI) vs. vehicle occurred in mice treated with SM08502 (80%, p Citation Format: Heekyung Chung, Lauren Sitts, Emily Creger, John Duc Nguyen, Brian Eastman, Chi-Ching Mak, Sunil KC, Betty Tam, Carine Bossard, Timothy Phalen, Steven Cha. SM08502, a novel, small-molecule CDC-like kinase (CLK) inhibitor, demonstrates strong inhibition of the Wnt signaling pathway and antitumor effects as monotherapy and in combination with chemotherapy in triple-negative breast cancer (TNBC) models [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-13-01.

The objective of this study was to analyze the expression and clinical role of Wnt pathway molecules in metastatic high-grade serous carcinoma (HGSC). mRNA expression by qPCR of 20 molecules related to Wnt signaling (WNT1, WNT2, WNT3, WNT4, WNT5A, WNT6, WNT7, WNT11, FZD1, FZD4, FZD5, FZD6, FZD7, FZD8, FZD10, LRP5, LRP6, DKK, CCND, RUNX2) was analyzed in 87 HGSC effusions. Thirty-nine surgical specimens (19 ovarian, 20 from other intra-abdominal sites) were analyzed for comparative purposes. Protein expression of YAP and LRP and their phosphorylated forms by western blotting were analyzed in 52 tumors. Significant differences in mRNA expression as a function of the anatomic site were observed for WNT3 (p = 0.005), WNT5A (p = 0.008), WNT7 (p

This study was conducted to investigate the effect of Shenning II decoction on renal function, renal pathology, epithelial-to-mesenchymal transition (EMT), and Wnt/beta-catenin signaling in unilateral ureteral obstruction (UUO) renal fibrosis. Sprague-Dawley rats were randomly divided into blank control, sham-operated, UUO model (untreated), and UUO with Shenning decoction treatment (high, medium, and low dose) groups. Renal function was evaluated based on blood urea nitrogen (BUN) and serum creatinine (Scr) levels. Histopathological analysis of rat kidney tubular tissue was carried out and E-cadherin, fibronectin, vimentin, Wnt4, glycogen synthase kinase (GSK)β, low-density lipoprotein receptor-related protein (LRP)5, LRP6, β-catenin, Snail, and fibroblast-specific protein (FSP)1 expression was evaluated by immunohistochemistry, western blotting, and real-time PCR. BUN and Scr were found to be increased in UUO when compared with the sham rats (P 0.05). Shenning II decoction decreased histopathological scores relative to the UUO rats (P β-catenin, and fibronectin was decreased in Shenning I-treated rats, when compared with the untreated UUO rats, as determined by immunohistochemistry and western blotting (P β-catenin, GSK-3β, LRP5, LRP6, Snail, and FSP1 mRNA levels were also downregulated by Shenning II decoction treatment (P < 0.05). Shenning II decoction, therefore, protects against renal fibrosis by blocking renal tubular EMT via suppression of Wnt/beta-catenin signaling.

Purpose: The signals responsible for homeostasis in the periodontal complex are unclear. The purpose of this study was to evaluate the role of Low-density lipoprotein receptor-related protein 5(LRP5) in this process by removing LRP5, and observing the effects of LRP5 depletion on cells of the periodontal structures. Material and Methods: The function of this LRP5 was evaluated by conditional elimination of the LRP5 gene using an Osteocalcin Cre driver. The OCN-Cre; mice were examined using micro-CT and histology, immunohistochemistry to evaluate the periodontal complex. Results: Elimination of LRP5 in the periodontal complex of OCN-Cre; mice results in a different expression of Fibromodulin in the periodontal ligament space. A decrease in osteoclastic activity was found in the periodontal ligament. Conclusion: Osteoclastic activities are decreased and expression of fibromodulin is decreased, which implies the involvement of LRP5 in homeostasis of the periodontal ligament.

Wnt signaling regulates immunomodulatory functions during infection and inflammation. Employing NCCIT and HCT116 cells, having high endogenous Wnt signaling, we observed elevated levels of low-density lipoprotein receptor–related protein 5/6 (LRP5/6) and Frizzled class receptor 10 (FZD10) and increases in β-catenin, doublecortin-like kinase 1 (DCLK1), CD44 molecule (CD44), and aldehyde dehydrogenase 1 family member A1 (ALDH1A1). siRNA-induced knockdown of these receptors antagonized TOPflash reporter activity and spheroid growth in vitro and elevated Wnt-inhibitory factor 1 (WIF1) activity. Elevated mRNA and protein levels of LRP5/6 and FZD10 paralleled expression of WNT2b and WNT4 in colonic crypts at days 6 and 12 post-infection with Citrobacter rodentium (CR) and tended to decline at days 20–34. The CR mutant escV or the tankyrase inhibitor XAV939 attenuated these responses. A three-dimensional organoid assay in colonic crypts isolated from CR-infected mice revealed elevated levels of LRP5/6 and FZD10 and β-catenin co-localization with enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2). Co-immunoprecipitation in the membrane fraction revealed that axin associates with LRP5/6 in CR-infected crypts, and this association was correlated with increased β-catenin. Colon tumors from either CR-infected ApcPMin/+ or azoxymethane/dextran sodium sulfate (AOM/DSS)-treated mice had high LRP5/6 or FZD10 levels, and chronic Notch blockade through the γ-secretase inhibitor dibenzazepine down-regulated LRP5/6 and FZD10 expression. In CR-responsive CT-26 cells, siRNA-induced LRP5/6 or FZD10 knockdown antagonized TOPflash reporter activity. Elevated miR-153-3p levels correlated with LRP5/6 and FZD10, and miR-153-3p sequestration via a plasmid-based miR inhibitor system attenuated Wnt signaling. We conclude that infection-induced signals from the plasma membrane epigenetically regulate Wnt signaling.

Background: Recurrent implantation failure (RIF) remains a critical and challenging problem in assisted reproductive technology mainly because of impaired decidualization. Endocytic and transcytotic activity in the endometrium are crucial for impaired decidualization. The most representative endocytic genes is the C-terminal Eps15 homology domain-containing 1 (EHD1). Whether the EHD1-mediated endocytic function is responsible for embryo implantation during decidualization remains to be determined. Methods: Endometrial tissues were collected from RIF patients (n=27) and fertile controls (n=27) between July 2017 and December 2018. Meanwhile, endometrial biopsies were performed on tissues from 10 women with infertility secondary to tubal factor in the late proliferative and mid-secretory phases of the menstrual cycle. Primary HESCs isolated from eutopic endometrial tissues were used to investigate the role of EHD1 in decidualization. Findings: RNA-seq analysis demonstrated that EHD1 expression was significantly higher in the mid-secretory endometrium of the RIF group than in that of the fertile control group. During the menstrual cycle, the expression of EHD1 increased in the mid-proliferative phase and decreased periodically in the mid-secretory phase and decidual phase. Furthermore, EHD1 overexpression impaired decidualization by suppressing the expression of prolactin (PRL) and insulin-like growth factor binding protein-1 (IGFBP-1) and the formation of the cytoskeleton. Mechanistically, Wingless-related MMTV integration site 4 (Wnt4) and its downregulated signaling showed significant changes following adenovirus-mediated overexpression of EHD1 in HESCs by RNA-seq analysis. The endocytosis pathway of the low-density-lipoprotein receptor-related proteins 5 and 6 (LRP5/6) co-receptor was decreased by EHD1 overexpression. Co-IP and confocal microscopy analysis showed that EHD1 bound to the Wnt4 protein, contributing to the decrease in Wnt4/β-catenin signaling during the decidualization of HESCs. Additionally, the Wnt4 agonist improved the impaired decidualization. Interpretation: Regulation of the EHD1-Wnt4 pathway may serve as a promising therapeutic strategy to improve endometrial receptivity in RIF women. Funding Statement: This work was supported by the National Key Research and Development Program of China (2018YFC1004401), the National Natural Science Foundation of China (81871165, 31872846, 81571402 and 31571189 ), a special grant for principal investigators from the Health Department of Jiangsu Province (ZDRCA2016070), and a special fund for the Jiangsu Province Social Development Project (NO.BE2018602). Declaration of Interests: All authors declare no conflicts of interest. Ethics Approval Statement: This study was carried out according to the Recommendations of Guidelines for Clinical Trials by the Ethics Committee of the Drum Tower Hospital. Informed consent was obtained from all participants before any study-related procedure was performed. This study was carried out according to the approval of Construction and Management of the Nanjing Multic-center Biobank Project (No. 2013-081-01).

Introduction & Objectives: Canonical Wnt signaling (Wnt/β-catenin signaling) maintains the bone homeostasis by promoting the osteoblastic activities. The inhibitory factor, Dickkopf (DKK)1, enhances the bone resorption, especially in malignancies. The low density lipoprotein related protein (LRP) 5 is a component of membranous co-receptor of Wnt/β-catenin signaling and is also involved in serum low density lipoprotein cholestrol (LDL-C) level regulation. The clear cell renal cell carcinoma bone metastasis (ccRCC-BM) is characterized by osteolytic bone resorption. Whether and how Wnt/β-catenin signaling plays roles in regulating the invasion, metastasis and osteolytic process of ccRCC to bone remain unclear. This study investigated the expression of DKK1, LRP5 proteins in primary and metastatic lesions of RCC-BM. The therapeutic potential of Wnt/β-catenin signaling target medication was also evaluated.Materials & Methods: ccRCC-BM patients with paired samples of primary and metastatic lesions were selected. ccRCC patients without any metastasis (ccRCC-only) were set as control. Slides of paraffin-embedded tissue underwent immunohistochemical staining with monoclonalanti-DKK1 antibody and polyclonal anti-LRP5 antibody. Semi-quantitatively scoring according to staining intensity was performed. The staining results in the renal tissue adjacent to RCC, the primary RCC lesions (with BM or without BM), and the RCC-BM lesions were recorded. The expression difference was analyzed by univariate analysis of variance (ANOVA).Results: The expression of DKK1 was significantly different amid renal tissue adjacent to RCC, primary RCC and RCC-BM tissues (p< 0.001). The expression of DKK1 in primary RCC was significantly lower than that in renal tissue adjacent to RCC (pConclusions: A "rebound" of DKK1 expression was found in bone metastasis lesions. Along with the decreasing LRP5 expression in primary lesions of RCC-BM patients, this suggests that the canonical Wnt signaling (Wnt/β-catenin signaling) is inhibited during the bone metastasis process in ccRCC. The overexpression of DKK1 and the down-regulation of LRP5 receptor are involved.

Chronic psychological stress is closely correlated with breast cancer growth and metastasis. Sini San (SNS) formula is a classical prescription for relieving depression-related symptoms in traditional Chinese medicine (TCM). Current researches have suggested that chronic psychological stress is closely correlated with cancer stem cells (CSCs) and endoplasmic reticulum (ER) stress. This study aimed to investigate the effects of chronic psychological stress on ER stress-mediated breast cancer stemness and the therapeutic implication of SNS. Chronic psychological stress promoted lung metastasis in 4T1 breast tumor-bearing mice and increased the stem cell-like populations and stemness-related gene expression. Meanwhile, GRP78, a marker of ER stress, was significantly increased in the breast tumors and lung metastases under chronic psychological stress. As a biochemical hallmark of chronic psychological stress, cortisol dramatically enhanced the stem cell-like populations and mammospheres formation by activating GRP78 transcriptionally. However, GRP78 inhibitors or shRNA attenuated the stemness enhancement mediated by cortisol. Similarly, SNS inhibited chronic psychological stress-induced lung metastasis and stemness of breast cancer cells, as well as reversed cortisol-induced stem cell-like populations and mammospheres formation by attenuating GRP78 expression. Co-localization and co-immunoprecipitation experiments showed that SNS interrupted the interaction between GRP78 and LRP5 on the cell surface, thus inhibiting the Wnt/β-catenin signaling of breast CSCs. Altogether, this study not only uncovers the biological influence and molecular mechanism of chronic psychological stress on breast CSCs but also highlights SNS as a promising strategy for relieving GRP78-induced breast cancer stemness via inhibiting GRP78 activation.

Nutritional microenvironment determines the specification of progenitor cells, and lipid availability was found to modulate osteogenesis in skeletal progenitors. Here, we investigated the implications of lipid scarcity in the osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) and the role of low-density lipoprotein receptor-related protein 5 (LRP5), a co-receptor transducing canonical Wnt/beta-catenin signals, in BMSC lipid uptake during osteogenesis. The osteogenic differentiation of murine BMSCs was suppressed by lipid scarcity and partially rescued by additional fatty acid treatment with oleate. The enhancement of osteogenesis by oleate was found to be dosage-dependent, along with the enhanced activation of beta-catenin and Wnt target genes. Conditional knockout (CKO) of Lrp5 gene in murine mesenchymal lineage using Lrp5fl/fl;Prrx1-cre mice led to decreased bone quality and altered fat distribution in vivo. After Lrp5 ablation using adenoviral Cre-recombinase, the accumulation of lipid droplets in BMSC cytoplasm was significantly reduced, and the osteogenesis of BMSCs was suppressed. Moreover, the impaired osteogenesis due to either lipid scarcity or Lrp5 ablation could be rescued by recombinant Wnt3a protein, indicating that the osteogenesis induced by Wnt/beta-catenin signaling was independent of LRP5-mediated lipid uptake. In conclusion, lipid scarcity suppresses BMSC osteogenic differentiation. LRP5 plays a role in the uptake of lipids in BMSCs and therefore mediates osteogenic specification.

Canonical Wnt signaling is involved in skeletal muscle cell biology. The exact way in which this pathway exerts its contribution to myogenesis or neuromuscular junctions (NMJ) is a matter of debate. Next to the common co-receptors of canonical Wnt signaling, Lrp5 and Lrp6, the receptor tyrosine kinase MuSK was reported to bind at NMJs WNT glycoproteins by its extracellular cysteine-rich domain. Previously, we reported canonical Wnt signaling being active in fast muscle fiber types. Here, we used conditional Lrp5 or Lrp6 knockout mice to investigate the role of these receptors in muscle cells. Conditional double knockout mice died around E13 likely due to ectopic expression of the Cre recombinase. Phenotypes of single conditional knockout mice point to a very divergent role for the two receptors. First, muscle fiber type distribution and size were changed. Second, canonical Wnt signaling reporter mice suggested less signaling activity in the absence of Lrps. Third, expression of several myogenic marker genes was changed. Fourth, NMJs were of fragmented phenotype. Fifth, recordings revealed impaired neuromuscular transmission. In sum, our data show fundamental differences in absence of each of the Lrp co-receptors and suggest a differentiated view of canonical Wnt signaling pathway involvement in adult skeletal muscle cells.

BackgroundThe healing environment within the posterolateral lumbar spine is one of the most clinically challenging bone healing environments in all of orthopaedics due to a lack of a contained space and the need to formde novobone in a non-bony environment. Our group has previously published data that suggests that sclerostin in expressed locally at high levels throughout the process of a spinal fusion mass maturing.MethodsWe computationally identified multiple FDA-approved drugs, as well as a novel drug, for their ability to disrupt the interaction between sclerostin and its receptor, LRP5/6. The drugs were tested in several in vitro biochemical assays using murine MC3T3 and MSCs, assessing their ability to (1) enhance canonical Wnt signaling, (2) promote the accumulation of the active (non-phosphorylated) form of β-catenin, and (3) enhance the intensity and signaling duration of BMP signaling. These drugs were then tested subcutaneously in rats as standalone osteoinductive agents on plain collagen sponges. Finally, the top drug candidates (called VA1 and C07) were tested in a rabbit posterolateral spine fusion model for their ability to achieve a successful fusion.ResultsWe show that by controlling GSK3b phosphorylation, these SMIs simultaneously enhance canonical Wnt signaling and potentiate canonical BMP signaling intensity and duration. We also demonstrate that the SMIs produce dose-dependent ectopic mineralizationin vivoin rats as well as significantly increase posterolateral spine fusion rates in rabbitsin vivo, both as standalone osteogenic drugs and in combination with autologous iliac crest bone graft.ConclusionsFew if any osteogenic small molecules have been described that possess the osteoinductive potency of BMP itself – that is, the ability to formde novoectopic bone as a standalone agent, particularly in stringentin vivoenvironments. Herein, we describe two such SMIs that have this unique ability and thus may have potential application as novel cost-effective biologic bone graft substitutes for achieving consistent spinal fusion or even or critical-sized fracture defects.FundingThis work was supported by a Veteran Affairs Career Development Award (IK2-BX003845).

Background: Familial exudative vitreoretinopathy (FEVR) is a complex form of blindness-causing retinal degeneration. This study investigated the potential disease-causing variant and molecular basis in two Chinese families with FEVR. Methods: All family members underwent detailed ophthalmological examinations, including best-corrected visual acuity, fundus examination, and fluorescein fundus angiography. Whole exome sequencing, bioinformatics analysis, and Sanger sequencing of available family members were used to confirm the disease-causing gene variant. Results: The proband F1-II:1, his mother, and proband F2-II:1 were diagnosed with FEVR based on clinical symptoms, fundus manifestation, and fundus fluorescein angiography. Whole exome sequencing showed that the proband F1-II:1 had a novel heterozygous variant in the TSPAN12 gene, c.236T>G p. (Met79Arg), which may disturb the transmembrane domain of the TSPAN12 protein. The variant was cosegregated with the phenotypes of FEVR in the family. The proband F2-II:1 carried novel compound heterozygous variants, c.1210G>A p. (Gly404Arg) and c.1612C>T p. (Arg538Trp), in the LRP5 gene, which may disturb the second β-propeller motif of the LRP5 protein. These three variants were classified as likely pathogenic variants. The variants were predicted to be damaging or deleterious using multiple lines of prediction algorithms; they were not frequently found in multiple population databases. The residues affected by these variants are highly conserved among different species. The three novel variants may be potential disease-causing variants in the two families. Conclusions: These results expand the spectrum of variants in TSPAN12 and LRP5 genes and enrich the understanding of the molecular etiology of FEVR.

© 2023 Pan-Arab Association of GastroenterologyBackground and study aims: Intestinal metaplasia (IM), and Helicobacter pylori (HP) infection can be shown as risk factors in the development of gastric cancer (GC). WNT signaling pathway plays a critical role in carcinogenesis. However, the literature studies are limited on the significance of this pathway for the transition from IM to GC. Patients and methods: We aimed to investigate the importance of the genes of WNT signaling pathways diagnostic and prognostic markers in the presence and absence of HP in conversion from IM to GC. 104 patients, (GC group n = 35, IM group n = 45, control group n = 25) were included in this case-control study. Expression of genes in WNT signalling were searched in study groups with qRT-PCR array and qRT-PCR method. Data were analysed using PCR array data analysis software. Results: Statistically significant overexpression of RHOA, CSNK1A1, DVL2, FZD8 and LRP5 genes was detected in the GC and IM groups compared to the control group (p < 0.05). Statistically significant overexpression of RHOA, CSNK1A1, DVL2, FZD8 and LRP5 genes was observed in patients with metastatic GC compared to patients with GC without metastasis (p < 0.05). It was found that the RHOA, CSNK1A1, DVL2, FZD8 and LRP5 genes were statistically significantly over-expressed in diffuse GC patients compared to non-diffuse GC patients (p < 0.05). Statistically significant overexpression of RHOA, CSNK1A1, DVL2, FZD8 and LRP5 genes was detected in HP positive IM patients compared to HP negative IM patients (p < 0.05). Conclusion: Overexpression of RHOA, CSNK1A1, DVL2, FZD8 and LRP5 genes in IM may suggest that these genes are important markers in the development of IM and inflammation with HP. In addition, these genes are linked to tumor burden in the GC group. Consequently, we can conclude that these genes are poor prognosis biomarkers for GC and have the potential to be used as markers for future treatment monitoring.

Intervertebral disc (IVD) degeneration is a leading cause of low back pain and characterized by accelerated extracellular matrix breakdown and IVD height loss but there is no approved pharmacological therapeutic. Deletion of Wnt signaling receptor Lrp5 induces IVD degeneration and suggests that Wnt signaling in the IVD may be responsive to inhibition of Wnt signaling inhibitors sost(gene)/sclerostin(protein) or dickkopf-1 (dkk1). Anti-sclerostin antibody (Scl-Ab) is an FDA-approved bone therapeutic that activates Wnt signaling. We (1) determined if pharmacological neutralization of sclerostin, dkk1 or their combination stimulate Wnt signaling and promote IVD structure and (2) determined the extent of the response of the IVD to global, persistent deletion of sost. Nine-week-old C57Bl/6J female mice (n=6-7/grp) were subcutaneously injected 2x/wk for 5.5 wk with scl-Ab (25 mg/kg), dkk1-Ab (25 mg/kg), 3:1 scl-Ab/dkk1-Ab (18.75:6.25 mg/kg) or vehicle (Veh). Separately, IVD of sost KO and WT (wildtype) mice (n=8, grp) were harvested at 16 weeks of age. First, compared to vehicle, scl-Ab, dkk1-Ab and 3:1 scl-Ab/dkk1-Ab similarly increased lumbar IVD height and β-catenin gene expression. Despite these similarities, scl-Ab decreased cellular stress-related heat shock protein gene expressions while neither dkk1-Ab nor scl-Ab/dkk1-Ab altered the same. Genetically and compared to WT, sost KO increased MRI-determined hydration and proteoglycan staining in the IVD. Notably, persistent deletion of sost was compensated by upregulation of dkk1, which consequently reduced the cell nuclear fraction for Wnt signaling transcription factor β-catenin in whole IVD. Lastly, RNA-sequencing pathway analysis confirmed the compensatory suppression of Wnt signaling and determined a reduction of cellular stress pathways. Together, suppression of sost/sclerostin or dkk1 each promote IVD structure by stimulating Wnt signaling, but sclerostin and dkk1 may differentially regulate cellular stress pathways. Ultimately, postmenopausal women prescribed scl-Ab injections to prevent vertebral fracture may also benefit from a restoration of IVD height and health.Graphical abstractSuppression of Wnt signaling inhibitors by genetic or pharmacological approaches promotes intervertebral disc structure and hydration by Wnt signaling. However, persistent activation of Wnt signaling induces a compensatory reduction of Wnt signaling that shifts IVD cells toward a chondrocyte-like (CLC) phenotype. AF: annulus fibrosus, NC: notochordal cell, NP: nucleus pulposus, PG: proteoglycan

Job syndrome is a rare genetic disorder caused by STAT3 mutations and primarily characterized by immune dysfunction along with comorbid skeleton developmental abnormalities including osteopenia, recurrent fracture of long bones, and scoliosis. So far, there is no definitive cure for the skeletal defects in Job syndrome, and treatments are limited to management of clinical symptoms only. Here, we have investigated the molecular mechanism whereby Stat3 regulates skeletal development and osteoblast differentiation. We showed that removing Stat3 function in the developing limb mesenchyme or osteoprogenitor cells in mice resulted in shortened and bow limbs with multiple fractures in long bones that resembled the skeleton symptoms in the Job Syndrome. However, Stat3 loss did not alter chondrocyte differentiation and hypertrophy in embryonic development, while osteoblast differentiation was severely reduced. Genome-wide transcriptome analyses as well as biochemical and histological studies showed that Stat3 loss resulted in down-regulation of Wnt/β-catenin signaling. Restoration of Wnt/β-catenin signaling by injecting BIO, a small molecule inhibitor of GSK3, or crossing with a Lrp5 gain of function (GOF) allele, rescued the bone reduction phenotypes due to Stat3 loss to a great extent. These studies uncover the essential functions of Stat3 in maintaining Wnt/β-catenin signaling in early mesenchymal or osteoprogenitor cells and provide evidence that bone defects in the Job Syndrome are likely caused by Wnt/β-catenin signaling reduction due to reduced STAT3 activities in bone development. Enhancing Wnt/β-catenin signaling could be a therapeutic approach to reduce bone symptoms of Job syndrome patients.

Genetic factors play a critical role in the pathogenesis of osteoporosis. The imbalance of WNT/β-catenin will cause the occurrence of osteoporosis. LRP5 and AXIN1 play an important role in the classical Wnt/β-catenin signaling pathway. Our study was aimed to determine the association between five candidate single nucleotide polymorphisms (SNPs) of LRP5 or AXIN1 and osteoporosis susceptibility in Chinese Han population. A total of 599 osteoporosis patients and 599 healthy individuals were recruited for this case-control study. Agena MassARRAY was used to genotype SNPs. The association between SNPs and osteoporosis susceptibility in different genetic models was analyzed by PLINK software. We used false-positive report probability (FPRP) analysis to detect whether the positive results were just chance or noteworthy observations. Multifactor dimension reduction (MDR) was used to analyze the interaction of SNP–SNP in the osteoporosis risk. Finally, haplotype analysis was performed by plink1.07 and Haploview software. We found that LRP5 rs11228240, AXIN1 rs2301522, and rs9921222 were significantly associated with the osteoporosis susceptibility. The results of subgroup analysis showed that LRP5 rs11228240 (protective factor) and AXIN1 rs2301522 (risk factor) were associated with the susceptibility of osteoporosis among participants who were age >60 years, female or BMI ≤ 24; AXIN1 rs9921222 significantly increased the risk of osteoporosis among participants with BMI ≤ 24. The genotype Ars2301522Crs9921222 could increase the susceptibility of osteoporosis (p = 0.026). The rs11228219LPR5, rs11228240 LPR5, rs2301522AXIN1, and rs9921222AXIN1 four-site model was the best model for predicting the osteoporosis risk (test accuracy = 0.541; CVC = 10/10). The LRP5-rs11228240, AXIN1-rs2301522, and AXIN1- rs9921222 were associated with osteoporosis susceptibility in Chinese Han population.

Wnt signaling plays crucial roles in development and tissue homeostasis, and its dysregulation leads to various diseases, notably cancer. Wnt/β-catenin signaling is initiated when the glycoprotein Wnt binds to and forms a ternary complex with the Frizzled and low-density lipoprotein receptor-related protein 5/6 (LRP5/6). Despite being identified as a Wnt co-receptor over 20 years ago, the molecular mechanisms governing how LRP6 senses Wnt and transduces downstream signaling cascades are still being deciphered. Due to its role as one of the main Wnt signaling components, the dysregulation or mutation of LRP6 is implicated in several diseases such as cancer, neurodegeneration, metabolic syndrome and skeletal disease. Herein, we will review how LRP6 is activated by Wnt stimulation and explore the various regulatory mechanisms involved. The participation of LRP6 in other signaling pathways will also be discussed. Finally, the relationship between LRP6 dysregulation and disease will be examined in detail.

Intestinal epithelial self-renewal is tightly regulated by signaling pathways controlling stem cell proliferation, determination and differentiation. In particular, Wnt/β-catenin signaling controls crypt cell division and survival and is required for maintenance of the intestinal stem cell niche. Most colorectal cancers are also initiated by mutations activating the Wnt/β-catenin pathway. Wnt signals are transduced through Frizzled receptors and LRP5/LRP6 coreceptors to downregulate GSK3β activity, resulting in increased nuclear β-catenin. Herein, we explored if LRP6 expression is required for maintenance of intestinal homeostasis, regeneration and oncogenesis. Mice with an intestinal epithelial cell-specific deletion of Lrp6 (Lrp6IEC-KO) were generated and their phenotype analyzed. No difference in intestinal architecture or in proliferative and stem cell numbers was found in Lrp6IEC-KO mice in comparison to controls. Nevertheless, using ex vivo intestinal organoid cultures, we found that LRP6 expression was critical for crypt cell proliferation and stem cell maintenance. When exposed to dextran sodium sulfate, Lrp6IEC-KO mice developed more severe colitis than control mice. However, loss of LRP6 did not affect tumorigenesis in Apc Min/+ mice nor growth of human colorectal cancer cells. By contrast, Lrp6 silencing diminished anchorage-independent growth of BRafV600E-transformed IEC. Thus, LRP6 controls intestinal stem cell functionality and is necessary for BRAF-induced IEC oncogenesis.

Objective: To investigate the variations in the expressions of LRP5, Runx2, Osterix, and RANKL factors in bone tissues associated with postmenopausal osteoporotic fractures (PMOPF). Method: Postmenopausal patients with femur fractures were initially divided into control (31 cases) and PMOPF groups (83 cases). All control group patients were operated within 1 day after injury. The patients with PMOPF were operated based on the time after fracture in the respective groups (patients were divided into groups A, B, and C based on the time after fracture). Samples were collected from femurs at fracture sites during the operation. The expression level of each factor in bone tissues was detected using RT-qPCR, and the bone mass samples were decalcified and then histologically analyzed by immunohistochemistry. We subsequently analyzed significant differences in the expressions of factors (LRP5, Runx2, Osterix, and RANKL) between PMOPF and control groups. Results: (1) LRP5, β-catenin, Runx2, and Osterix were under-expressed in patients with PMOPF relative to the controls (P(2) the expressions of LRP5 and Runx2 were lowest in Group A patients (1–3 days after fracture). Osterix expression was lowest in Group C patients (8–14 days after fracture). Conversely, RANKL expression was highest in Group B patients (4–7 days after fracture). Conclusion: The inhibition or reduction in the expressions of osteogenic factors including LRP5, Runx2, and Osterix of the Wnt/β-catenin and BMP-2/Runx2/Osterix signaling pathways are associated with PMOPF incidence. Specifically, upregulation of RANKL in the RANKL/RANK signaling pathway is associated with the incidence of PMOPF. LRP5 and Runx2 expressions decreased considerably within 1-3 days after fracture; Osterix expression decreased considerably within 8-14 days after fracture; RANKL expression was highest within 4-7 days after fracture, which could be associated with bone repair in PMOPF. The expression level of the aforementioned factors affects the development and progression of PMOPF.

The E3 ubiquitin ligases RING finger protein 43 (RNF43) and zinc and RING finger 3 (ZNRF3) have received great attention for their critical role in regulating WNT signalling during adult stem cell homeostasis. By promoting the turnover of WNT receptors, Frizzled and LRP5/6, RNF43 and ZNRF3 ensure that proper levels of WNT activity are maintained in stem cells. The molecular mechanism of RNF43/ZNRF3 activity is beginning to emerge from several recent studies, yet little is known about the regulation of RNF43/ZNRF3 at the post-translational level. A study in this issue of EMBO Reports identifies the deubiquitinating enzyme USP42 as a key regulator of WNT signalling, which acts by antagonizing the ubiquitin-dependent clearance of RNF43/ZNRF3 induced by R-spondins (Giebel et al, 2021).

Background Early‐onset osteoporosis (EOOP) is defined by low bone mineral density (BMD), which increases the risk of fracture. Although the prevalence of osteoporosis at a young age is unknown, low BMD is highly linked to genetic background. Heterozygous pathogenic variants in low‐density lipoprotein receptor‐related protein 5 (LRP5) are associated with EOOP. This study aimed to investigate the genetic profile in patients with EOOP to better understand the variation in phenotype severity by using a targeted gene sequencing panel associated with bone fragility. Method and Results We used a sequencing panel with 17 genes reported to be related to bone fragility for analysis of 68 patients with EOOP. We found a high positivity rate of EOOP with LRP5 variants (14 patients, 20.6%). The remaining 79.4% of patients with EOOP but without LRP5 variants showed variable disease severity, as observed in patients with at least one variant in this gene. One patient, with multiple fractures and spine L1‐L4 BMD Z‐score −2.9, carried a novel pathogenic homozygous variant, c.2918T>C, p.(Leu973Pro), without any pseudoglioma. In addition to carrying the LRP5 variant, 2 other patients carried a heterozygous variant in Wnt signaling pathway genes: dickkopf WNT signaling pathway inhibitor 1 (DKK1) [NM_012242.4: c.359G>T, p.(Arg120Leu)] and Wnt family member 3A (WNT3A) [NM_033131.3: c.377G>A, p. (Arg126His)]. As compared with single‐variant LRP5 carriers, double‐variant carriers had a significantly lower BMD Z‐score (−4.1 ± 0.8) and higher mean number of fractures (6.0 ± 2.8 vs. 2.2 ± 1.9). Analysis of the family segregation suggests the inheritance of BMD trait. Conclusion Severe forms of EOOP may occur with carriage of 2 pathogenic variants in genes encoding regulators of the Wnt signaling pathway. Two‐variant carriers of Wnt pathway genes had severe EOOP. Moreover, DKK1 and WNT3A genes should be included in next‐generation sequence analyses of bone fragility., Gene association may occur in the same signaling pathway and can generate a severe bone phenotype in early‐onset osteoporosis. Recessive form associated with lipoprotein receptor‐related protein 5 could be responsible for a stronger phenotype. Interestingly this recessive form is not associated with ocular problems as observed in pseudoglioma osteoporosis or vitreoretinopathy. Assessment of genetics based on an next generation sequencing panel should include WNT3A and DKK1.

Ehrlichia chaffeensis expresses the TRP120 multifunctional effector, which is known to play a role in phagocytic entry, on the surface of infectious dense-cored ehrlichiae, but a cognate host receptor has not been identified. We recently reported that E. chaffeensis activates canonical Wnt signaling in monocytes to promote bacterial uptake and intracellular survival and that TRP120 was involved in this activation event. To identify the specific mechanism of pathway activation, we hypothesized that TRP120 is a Wnt signaling ligand mimetic that initiates Wnt pathway activity through direct interaction with the Wnt pathway Frizzled family of receptors. In this study, we used confocal immunofluorescence microscopy to demonstrate very strong colocalization between E. chaffeensis and Fzd2, 4, 5, 7, and 9 as well as coreceptor LRP5 at 1 to 3 h postinfection. Direct binding between TRP120 and multiple Fzd receptors was further confirmed by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR). Interfering RNA knockdown of Wnt receptors, coreceptors, and signaling pathway components significantly reduced E. chaffeensis infection, demonstrating that complex and redundant interactions are involved in Wnt pathway exploitation. We utilized in silico approaches to identify a repetitive short linear motif (SLiM) in TRP120 that is homologous to Wnt ligands and used mutant SLiM peptides and an α-TRP120-Wnt-SLiM antibody to demonstrate that the TRP120 Wnt SLiM activates the canonical Wnt pathway and promotes E. chaffeensis infection. This study reports the first example of bacterial mimicry of Wnt pathway ligands and highlights a pathogenic mechanism with potential for targeting by antimicrobial therapeutics. IMPORTANCE Upon infecting mammalian hosts, Ehrlichia chaffeensis establishes a replicative niche in microbe-eating immune system cells where it expertly orchestrates infection and spread. One of the ways Ehrlichia survives within these phagocytes is by activating evolutionarily conserved signaling pathways including the Wnt pathway; however, the molecular details of pathway hijacking have not been defined. This study is significant because it identifies an ehrlichial protein that directly interacts with components of the Wnt receptor complex, influencing pathway activity and promoting infection. Consequentially, Ehrlichia serves as a unique tool to investigate the intricacies of how pathogens repurpose human immune cell signaling and provides an opportunity to better understand many cellular processes in health and disease. Furthermore, understanding how this bacterium utilizes its small genome to survive within cells that evolved to destroy pathogens will facilitate the development of antibacterial therapeutics that could target Ehrlichia as well as other intracellular agents of human disease.

Genomewide association studies (GWAS) have improved our understanding of the genetic architecture of common complex diseases such as osteoporosis. Nevertheless, to attribute functional skeletal contributions of candidate genes to osteoporosis-related traits, there is a need for efficient and cost-effective in vivo functional testing. This can be achieved through CRISPR-based reverse genetic screens, where phenotyping is traditionally performed in stable germline knockout (KO) mutants. Recently it was shown that first-generation (F0) mosaic mutant zebrafish (so-called crispants) recapitulate the phenotype of germline KOs. To demonstrate feasibility of functional validation of osteoporosis candidate genes through crispant screening, we compared a crispant to a stable KO zebrafish model for the lrp5 gene. In humans, recessive loss-of-function mutations in LRP5, a co-receptor in the Wnt signaling pathway, cause osteoporosis-pseudoglioma syndrome. In addition, several GWAS studies identified LRP5 as a major risk locus for osteoporosis-related phenotypes. In this study, we showed that early stage lrp5 KO larvae display decreased notochord mineralization and malformations of the head cartilage. Quantitative micro-computed tomography (micro-CT) scanning and mass-spectrometry element analysis of the adult skeleton revealed decreased vertebral bone volume and bone mineralization, hallmark features of osteoporosis. Furthermore, regenerating fin tissue displayed reduced Wnt signaling activity in lrp5 KO adults. We next compared lrp5 mutants with crispants. Next-generation sequencing analysis of adult crispant tissue revealed a mean out-of-frame mutation rate of 76%, resulting in strongly reduced levels of Lrp5 protein. These crispants generally showed a milder but nonetheless highly comparable skeletal phenotype and a similarly reduced Wnt pathway response compared with lrp5 KO mutants. In conclusion, we show through faithful modeling of LRP5-related primary osteoporosis that crispant screening in zebrafish is a promising approach for rapid functional screening of osteoporosis candidate genes. (C) 2021 American Society for Bone and Mineral Research. (C) 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Mendelian bone fragility disorders are caused by genetic variants that can be inherited in an autosomal dominant, autosomal recessive or X-linked manner and have a large detrimental effect on bone strength. As a rule, the more damaging the genetic defect is, the earlier the first fracture will occur, typically during bone development. This review focusses on conditions where bone fragility is the most conspicuous characteristic, of which osteogenesis imperfecta (OI) is the best-known disorder. The large majority of individuals with an OI phenotype have disease-causing dominant variants in COL1A1 or COL1A2, the genes coding for collagen type I. Interestingly, large sequencing databases indicate that there are about 10 times more carriers of COL1A1/COL1A2 variants that should lead to OI than there are individuals with a diagnosis of OI. It is possible that at least some of these variants lead to incomplete OI phenotypes and are diagnosed as osteoporosis during adulthood. Apart from mutations affecting collagen type I production, biallelic mutations in LRP5 and WNT1 can cause very rare and severe bone fragility disorders. Heterozygous pathogenic variants in these genes are much more common and can cause the clinical picture of primary osteoporosis. As sequencing studies are more widely performed in adults with bone fragility disorders, evidence is emerging that what appears as primary osteoporosis in fact can be due to mutations in bona fide OI genes. The distinction between OI and primary osteoporosis is therefore likely to blur in future.

Recently, the emerging role of microRNAs (miRNAs) has been identified in osteogenesis and the development of osteoporosis. Here, we found that miR-545-3p was decreased with the progression of osteogenic differentiation of MC3T3-E1 cells. Gain-of-function assay elucidated that ectopic expression of miR-545-3p led to abolishment on the levels of osteogenic differentiation markers including OC, ALP and Runx2, as well as increase on the expression of SOST, a negative regulator of osteogenic differentiation. Meanwhile, we explained that the inhibitory role of miR-545-3p in the proliferation of differentiated MC3T3-E1 cells was attributed to its induction on apoptosis. Furthermore, the mechanistic investigations validated that miR-545-3p inactivated Wnt/β-catenin signaling pathway by post-transcriptionally silencing LRP5. Importantly, we verified that miR-545-3p-confined osteogenic differentiation was mediated by the inhibition of LRP5-dependent Wnt/β-catenin pathway. Furthermore, it was identified that miR-545-3p downregulation in osteogenic differentiation was due to the positive transcriptional regulation by SP1, an osteoporosis-promoting transcription factor that was proved to be lessened along with osteoblastic differentiation. Jointly, this study elaborated that the SP1-modulated miR-545-3p functions as an osteogenesis-inhibitory factor through targeting LRP5 to inactivate Wnt/β-catenin signaling. Remarkably, strategies targeting miR-545-3p might be an innovative idea for the therapy of patients with osteoporosis.

Wnt ligands signal through canonical or non-canonical signaling pathways. Although both routes share common elements, such as the Fz2 receptor, they differ in the co-receptor and in many of the final responses; for instance, whereas canonical Wnts increase β-catenin stability, non-canonical ligands downregulate it. However, both types of ligands stimulate tumor cell invasion. We show here that both the canonical Wnt3a and the non-canonical Wnt5a stimulate Fz2 tyrosine phosphorylation, Fyn binding to Fz2, Fyn activation and Fyn-dependent Stat3 phosphorylation. Wnt3a and Wnt5a require Src for Fz2 tyrosine phosphorylation; Src binds to canonical and non-canonical co-receptors (LRP5/6 and Ror2, respectively) and is activated by Wnt3a and Wnt5a. This Fz2/Fyn/Stat3 branch is incompatible with the classical Fz2/Dvl2 pathway as shown by experiments of over-expression or depletion. Fyn is necessary for transcription of genes associated with invasiveness, such as Snail1, and for activation of cell invasion by both Wnt ligands. Our results extend the knowledge about canonical Wnt pathways, demonstrating additional roles for Fyn in this pathway and describing how this protein kinase is activated by both canonical and non-canonical Wnts.

Objective To explore genetic polymorphisms of the Wnt/β-catenin signalling pathway in primary SS (PSS). Methods We included 98 patients with PSS and 165 healthy volunteers. Genomic DNA was extracted from peripheral blood samples. Through an open-array platform of low density, we genotyped 25 polymorphisms from 14 genes (WISP1, DKK1, SOST, FRZB, LRP1, LRP4, LRP5, LRP6, GSKB, ADAMTS5, GDF5, FMN2, ADIPOQ and COL11A1) involved in the Wnt/β-catenin signalling pathway. We compared the allelic and genotypic frequencies with Fisher’s exact test and logistic regression analysis adjusted by age, gender and individual admixture, as well as bootstrap-resampling analysis. We assessed the gene–gene interaction by the multifactor dimensionality reduction method. Results We found a positive significant association with four polymorphisms: LRP5 rs606989, FRZB rs409238, GSK3B rs2037547 and ADIPOQ rs2241766. All of them conferred risk for PSS, being the highest among subjects carrying three to four risk alleles (P < 0.001). According to a multifactor dimensionality reduction analysis, the best models included the LRP5 (rs606989), FRZB (rs409238) and ADIPOQ (rs2241766) polymorphisms. Conclusion LRP5, FRZB and ADIPOQ genes related in the Wnt/β-catenin signalling pathway increased the risk of PSS. Further research is needed to establish their functional role in this clinical entity.

Bone adapts to the mechanical forces that it experiences. Orthodontic tooth movement harnesses the cell- and tissue-level properties of mechanotransduction to achieve alignment and reorganization of the dentition. However, the mechanisms of action that permit bone resorption and formation in response to loads placed on the teeth are incompletely elucidated, though several mechanisms have been identified. Wnt/Lrp5 signalling in osteocytes is a key pathway that modulates bone tissue's response to load. Numerous mouse models that harbour knock-in, knockout and transgenic/overexpression alleles targeting genes related to Wnt signalling point to the necessity of Wnt/Lrp5, and its localization to osteocytes, for proper mechanotransduction in bone. Alveolar bone is rich in osteocytes and is a highly mechanoresponsive tissue in which components of the canonical Wnt signalling cascade have been identified. As Wnt-based agents become clinically available in the next several years, the major challenge that lies ahead will be to gain a more complete understanding of Wnt biology in alveolar bone so that improved/expedited tooth movement becomes a possibility.

Background/aim: Genetic aspects play a role in insulin resistance in children. In this study, for the first time, the association of LRP5 (rs556442) polymorphism and insulin resistance in Iranian children and adolescents was investigated.Materials and methods: The study population comprises children and adolescents aged 9-18 years. Anthropometric and biochemical parameters were assessed. Insulin resistance/sensitivity was determined by the quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment-insulin resistance (HOMA-IR), insulin-to-glucose ratio, McAuley index, revised McAuley index, fasting insulin resistance index (FIRI), and Bennett's index. LRP5 (rs566442) single nucleotide polymorphism (SNP) was identified using restriction fragment length polymorphism (RFLP). Linear regression analysis was used to determine the association between the LRP5 polymorphism (rs556442) and insulin sensitivity indexes.Results: Significant differences were found between GG genotype vs. AG/AA genotypes for McAuley index (P = 0.049) and revised McAuley index (P = 0.044) when adjusted for interaction factors (age, sex, and puberty) in regression models. No significant association was found between LRP5 (rs566442) and other insulin resistance indexes. Also, LRP5 (rs566442) did not show a significant impact on biochemical parameters. Conclusion: This study showed that LRP5 polymorphism (rs556442) was associated with insulin resistance in Iranian children and adolescents.