RESUMEN

Sclerostin (SOST), a Wnt signaling pathway inhibitor, is involved in the pathogenesis of skeletal disorders. This study investigated the impact of the GKWWRPS motif on the PNAIG motif in Loop 2 of SOST, which is accountable for the interactions with the LRP6 protein that triggers the down-regulation of the Wnt signaling pathway. Single amino acid mutations on the GKWWRPS motif, hypothesized to have a probable stabilization effect towards the PNAIG motif, led to a significant reduction in the primary interactions between the SOST and LRP6 proteins. Protein-protein docking and molecular dynamic studies were conducted to investigate the role of the motif. The study found that a solitary mutation in the GKWWRPS motif significantly reduced the primary interactions between SOST and LRP6 proteins, except for probable cold-spot residues. The study's findings establish the GKWWRPS motif as a promising target for therapeutic interventions. Based on the obtained results, it can be inferred that alterations implemented within the GKWWRPS motif could lead to the destabilization of the PNAIG motif, which would directly modulate the interactions between the SOST and LRP6 proteins. The present investigation thus presents novel opportunities in the field of anti-sclerostin interventions.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales , Secuencias de Aminoácidos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Mutación Puntual , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/química , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Humanos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/química , Simulación de Dinámica Molecular , Simulación del Acoplamiento Molecular

RESUMEN

BACKGROUND: Recent studies suggested that genetic variants associated with monogenic bone disorders were involved in the pathogenesis of atypical femoral fractures (AFF). Here, we aim to identify rare genetic variants by whole exome sequencing in genes involved in monogenic rare skeletal diseases in 12 women with AFF and 4 controls without any fracture. RESULTS: Out of 33 genetic variants identified in women with AFF, eleven (33.3%) were found in genes belonging to the Wnt pathway (LRP5, LRP6, DAAM2, WNT1, and WNT3A). One of them was rated as pathogenic (p.Pro582His in DAAM2), while all others were rated as variants of uncertain significance according to ClinVar and ACMG criteria. CONCLUSIONS: Osteoporosis, rare bone diseases, and AFFs may share the same genes, thus making it even more difficult to identify unique risk factors.

Asunto(s)

Secuenciación del Exoma , Fracturas del Fémur , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Humanos , Femenino , Fracturas del Fémur/genética , Fracturas del Fémur/patología , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Persona de Mediana Edad , Anciano , Predisposición Genética a la Enfermedad , Proteína Wnt1/genética , Proteína Wnt3A/genética , Vía de Señalización Wnt/genética , Osteoporosis/genética , Osteoporosis/patología , Enfermedades Óseas/genética , Estudios de Casos y Controles

RESUMEN

Coxsackievirus A10 (CV-A10) infection, a prominent cause of childhood hand-foot-and-mouth disease (HFMD), frequently manifests with the intriguing phenomenon of onychomadesis, characterized by nail shedding. However, the underlying mechanism is elusive. Here, we found that CV-A10 infection in mice could suppress Wnt/ß-catenin signaling by restraining LDL receptor-related protein 6 (LRP6) phosphorylation and ß-catenin accumulation and lead to onychomadesis. Mechanistically, CV-A10 mimics Dickkopf-related protein 1 (DKK1) to interact with Kringle-containing transmembrane protein 1 (KRM1), the CV-A10 cellular receptor. We further found that Wnt agonist (GSK3ß inhibitor) CHIR99021 can restore nail stem cell differentiation and protect against nail shedding. These findings provide novel insights into the pathogenesis of CV-A10 and related viruses in onychomadesis and guide prognosis assessment and clinical treatment of the disease.

Asunto(s)

Péptidos y Proteínas de Señalización Intercelular , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Vía de Señalización Wnt , Animales , Vía de Señalización Wnt/efectos de los fármacos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Ratones , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Péptidos y Proteínas de Señalización Intercelular/genética , Humanos , beta Catenina/metabolismo , Enfermedades de la Uña/metabolismo , Enfermedades de la Uña/virología , Enfermedades de la Uña/patología , Uñas/metabolismo , Uñas/patología , Diferenciación Celular/efectos de los fármacos , Ratones Endogámicos C57BL , Enfermedad de Boca, Mano y Pie/virología , Enfermedad de Boca, Mano y Pie/metabolismo , Enfermedad de Boca, Mano y Pie/patología , Enfermedad de Boca, Mano y Pie/complicaciones , Fosforilación/efectos de los fármacos , Infecciones por Coxsackievirus/complicaciones , Infecciones por Coxsackievirus/metabolismo , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Piridinas/farmacología , Pirimidinas

RESUMEN

BACKGROUND AND PURPOSE: Insulin and exenatide are two hypoglycaemic agents that exhibit different osteogenic effects. This study compared the differences between exenatide and insulin in osseointegration in a rat model of Type 2 diabetes (T2D) and explored the mechanisms promoting osteogenesis in this model of T2D. EXPERIMENTAL APPROACH: In vivo, micro-CT was used to detect differences in the peri-implant bone microstructure in vivo. Histology, dual-fluorescent labelling, immunofluorescence and immunohistochemistry were used to detect differences in tissue, cell and protein expression around the implants. In vitro, RT-PCR and western blotting were used to measure the expression of osteogenesis- and Wnt signalling-related genes and proteins in bone marrow mesenchymal stromal cells (BMSCs) from rats with T2D (TBMSCs) after PBS, insulin and exenatide treatment. RT-PCR was used to detect the expression of Wnt bypass cascade reactions under Wnt inactivation. KEY RESULTS: Micro-CT and section staining showed exenatide extensively promoted peri-implant osseointegration. Both in vivo and in vitro experiments showed exenatide substantially increased the expression of osteogenesis-related and activated the LRP5/6/GSK-3ß/ß-catenin-related Wnt pathway. Furthermore, exenatide suppressed expression of Bmpr1a to inhibit lipogenesis and promoted expression of Btrc to suppress inflammation. CONCLUSION AND IMPLICATIONS: Compared to insulin, exenatide significantly improved osteogenesis in T2D rats and TBMSCs. In addition to its dependence on LRP5/6/GSK-3ß/ß-catenin signalling for osteogenic differentiation, exenatide-mediated osteomodulation also involves inhibition of inflammation and adipogenesis by BMPR1A and ß-TrCP, respectively.

Asunto(s)

Diabetes Mellitus Tipo 2 , Exenatida , Insulina , Osteogénesis , beta Catenina , Animales , Masculino , Ratas , beta Catenina/metabolismo , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Exenatida/farmacología , Exenatida/administración & dosificación , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Hipoglucemiantes/farmacología , Insulina/metabolismo , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Oseointegración/efectos de los fármacos , Osteogénesis/efectos de los fármacos , Ratas Sprague-Dawley

RESUMEN

Neurons on the left and right sides of the nervous system often show asymmetric properties, but how such differences arise is poorly understood. Genetic screening in zebrafish revealed that loss of function of the transmembrane protein Cachd1 resulted in right-sided habenula neurons adopting left-sided identity. Cachd1 is expressed in neuronal progenitors, functions downstream of asymmetric environmental signals, and influences timing of the normally asymmetric patterns of neurogenesis. Biochemical and structural analyses demonstrated that Cachd1 can bind simultaneously to Lrp6 and Frizzled family Wnt co-receptors. Consistent with this, lrp6 mutant zebrafish lose asymmetry in the habenulae, and epistasis experiments support a role for Cachd1 in modulating Wnt pathway activity in the brain. These studies identify Cachd1 as a conserved Wnt receptor-interacting protein that regulates lateralized neuronal identity in the zebrafish brain.

Asunto(s)

Canales de Calcio , Habénula , Neurogénesis , Neuronas , Vía de Señalización Wnt , Proteínas de Pez Cebra , Pez Cebra , Animales , Receptores Frizzled/metabolismo , Receptores Frizzled/genética , Habénula/metabolismo , Habénula/embriología , Mutación con Pérdida de Función , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/genética , Neuronas/metabolismo , Receptores Wnt/metabolismo , Receptores Wnt/genética , Pez Cebra/embriología , Pez Cebra/genética , Proteínas de Pez Cebra/metabolismo , Proteínas de Pez Cebra/genética , Canales de Calcio/genética , Canales de Calcio/metabolismo

RESUMEN

Wnt/ß-catenin signaling is critical for various cellular processes in multiple cell types, including osteoblast (OB) differentiation and function. Exactly how Wnt/ß-catenin signaling is regulated in OBs remain elusive. ATP6AP2, an accessory subunit of V-ATPase, plays important roles in multiple cell types/organs and multiple signaling pathways. However, little is known whether and how ATP6AP2 in OBs regulates Wnt/ß-catenin signaling and bone formation. Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions. Conditionally knocking out (CKO) ATP6AP2 in the OB-lineage cells (Atp6ap2Ocn-Cre) reduced trabecular, but not cortical, bone formation and bone mass. Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in ATP6AP2-KO BMSCs and OBs, but not osteocytes. Additional in vitro and in vivo studies revealed impaired ß-catenin signaling in ATP6AP2-KO BMSCs and OBs, but not osteocytes, under both basal and Wnt stimulated conditions, although LRP5 was decreased in ATP6AP2-KO osteocytes, but not BMSCs. Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression of ß-catenin phosphorylation, but necessary for LRP6/ß-catenin and N-cadherin/ß-catenin protein complex distribution at the cell membrane, thus preventing their degradation. Expression of active ß-catenin diminished the OB differentiation deficit in ATP6AP2-KO BMSCs. Taken together, these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability, and thus regulating ß-catenin levels, demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/ß-catenin signaling and trabecular bone formation.

Asunto(s)

Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Ratones Noqueados , Osteoblastos , Osteogénesis , ATPasas de Translocación de Protón Vacuolares , Vía de Señalización Wnt , beta Catenina , Animales , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Vía de Señalización Wnt/fisiología , beta Catenina/metabolismo , beta Catenina/genética , Osteoblastos/metabolismo , Osteogénesis/fisiología , Ratones , ATPasas de Translocación de Protón Vacuolares/metabolismo , ATPasas de Translocación de Protón Vacuolares/genética , Transporte de Proteínas , Diferenciación Celular , Osteocitos/metabolismo , Receptor de Prorenina

RESUMEN

Wnt/ß-catenin signaling plays a crucial role in the migration of mesenchymal stem cells (MSCs). However, our study has revealed an intriguing phenomenon where Dickkopf-1 (DKK1), an inhibitor of Wnt/ß-catenin signaling, promotes MSC migration at certain concentrations ranging from 25 to 100 ng/mL while inhibiting Wnt3a-induced MSC migration at a higher concentration (400 ng/mL). Interestingly, DKK1 consistently inhibited Wnt3a-induced phosphorylation of LRP6 at all concentrations. We further identified cytoskeleton-associated protein 4 (CKAP4), another DKK1 receptor, to be localized on the cell membrane of MSCs. Overexpressing the CRD2 deletion mutant of DKK1 (ΔCRD2), which selectively binds to CKAP4, promoted the accumulation of active ß-catenin (ABC), the phosphorylation of AKT (Ser473) and the migration of MSCs, suggesting that DKK1 may activate Wnt/ß-catenin signaling via the CKAP4/PI3K/AKT cascade. We also investigated the effect of the CKAP4 intracellular domain mutant (CKAP4-P/A) that failed to activate the PI3K/AKT pathway and found that CKAP4-P/A suppressed DKK1 (100 ng/mL)-induced AKT activation, ABC accumulation, and MSC migration. Moreover, CKAP4-P/A significantly weakened the inhibitory effects of DKK1 (400 ng/mL) on Wnt3a-induced MSC migration and Wnt/ß-catenin signaling. Based on these findings, we propose that DKK1 may activate the PI3K/AKT pathway via CKAP4 to balance the inhibitory effect on Wnt/ß-catenin signaling and thus regulate Wnt3a-induced migration of MSCs. Our study reveals a previously unrecognized role of DKK1 in regulating MSC migration, highlighting the importance of CKAP4 and PI3K/AKT pathways in this process.

Asunto(s)

Movimiento Celular , Péptidos y Proteínas de Señalización Intercelular , Células Madre Mesenquimatosas , Fosfatidilinositol 3-Quinasas , Proteínas Proto-Oncogénicas c-akt , Vía de Señalización Wnt , Proteína Wnt3A , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Células Madre Mesenquimatosas/metabolismo , Movimiento Celular/efectos de los fármacos , Proteína Wnt3A/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Vía de Señalización Wnt/efectos de los fármacos , Humanos , Animales , beta Catenina/metabolismo , Fosforilación/efectos de los fármacos , Ratones , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética

RESUMEN

The study investigated the potential association of the low-density lipoprotein (LDL) genome with endometrial cancer progression based on the Gene Expression Omnibus data set and The Cancer Genome Atlas data set. Differential and weighted gene coexpression network analysis was performed on endometrial cancer transcriptome datasets GSE9750 and GSE106191. The protein-protein interaction network was built using LDL-receptor proteins and the top 50 tumor-associated genes. Low-density lipoprotein-related receptors 5/6 (LRP5/6) in endometrial cancer tissues were correlated with oncogenes, cell cycle-related genes, and immunological checkpoints using Spearman correlation. MethPrimer predicted the LRP5/6 promoter CpG island. LRP2, LRP6, LRP8, LRP12, low-density lipoprotein receptor-related protein-associated protein, and LRP5 were major LDL-receptor-related genes associated with endometrial cancer. LRP5/6 was enriched in various cancer-related pathways and may be a key LDL-receptor-related gene in cancer progression. LRP5/6 may be involved in the proliferation process of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may be involved in the proliferation of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may promote the immune escape of cancer cells by promoting the expression of immune checkpoints, promoting endometrial cancer progression. The MethPrimer database predicted that the LRP5/6 promoter region contained many CpG islands, suggesting that DNA methylation can occur in the LRP5/6 promoter region. LRP5/6 may aggravate endometrial cancer by activating the phosphoinositide 3-kinase/protein kinase B pathway.

Asunto(s)

Neoplasias Endometriales , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad , Humanos , Femenino , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/genética , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Fosfatidilinositol 3-Quinasas , Receptores de LDL , Neoplasias Endometriales/genética , Lipoproteínas LDL

RESUMEN

Low-density lipoprotein receptor-related protein 6 (LRP6) is a co-receptor of the Wnt signaling pathway, which plays an essential role in various biological activities during embryonic and postnatal development. LRP6 is exceptionally associated with rare diseases and always with autosomal dominant inheritance. Here we report a familial phenotype of high bone mass associated with skeletal anomalies and oligodontia but also persistent left superior vena cava, inguinal hernia, hepatic cysts, abnormal posterior fossa and genital malformations. Molecular analysis revealed a novel heterozygous variant, NM_002336.2: c.724T>C, p.(Trp242Arg), in affected individuals. This variant is located in the first ß-propellant motif of LRP6, to which sclerostin (SOST) and dickkopf1 (DKK1), two LRP6 co-receptor inhibitors and various Wnt ligands bind. According to the literature and integrating data from structural analysis, this variant distorts the binding of SOST and DKK1, thus leading to overactivation of Wnt signaling pathways involved in osteoblast differentiation. This novel heterozygous variant in LRP6 underlies the role of LRP6 in skeletal and dental disorders as well as, probably, cardiac, cerebral and genital developments.

Asunto(s)

Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Humanos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Masculino , Femenino , Fenotipo , Mutación/genética , Vía de Señalización Wnt/genética , Linaje , Péptidos y Proteínas de Señalización Intercelular/genética , Proteínas Adaptadoras Transductoras de Señales/genética

RESUMEN

Low-density lipoprotein receptor-related protein 6 (LRP6) is a receptor protein for Wnt ligands. Yet, their role in immune cell regulation remains elusive. Here we demonstrated that genetic deletion of LRP6 in macrophages using LysM-cre Lrp6fl/fl (Lrp6MKO) mice showed differential inhibition of inflammation in the bleomycin (BLM)-induced lung injury model and B16F10 melanoma lung metastasis model. Lrp6MKO mice showed normal immune cell populations in the lung and circulating blood in homeostatic conditions. In the BLM-induced lung injury model, Lrp6MKO mice showed a decreased number of monocyte-derived alveolar macrophages, reduced collagen deposition and alpha-smooth muscle actin (αSMA) protein levels in the lung. In B16F10 lung metastasis model, Lrp6MKO mice reduced lung tumor foci. Monocytic and granulocytic-derived myeloid-derived suppressor cells (M-MDSCs and G-MDSCs) were increased in the lung. In G-MDSCs, hypoxia-inducible factor 1α (HIF1α)+ PDL1+ population was markedly decreased but not in M-MDSCs. Taken together, our results show that the role of LRP6 in macrophages is differential depending on the inflammation microenvironment in the lung.

Asunto(s)

Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Lesión Pulmonar , Neoplasias Pulmonares , Neumonía , Animales , Ratones , Bleomicina , Inflamación/genética , Inflamación/patología , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Pulmón/patología , Lesión Pulmonar/genética , Lesión Pulmonar/patología , Neoplasias Pulmonares/patología , Macrófagos/metabolismo , Neumonía/patología , Microambiente Tumoral

RESUMEN

Renal cell carcinoma is the most common and most lethal genitourinary tumor. The causes of renal clear cell carcinoma are complex and the heterogeneity of the tumor tissue is high, so patient outcomes are not very satisfactory. Exploring biomarkers in the progression of renal clear cell carcinoma is crucial to improve the diagnosis and guide the treatment of renal clear cell carcinoma. LRP6 is a co-receptor of the Wnt/ß-catenin signaling pathway, which is involved in cell growth, inflammation and cell transformation through activation of the Wnt/ß-catenin signaling pathway. Abnormal expression of LRP6 is associated with the malignant phenotype, metastatic potential and poor prognosis of various tumors. In this study, we found that LRP6 was abnormally highly expressed in a variety of tumors and significantly correlated with microsatellite instability, tumor mutation burden, and immune cell infiltration and immune checkpoint expression in a variety of tumors. Moreover, we found that LRP6 was significantly associated with the prognosis of renal clear cell carcinoma. Further we found a significant correlation between LRP6 and the expression of m6A-related genes and ferroptosis-related genes. Finally, we also found a significant correlation between the expression of LRP6 and the sensitivity to common drugs used in kidney clear cell carcinoma treatment. These results suggest that LRP6 is likely to be a potential target for kidney clear cell carcinoma treatment.

Asunto(s)

Carcinoma de Células Renales , Neoplasias Renales , Humanos , Carcinoma de Células Renales/genética , Vía de Señalización Wnt , Neoplasias Renales/genética , Pronóstico , Biomarcadores , Riñón/metabolismo , beta Catenina/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo

RESUMEN

The lipid synthesis of fatty acid (FA) represents a significant hallmark in the occurrence and progression of malignant tumor, which are associated with lymph node (LN) metastasis. Elucidation of the molecular mechanisms underlying LN metastasis could provide therapeutic strategies for cervical cancer (CCa). N6-Methyladenosine (m6A), the most prevalent and abundant RNA modification, exerts specific regulatory control over a series of oncogene expressions. This study demonstrated a clinical correlation between the upregulation of the m6A reader YTHDF3 and LN metastasis, thereby contributing to poor overall survival probability (OS) among CCa patients. The mechanistic investigation revealed that SREBF1 transcriptionally activated YTHDF3 expression by binding to its promoter. Functional experiments demonstrated that the upregulation of YTHDF3 significantly enhanced the in vitro proliferative, migratory, and invasive capacities of CCa cells, while also promoting lymphangiogenesis and facilitating LN metastasis in vivo. Mechanistically, the upregulation of LRP6 through YTHDF3-mediated m6A modification resulted in increased expression of FASN and ACC1, leading to both lipolysis of lipid droplets and synthesis of free fatty acid. Ultimately, this promoted fatty acid metabolism and enhanced LN metastasis by activating the LRP6-YAP-VEGF-C axis, which could induce lymphangiogenesis in CCa. Our study highlighted that YTHDF3 can serve as a promising therapeutic target and predictive biomarker for CCa patients with LN metastasis.

Asunto(s)

Metabolismo de los Lípidos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Proteínas de Unión al ARN , Neoplasias del Cuello Uterino , Femenino , Humanos , Ácidos Grasos , Lipogénesis , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Metástasis Linfática , Neoplasias del Cuello Uterino/genética , Proteínas de Unión al ARN/genética

RESUMEN

The relative abundance of Wnt receptors plays a crucial role in controlling Wnt signaling in tissue homeostasis and human disease. While the ubiquitin ligases that ubiquitylate Wnt receptors are well-characterized, the deubiquitylase that reverses these reactions remains unclear. Herein, we identify USP46, UAF1, and WDR20 (USP46 complex) as positive regulators of Wnt signaling in cultured human cells. We find that the USP46 complex is similarly required for Wnt signaling in Xenopus and zebrafish embryos. We demonstrate that Wnt signaling promotes the association between the USP46 complex and cell surface Wnt coreceptor, LRP6. Knockdown of USP46 decreases steady-state levels of LRP6 and increases the level of ubiquitylated LRP6. In contrast, overexpression of the USP46 complex blocks ubiquitylation of LRP6 by the ubiquitin ligases RNF43 and ZNFR3. Size exclusion chromatography studies suggest that the size of the USP46 cytoplasmic complex increases upon Wnt stimulation. Finally, we show that USP46 is essential for Wnt-dependent intestinal organoid viability, likely via its role in LRP6 receptor homeostasis. We propose a model in which the USP46 complex increases the steady-state level of cell surface LRP6 and facilitates the assembly of LRP6 into signalosomes via a pruning mechanism that removes sterically hindering ubiquitin chains.

Asunto(s)

Endopeptidasas , Vía de Señalización Wnt , beta Catenina , Animales , Humanos , beta Catenina/genética , beta Catenina/metabolismo , Ligasas/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Receptores Wnt , Ubiquitina , Pez Cebra/metabolismo , Endopeptidasas/metabolismo

RESUMEN

PURPOSE: This research aimed to explore the regulatory molecular mechanism among circular RNA (circ)_0011373, microRNA (miR)-1271, and lipoprotein receptor-related protein 6 (LRP6) in papillary thyroid carcinoma (PTC). METHODS: Quantitative real-time PCR (qRT-PCR) assay was adopted to measure the expression of circ_0011373, miR-1271, and LRP6 mRNA. Furthermore, cell cycle distribution, apoptosis, migration and invasion were investigated by flow cytometry and transwell assay, respectively. The target relationship between miR-1271 and circ_0011373 or LRP6 was predicted by using the Starbase website and DIANA TOOL and verified by dual-luciferase reporter and RIP assay. Protein expression levels of LRP6, p-mTOR, mTOR, p-AKT, AKT, p-PI3K, and PI3K were tested by Western blot. The function of circ_0011373 on PTC tumor growth was validated by the xenograft tumor model in vivo. RESULTS: Circ_0011373 and LRP6 were upregulated, while miR-1271 was downregulated in PTC tissues and cell lines. Moreover, knockdown of circ_0011373 inhibited cell cycle, migration, and invasion and promoted apoptosis. Of particular importance was the fact that circ_0011373 directly interacted with miR-1271 and miR-1271 inhibitor was able to reverse the effect of circ_0011373 knockdown on PTC cell progression. Meanwhile, LRP6 was directly targeted by miR-1271, and its expression was positively regulated by circ_0011373. We further confirmed that miR-1271 overexpression suppressed cell cycle, migration, and invasion and enhanced apoptosis by regulating LRP6. In addition, circ_0011373 knockdown restrained PTC tumor growth in vivo. CONCLUSION: Circ_0011373 might be able to regulate PTC cell cycle, migration, invasion, and apoptosis by regulating the miR-1271/LRP6 axis.

Asunto(s)

MicroARNs , Neoplasias de la Tiroides , Humanos , Cáncer Papilar Tiroideo/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteínas Proto-Oncogénicas c-akt , ARN Circular/genética , Neoplasias de la Tiroides/genética , Fosfatidilinositol 3-Quinasas , MicroARNs/genética , Proliferación Celular/genética , Línea Celular Tumoral

RESUMEN

Low-density lipoprotein receptor-related protein 6 (LRP6), a member of the low-density lipoprotein receptor (LDLR) family, displays a unique structure and ligand-binding function. As a co-receptor of the Wnt/ß-catenin signaling pathway, LRP6 is a novel therapeutic target that plays an important role in the regulation of cardiovascular disease, lipid metabolism, tumorigenesis, and some classical signals. By using capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX), with recombinant human LRP-6 as the target, four candidate aptamers with a stem-loop structure were selected from an ssDNA library-AptLRP6-A1, AptLRP6-A2, AptLRP6-A3, and AptLRP6-A4. The equilibrium dissociation constant KD values between these aptamers and the LRP6 protein were in the range of 0.105 to 1.279 µmol/L, as determined by CE-LIF analysis. Their affinities and specificities were further determined by the gold nanoparticle (AuNP) colorimetric method. Among them, AptLRP6-A3 showed the highest affinity with LRP6-overexpressed human breast cancer cells. Therefore, the LRP6 aptamer identified in this study constitutes a promising modality for the rapid diagnosis and treatment of LRP6-related diseases.

Asunto(s)

Aptámeros de Nucleótidos , Nanopartículas del Metal , Humanos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Lipoproteínas LDL , Oro , ADN de Cadena Simple , Aptámeros de Nucleótidos/química

RESUMEN

Low-density lipoprotein receptor-related protein-6 (LRP6) is overexpressed in various cancers. The small molecule salinomycin sodium inhibits LRP6. We observed a higher proportion of subjects with non-germinal center B (non-GCB) subtypes having high LRP6 expression than those with GCB subtypes by immunohistochemistry. The PCR and Western blot assays demonstrated increased LRP6 expression in non-GCB subtype cells. In addition, CCK-8 assays and transwell cell migration assays revealed that salinomycin sodium exhibited dose- and time-dependent inhibition of proliferation and migration in non-GCB subtype cells. Furthermore, Western blot assays showed that salinomycin sodium decreased the expression of Bcl2, while increasing the expression of Bax. Additionally, salinomycin sodium suppressed LRP6 expression, blocked LRP6 phosphorylation, and inhibited the Wnt/ß-catenin and mTORC1 signaling pathways. Our results suggest that LRP6 is highly expressed in non-GCB subtype. Furthermore, salinomycin sodium inhibited LRP6 expression and the Wnt/ß-catenin and mTORC1 signaling in non-GCB subtype cells, and displayed potent anticancer activity.

Asunto(s)

Linfoma de Células B , beta Catenina , Humanos , beta Catenina/genética , beta Catenina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina , Sodio , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética

RESUMEN

Mammalian preimplantation development depends on the interaction between embryonic autocrine and maternal paracrine signaling. Despite the robust independence of preimplantation embryos, oviductal factors are thought to be critical to pregnancy success. However, how oviductal factors regulate embryonic development and the underlying mechanism remain unknown. In the present study, focusing on WNT signaling, which has been reported to be essential for developmental reprogramming after fertilization, we analyzed the receptor-ligand repertoire of preimplantation embryonic WNT signaling, and identified that the WNT co-receptor LRP6 is necessary for early cleavage and has a prolonged effect on preimplantation development. LRP6 inhibition significantly impeded zygotic genome activation and disrupted relevant epigenetic reprogramming. Focusing on the potential oviductal WNT ligands, we found WNT2 as the candidate interacting with embryonic LRP6. More importantly, we found that WNT2 supplementation in culture medium significantly promoted zygotic genome activation (ZGA) and improved blastocyst formation and quality following in vitro fertilization (IVF). In addition, WNT2 supplementation significantly improved implantation rate and pregnancy outcomes following embryo transfer. Collectively, our findings not only provide novel insight into how maternal factors regulate preimplantation development through maternal-embryonic communication, but they also propose a promising strategy for improving current IVF systems.

Asunto(s)

Desarrollo Embrionario , Cigoto , Embarazo , Humanos , Animales , Femenino , Ligandos , Desarrollo Embrionario/genética , Implantación del Embrión , Oviductos , Mamíferos , Proteína wnt2/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética

RESUMEN

The membrane-tethered protease Tiki antagonizes Wnt3a signaling by cleaving and inactivating Wnt3a in Wnt-producing cells. Tiki also functions in Wnt-receiving cells to antagonize Wnt signaling by an unknown mechanism. Here, we demonstrate that Tiki inhibition of Wnt signaling at the cell surface requires Frizzled (FZD) receptors. Tiki associates with the Wnt-FZD complex and cleaves the N-terminus of Wnt3a or Wnt5a, preventing the Wnt-FZD complex from recruiting and activating the coreceptor LRP6 or ROR1/2 without affecting Wnt-FZD complex stability. Intriguingly, we demonstrate that the N-terminus of Wnt3a is required for Wnt3a binding to LRP6 and activating ß-catenin signaling, while the N-terminus of Wnt5a is dispensable for recruiting and phosphorylating ROR1/2. Both Tiki enzymatic activity and its association with the Wnt-FZD complex contribute to its inhibitory function on Wnt5a. Our study uncovers the mechanism by which Tiki antagonizes Wnt signaling at the cell surface and reveals a negative role of FZDs in Wnt signaling by acting as Tiki cofactors. Our findings also reveal an unexpected role of the Wnt3a N-terminus in the engagement of the coreceptor LRP6.

Asunto(s)

Receptores Frizzled , Vía de Señalización Wnt , Receptores Frizzled/metabolismo , Proteína Wnt3A/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Membrana Celular/metabolismo , beta Catenina/metabolismo

RESUMEN

OBJECTIVE: Intrauterine growth restriction followed by postnatal catch-up growth (CG-IUGR) increases the risk of insulin resistance-related diseases. Low-density lipoprotein receptor-related protein 6 (LRP6) plays a substantial role in glucose metabolism. However, whether LRP6 is involved in the insulin resistance of CG-IUGR is unclear. This study aimed to explore the role of LRP6 in insulin signaling in response to CG-IUGR. METHODS: The CG-IUGR rat model was established via a maternal gestational nutritional restriction followed by postnatal litter size reduction. The mRNA and protein expression of the components in the insulin pathway, LRP6/ß-catenin and mammalian target of rapamycin (mTOR)/S6 kinase (S6K) signaling, was determined. Liver tissues were immunostained for the expression of LRP6 and ß-catenin. LRP6 was overexpressed or silenced in primary hepatocytes to explore its role in insulin signaling. RESULTS: Compared with the control rats, CG-IUGR rats showed higher homeostasis model assessment for insulin resistance (HOMA-IR) index and fasting insulin level, decreased insulin signaling, reduced mTOR/S6K/ insulin receptor substrate-1 (IRS-1) serine307 activity, and decreased LRP6/ß-catenin in the liver tissue. The knockdown of LRP6 in hepatocytes from appropriate-for-gestational-age (AGA) rats led to reductions in insulin receptor (IR) signaling and mTOR/S6K/IRS-1 serine307 activity. In contrast, LRP6 overexpression in hepatocytes of CG-IUGR rats resulted in elevated IR signaling and mTOR/S6K/IRS-1 serine307 activity. CONCLUSION: LRP6 regulated the insulin signaling in the CG-IUGR rats via two distinct pathways, IR and mTOR-S6K signaling. LRP6 may be a potential therapeutic target for insulin resistance in CG-IUGR individuals.

Asunto(s)

Retardo del Crecimiento Fetal , Resistencia a la Insulina , Insulina , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Proteínas Quinasas S6 Ribosómicas , Animales , Femenino , Humanos , Ratas , beta Catenina/genética , Retardo del Crecimiento Fetal/genética , Retardo del Crecimiento Fetal/metabolismo , Insulina/metabolismo , Resistencia a la Insulina/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Receptor de Insulina/genética , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo

RESUMEN

Synapse loss strongly correlates with cognitive decline in Alzheimer's disease (AD), but the underlying mechanisms are poorly understood. Deficient Wnt signaling contributes to synapse dysfunction and loss in AD. Consistently, a variant of the LRP6 receptor, (LRP6-Val), with reduced Wnt signaling, is linked to late-onset AD. However, the impact of LRP6-Val on the healthy and AD brain has not been examined. Knock-in mice, generated by gene editing, carrying this Lrp6 variant develop normally. However, neurons from Lrp6-val mice do not respond to Wnt7a, a ligand that promotes synaptic assembly through the Frizzled-5 receptor. Wnt7a stimulates the formation of the low-density lipoprotein receptor-related protein 6 (LRP6)-Frizzled-5 complex but not if LRP6-Val is present. Lrp6-val mice exhibit structural and functional synaptic defects that become pronounced with age. Lrp6-val mice present exacerbated synapse loss around plaques when crossed to the NL-G-F AD model. Our findings uncover a previously unidentified role for Lrp6-val in synapse vulnerability during aging and AD.

Asunto(s)

Enfermedad de Alzheimer , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad , Ratones , Animales , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/metabolismo , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Vía de Señalización Wnt , Sinapsis/metabolismo , Envejecimiento/genética