scholarly journals Canonical Wnt Signaling Inhibition in Renal Cell Carcinoma Bone Metastasis: Immunohistochemical Study of DKK1 and LRP5 Expression

2021 ◽  
Author(s):  
Zixiong Huang ◽  
Yiqing Du ◽  
Huaqi Yin ◽  
Gongwei Wang ◽  
Tao Xu
Keyword(s):  
Bone Metastasis ◽  
Wnt Signaling ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Renal Tissue ◽  
Primary Lesion ◽  
Canonical Wnt Signaling ◽  
Metastatic Lesions ◽  
Dkk1 Expression ◽  
Canonical Wnt

Abstract 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 (p<0.001). No difference was found between ccRCC-BM group and ccRCC-only group. DKK1 expression in bone metastasis was significantly higher than that in primary tumor (p < 0.001). The expression of LRP5 in the primary tumor of ccRCC-BM group was significantly lower than that of adjacent renal tissue (p<0.01). Tendency of decreasing expression was found between primary lesion of ccRCC-BM group and primary lesion of ccRCC-only group (p=0.073). In bone metastasis, the expression of LRP5 protein was not significantly different from that in adjacent renal tissue and RCC primary lesion.Conclusions: 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.

scholarly journals Exploring the mechanistic and temporal regulation of LRP6 endocytosis in canonical WNT signaling

2020 ◽  
Vol 133 (15) ◽  
pp. jcs243675 ◽  
Author(s):  
Fiete Haack ◽  
Kai Budde ◽  
Adelinde M. Uhrmacher
Keyword(s):  
Wnt Signaling ◽  
Temporal Dynamics ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cell Types ◽  
Receptor Internalization ◽  
Canonical Wnt Signaling ◽  
Temporal Regulation ◽  
Density Lipoprotein Receptor ◽  
Canonical Wnt

ABSTRACTEndocytosis plays a pivotal regulatory role in canonical WNT signaling. Internalization of the low-density lipoprotein receptor-related protein 6 (LRP6) receptor complex can either promote or attenuate canonical WNT signaling, depending on the employed internalization pathway. Detailed analysis of the mechanism of LRP6 internalization and its temporal regulation is crucial for understanding the different cellular responses to WNT stimulation under varying conditions and in various cell types. Here, we elucidate the mechanisms involved in the internalization of LRP6 and re-evaluate existing, partly contradicting, theories on the regulation of LRP6 receptor internalization. We utilize a computational approach that aims at finding a set of mechanisms that accounts for the temporal dynamics of LRP6 receptor internalization upon WNT stimulation. Starting with a simple simulation model, we successively extend and probe the model's behavior based on quantitative measurements. The final model confirms that LRP6 internalization is clathrin independent in vertebrates, is not restricted to microdomains, and that signalosome formation delays LRP6 internalization within the microdomains. These findings partly revise the current understanding of LRP6 internalization in vertebrates.

scholarly journals Caprin-2 enhances canonical Wnt signaling through regulating LRP5/6 phosphorylation

2008 ◽  
Vol 182 (5) ◽  
pp. 865-872 ◽  
Author(s):  
Yu Ding ◽  
Ying Xi ◽  
Ting Chen ◽  
Ji-yong Wang ◽  
Dong-lei Tao ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Mammalian Cells ◽  
Target Genes ◽  
Glycogen Synthase ◽  
Signal Transmission ◽  
Low Density Lipoprotein ◽  
Wnt Signaling Pathway ◽  
Density Lipoprotein ◽  
Canonical Wnt Signaling ◽  
Canonical Wnt

The low-density lipoprotein receptor–related proteins 5 and 6 (LRP5/6) are coreceptors for Frizzled and transmit signals from the plasma membrane to the cytosol. However, the mechanism for LRP5/6 signal transmission remains undefined. Here, we identify cytoplasmic activation/proliferation-associated protein 2 (Caprin-2) as a LRP5/6-binding protein. Our data show that Caprin-2 stabilizes cytosolic β-catenin and enhances lymphoid enhancer-binding factor 1/T cell factor–dependent reporter gene activity as well as the expression of Wnt target genes in mammalian cells. Morpholino-mediated knockdown of Caprin-2 in zebrafish embryos inhibits Wnt/β-catenin signaling and results in a dorsalized phenotype. Moreover, Caprin-2 facilitates LRP5/6 phosphorylation by glycogen synthase kinase 3, and thus enhances the interaction between Axin and LRP5/6. Therefore, Caprin-2 promotes activation of the canonical Wnt signaling pathway by regulating LRP5/6 phosphorylation.

scholarly journals Clathrin and AP2 are required for PtdIns(4,5)P2-mediated formation of LRP6 signalosomes

2013 ◽  
Vol 200 (4) ◽  
pp. 419-428 ◽  
Author(s):  
Ingyu Kim ◽  
Weijun Pan ◽  
Sara A. Jones ◽  
Youxin Zhang ◽  
Xiaowei Zhuang ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Super Resolution ◽  
Adaptor Protein ◽  
Related Protein ◽  
Cell Surfaces ◽  
Wnt Proteins ◽  
Canonical Wnt ◽  
Wnt3a Stimulation

Canonical Wnt signaling is initiated by the binding of Wnt proteins to their receptors, low-density lipoprotein-related protein 5 and 6 (LRP5/6) and frizzled proteins, leading to phosphatidylinositol (4,5)bisphosphate (PtdIns(4,5)P2) production, signalosome formation, and LRP phosphorylation. However, the mechanism by which PtdIns(4,5)P2 regulates the signalosome formation remains unclear. Here we show that clathrin and adaptor protein 2 (AP2) were part of the LRP6 signalosomes. The presence of clathrin and AP2 in the LRP6 signalosomes depended on PtdIns(4,5)P2, and both clathrin and AP2 were required for the formation of LRP6 signalosomes. In addition, WNT3A-induced LRP6 signalosomes were primarily localized at cell surfaces, and WNT3A did not induce marked LRP6 internalization. However, rapid PtdIns(4,5)P2 hydrolysis induced artificially after WNT3A stimulation could lead to marked LRP6 internalization. Moreover, we observed WNT3A-induced LRP6 and clathrin clustering at cell surfaces using super-resolution fluorescence microscopy. Therefore, we conclude that PtdIns(4,5)P2 promotes the assembly of LRP6 signalosomes via the recruitment of AP2 and clathrin and that LRP6 internalization may not be a prerequisite for Wnt signaling to β-catenin stabilization.

scholarly journals Canonical Wnt signaling in megakaryocytes regulates proplatelet formation

Blood ◽  
2013 ◽  
Vol 121 (1) ◽  
pp. 188-196 ◽  
Author(s):  
Iain C. Macaulay ◽  
Jonathan N. Thon ◽  
Marloes R. Tijssen ◽  
Brian M. Steele ◽  
Bryan T. MacDonald ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Fetal Liver ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Wild Type ◽  
Density Lipoprotein Receptor ◽  
Proplatelet Formation ◽  
And Function ◽  
Canonical Wnt ◽  
Whole Genome Expression

Abstract Wnt signaling is involved in numerous aspects of vertebrate development and homeostasis, including the formation and function of blood cells. Here, we show that canonical and noncanonical Wnt signaling pathways are present and functional in megakaryocytes (MKs), with several Wnt effectors displaying MK-restricted expression. Using the CHRF288-11 cell line as a model for human MKs, the canonical Wnt3a signal was found to induce a time and dose-dependent increase in β-catenin expression. β-catenin accumulation was inhibited by the canonical antagonist dickkopf-1 (DKK1) and by the noncanonical agonist Wnt5a. Whole genome expression analysis demonstrated that Wnt3a and Wnt5a regulated distinct patterns of gene expression in MKs, and revealed a further interplay between canonical and noncanonical Wnt pathways. Fetal liver cells derived from low-density-lipoprotein receptor-related protein 6-deficient mice (LRP6−/−), generated dramatically reduced numbers of MKs in culture of lower ploidy (2N and 4N) than wild-type controls, implicating LRP6-dependent Wnt signaling in MK proliferation and maturation. Finally, in wild-type mature murine fetal liver-derived MKs, Wnt3a potently induced proplatelet formation, an effect that could be completely abrogated by DKK1. These data identify novel extrinsic regulators of proplatelet formation, and reveal a profound role for Wnt signaling in platelet production.

scholarly journals In situ Fucosylation for Modulating Wnt Signaling in Live Cells

2019 ◽  
Author(s):  
Senlian Hong ◽  
Lei Feng ◽  
Hao Jiang ◽  
Xiaomeng Hou ◽  
Peng Guo ◽  
...  
Keyword(s):  
Cell Surface ◽  
Wnt Signaling ◽  
Intracellular Signaling ◽  
Chinese Hamster ◽  
Density Lipoprotein ◽  
Cell Surface Receptor ◽  
Live Cells ◽  
Canonical Wnt Signaling ◽  
Canonical Wnt

ABSTRACTWnt/β-catenin signaling, also known as canonical Wnt signaling, regulates critical, context-dependent transcription in numerous (patho) physiological events. Amongst the well-documented mechanisms of canonical Wnt signaling, modification of N-glycans by L-fucose (Fuc) is the newest and the least understood. Using a combination of Chinese Hamster Ovary (CHO) cell mutants with different fucosylation levels and in situ cell-surface Fuc editing (ISF), we report that α(1-3)-fucosylation of N-acetylglucosamine in the LacNAc (Galβ(1-4)-GlcNAc) sequences of complex N-glycans modulates Wnt signaling by regulating the endocytosis of low density lipoprotein receptor-related protein 6 (LRP6). Pulse-chase experiments reveal that increasing N-glycan LacNAc fucosylation elevates endocytosis of lipid-raft-localized LRP6, leading to the suppression of Wnt-β-catenin signaling. Inhibiting endocytosis by inhibiting dynamin 1, a GTPase responsible for endocytosis in eukaryotic cells, partially rescues Wnt signaling. Remarkably, inhibition of Wnt signaling by N-glycan LacNAc fucosylation is fully rescued by the addition of free Fuc to the medium, suggesting that endocytosis of N-glycan fucosylated LRP6 may be mediated by a receptor that recognizes the bound α(1-3)-Fuc. This work provides the first evidence that in situ cell-surface fucosylation can be exploited to regulate a specific signaling pathway via endocytosis, revealing a novel regulatory mechanism linking glycosylation of a cell surface receptor with its intracellular signaling.

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