Mammary Development, Carcinomas and Progesterone: Role of Wnt Signalling

2008 ◽  
pp. 151-170 ◽  
Author(s):  
R. Lamb ◽  
H. Harrison ◽  
R. B. Clarke
Keyword(s):  
Mammary Development ◽  
Wnt Signalling

TCF: Lady Justice Casting the Final Verdict on the Outcome of Wnt Signalling

2002 ◽  
Vol 383 (2) ◽  
pp. 255-261 ◽  
Author(s):  
H. Brantjes ◽  
N. Barker ◽  
J. van Es ◽  
H. Clevers
Keyword(s):  
Cell Fate ◽  
Target Genes ◽  
Signal Transduction Pathway ◽  
Wnt Signalling ◽  
Early Event ◽  
Embryonic Patterning ◽  
Repressor Proteins ◽  
Downstream Effectors ◽  
Signalling Cascade

Abstract The Wnt signalling cascade plays an important role during embryonic patterning and cell fate determination and is highly conserved throughout evolution. Factors of the TCF/LEF HMG domain family (Tcfs) are the downstream effectors of this signal transduction pathway. Upon Wnt signalling, a cascade is initiated that results in the translocation of βcatenin to the nucleus, where it interacts with Tcf to generate a transcriptionally active complex. This bipartite transcription factor is targeted to the upstream regulatory regions of Tcf target genes. In the absence of Wnt signals, βcatenin is degraded in the cytoplasm via the ubiquitinproteasome pathway. Several proteins are instrumental in achieving this tight regulation of βcatenin levels in the cell, including adenomatous polyposis coli (APC), GSK3 β, and Axin/Conductin. Deregulation of the Wnt signalling pathway is implicated in several forms of cancer, such as colon carcinoma and melanoma. This deregulation is achieved via mutation of APC, βcatenin or Axin, resulting in elevated βcatenin levels and the presence of constitutively active Tcfβcatenin complexes in the nucleus. The accompanying inappropriate activation of target genes is considered to be a critical, early event in this carcinogenesis. In addition to regulating βcatenin levels, normal healthy cells have evolved a second level of regulation, by manipulating the activity of the Tcf proteins themselves. In the absence of Wnt signalling, Tcf complexes with several transcriptional repressor proteins ensuring active repression of Tcf target genes. In this review the dual role of Tcf proteins in the Wnt signalling cascade will be discussed.

scholarly journals Role of Wnt signalling in advanced prostate cancer

2018 ◽  
Vol 245 (1) ◽  
pp. 3-5 ◽  
Author(s):  
Imran Ahmad ◽  
Owen J Sansom
Keyword(s):  
Prostate Cancer ◽  
Advanced Prostate Cancer ◽  
Wnt Signalling

scholarly journals An improved, scalable synthesis of Notum inhibitor LP-922056 using 1-chloro-1,2-benziodoxol-3-one as a superior electrophilic chlorinating agent

2019 ◽  
Vol 15 ◽  
pp. 2790-2797 ◽  
Author(s):  
Nicky J Willis ◽  
Elliott D Bayle ◽  
George Papageorgiou ◽  
David Steadman ◽  
Benjamin N Atkinson ◽  
...  
Keyword(s):  
Wnt Signalling ◽  
Negative Regulator ◽  
Cell Permeability ◽  
Pharmacokinetic Studies ◽  
Good Efficiency ◽  
Active Inhibitor ◽  
Wnt Proteins ◽  
Cns Penetration ◽  
Scalable Synthesis

Background: The carboxylesterase Notum has been shown to act as a key negative regulator of the Wnt signalling pathway by mediating the depalmitoleoylation of Wnt proteins. LP-922056 (1) is an orally active inhibitor of Notum. We are investigating the role of Notum in modulating Wnt signalling in the central nervous system and wished to establish if 1 would serve as a peripherally restricted control. An accessible and improved synthetic route would allow 1 to become more readily available as a chemical tool to explore the fundamental biology of Notum and build target validation to underpin new drug discovery programs. Results: An improved, scalable synthesis of 1 is reported. Key modifications include: (1) the introduction of the C7-cyclopropyl group was most effectively achieved with a Suzuki–Miyaura cross-coupling reaction with MIDA-boronate 11 (5 → 6), and (2) C6 chlorination was performed with 1-chloro-1,2-benziodoxol-3-one (12) (6 → 7) as a mild and selective electrophilic chlorination agent. This 7-step route from 16 has been reliably performed on large scale to produce multigram quantities of 1 in good efficiency and high purity. Pharmacokinetic studies in mouse showed CNS penetration of 1 is very low with a brain/plasma concentration ratio of just 0.01. A small library of amides 17 were prepared from acid 1 to explore if 1 could be modified to deliver a CNS penetrant tool by capping off the acid as an amide. Although significant Notum inhibition activity could be achieved, none of these amides demonstrated the required combination of metabolic stability along with cell permeability without evidence of P-gp mediated efflux. Conclusion: Mouse pharmacokinetic studies demonstrate that 1 is unsuitable for use in models of disease where brain penetration is an essential requirement of the compound but would be an ideal peripherally restricted control. These data will contribute to the understanding of drug levels of 1 to overlay with appropriate in vivo efficacy endpoints, i.e., the PK-PD relationship. The identification of a suitable analogue of 1 (or 17) which combines Notum inhibition with CNS penetration would be a valuable chemical probe for investigating the role of Notum in disease models.

scholarly journals Identification of dkk4 as a target of Eda-A1/Edar pathway reveals an unexpected role of ectodysplasin as inhibitor of Wnt signalling in ectodermal placodes

2008 ◽  
Vol 320 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Ingrid Fliniaux ◽  
Marja L. Mikkola ◽  
Sylvie Lefebvre ◽  
Irma Thesleff
Keyword(s):  
Wnt Signalling

The role of the Wnt signalling pathway in colorectal tumorigenesis

2005 ◽  
Vol 33 (4) ◽  
pp. 672-675 ◽  
Author(s):  
J. Behrens
Keyword(s):  
Wnt Pathway ◽  
Genetic Alterations ◽  
Wnt Signalling ◽  
Tumour Suppressor ◽  
Tumour Suppressor Genes ◽  
Adenomatous Polyposis ◽  
Polyposis Coli ◽  
Colorectal Tumorigenesis ◽  
Constitutive Activation

Colorectal cancer (CRC) is the second largest cause of cancer-related deaths in Western countries. CRC arises from the colorectal epithelium as a result of the accumulation of genetic alterations in defined oncogenes and tumour suppressor genes. Mutations in the tumour suppressor APC (adenomatous polyposis coli) genes occur early in the development of CRC and lead to the stabilization of the Wnt pathway component β-catenin and to the constitutive activation of Wnt signalling. Stabilizing mutations of β-catenin can also lead to its accumulation, qualifying β-catenin as a proto-oncogene. Here I will summarize the biochemical interactions occurring in Wnt signalling and describe how alterations in Wnt pathway components lead to CRC.

scholarly journals Epigenetic repression of Wnt receptors in AD: a role for Sirtuin2-induced H4K16ac deacetylation of Frizzled1 and Frizzled7 promoters

2021 ◽  
Author(s):  
Ernest Palomer ◽  
Núria Martin-Flores ◽  
Sarah Jolly ◽  
Patricia Pascual-Vargas ◽  
Stefano Benvegnù ◽  
...  
Keyword(s):  
Synapse Formation ◽  
Late Onset ◽  
Wnt Signalling ◽  
Mrna Levels ◽  
Preclinical Ad ◽  
Synapse Degeneration ◽  
Epigenetic Repression

Growing evidence supports a role for deficient Wnt signalling in synapse degeneration in Alzheimer′s disease (AD). First, the Wnt antagonist DKK1 is elevated in the AD brain and is required for amyloidβ-induced synapse loss. Second, LRP6 Wnt co-receptor is required for synapse integrity and three variants of this receptor are linked to late-onset AD. However, the expression/role of other Wnt signalling components remain poorly explored in AD. Wnt receptors Frizzled1 (Fzd1), Fzd5, Fzd7 and Fzd9 are of particular interest due to their role in synapse formation and plasticity. Our analyses showed that FZD1 and FZD7 mRNA levels were reduced in the hippocampus of human preclinical AD (PAD) cases and in the hAPPNLGF/NLGF mouse model. This transcriptional downregulation was accompanied by reduced levels of the pro-transcriptional histone mark H4K16ac and a concomitant increase of its deacetylase Sirt2 at Fzd1 and Fzd7 promoters in AD. In vitro and in vivo inhibition of Sirt2 rescued Fzd1 and Fzd7 mRNA expression and H4K16ac levels at their promoters. In addition, we showed that Sirt2 recruitment to Fzd1 and Fzd7 promoters is dependent on FoxO1 activity in AD, thus acting as a co-repressor. Finally, we found reduced levels of inhibitory phosphorylation on Sirt2 in nuclear PAD samples and increased levels of the Sirt2 phosphatase PP2C, leading to hyperactive nuclear Sirt2 and favouring Fzd1 and Fzd7 repression in AD. Collectively, our findings define a novel role for nuclear hyperactivated Sirt2 in repressing Fzd1 and Fzd7 expression via H4K16ac deacetylation in AD. We propose Sirt2 as an attractive target to ameliorate AD pathology.

scholarly journals Role of canonical Wnt-signalling in joint formation

2006 ◽  
Vol 12 ◽  
pp. 71-80 ◽  
Author(s):  
D Später ◽  
◽  
TP Hill ◽  
M Gruber ◽  
C Hartmann
Keyword(s):  
Wnt Signalling ◽  
Joint Formation ◽  
Canonical Wnt
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