4-5: Wnt

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Questions and Answers

Which modification ensures proper Wnt protein secretion?

  • Methylation
  • Ubiquitination
  • Phosphorylation
  • Glycosylation (correct)

What role do Wnt proteins play in Wnt signaling?

  • They act as receptors.
  • They act as structural proteins.
  • They act as ligands. (correct)
  • They act as enzymes.

What is the primary function of Wnt signaling during embryonic development?

  • Controlling segment polarity and body axis formation (correct)
  • Regulating nutrient supply to the embryo
  • Developing the nervous system
  • Establishing the circulatory system

Which component directly binds to Wnt proteins to initiate the Wnt signaling pathway?

<p>Frizzled receptors (B)</p> Signup and view all the answers

What is the ultimate effect of Wnt signaling on transcription?

<p>Activation of target gene transcription (D)</p> Signup and view all the answers

Which of the following must occur for β-catenin to accumulate and enter the nucleus?

<p>Wnt signaling must inactivate the destruction complex. (C)</p> Signup and view all the answers

What complex does β-catenin form in the nucleus to activate Wnt target genes?

<p>TCF complex (C)</p> Signup and view all the answers

What event directly precedes β-catenin's entry into the nucleus during Wnt signaling?

<p>Transduction of the signal through cytoplasmic relays (A)</p> Signup and view all the answers

Which of the following is a characteristic of Wnt proteins?

<p>They are highly conserved secreted signaling molecules. (D)</p> Signup and view all the answers

What is the result of Wnt stimulation on cytoplasmic YAP/TAZ?

<p>YAP/TAZ nuclear accumulation (B)</p> Signup and view all the answers

Which of the following does the data suggest is a function of YAP/TAZ in Wnt OFF conditions?

<p>Interact with Axin (B)</p> Signup and view all the answers

Deficiency in which protein is associated with decreased β-TrCP in the destruction complex?

<p>YAP/TAZ (B)</p> Signup and view all the answers

How does the model propose Yap and Taz function in the absence of Wnt signals?

<p>As part of the destruction complex that recruit beta-TrCP (A)</p> Signup and view all the answers

When Axin1 is depleted, where do YAP/TAZ localize?

<p>Nucleus (A)</p> Signup and view all the answers

What key insight was revealed regarding Axin1's binding partners?

<p>Axin1 binds to endogenous YAP and TAZ. (C)</p> Signup and view all the answers

How does Wnt stimulation affect the association between YAP/TAZ and Axin1?

<p>Association rapidly decreases. (C)</p> Signup and view all the answers

According to current research, which factor modulates both the Wnt and Hippo signaling pathways?

<p>YAP/TAZ (C)</p> Signup and view all the answers

Which of the following diseases is NOT directly associated with mutations in Wnt pathway components?

<p>Alzheimer's disease (B)</p> Signup and view all the answers

Which process involving GSK3β is integral to Wnt signaling?

<p>GSK3β differential phosphorylation (B)</p> Signup and view all the answers

How does raising the dose of LRP6 experimentally affect the interaction of Axin1 with YAP/TAZ in Wnt-ON cells?

<p>Titrates Axin1 away from interaction with YAP/TAZ (D)</p> Signup and view all the answers

In the experiment with mice injected with tamoxifen, what was the observed outcome when the Villin-CreERT2;Apcfl/fl mice became moribund?

<p>Decreased survival (C)</p> Signup and view all the answers

What does the presence of active Wnt signaling in crypt cells contribute to in the intestinal epithelium model?

<p>Normal replenishment of intestinal tissue (D)</p> Signup and view all the answers

How do YAP/TAZ affect tumor suppression?

<p>Maintain survival, block cell death (B)</p> Signup and view all the answers

What has been identified as a key step in the carcinogenesis of colorectal cancer (CRC)?

<p>The loss of APC function (C)</p> Signup and view all the answers

What method was used to determine that Axin1 binds to endogenous YAP and TAZ?

<p>Immunoprecipitation (D)</p> Signup and view all the answers

In which cellular compartment is YAP mostly found in confluent and untreated cells?

<p>Cytoplasm (A)</p> Signup and view all the answers

How does Axin1 impact Yap and Taz?

<p>Localization (A)</p> Signup and view all the answers

Why are YAP and TAZ defined as crucial for cell reprogramming?

<p>They can interact with Wnt signalling (C)</p> Signup and view all the answers

How does the first finding for the Wnt pathway lead to its characterization?

<p>Mouse proto-oncogene development (D)</p> Signup and view all the answers

What type of mammalian genomes harbor Wnt genes and how many?

<p>Most mammalian genomes including the human genome harbor 19 genes (B)</p> Signup and view all the answers

What can co-receptors govern in Wnt signaling molecules?

<p>The type of signaling as well as the isoform of the Wnt signaling molecule (A)</p> Signup and view all the answers

In cell culture, what do you need when using Matrigel as it relates to the experiment?

<p>Matrigel together with the Wnt-agonist agonist R-Spondin essential for crypt maintenance and growth in 3-D culture (A)</p> Signup and view all the answers

How does glycosylation contribute to the function of Wnt proteins?

<p>It ensures their proper secretion. (C)</p> Signup and view all the answers

What is the significance of palmitoylation for Wnt proteins?

<p>It modifies them as lipid-modified glycoproteins for proper function. (C)</p> Signup and view all the answers

How does Wnt signaling influence embryonic development?

<p>By controlling segment polarity involved in the formation of the body axis and lateral symmetry. (D)</p> Signup and view all the answers

Which role does the Frizzled family of receptors play in Wnt signaling?

<p>They bind Wnt proteins on the cell surface to initiate the signaling cascade. (A)</p> Signup and view all the answers

What is the role of Dishevelled (Dsh) in the Wnt signaling pathway?

<p>To act as a cytoplasmic relay component of the signal. (B)</p> Signup and view all the answers

How does glycogen synthase kinase 3 beta (GSK3β) participate in the Wnt signaling pathway?

<p>It promotes differential phosphorylation of beta-catenin. (A)</p> Signup and view all the answers

What is the consequence of β-catenin entering the nucleus during Wnt signaling?

<p>It forms a complex with TCF to activate transcription of Wnt target genes. (D)</p> Signup and view all the answers

What describes the relationship between Wnt genes and cancer?

<p>Wnt genes and Wnt signaling are implicated in cancer. (D)</p> Signup and view all the answers

Which of the following is a key insight in Wnt action gained from studying various model organisms and cell lines?

<p>The mechanisms of Wnt action have emerged from several systems: <em>Drosophila, Caenorhabditis elegans</em>, <em>Xenopus</em> embryos, mice, cancer cell lines. (B)</p> Signup and view all the answers

Which of the following is a function of PORCN (Porcupine) enzyme in Wnt signaling?

<p>Lipid modification of Wnt proteins in the endoplasmic reticulum. (C)</p> Signup and view all the answers

What is essential for the transport and secretion of Wnt proteins by the Porcupine (Porc) enzyme?

<p>The Evi/Wntless multiple pass transmembrane protein. (C)</p> Signup and view all the answers

What process involving Evi/Wntless endosomal vesicles is vital for Wnt secretion?

<p>The Retromer complex recycling. (B)</p> Signup and view all the answers

How does Wnt stimulation affect Axin1 regarding YAP/TAZ association?

<p>Reduces their association, releasing YAP/TAZ. (C)</p> Signup and view all the answers

Which mechanism has been identified to explain how Wnt signaling inactivation can be treated?

<p>Genome editing of APC to model cancer in organoids. (D)</p> Signup and view all the answers

According to Figure3A from the content, where are YAP and TAZ expressed in the intestinal environment?

<p>Specifically expressed in the Crypt. (A)</p> Signup and view all the answers

What is correct about how intestinal stem cells replenish the tissue?

<p>Wnt signaling is active on all crypt cells. (D)</p> Signup and view all the answers

How and why can Wnt signaling be beneficial?

<p>In vitro regeneration cryptlike structures, or crypt organoids, and for epithelial repair in vivo. (C)</p> Signup and view all the answers

What is correct regarding AXIN1?

<p>Strongly associated to endogenous YAP and TAZ. (C)</p> Signup and view all the answers

What can you say regarding a cell in the absence of AXIN1?

<p>YAP/TAZ localize to the nucleus (B)</p> Signup and view all the answers

In quiescent cells, how does YAP/TAZ effect β-catenin

<p>It recruits TrCP to aid β-catenin degradation. (D)</p> Signup and view all the answers

How do secondary messengers drive their function in Wnt signal trasnduction?

<p>Through driving the transcription of Wnt target genes. (C)</p> Signup and view all the answers

How would the functional role of YAP and TAZ need to adapt if it were in a Wnt stimulation environment?

<p>Eliminating or inhibiting cytoplasmic YAP/TAZ, causing b-catenin stabilization, as well as YAP/TAZ nuclear accumulation. (B)</p> Signup and view all the answers

How can the research that combines genetic techniques determine the function of YAP and TAZ?

<p>By establishing that YAP and TAZ are integral components of the B-catenin destruction complex. (D)</p> Signup and view all the answers

What is a common characteristic of tissue that has concerted activation and restriction of distinct gene-expression programs?

<p>Growth, tissue regeneration, and tissue replenishment. (A)</p> Signup and view all the answers

How could LRP6 doses play a role in Wnt-ON cells?

<p>The LRP6 should titrate Axin1 away from interacting with YAP/TAZ. (C)</p> Signup and view all the answers

What is a direct cause for colorectal cancer?

<p>APC (B)</p> Signup and view all the answers

When can a tissue follow to homeostasis and regeneration?

<p>Being extensively used as model to study Wnt driven. (C)</p> Signup and view all the answers

What were used to show that YAP and TAZ are integral components of the b-catenin destruction complex and Wnt signaling?

<p>Different models, involving biochemical, gene expression, functional, genetic evidence. (A)</p> Signup and view all the answers

In a Wnt-OFF state, where are YAP/TAZ primarily located within the cell, and what is their function?

<p>Destruction complex; recruit β-TrCP to degrade β-catenin (C)</p> Signup and view all the answers

A cell undergoing Wnt stimulation experiences a shift in YAP/TAZ function. What is the subsequent effect of YAP/TAZ?

<p>Acts as transcriptional effector for Wnt signaling (C)</p> Signup and view all the answers

What function does the Retromer perform during Wnt secretion?

<p>Recycles Evi/Wntless. (A)</p> Signup and view all the answers

How does Axin1 contribute to tumor suppression?

<p>Inactivation of Wnt signaling. (D)</p> Signup and view all the answers

A laboratory is investigating the effects of a novel drug on Wnt signaling in colorectal cancer cells. How could they leverage genome editing?

<p>Model cancer in organoids. (A)</p> Signup and view all the answers

YAP and TAZ nuclear localization in the crypt has been determined to be which of the following?

<p>At least consistent with their proposed regulation by endogenous Wnt signals. (D)</p> Signup and view all the answers

A recent experiment was investigating the effects of Villin on mouse. What could have been a sign that can be expected to be observed?

<p>YAP and TAZ are ectopically stabilized in villi. (D)</p> Signup and view all the answers

Two sets of mice have been injected by tamoxifen, one has been initially sacrificed, what conclusion can you make?

<p>Apcfl/fl mice had become moribund, or almost dead. (A)</p> Signup and view all the answers

To what extent are the triple mutant mice still alive or do they show signs of aberrant crypt hyperplasia after three weeks?

<p>They don't show signs of aberrant crypt hyperplasia and are alive. (A)</p> Signup and view all the answers

A scientist is working with Matrigel and is seeking essential conditions for crypt maintenance and growth. What should they do?

<p>Seed it with the Wnt-agonist R-Spondin. (D)</p> Signup and view all the answers

If Tamoxifen is introduced in Wnt related experiments, what can then be predicted for the mutant crypts?

<p>Demise of the mutant crypts. (D)</p> Signup and view all the answers

What developmental process is influenced by Wnt's control over segment polarity?

<p>Formation of the body axis and lateral symmetry (A)</p> Signup and view all the answers

How does Wnt protein palmitoylation contribute to its function?

<p>Palmitoylation is essential for attaching carbohydrate for proper secretion (D)</p> Signup and view all the answers

What is the immediate effect of Wnt protein binding to Frizzled receptors?

<p>Transduction of a signal involving GSK3β differential phosphorylation (D)</p> Signup and view all the answers

How do co-receptors influence Wnt signaling pathways?

<p>By dictating the specific type of signaling pathway activated and the Wnt isoform used (B)</p> Signup and view all the answers

What is the role of Evi/Wntless in Wnt secretion?

<p>Further transport and secretion of Wnt proteins by multiple pass transmembrane protein (C)</p> Signup and view all the answers

How can Wnt signaling lead to carcinogenesis in colorectal cancer (CRC)?

<p>Through the loss of APC function, a key component in the destruction complex (D)</p> Signup and view all the answers

What is the primary role of beta-catenin in the Wnt signaling pathway?

<p>To serve as a secondary messenger by regulating transcription when bound to TCF/Lef (B)</p> Signup and view all the answers

When Wnt is absent, what is the state of β-catenin?

<p>It is associated with the destruction complex and degraded (D)</p> Signup and view all the answers

What causes the functional inactivation of the destruction complex?

<p>The binding of a Wnt ligand (B)</p> Signup and view all the answers

What is the consequence of TCF binding to Groucho in the Wnt pathway?

<p>Repression of target gene expression (B)</p> Signup and view all the answers

Based on the research paper, what is the relationship between YAP/TAZ and beta-catenin activity?

<p>Phosphorylated beta-catenin promotes the degradation of TAZ. (C)</p> Signup and view all the answers

What is the proposed function of cytoplasmic YAP/TAZ in cells that are not under Wnt stimulation?

<p>Degrading beta-catenin by binding to the destruction complex. (D)</p> Signup and view all the answers

According to current understanding, how does Wnt stimulation affect cytoplasmic YAP/TAZ?

<p>It causes cytoplasmic YAP/TAZ to be eliminated or inhibited, leading to β-catenin stabilization. (D)</p> Signup and view all the answers

Which method was employed to detect the proteins associated with Axin1 in Wnt OFF cells?

<p>Immunoprecipitation followed by western blotting (D)</p> Signup and view all the answers

In the absence of Axin, what is the localization pattern of YAP/TAZ?

<p>They are localized to the nucleus (C)</p> Signup and view all the answers

What role do YAP and TAZ play in the context of tissue regeneration?

<p>They are integral in the concerted activation/restriction of distinct gene-expression programs. (A)</p> Signup and view all the answers

According to Figure 2F, how does the addition of Wnt3A impact the relationship between Axin1 and YAP/TAZ over time?

<p>Their association rapidly decreases, becoming undetectable after a short period. (C)</p> Signup and view all the answers

In the experiment relating to the intestine, in which specific region are both YAP and TAZ proteins expressed in dissected tissue?

<p>They are specifically expressed in the Crypt compartment (A)</p> Signup and view all the answers

After intestinal-specific knockout of APC in mice, what happens to YAP and TAZ proteins in villi, according to Figure 3A?

<p>They are ectopically stabilized (B)</p> Signup and view all the answers

When control Villin-CreERT2 mice or those carrying double YAP/TAZ conditional alleles are used to explant Crypt tissue, what happens next?

<p>A Matrigel is used with a cocktail of essential components for crypt maintanence. (D)</p> Signup and view all the answers

What processes does YAP/TAZ control, after the Tamoxifen-mediated combined deletion?

<p>YAP/TAZ control crypt growth and maintain them. (A)</p> Signup and view all the answers

According to Figure 4, what is affected by the loss of YAP/TAZ in the Axin1 complex?

<p>In Figure 4A, knockout of YAP/TAZ leads to less B-TrCP in the destruction complex (B)</p> Signup and view all the answers

What happens during HEK293 transfection in association to TOP-FLASH, according to Figure 4?

<p>YAP/TAZ is depleted and leads to increased TOP-FLASH reporter (Wnt signaling). (B)</p> Signup and view all the answers

According to Figure 5, what can be said about YAP/TAZ and B-cantenin?

<p>YAP/TAZ inhibits Wnt activity through B-cantenin (C)</p> Signup and view all the answers

According to Figure 5, what do you need to do to perform an effective experiment in luciferase with the TOP-FLASH reporter in HEK293 cells?

<p>Two distinct TOP-FLASH or YAP/TAZ siRNAs for effective output. (D)</p> Signup and view all the answers

According to Figure 6, what is used to propagate Stem Cells?

<p>Inhibitors targeting MEK and GSK3 (C)</p> Signup and view all the answers

According to Figure 6, knocking out what is equivalent to having CH present for stem cells?

<p>YAP/TAZ being equivalent by report rex1GFPd2 (D)</p> Signup and view all the answers

For stem cells, what can now be maintained by only doing only one direct experiment?

<p>You can knock out YAP/TAZ without the drugs required. (B)</p> Signup and view all the answers

According to Figure 6, when discussing b-cantenin on TCF, what is also required at the same time?

<p>Under regulation of secondary messenger YAP/TAZ (D)</p> Signup and view all the answers

After reviewing the content, which of the methods would help to show that components are integral to the b-cantenin destruction complex?

<p>Biochemical experiments, gene expression, localization and systems. (A)</p> Signup and view all the answers

According to the content here, which of the following options can the Azzolin method show to be the double role of YAP and TAZ?

<p>To recruit b-TrCP when wnt is absent, and YAP/TAZ can be displaced by LRP on Axin1. (B)</p> Signup and view all the answers

Flashcards

Wnt signaling pathway

A signaling cascade involved in development and cancer, initiated by Wnt ligands binding to Frizzled receptors.

Wnt proteins

Secreted lipid-modified glycoproteins that act as ligands in the Wnt signaling pathway.

Frizzled family (GPCRs)

Receptors on the cell surface that bind Wnt proteins, initiating the Wnt signaling cascade.

β-catenin

A cytoplasmic protein that is phosphorylated by GSK3β, leading to its degradation unless Wnt signaling is active.

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Destruction complex

A protein complex that phosphorylates β-catenin, marking it for degradation in the absence of Wnt signals.

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GSK3β

Glycogen synthase kinase 3 beta, a kinase that phosphorylates β-catenin in the destruction complex.

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TCF

A transcription factor that binds to β-catenin, activating transcription of Wnt target genes in the nucleus.

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Wnt proteins

Form a family of highly conserved secreted signaling molecules involved in embryogenesis

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GSK3β differential phosphorylation

Process by which GSK3β phosphorylates β-catenin to regulate Wnt signaling.

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Porcupine (Porc)

Endoplasmic reticulum enzyme that modifies Wnt proteins with lipids.

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Evi/Wntless

Protein required for the transport and secretion of lipid-modified Wnt proteins.

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Proteosome degradation

The process where proteasomes degrade proteins, regulating Wnt signaling.

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vATPase

A process promoting vesicle acidification essential for Wnt signaling.

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beta-catenin

A process of ubiquitylation and proteasomal degradation.

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YAP and TAZ

Hippo signal transducer proteins.

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Kinases

A complex that phosphorylates β-catenin.

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Multivesicular bodies (MVBs)

A membrane structure required for transport.

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APC function

Main driver of Wnt signaliing in colorectal cancer.

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Wnt growth factors

Controls cell fate, proliferation and stem cell maintenance.

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Study Notes

Wnt Signaling Pathway Discovery

  • Wnt signaling was discovered through oncogenic retrovirus research
  • In 1982, Roel Nusse and Harold Varmus identified a new mouse proto-oncogene called int1, or integration 1
  • Int1 was later characterized as a Wnt or Wingless-related integration 1 signaling molecule during studies of a mouse mammary tumor virus

Wnt Function and Characteristics

  • Wnt regulates segment polarity during embryonic development, influencing body axis formation and lateral symmetry
  • Wnt proteins are secreted lipid-modified glycoproteins that undergo palmitoylation and glycosylation to ensure proper secretion
  • Wnt proteins act as ligands to activate different Wnt pathways in paracrine and autocrine manners

Wnt Genes and Signaling

  • Most mammalian genomes, including the human genome, contain 19 Wnt genes categorized into 12 conserved Wnt subfamilies
  • Wnt signaling can be canonical or non-canonical
  • Different co-receptors and Wnt signaling molecule isoforms determine the specific type of signaling

Wnt Signaling Components

  • Wnt proteins bind to Frizzled family receptors which are GPCRs on the cell surface
  • The signal transduction involves several cytoplasmic relay components, including GSK3β differential phosphorylation
  • Beta-catenin is transduced and enters the nucleus to form a complex with TCF, which activates the transcription of Wnt target genes

Degradation Regulation

  • Proteosome degradation impacts Wnt activation and signaling

YAP/TAZ in Wnt Signaling: Overview

  • This study focuses on the interplay between Wnt and Hippo signaling via Hippo signal transducer proteins Yap and Taz
  • YAP/TAZ and Wnt/β-catenin do not operate independently and are hypothesized to influence each other
  • Phosphorylated β-catenin encourages TAZ degradation by acting as a presenting factor for TAZ to b-TrCP, or ubiquitin ligase

Hypothesis on Cytoplasmic YAP/TAZ

  • Cytoplasmic YAP/TAZ are proposed as integral factors within the destruction complex
  • Cells lacking Wnt would sequester YAP/TAZ within the destruction complex to degrade β-catenin
  • Wnt stimulation eliminates or inhibits cytoplasmic YAP/TAZ, resulting in β-catenin stabilization and YAP/TAZ nuclear accumulation

Immunoprecipitation (IP) in Protein-Protein Interactions

  • Immunoprecipitation was employed to determine protein-protein interactions
  • Protein composition in Wnt OFF cells was identified through immunoprecipitations for endogenous Axin1
  • Proteins that associate are detected using western blotting

Axin1 Binding and Data Support

  • Axin1 binds established elements of the destruction complex and also strongly binds to endogenous YAP and TAZ
  • In Wnt OFF conditions, YAP/TAZ associates with the destruction complex through interaction with Axin
  • YAP/TAZ localizes to the nucleus when Axin is absent

Purified Wnt3A Ligand Effect

  • The effect of purified Wnt3A ligand was monitored on the subcellular localization of endogenous YAP by immunofluorescence in various cell types
  • YAP was primarily cytoplasmic in confluent, untreated cells but relocalized markedly to the nucleus following Wnt treatment

Consequences of Wnt-Induced YAP/TAZ

  • Wnt induced YAP/TAZ nuclear localization connects with transcriptional activation of the synthetic TEAD reporter or 8xGTIIC-Lux
  • Paralleled also with direct YAP/TAZ target genes Cyr61 and Ankrd1 are activated
  • YAP/TAZ nuclear accumulation and TEAD reporter activation were detected as early as 30 minutes post-Wnt stimulation
  • This timing is comparable to initial detection of the TCF/b-catenin reporter TOP-FLASH

Wnt Stimulation and Molecular Changes

  • Wnt stimulation alters the complex's composition relative to YAP/TAZ such that their association with Axin1 rapidly decreases
  • Association with Axin1 becomes undetectable after 30 minutes for TAZ and 2 hours for YAP following Wnt3A addition

Wnt-ON cells and LRP6 function

  • LRP6 releases YAP/TAZ from the destruction complex by displacing them from Axin1
  • Figures H-J validates raising the doses of LRP6 to titrate Axin1 away from interacting with YAP/TAZ

Intestinal Study and Tissue Homeostasis

  • Intestinal epithelium serves as a model for Wnt-driven tissue homeostasis and regeneration
  • Wnt signaling is active in crypt cells,devoted to intestinal tissue replenishment, but inactive in villi, also important for epithelial repair
  • Both YAP and TAZ show specific expression in the crypt compartment

Additional YAP/TAZ Insights

  • YAP/TAZ nuclear localization in crypt cells is consistent with regulation by endogenous Wnt signals
  • YAP and TAZ proteins become ectopically stabilized in villi after intestinal-specific knockout of APC

APC and Mutant Analysis

  • APC, or adenomatous polyposis coli, functions as an intestinal tumor suppressor and is part of the destruction complex
  • Adult mice, injected with tamoxifen and sacrificed after 3 days, time point when Villin-CreERT2;Apcfl/fl mice became moribund
  • Triple mutant mice showed with no signs of aberrant crypt hyperplasia after 3 weeks
  • This was the set end-point for observation of tumors/cancers

Crypt Study and Mutations

  • Crypt mutations were examined in an organoid model, a system requiring Wnt signaling and is reminiscent of in vivo regeneration
  • Crypts were explanted from control Villin-CreERT2 mice or from mice carrying double YAP/TAZ conditional alleles
  • Crypts were then seeded in Matrigel with Wnt-agonist R-Spondin which is essential for crypt maintenance and growth in 3-D culture, also known as organoid

YAP/TAZ Results

  • Tamoxifen deletion of YAP/TAZ blocked crypt growth
  • Led to the demise of the mutant crypts, to demonstrate the role of YAP/TAZ in these processes

YAP/TAZ with Wnt

  • Lack of YAP can lead to greater amounts of beta-TrCP in the destruction complex
  • There is reporter expression, controlled by β-catenin/TCF and shows that YAP/TAZ influence levels of nuclear β-catenin

HEK293 Cell Study on Effects

  • In Lane 1: YAP/TAZ depletion activates TOP-FLASH reporter, a wnt signaling
  • In Lane 2: knocking down endogenous β-catenin gets rid of the effects of YAP/TAZ Depletion
  • In Lanes 3 and 4: cells had β-catenin siRNA and reconstituted with either wild-type or phosphomutant siRNA-insensitive β-catenin
  • There seems to be a greater basal activity that is is not further increased after YAP/TAZ Knockdown

Wnt3A effects

  • Interactions with Axin1 will happen after Wnt3A stimulation

ES Cell Info and Goals

  • With mouse embryonic stem cells as these can be propagated in an undifferentiated and pluripotent state
  • When cultured with two MEK and GSK3 inhibitors, with transcriptional responses for cell maintenance and genetic ablation

Model Insights

  • The work demonstrates the integration of YAP and TAZ into the β-catenin destruction complex
  • Contributes insights in cell reprogamming with Wnt Singaling

Azzolin Model

  • Demonstrates a double role for YAP/TAZ.
  • In the absence of Wnt ligands, YAP/TAZ become complex and recruit β-TrCP in order to regulate Wnt singaling
  • In an activated pathway, YAP/TAZ and bound B-TCrP shift from Axin 1 because LRP sequesters the distruction complex
  • Free YAP/TAZ is a factor that effects Wnt Signials, showing Hippo and Wnts strong connection.

Wnt and Impact to Cancer

  • Has a huge impact on carcinogenesis regarding colorectal cancer, very well understood
  • Loss of APC is also understood in colorectal cancer
  • Genome editing via editing shows CRC can be solved without going the traditional pathway.

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