Mitotic and mitogenic Wnt signalling.
Ontology highlight
ABSTRACT:
SUBMITTER: Niehrs C
PROVIDER: S-EPMC3380213 | biostudies-other | 2012 Jun
REPOSITORIES: biostudies-other
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Project description:The role of WNT/β-catenin signalling in mouse neocortex development remains ambiguous. Most studies demonstrate that WNT/β-catenin regulates progenitor self-renewal but others suggest it can also promote differentiation. Here we explore the role of WNT/STOP signalling, which stabilizes proteins during G2/M by inhibiting glycogen synthase kinase (GSK3)-mediated protein degradation. We show that mice mutant for cyclin Y and cyclin Y-like 1 (Ccny/l1), key regulators of WNT/STOP signalling, display reduced neurogenesis in the developing neocortex. Specifically, basal progenitors, which exhibit delayed cell cycle progression, were drastically decreased. Ccny/l1-deficient apical progenitors show reduced asymmetric division due to an increase in apical-basal astral microtubules. We identify the neurogenic transcription factors Sox4 and Sox11 as direct GSK3 targets that are stabilized by WNT/STOP signalling in basal progenitors during mitosis and that promote neuron generation. Our work reveals that WNT/STOP signalling drives cortical neurogenesis and identifies mitosis as a critical phase for neural progenitor fate.
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Project description:The role of WNT/β-catenin signalling in mouse neocortex development remains ambiguous. Most studies demonstrate that WNT/β-catenin regulates progenitor self-renewal but others suggest it can also promote differentiation. Here we explore the role of WNT/STOP signalling, which stabilizes proteins during G2/M by inhibiting glycogen synthase kinase (GSK3)-mediated protein degradation. We show that mice mutant for cyclin Y and cyclin Y-like 1 (Ccny/l1), key regulators of WNT/STOP signalling, display reduced neurogenesis in the developing neocortex. Specifically, basal progenitors, which exhibit delayed cell-cycle progression, were drastically decreased. Ccny/l1-deficient apical progenitors show reduced asymmetric division due to an increase in apical-basal astral microtubules. We identify the neurogenic transcription factors Sox4 and Sox11 as direct GSK3 targets that are stabilized by WNT/STOP signalling in basal progenitors during mitosis and that promote neuron generation. Our work reveals that WNT/STOP signalling drives cortical neurogenesis and identifies mitosis as a critical phase for neural progenitor fate.
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Project description:Uncontrolled cell division is a hallmark of cancer. Deregulation of Wnt components has been linked to aberrant cell division by multiple mechanisms, including Wnt-mediated stabilisation of proteins signalling, which was notably observed in mitosis. Analysis of Wnt components revealed an unexpected role of B-cell CLL/lymphoma 9 (BCL9) in maintaining mitotic Wnt signalling to promote precise cell division and growth of cancer cell. Mitotic interactome analysis revealed a mechanistic role of BCL9 in inhibiting clathrin-mediated degradation of LRP6 signalosome components by interacting with clathrin and the components in Wnt destruction complex; this function was further controlled by CDK1-driven phosphorylation of BCL9 N-terminal, especially T172. Interestingly, T172 phosphorylation was correlated with cancer patient prognosis and enriched in tumours. Thus, our results revealed a novel role of BCL9 in controlling mitotic Wnt signalling to promote cell division and growth.
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Project description:Hypothesis and proof of concept:
Our hypothesis is that increase in cellular iron import proteins (TfR1, DMT1) occur early in the adenoma-carcinoma sequence through mutations in APC and lead to cellular iron loading. As demonstrated in our previous work the effects of this iron loading is to mediate increased Wnt signalling resulting in c-myc induction. This in turn serves to increase the expression of iron import proteins (TfR1, DMT1) and decrease the expression of iron export (ferroportin [FPN]) and storage (ferritin) proteins. Such a hypothesis explains how Wnt signalling controls iron metabolism and ensures that there is adequate cellular iron for ATP generation and cellular proliferation.
Experimental design:
To test such a hypothesis we aim to prospectively collect the following colorectal tissue from patients attending for colonoscopy:
1. Normal colonic mucosa in patients with no colorectal pathology (n = 30)
2. Polyps and matched normal colon (n = 30)
3. Colorectal cancers and matched normal colon (n = 30)
We also intend to collect serum and urine from the following patient groups:
4. Normal colonoscopy (n = 30)
5. Colorectal adenomas (n = 30)
6. Colorectal cancers (n = 30)
Primary outcome(s): Measured at baseline, using the expression of proteins in the tissue and serum to detect the cellular and systemic iron transport proteins. The techniques used will include mass spectrometry, western blotting, real time PCR and immunohistochemistry.
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Project description:Uncontrolled cell division is a hallmark of cancer. Deregulation of Wnt components has been linked to aberrant cell division by multiple mechanisms, including Wnt-mediated stabilization of proteins signalling, which was notably observed in mitosis. Analysis of Wnt components revealed an unexpected role of B-cell CLL/lymphoma 9 (BCL9) in maintaining mitotic Wnt signalling to promote precise cell division and growth of cancer cell. Mitotic interactome analysis revealed a mechanistic role of BCL9 in inhibiting Clathrin-mediated degradation of LRP6 signalosome components by interacting with Clathrin and the components in Wnt destruction complex; this function was further controlled by CDK1-driven phosphorylation of BCL9 N-terminal, especially T172. Interestingly, T172 phosphorylation was correlated with cancer patient prognosis and enriched in tumours. Thus, our results revealed a novel role of BCL9 in controlling mitotic Wnt signalling to promote cell division and growth.
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