Project description:The impact of WNT signalling activity on the acquisition and restriction of lineage propensity of germ layer progenitors and the gene network activity for cell fate decision during the development of the embryonic head was modelled in the epiblast stem cells derived and maintained under different signalling conditions. Our findings showed that the modulation of WNT activity is critical for the specification of the anterior (head) tissue progenitors in the multipotent early epiblast and the repression of WNT activity enhances the ectoderm lineage potency of the epiblast cells and poises the activation of endogenous WNT activity that drives neurogenesis during head morphogenesis.
Project description:The modulation of WNT activity is critical for the specification of the anterior (head) tissue progenitors in the multipotent early epiblast and the repression of WNT activity enhances the ectoderm lineage potency of the epiblast cells and poises the activation of endogenous WNT activity that drives neurogenesis during head morphogenesis.
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.
Project description:During gastrulation, epiblast cells are pluripotent and their fate is thought to be constrained principally by their position. Cell fate is progressively restricted by localised signalling cues from areas including the primitive streak (PS). However, it is unknown whether this restriction accompanies, at the single cell level, a reduction in potency. Investigation of these early transition events in vitro is possible via the use of Epiblast Stem Cells (EpiSCs), self-renewing pluripotent cell lines equivalent to the postimplantation epiblast. Strikingly, EpiSCs express various early lineage-specific markers in self-renewing conditions. However, it is unknown whether cells that express these markers are pluripotent, spontaneously differentiated, or biased towards specific lineages. Here we show that EpiSC are inherently heterogeneous and contain two major and mutually exclusive subpopulations with PS and neural characteristics respectively. Using differentiation assays and embryo grafting we demonstrate that PS-like EpiSCs are biased towards mesoderm and endoderm differentiation but they still retain their pluripotent character. The acquisition of a PS character by undifferentiated EpiSC is mediated by paracrine Wnt signalling. Elevation of Wnt activity promotes further restriction into PS-associated cell fates which occurs via the generation of distinct clonal mesendodermal and neuromesodermal precursors. Collectively, our data suggest that primed pluripotency encompasses a range of reversible lineage-biased states reflecting the birth of pioneer lineage precursors from a pool of uncommitted EpiSCs similar to the earliest cell fate restriction events taking place in the gastrula-stage epiblast. Total RNA obtained (3 biological replicates) from flow sorted dsRed2+, dsRed2-, and +CHIRON treated for 48h cells was isolated and labelled/amplified using the IlluminaM-BM-. TotalPrepM-bM-^DM-" RNA Amplification Kit (Life Technologies)
Project description:During gastrulation, epiblast cells are pluripotent and their fate is thought to be constrained principally by their position. Cell fate is progressively restricted by localised signalling cues from areas including the primitive streak (PS). However, it is unknown whether this restriction accompanies, at the single cell level, a reduction in potency. Investigation of these early transition events in vitro is possible via the use of Epiblast Stem Cells (EpiSCs), self-renewing pluripotent cell lines equivalent to the postimplantation epiblast. Strikingly, EpiSCs express various early lineage-specific markers in self-renewing conditions. However, it is unknown whether cells that express these markers are pluripotent, spontaneously differentiated, or biased towards specific lineages. Here we show that EpiSC are inherently heterogeneous and contain two major and mutually exclusive subpopulations with PS and neural characteristics respectively. Using differentiation assays and embryo grafting we demonstrate that PS-like EpiSCs are biased towards mesoderm and endoderm differentiation but they still retain their pluripotent character. The acquisition of a PS character by undifferentiated EpiSC is mediated by paracrine Wnt signalling. Elevation of Wnt activity promotes further restriction into PS-associated cell fates which occurs via the generation of distinct clonal mesendodermal and neuromesodermal precursors. Collectively, our data suggest that primed pluripotency encompasses a range of reversible lineage-biased states reflecting the birth of pioneer lineage precursors from a pool of uncommitted EpiSCs similar to the earliest cell fate restriction events taking place in the gastrula-stage epiblast.
Project description:The function of the FAM83F protein, like the functions of many members of the FAM83 family, is poorly understood. Here we show that injection of Fam83f mRNA into Xenopus embryos causes axis duplication, a phenotype indicative of enhanced Wnt signalling. Consistent with this, overexpression of FAM83F activates Wnt signalling, whilst ablation of FAM83F from human colorectal cancer (CRC) cells attenuates it. We demonstrate that FAM83F is farnesylated and interacts and co-localises with CK1α at the plasma membrane. This interaction with CK1α is essential for FAM83F to activate Wnt signalling, and FAM83F mutants that do not interact with CK1α fail to induce axis duplication in Xenopus embryos and to activate Wnt signalling in cells. FAM83F acts upstream of GSK-3β, because the attenuation of Wnt signalling caused by loss of FAM83F can be rescued by GSK-3 inhibition. Introduction of a farnesyl-deficient mutant of FAM83F in cells through CRISPR/Cas9 genome editing redirects the FAM83F-CK1α complex away from the plasma membrane and significantly attenuates Wnt signalling, indicating that FAM83F exerts its effects on Wnt signalling at the plasma membrane.