Project description:BACKGROUND: p53 is an important tumor suppressor with a known role in the later stages of colorectal cancer, but its relevance to the early stages of neoplastic initiation remains somewhat unclear. Although p53-dependent regulation of Wnt signalling activity is known to occur, the importance of these regulatory mechanisms during the early stages of intestinal neoplasia has not been demonstrated. METHODS: We have conditionally deleted the Adenomatous Polyposis coli gene (Apc) from the adult murine intestine in wild type and p53 deficient environments and subsequently compared the phenotype and transcriptome profiles in both genotypes. RESULTS: Expression of p53 was shown to be elevated following the conditional deletion of Apc in the adult small intestine. Furthermore, p53 status was shown to impact on the transcription profile observed following Apc loss. A number of key Wnt pathway components and targets were altered in the p53 deficient environment. However, the aberrant phenotype observed following loss of Apc (rapid nuclear localisation of beta-catenin, increased levels of DNA damage, nuclear atypia, perturbed cell death, proliferation, differentiation and migration) was not significantly altered by the absence of p53. CONCLUSION: p53 related feedback mechanisms regulating Wnt signalling activity are present in the intestine, and become activated following loss of Apc. However, the physiological Wnt pathway regulation by p53 appears to be overwhelmed by Apc loss and consequently the activity of these regulatory mechanisms is not sufficient to modulate the immediate phenotypes seen following Apc loss. Thus we are able to provide an explanation to the apparent contradiction that, despite having a Wnt regulatory capacity, p53 loss is not associated with early lesion development. Samples were collected from genetically modified mice. Gene recombination was induced using IP administration of beta-napthoflavone.
Project description:BACKGROUND: p53 is an important tumor suppressor with a known role in the later stages of colorectal cancer, but its relevance to the early stages of neoplastic initiation remains somewhat unclear. Although p53-dependent regulation of Wnt signalling activity is known to occur, the importance of these regulatory mechanisms during the early stages of intestinal neoplasia has not been demonstrated. METHODS: We have conditionally deleted the Adenomatous Polyposis coli gene (Apc) from the adult murine intestine in wild type and p53 deficient environments and subsequently compared the phenotype and transcriptome profiles in both genotypes. RESULTS: Expression of p53 was shown to be elevated following the conditional deletion of Apc in the adult small intestine. Furthermore, p53 status was shown to impact on the transcription profile observed following Apc loss. A number of key Wnt pathway components and targets were altered in the p53 deficient environment. However, the aberrant phenotype observed following loss of Apc (rapid nuclear localisation of beta-catenin, increased levels of DNA damage, nuclear atypia, perturbed cell death, proliferation, differentiation and migration) was not significantly altered by the absence of p53. CONCLUSION: p53 related feedback mechanisms regulating Wnt signalling activity are present in the intestine, and become activated following loss of Apc. However, the physiological Wnt pathway regulation by p53 appears to be overwhelmed by Apc loss and consequently the activity of these regulatory mechanisms is not sufficient to modulate the immediate phenotypes seen following Apc loss. Thus we are able to provide an explanation to the apparent contradiction that, despite having a Wnt regulatory capacity, p53 loss is not associated with early lesion development.
Project description:Vil-CreERT2 was used to drive loss of APC (Adenomatous polyposis coli) in the murine intestinal epithelium. 4 days post induction, mice were sampled and 1cm of tissue from the proximal intestine was collected into RNA later. This was compared to control (wild-type) intestine. This analysis allows investigation of transcriptional changes following APC loss (and therefore activation of the WNT signalling pathway).
Project description:Here we investigate the transcription changes in the murine intestine 4 days following loss of APC under the control of Vil-CreErT2 driver. We compare the RNAseq data from epithelial organoids generated from control (APC loss) intestines to organoids generated from lacking VAV2, VAV3 and TIAM1. We show that loss of these GEFs supress the APC WNT driven intestinal phenotype in a RAC-dependent manner.
Project description:Genome wide expression profiling to determine the overlap of Affymetrix-signals with SOLID sequencing RNA was extracted using the Qiagen RNeasy kit following the manufacturers guidelines, arrays were prepared and hybridized following the Affymetrix protocol. Mus musculus samples from small intestine and colon, to be compared to transcript data aquired with other techniques
Project description:Dysregulated Wnt signalling is seen in approximately 30% of hepatocellular cancers, thus finding pathways downstream of activation of Wnt signalling is key. Using cre lox technology we have deleted the the adenomatous polyposis coli tumour suppressor protein (Apc) within the adult mouse liver and observed a rapid increase in nuclear beta-catenin and C-Myc. This is associated with an induction of proliferation leading to hepatomegally within 4 days of gene deletion. To investigate the downstream pathways responsible for these phenotypes we analysed the impact of inactivating Apc in the context of deficiency of the potentially key effectors beta-catenin and c-Myc. beta-catenin loss rescues both the proliferation and hepatomegally phenotypes following Apc loss. However c-Myc deletion, which rescues the phenotypes of Apc loss in the intestine, had no effect on the phenotypes of Apc loss. The consequences of deregulation the Wnt pathway within the liver are therefore strikingly different to those observed within the intestine, with the vast majority of Wnt targets beta-catenin dependent but c-Myc independent in the liver. Samples were collected from Genetcially modified mice of the genotypes indicated in the characteristics field. Gene recombination was induced using IP administration of beta-napthoflavone. Cohorts of samples were used to compare the affects of APC loss, cMYC loss and combined APC and cMYC loss in the liver (and compared to matched control samples in which the genes were not recombined).
Project description:The ketogenic diet has been successful in promoting weight loss among patients that have struggled with weight gain. This is due to the cellular switch in metabolism that utilizes liver-derived ketone bodies for the primary energy source rather than glucose. Fatty acid transport protein 2 (FATP2) is highly expressed in liver, small intestine, and kidney where it functions in both the transport of exogenous long chain fatty acids (LCFA) and in the activation to CoA thioesters of very long chain fatty acids (VLCFA). We have completed a multi-omic study of FATP2-null (Fatp2-/-) mice maintained on a ketogenic diet (KD) or paired control diet (CD), with and without a 24-hour fast (KD-fasted and CD-fasted) to address the impact of deleting FATP2 under high-stress conditions. Control (wt/wt) and Fatp2-/- mice were maintained on their respective diets for 4-weeks. Afterwards, half the population was sacrificed while the remaining were fasted for 24-hours prior to sacrifice. We then performed paired-end RNA-sequencing on the whole liver tissue to investigate differential gene expression. The differentially expressed genes mapped to ontologies such as the metabolism of amino acids and derivatives, fatty acid metabolism, protein localization, and components of the immune system’s complement cascade, and were supported by the proteome and histological staining.