Project description:The gene expression of mice with osteoblast-specific beta-catenin activation or FoxO1 deactivation are each compared to that of Wt. A. Wt mice (n=4) B. Osteoblast specific beta-catenin constitutively expressed mice (n=3) C. Osteoblast specific FoxO1 deleted mice (n=3)
Project description:The gene expression of mice with osteoblast-specific beta-catenin activation or FoxO1 deactivation are each compared to that of Wt.
Project description:The tumor suppressor gene adenomatous polyposis coli (APC) is mutated in most colorectal cancers (CRC) resulting in constitutive Wnt activation. To understand the Wnt-activating mechanism of APC mutation, we applied CRISPR/Cas9 technology to engineer various APC-truncated isogenic lines. We find that the β-catenin inhibitory domain (CID) in APC represents the threshold for pathological levels of Wnt activation and tumor transformation. Mechanistically, CID-deleted APC truncation promotes β-catenin deubiquitination through reverse binding of β-TrCP and USP7 to the destruction complex. USP7 depletion in APC-mutated CRC inhibits Wnt activation by restoring β-catenin ubiquitination, drives differentiation and suppresses xenograft tumor growth. Finally, the Wnt-activating role of USP7 is specific to APC mutations, thus can be used as tumor-specific therapeutic target for most CRCs.
Project description:We used RNA sequencing to compare the transcripts of the cochleae from control mice and from mice with β-catenin activation, Notch1 deletion, and β-catenin activation combined with Notch1 deletion in Sox2+ SCs. We identified the genes involved in the proliferation and transdifferentiation process that are either controlled by individual signaling pathways or by the combination of Wnt and Notch signaling.
Project description:The effect of liver specific deletion of the insulin receptor substrate-1 (Irs1) and/or Irs2 upon gene expression in the fasted and fed liver of mice; and the effect of liver specific Foxo1 deletion in the Irs1 and Irs2 knockout liver during fasting and feeding.
Project description:To identify novel transcriptional targets of beta-catenin and FoxO1 and FoxO3 in renal epithelial cells, we used conditionally immortalized murine proximal tubule (PT) cells (these cells, from Tgfbr2floxed mice, are described in detail in manuscript PMID: 23160515 in which Leslie Gewin is first author, JASN 2012). PT cells were either treated with Wnt3a (to activate beta-catenin) or the control diluting buffer, H2O2 to induce oxidative stress, and some were transfected with FoxO1, FoxO3, FoxO1 and 3, or scramble siRNA prior to Wnt and H2O2 treatment.
Project description:Activation of Wnt/β-catenin signaling is frequent in human and rodent hepatocarcinogenesis. Although in mice, the tumor promoting activity of agonists of constitutive androstane receptor (CAR) occurs via selection of carcinogen-initiated cells harbouring β-catenin mutations, the molecular alterations leading to hepatocellular carcinoma (HCC) development by The CAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP), in the absence of genotoxic injury are unknown. Here we show that CAR activation per se induced HCC in mice and that 91% of them carried β-catenin point mutations or large in-frame deletions/exon skipping targeting Ctnnb1 exon 3. Point mutations in HCCs induced by TCPOBOP alone displayed different nucleotide substitutions compared to those found in HCCs from mice pre-treated with diethylnitrosamine (DENA). Moreover, unlike those occurring in HCCs from DENA+TCPOBOP mice, they did not result in increased expression of β-catenin target genes, such as Glul, Lgr5, Rgn, Lect2 and Ccnd1, or nuclear translocation of β-catenin when compared to the control liver. Remarkably, in the non-tumoral liver tissue, chronic CAR activation led to down-regulation of these genes and to a partial loss of glutamine synthetase (GS)-positive hepatocytes. These results thus show that while chronic CAR activation per se induces HCCs carrying β-catenin mutations, it concurrently down-regulates the Wnt/β-catenin pathway in non-tumoral liver. They also indicate that the relationship between CAR and β-catenin may be profoundly different between normal and neoplastic hepatocytes.
Project description:Progression and disease relapse of chronic myeloid leukemia (CML) depends on leukemia-initiating cells (LIC) that resist treatment. Using mouse genetics, we observed that compound constitutive activation of β-catenin and deletion of Irf8 results in progression of CML-like disease into fatal blast crisis, elevated leukemic potential of BCR-ABL-induced LICs, and accumulation of Imatinib-resistant LICs in GMP-like populations. We found that progression of the disease is tightly connected to the magnitude of gene expression and that activated β-catenin enhances a pre-existing Irf8-deficient gene signature that was defined as a “progression specific signature” (PSS). We identified β-catenin as an amplifier of disease progression and as a critical step in the shift of CML to blast crisis. Collectively, our data uncover Irf8 as a roadblock for β-catenin-driven leukemia and imply both factors as targets in combinatorial therapy. We used microarrays to identify the gene expression signature in GMPs underlying CML-like disease progression and identified distinct classes of up- and down-regulated genes during this process defined as a “progression specific signature (PSS)”.
Project description:It has been shown that hypertrophic chondrocyte (HC) can become osteoblast, contributing to the formation of trabecular bone and endosteum. However, it is unclear what genes regulate the process of differentiation from chondrocyte to osteoblast. Conditional knock-out of β‑catenin in HCs can reduce the trabecular bone amount and there is also some evidence that ablation of β‑catenin in HCs can promote bone marrow adipogenesis. Conditional stabilization of β‑catenin in HCs results in osteopetrosis. In order to investigate the gene regulatory network with different dosage of β‑catenin in HC descendants (i.e. in Loss-of-Function mutant, Gain-of-Function mutant and Wildtype control), we collected HC descendant cells from proximal tibia of mice at postnatal day 5 and performed bulk RNA seq to profile the gene expression pattern in HC descendants.
Project description:Tubular injury and peripheral fibroblast activation are the hallmarks of chronic kidney disease (CKD) and renal fibrosis, suggesting intimate communication between the two diseases. However, the underlying mechanisms remain to be determined. Exosomes play a role in shuttling proteins and other materials to recipient cells. In our study, we found that tubular cell-derived exosomes were aroused by β-catenin in kidney fibrogenesis. Osteopontin (OPN), especially its N-terminal fragments (N-OPN), was encapsulated in β-catenin-controlled tubular cell-derived exosome cargo, and subsequently passed to fibroblasts. Through binding with CD44, exosomal OPN promoted fibroblast proliferation and activation. Gene deletion of β-catenin in tubular cells (Ksp-β-catenin−/−) or gene ablation of CD44 (CD44−/−) greatly ameliorated renal fibrosis. Notably, N-OPN was secreted by exosome into the urine of patients with CKD, and negatively correlated with kidney function. The urinary exosomes from patients with CKD greatly accelerated renal fibrosis, which was blocked by CD44 deletion. These results suggest that exosome-mediated activation of the OPN/CD44 axis plays a key role in renal fibrosis, which is controlled by β-catenin.
