Expression data of liver tissue from wild type and Cdc42 liver-specific knockout mice at 2-month-old
Ontology highlight
ABSTRACT: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death. However, the mechanism for HCC initiation remains poorly known. Cdc42, a small Rho GTPase, with multiple cellular functions has been shown involved in variant types of human cancers, but its role in HCC initiation remains unclear. Cdc42 liver-specific knockout mice (Cdc42LK) developed HCC at 6-month-old. We used microarrays to detail the global programme of gene expression induced by Cdc42 deletion and identified distinct classes of up or down-regulated genes during HCC initial time.
Project description:Epithelial polarity is controlled by a polarity machinery including the Rho GTPase CDC42 and Scribble/PAR. By using intestinal stem cell (ISC)-specific deletion of CDC42 in Olfm4-IRES-eGFPCreERT2;CDC42flox/flox mice, we found that ISC-initiated CDC42 loss caused a drastic hyper-proliferation of transit amplifying (TA) cells and disrupted epithelial polarity. CDC42-null crypts displayed expanded TA cell and diminished ISC populations, accompanied by elevated hippo signaling via YAP/TAZ - Ereg and mTOR activation, independent from canonical Wnt signaling. YAP/TAZ conditional knockout restored the balance of ISC/TA cell populations and crypt proliferation but did not rescue the polarity in CDC42-null small intestine. mTOR or EGFR inhibitor treatment of CDC42 KO mice exhibited similar rescuing effects without affecting YAP/TAZ signaling. Inducible ablation of Scribble in intestinal epithelial cells mimics that of CDC42 KO defects including crypt hyperplasia and hippo signaling activation. Mammalian epithelial polarity regulates ISC and TA cell fate and proliferation via a hippo-Ereg-mTOR cascade.
Project description:Cell division cycle 42 (Cdc42) is a member of the Rho GTPase family and has pivotal functions in actin organization, cell migration and proliferation. Cdc42 has been shown to regulate antigen (Ag)-uptake in immature dendritic cells (DC) and controls their migration from tissues to lymph nodes. Previous reports demonstrated that Cdc42 is inactivated upon DC-maturation to avoid continued Ag-acquisition. To further study the molecular mechanisms of DC-control by Cdc42, we used bone marrow-derived DCs from Cdc42-deficient mice. We show that Cdc42-deficient DCs are phenotypically mature without additional maturation stimuli, as they upregulate CD86 from intracellular storages to the cell surface. They also accumulate invariant chain (Ii)-MHC class II complexes at the cell surface, which cannot efficiently present peptide Ag for priming of Ag-specific CD4 T cells. Lack of Cdc42 in immature DCs does not allow MHC class II maturation, as lysosomal Cathepsins are lost into the supernatant and Ii-MHC class II complexes cannot mature. Therefore Cdc42-deficient DCs are "pseudomature" and lose most functional hallmarks of antigen-presenting cells. Our results propose that Cdc42 keeps DCs in an immature state, while downregulation of Cdc42-activity during maturation facilitates generation of CD86+MHCII+ mature DCs.
Project description:ARHGEF4 expression is associated with t(12;21) acute lymphoblastic leukaemia (ALL). Our study investigated the substrate specificity of ARHGEF4, a member of the diffuse B-cell lymphoma (DBL) family of guanine nucleotide exchange factors (GEFs), in t(12;21) ALL REH cells. ARHGEF4 was found to activate the small guanine nucleotide binding protein (GTPase) CDC42. In order to determine the function of CDC42 in t(12;21) ALL cells, we performed RNAseq analysis on REH cells treated for 24 hours with DMSO vehicle control in comparison to 25uM ML141, a CDC42 inhibitor.
Project description:We previously identified inactivating mutations in roundabout guidance receptor 1 (ROBO1) in patients with myelodysplastic syndrome (MDS), which was associated with poor prognosis and susceptibility to acute myeloid leukemia (AML) transformation. Nonetheless, the exact role of ROBO1 in hematopoiesis remains poorly delineated. Here we report that the ablation of Robo1 in mice is sufficient to confer MDS-like disease with anemia and multilineage dysplasia. More specifically, Robo1 deficiency impairs the self-renewal and differentiation capacity of hematopoietic stem progenitor cells (HSPCs) and disrupts HSPC pool, especially the reduction of megakaryocyte erythroid progenitors (MEPs), which causes a blockage in the early stages of erythropoiesis in mice. Similarly, Robo1-deficienct HSPCs recapitulated MDS-like disease with anemia and multilineage dysplasia in transplanted mice. Correspondingly, clinical data also reveal that low expression of ROBO1 is associated with shortened survival, severe anemia and a high risk of AML transformation in patients with MDS. Mechanistically, transcriptional profiling indicates that Cdc42, a member of the Rho-GTPase family, serves as a downstream target gene for Robo1 in HSPCs. Overexpression of Cdc42 partially restores the proliferation of erythroid colonies in Robo1 deficient mice. In contrast, Cdc42 inhibitor (CASIN) effectively attenuates the erythroid colony formation of HSPCs. Collectively, our results suggest that Robo1 deficiency may provide a promising therapeutic target against MDS by impairing HSPC self-renewal and erythropoiesis via CDC42, predicting a poor prognosis for severe anemia and a high risk of AML transformation in MDS.
Project description:Aim of study was to determine what was causing the liver tumors in the SART1+/- mice HAF (SART1) is an oxygen-independent ubiquitin ligase for HIF-1α whose physiological role is unknown. Here we show that HAF knockout mice are embryonic lethal suggesting an essential developmental role. Additionally, male SART1+/- mice spontaneously developed hepatocellular carcinoma (HCC) preceded by steatosis, enhanced liver-neutrophil infiltration and upregulation of HIF-1α in peripheral and liver-infiltrating immune cells. From a cytokine array, we identified a marked (>100-fold) increase in the HIF-1 dependent chemokine, RANTES from SART1+/- -derived Kupffer cells compared to wild-type. Inhibition of RANTES decreased liver neutrophil infiltration, and HCC tumor initiation and growth in SART1+/- mice. These findings establish new roles for HAF in metabolism and immune cell function, and identify RANTES as a novel target for the treatment of HCC.
Project description:The human transcriptome contains thousands of small open reading frames (sORFs) that encode microproteins whose functions remain largely unexplored. Here, we show that TINCR lncRNA encodes pTINCR, an evolutionary conserved ubiquitin-like protein (UBL) expressed in many epithelia and upregulated upon differentiation and under cellular stress. By gain- and loss-of-function studies, we demonstrate that pTINCR is a key inducer of epithelial differentiation in vitro and in vivo. Interestingly, low expression of TINCR associates with worse prognosis in several epithelial cancers, and pTINCR overexpression reduces malignancy in patient-derived xenografts. At the molecular level, pTINCR binds to SUMO through its SUMO interacting motif (SIM) and to CDC42, a Rho-GTPase critical for actin cytoskeleton remodeling and epithelial differentiation. Moreover, pTINCR increases CDC42 SUMOylation and promotes its activation, triggering a pro-differentiation cascade. Our findings suggest that the microproteome is a source of new regulators of cell identity relevant for cancer.
Project description:Influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. Although signals/sequences in NA for translocation, sorting and raft association have been identified, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. In this report, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. Interestingly, expression of constitutively active Cdc42 or depletion of the Cdc42-specific GAP, ARHGAP21, promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targrting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Furthermore, silencing of Cdc42 or ARHGAP21 had significant effects on influenza A virus replication. Together, our results reveal that ARHGAP21 and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication. This microarray experiment was carried out to find out whether Cdc42 and ARHGAP21 expression levels in A549 cell were changed after WSN infection. Total RNAs were extracted from three different groups of A549 cells that had been infected with or without WSN for 10 h, using TRIzol reagent (Invitrogen, Carlsbad, CA). Samples were amplified and labeled using a NimbleGen One-Color DNA Labeling Kit.
Project description:Treg cells play an important role in immune tolerance and tumor immune evasion through suppression of effector T cells. Treg cell lineage instability may be harnessed to trigger anti-tumor T cell immunity. However, the mechanism underlying Treg cell stability remains poorly understand. By characterizing Treg cell-specific heterozygous and homozygous Cdc42 knockout mice, we found that Cdc42 is essential for Treg cell stability. By RNA sequencing of heterozygous and homozygous Cdc42 knockout Treg cells, we found that Cdc42 maintains Treg cell stability through suppression of carbonic anhydrase I (CAI) expression.
Project description:The human transcriptome contains thousands of small open reading frames (sORFs) that have been largely overlooked because of their small size. Some of these sORFs code for bioactive small proteins although none have been associated to the regulation of cell identity. Here, we show that TINCR lncRNA encodes pTINCR, an evolutionary conserved ubiquitin-like protein with a SUMO interacting motif (SIM) that is expressed in many epithelia. pTINCR binds to SUMO and modifies global cell SUMOylation patterns. One of its main targets is CDC42, a Rho-GTPase critical for actin cytoskeleton remodeling and for epidermal differentiation. pTINCR increases CDC42 SUMOylation and promotes its activation in a SIM-dependent manner. pTINCR is necessary and sufficient for epithelial cell differentiation in vitro, and promotes epidermal differentiation in vivo. Consistent with its pro-differentiation role, pTINCR expression is lost in human cutaneous squamous cell carcinomas (cSCC), and its overexpression reduces cSCC growth in vitro and in vivo. Moreover, pTINCR is a target of the tumor suppressor p53, and the expression of pTINCR in epithelial cancers correlates with better prognosis. Our results identify pTINCR as a novel regulator of epithelial differentiation with tumor suppressor activity. More generally, our findings suggest that the proteome encoded by previously assumed non-coding RNAs can indeed be a source of new regulators of cell identity relevant for cancer.