Project description:To investigate the trancriptomic changes of endothelial cells (ECs) by Nf2/Merlin, Lewis Lung Carcinoma (LLC) tumor ECs from Ctrl and NF2 KO mice were sorted by FACS and single-cell RNA seq was performed.
Project description:Understanding of transciptome changes of endothelial cells (ECs) in mouse brain by Nf2/Merlin is unknown. Here, we performed bulk RNA sequencing to investigate the changes of expression patterns by Nf2/Merlin deletion in mouse brain ECs
Project description:Neurofibromatosis type 2 is an inherited neoplastic disease consisting of schwannomas, meningiomas, and ependymomas that is caused by inactivation of the tumor suppressor gene NF2. The NF2 gene product, merlin, has no intrinsic catalytic activity; its tumor suppressor function is mediated through the proteins with which it interacts. However, there is no consensus about which merlin interactions are necessary for tumor suppression. We used proximity biotinylation followed by mass spectrometry and direct binding assays to characterize the proteins that associate with merlin and merlin mutants in immortalized Schwann cells. We identified 52 proteins that associate with merlin, including a previously unreported merlin binding protein, ASPP2. Our results identify merlin as a component of mechanosensing signal transduction pathways in cell junctions, in the context of a specific set of structures and molecules through which it acts, in a cell type relevant to schwannoma formation.
Project description:Merlin is the tumor suppressor protein encoded by the NF2 gene. The expression of Merlin is remarkably decreased in metastatic breast cancer tissues irrespective of the breast cancer subtype. In order to ascribe clinical relevance, we re-capitulated the loss of Merlin in breast cancer cells. Merlin deficiency elicited a markedly invasive phenotype. In order to overcome the challenge of embryonic lethality of a total Nf2-knockout, we generated a unique mammary-specific Nf2-knockout mouse mammary tumor model. Both, the Nf2-knockout mouse embryonic fibroblasts (MEF) and Merlin-deficient breast tumor cells displayed a robust invasive phenotype. Transcriptomic assessment of Nf2-knockout MEFs revealed notable alterations in glutathione transferase and antioxidant networks indicating a role for Merlin in redox biology. This programmatic alteration resonated with the pathways that emerged from breast tumor cells engineered for Merlin deficiency.
Project description:The transcriptional coactivator YAP is the key downstream effector of the Hippo pathway. YAP overexpression in the developing mouse brain results in excessive expansion of the neural progenitor pool and severe perturbation of brain development. Nf2/Merlin is a tumor suppressor whose mutations are found in many human cancers. Loss of Merlin during brain development causes overexpansion of the neural progenitor pool. We used microarrays to identify the gene expression changes caused by YAP overexpression and Nf2 deletion. We used a double-transgenic system to overexpress YAP in the developing mouse brain by crossing mice carrying a doxycycline-dependent allele of YAP1-S127A (TetO-YAP1) with those expressing the reverse tetracycline-dependent transactivator rtTA under the control of the neural progenitor-specific Nestin promoter (Nes-rtTA) and feeding the dam with doxycycline-containing food (200 mg/kg) from E7.5. We conditionally deleted Nf2 using the telencephalon-specific Emx1-Cre.
Project description:The transcriptional coactivator YAP is the key downstream effector of the Hippo pathway. YAP overexpression in the developing mouse brain results in excessive expansion of the neural progenitor pool and severe perturbation of brain development. Nf2/Merlin is a tumor suppressor whose mutations are found in many human cancers. Loss of Merlin during brain development causes overexpansion of the neural progenitor pool. We used microarrays to identify the gene expression changes caused by YAP overexpression and Nf2 deletion.
Project description:Current models imply that the FERM domain protein Merlin, encoded by the tumor suppressor NF2, inhibits mitogenic signaling at or near the plasma membrane. Here, we show that the closed, growth inhibitory form of Merlin accumulates in the nucleus, binds to the E3 ubiquitin ligase CRL4DCAF1, and suppresses its activity. Depletion of DCAF1 blocks the promitogenic effect of inactivation of Merlin. Conversely, enforced expression of a Merlin-insensitive mutant of DCAF1 counteracts the antimitogenic effect of Merlin. Re-expression of Merlin and silencing of DCAF1 induce a similar, tumor-suppressive program of gene expression. Tumor-derived mutations invariably disrupt Merlinâs ability to interact with or inhibit CRL4DCAF1. Finally, depletion of DCAF1 inhibits the hyperproliferation of Schwannoma cells from NF2 patients and suppresses the oncogenic potential of Merlin-deficient tumor cell lines. We propose that Merlin suppresses tumorigenesis by translocating to the nucleus to inhibit CRL4DCAF1. To examine if Merlin controls gene expression through inhibition of CRL4DCAF1, and define the general function of this ligase, we compared the gene expression program activated by expression of Merlin or by depletion of DCAF1 in Merlin-null FC-1801 mouse Schwannoma cells
Project description:Current models imply that the FERM domain protein Merlin, encoded by the tumor suppressor NF2, inhibits mitogenic signaling at or near the plasma membrane. Here, we show that the closed, growth inhibitory form of Merlin accumulates in the nucleus, binds to the E3 ubiquitin ligase CRL4DCAF1, and suppresses its activity. Depletion of DCAF1 blocks the promitogenic effect of inactivation of Merlin. Conversely, enforced expression of a Merlin-insensitive mutant of DCAF1 counteracts the antimitogenic effect of Merlin. Re-expression of Merlin and silencing of DCAF1 induce a similar, tumor-suppressive program of gene expression. Tumor-derived mutations invariably disrupt Merlin’s ability to interact with or inhibit CRL4DCAF1. Finally, depletion of DCAF1 inhibits the hyperproliferation of Schwannoma cells from NF2 patients and suppresses the oncogenic potential of Merlin-deficient tumor cell lines. We propose that Merlin suppresses tumorigenesis by translocating to the nucleus to inhibit CRL4DCAF1.
Project description:The NF2 gene, which encodes the Merlin protein, is a bona fide tumor suppressor whose mutations underlie inherited tumor syndrome Neurofibromatosis Type 2 (NF2). Recent large-scale genome sequencing studies have also identified NF2 as one of the most frequently mutated genes in VHL-wild-type kidney cancers. Even though a wide array of downstream signaling pathways has been described for Merlin/NF2, the molecular mechanisms underpinning the growth and survival of NF2 mutant tumors remain poorly understood. Using an inducible orthotopic kidney tumor model, we demonstrate for the first time that silencing of YAP/TAZ is sufficient to induce regression of pre-established NF2 deficient kidney tumors. Mechanistically, we show that YAP/TAZ ablation severely diminishes glycolysis by downregulating the transcription of several glycolytic enzymes and growth factors and RTK-PI3K-AKT signaling, resulting in growth arrest. On the other hand, YAP/TAZ depletion significantly increases mitochondrial respiration and overproduction of mitochondrial ROS, resulting in redox imbalance and oxidative stress cell death when challenged by nutrient stress. Furthermore, we identify lysosome-mediated cAMP-PKA/EPACdependent activation of the RAF-MEK-ERK pathway to be a novel resistance mechanism that allows NF2 deficient tumor cells to survive YAP/TAZ inhibition in vitro and in vivo. Finally, unbiased analysis of TCGA primary kidney tumor transcriptomes confirms strong correlations of a YAP/TAZ signature with the expression of glycolysis, oxidative phosphorylation and lysosomal genes, validating the clinical relevance of our findings.
Project description:Studies in drosophila have suggested that Merlin/NF2 suppresses tumorigenesis by activating upstream components of the Hippo pathway at or near the plasma membrane. In contrast, studies of Merlin-deficient tumor cells have indicated that Merlin suppresses tumorigenesis by entering into the nucleus where it inhibits the E3 ubiquitin ligase CRL4DCAF1. We found that CRL4DCAF1 promotes YAP and TEAD-dependent transcription by ubiquitylating and thereby inhibiting Lats1 and 2 in the nucleus. Genetic epistasis experiments and analysis of tumor-derived missense mutations indicate that this signaling connection sustains the oncogenicity of Merlin-deficient tumor cells. Analysis of clinical samples confirms that this pathway operates in NF2 mutant mesotheliomas, schwannomas and meningiomas. We conclude that de-repressed CRL4DCAF1 controls the output of the Hippo pathway by inhibiting Lats1 and 2 in the nucleus.