Browsing by Subject "Gene Knockout Techniques"

Now showing 1 - 4 of 4
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    DOK2 inhibits EGFR-mutated lung adenocarcinoma.
    (PloS one, 2013-01) Berger, Alice H; Chen, Ming; Morotti, Alessandro; Janas, Justyna A; Niki, Masaru; Bronson, Roderick T; Taylor, Barry S; Ladanyi, Marc; Van Aelst, Linda; Politi, Katerina; Varmus, Harold E; Pandolfi, Pier Paolo
    Somatic mutations in the EGFR proto-oncogene occur in ~15% of human lung adenocarcinomas and the importance of EGFR mutations for the initiation and maintenance of lung cancer is well established from mouse models and cancer therapy trials in human lung cancer patients. Recently, we identified DOK2 as a lung adenocarcinoma tumor suppressor gene. Here we show that genomic loss of DOK2 is associated with EGFR mutations in human lung adenocarcinoma, and we hypothesized that loss of DOK2 might therefore cooperate with EGFR mutations to promote lung tumorigenesis. We tested this hypothesis using genetically engineered mouse models and find that loss of Dok2 in the mouse accelerates lung tumorigenesis initiated by oncogenic EGFR, but not that initiated by mutated Kras. Moreover, we find that DOK2 participates in a negative feedback loop that opposes mutated EGFR; EGFR mutation leads to recruitment of DOK2 to EGFR and DOK2-mediated inhibition of downstream activation of RAS. These data identify DOK2 as a tumor suppressor in EGFR-mutant lung adenocarcinoma.
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    Heme Oxygenase-1/Carbon Monoxide System and Embryonic Stem Cell Differentiation and Maturation into Cardiomyocytes.
    (Antioxid Redox Signal, 2016-03-01) Suliman, Hagir B; Zobi, Fabio; Piantadosi, Claude A
    AIMS: The differentiation of embryonic stem (ES) cells into energetically efficient cardiomyocytes contributes to functional cardiac repair and is envisioned to ameliorate progressive degenerative cardiac diseases. Advanced cell maturation strategies are therefore needed to create abundant mature cardiomyocytes. In this study, we tested whether the redox-sensitive heme oxygenase-1/carbon monoxide (HO-1/CO) system, operating through mitochondrial biogenesis, acts as a mechanism for ES cell differentiation and cardiomyocyte maturation. RESULTS: Manipulation of HO-1/CO to enhance mitochondrial biogenesis demonstrates a direct pathway to ES cell differentiation and maturation into beating cardiomyocytes that express adult structural markers. Targeted HO-1/CO interventions up- and downregulate specific cardiogenic transcription factors, transcription factor Gata4, homeobox protein Nkx-2.5, heart- and neural crest derivatives-expressed protein 1, and MEF2C. HO-1/CO overexpression increases cardiac gene expression for myosin regulatory light chain 2, atrial isoform, MLC2v, ANP, MHC-β, and sarcomere α-actinin and the major mitochondrial fusion regulators, mitofusin 2 and MICOS complex subunit Mic60. This promotes structural mitochondrial network expansion and maturation, thereby supporting energy provision for beating embryoid bodies. These effects are prevented by silencing HO-1 and by mitochondrial reactive oxygen species scavenging, while disruption of mitochondrial biogenesis and mitochondrial DNA depletion by loss of mitochondrial transcription factor A compromise infrastructure. This leads to failure of cardiomyocyte differentiation and maturation and contractile dysfunction. INNOVATION: The capacity to augment cardiomyogenesis via a defined mitochondrial pathway has unique therapeutic potential for targeting ES cell maturation in cardiac disease. CONCLUSION: Our findings establish the HO-1/CO system and redox regulation of mitochondrial biogenesis as essential factors in ES cell differentiation as well as in the subsequent maturation of these cells into functional cardiac cells.
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    In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K-AKT Signaling at Endosomes.
    (Cancer discovery, 2015-07) Li Chew, Chen; Lunardi, Andrea; Gulluni, Federico; Ruan, Daniel T; Chen, Ming; Salmena, Leonardo; Nishino, Michiya; Papa, Antonella; Ng, Christopher; Fung, Jacqueline; Clohessy, John G; Sasaki, Junko; Sasaki, Takehiko; Bronson, Roderick T; Hirsch, Emilio; Pandolfi, Pier Paolo
    The phosphatases PTEN and INPP4B have been proposed to act as tumor suppressors by antagonizing PI3K-AKT signaling and are frequently dysregulated in human cancer. Although PTEN has been extensively studied, little is known about the underlying mechanisms by which INPP4B exerts its tumor-suppressive function and its role in tumorigenesis in vivo. Here, we show that a partial or complete loss of Inpp4b morphs benign thyroid adenoma lesions in Pten heterozygous mice into lethal and metastatic follicular-like thyroid cancer (FTC). Importantly, analyses of human thyroid cancer cell lines and specimens reveal INPP4B downregulation in FTC. Mechanistically, we find that INPP4B, but not PTEN, is enriched in the early endosomes of thyroid cancer cells, where it selectively inhibits AKT2 activation and in turn tumor proliferation and anchorage-independent growth. We therefore identify INPP4B as a novel tumor suppressor in FTC oncogenesis and metastasis through localized regulation of the PI3K-AKT pathway at the endosomes.Although both PTEN and INPP4B can inhibit PI3K-AKT signaling through their lipid phosphatase activities, here we demonstrate lack of an epistatic relationship between the two tumor suppressors. Instead, the qualitative regulation of PI3K-AKT2 signaling by INPP4B provides a mechanism for their cooperation in suppressing thyroid tumorigenesis and metastasis.
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    The characterization of twenty sequenced human genomes.
    (PLoS Genet, 2010-09-09) Pelak, Kimberly; Shianna, Kevin V; Ge, Dongliang; Maia, Jessica M; Zhu, Mingfu; Smith, Jason P; Cirulli, Elizabeth T; Fellay, Jacques; Dickson, Samuel P; Gumbs, Curtis E; Heinzen, Erin L; Need, Anna C; Ruzzo, Elizabeth K; Singh, Abanish; Campbell, C Ryan; Hong, Linda K; Lornsen, Katharina A; McKenzie, Alexander M; Sobreira, Nara LM; Hoover-Fong, Julie E; Milner, Joshua D; Ottman, Ruth; Haynes, Barton F; Goedert, James J; Goldstein, David B
    We present the analysis of twenty human genomes to evaluate the prospects for identifying rare functional variants that contribute to a phenotype of interest. We sequenced at high coverage ten "case" genomes from individuals with severe hemophilia A and ten "control" genomes. We summarize the number of genetic variants emerging from a study of this magnitude, and provide a proof of concept for the identification of rare and highly-penetrant functional variants by confirming that the cause of hemophilia A is easily recognizable in this data set. We also show that the number of novel single nucleotide variants (SNVs) discovered per genome seems to stabilize at about 144,000 new variants per genome, after the first 15 individuals have been sequenced. Finally, we find that, on average, each genome carries 165 homozygous protein-truncating or stop loss variants in genes representing a diverse set of pathways.