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Zhou, Yi

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Zhou

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Yi

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Zhou, Yi

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Now showing 1 - 10 of 14
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    Zebrafish Globin Switching Occurs in Two Developmental Stages and Is Controlled by the LCR
    (Elsevier BV, 2012) Ganis, Jared Jason; Hsia, Nelson; Trompouki, Eirini; de Jong, Jill L.O.; DiBiase, Anthony; Lambert, Janelle S.; Jia, Zhiying; Sabo, Peter J.; Weaver, Molly; Sandstrom, Richard; Stamatoyannopoulos, John A.; Zhou, Yi; Zon, Leonard
    Globin gene switching is a complex, highly regulated process allowing expression of distinct globin genes at specific developmental stages. Here, for the first time, we have characterized all of the zebrafish globins based on the completed genomic sequence. Two distinct chromosomal loci, termed major (chromosome 3) and minor (chromosome 12), harbor the globin genes containing α/β pairs in a 5′–3′ to 3′–5′ orientation. Both these loci share synteny with the mammalian α-globin locus. Zebrafish globin expression was assayed during development and demonstrated two globin switches, similar to human development. A conserved regulatory element, the locus control region (LCR), was revealed by analyzing DNase I hypersensitive sites, H3K4 trimethylation marks and GATA1 binding sites. Surprisingly, the position of these sites with relation to the globin genes is evolutionarily conserved, despite a lack of overall sequence conservation. Motifs within the zebrafish LCR include CACCC, GATA, and NFE2 sites, suggesting functional interactions with known transcription factors but not the same LCR architecture. Functional homology to the mammalian α-LCR MCS-R2 region was confirmed by robust and specific reporter expression in erythrocytes of transgenic zebrafish. Our studies provide a comprehensive characterization of the zebrafish globin loci and clarify the regulation of globin switching.
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    High-Throughput Cell Transplantation Establishes That Tumor-Initiating Cells Are Abundant in Zebrafish T-Cell Acute Lymphoblastic Leukemia
    (American Society of Hematology, 2010) Smith, Alexandra C. H.; Raimondi, Aubrey R.; Salthouse, Chris D.; Ignatius, Myron S.; Blackburn, Jessica S.; Mizgirev, Igor V.; Storer, Narie Yoo; de Jong, Jill L. O.; Chen, Aye Tin Maung; Zhou, Yi; Revskoy, Sergei; Zon, Leonard; Langenau, David
    Self-renewal is a feature of cancer and can be assessed by cell transplantation into immune-compromised or immune-matched animals. However, studies in zebrafish have been severely limited by lack of these reagents. Here, Myc-induced T-cell acute lymphoblastic leukemias (T-ALLs) have been made in syngeneic, clonal zebrafish and can be transplanted into sibling animals without the need for immune suppression. These studies show that self-renewing cells are abundant in T-ALL and comprise 0.1% to 15.9% of the T-ALL mass. Large-scale single-cell transplantation experiments established that T-ALLs can be initiated from a single cell and that leukemias exhibit wide differences in tumor-initiating potential. T-ALLs also can be introduced into clonal-outcrossed animals, and T-ALLs arising in mixed genetic backgrounds can be transplanted into clonal recipients without the need for major histocompatibility complex matching. Finally, high-throughput imaging methods are described that allow large numbers of fluorescent transgenic animals to be imaged simultaneously, facilitating the rapid screening of engrafted animals. Our experiments highlight the large numbers of zebrafish that can be experimentally assessed by cell transplantation and establish new high-throughput methods to functionally interrogate gene pathways involved in cancer self-renewal.
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    A point mutation of zebrafish c-cbl gene in the ring finger domain produces a phenotype mimicking human myeloproliferative disease
    (Springer Nature, 2015) Peng, Xiaolan; Dong, M; Ma, L; Jia, X-E; Mao, J; Jin, C; Chen, Y; Gao, L; Liu, X; Ma, K; Wang, L; Du, T; Jin, Y; Huang, Q; Li, K; Zon, Leonard; Liu, T; Deng, M; Zhou, Y; Xi, X; Zhou, Yi; Chen, S
    Controlled self-renewal and differentiation of hematopoietic stem/progenitor cells (HSPCs) are critical for vertebrate development and survival. These processes are tightly regulated by the transcription factors, signaling molecules and epigenetic factors. Impaired regulations of their function could result in hematological malignancies. Using a large-scale zebrafish N-ethyl-N-nitrosourea mutagenesis screening, we identified a line named LDD731, which presented significantly increased HSPCs in hematopoietic organs. Further analysis revealed that the cells of erythroid/myeloid lineages in definitive hematopoiesis were increased while the primitive hematopoiesis was not affected. The homozygous mutation was lethal with a median survival time around 14-15 days post fertilization. The causal mutation was located by positional cloning in the c-cbl gene, the human ortholog of which, c-CBL, is found frequently mutated in myeloproliferative neoplasms (MPN) or acute leukemia. Sequence analysis showed the mutation in LDD731 caused a histidine-to-tyrosine substitution of the amino acid codon 382 within the RING finger domain of c-Cbl. Moreover, the myeloproliferative phenotype in zebrafish seemed dependent on the Flt3 (fms-like tyrosine kinase 3) signaling, consistent with that observed in both mice and humans. Our study may shed new light on the pathogenesis of MPN and provide a useful in vivo vertebrate model of this syndrome for screening drugs.Leukemia advance online publication, 14 July 2015; doi:10.1038/leu.2015.154.
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    Characterization of immune-matched hematopoietic transplantation in zebrafish
    (American Society of Hematology, 2011) de Jong, J. L. O.; Burns, Caroline; Chen, A. T.; Pugach, E.; Mayhall, E. A.; Smith, A. C. H.; Feldman, Henry; Zhou, Yi; Zon, Leonard
    Evaluating hematopoietic stem cell (HSC) function in vivo requires a long-term transplantation assay. Although zebrafish are a powerful model for discovering the genetics of hematopoiesis, hematopoietic transplantation approaches have been underdeveloped. Here we established a long-term reconstitution assay in adult zebrafish. Primary and secondary recipients showed multilineage engraftment at 3 months after transplantation. Limiting dilution data suggest that at least 1 in 65 000 zebrafish marrow cells contain repopulating activity, consistent with mammalian HSC frequencies. We defined zebrafish haplotypes at the proposed major histocompatibility complex locus on chromosome 19 and tested functional significance through hematopoietic transplantation. Matching donors and recipients dramatically increased engraftment and percentage donor chimerism compared with unmatched fish. These data constitute the first functional test of zebrafish histocompatibility genes, enabling the development of matched hematopoietic transplantations. This lays the foundation for competitive transplantation experiments with mutant zebrafish HSCs and chemicals to test for effects on engraftment, thereby providing a model for human hematopoietic diseases and treatments not previously available.
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    Allergic Lung Inflammation Aggravates Angiotensin II–Induced Abdominal Aortic Aneurysms in Mice
    (Ovid Technologies (Wolters Kluwer Health), 2015) Liu, Cong-Lin; Wang, Yi; Liao, Mengyang; Wemmelund, Holger; Ren, Jingyuan; Fernandes, Cleverson; Zhou, Yi; Sukhova, Galina; Lindholt, Jes S.; Johnsen, Søren P.; Zhang, Jin-Ying; Cheng, Xiang; Huang, Xiaozhu; Daugherty, Alan; Levy, Bruce; Libby, Peter; Shi, Guo-Ping
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    Activated N-Ras signaling regulates arterial-venous specification in zebrafish
    (BioMed Central, 2013) Ren, Chun-Guang; Wang, Lei; Jia, Xiao-E; Liu, Yi-Jie; Dong, Zhi-Wei; Jin, Yi; Chen, Yi; Deng, Min; Zhou, Yong; Zhou, Yi; Ren, Rui-Bao; Pan, Wei-Jun; Liu, Ting-Xi
    Background: The aberrant activation of Ras signaling is associated with human diseases including hematological malignancies and vascular disorders. So far the pathological roles of activated Ras signaling in hematopoiesis and vasculogenesis are largely unknown. Methods: A conditional Cre/loxP transgenic strategy was used to mediate the specific expression of a constitutively active form of human N-Ras in zebrafish endothelial and hematopoietic cells driven by the zebrafish lmo2 promoter. The expression of hematopoietic and endothelial marker genes was analyzed both via whole mount in situ hybridization (WISH) assay and real-time quantitative PCR (qPCR). The embryonic vascular morphogenesis was characterized both by living imaging and immunofluorescence on the sections with a confocal microscopy, and the number of endothelial cells in the embryos was quantified by flow cytometry. The functional analyses of the blood circulation were carried out by fluorescence microangiography assay and morpholino injection. Results: In the activated N-Ras transgenic embryos, the primitive hematopoiesis appeared normal, however, the definitive hematopoiesis of these embryos was completely absent. Further analysis of endothelial cell markers confirmed that transcription of arterial marker ephrinB2 was significantly decreased and expression of venous marker flt4 excessively increased, indicating the activated N-Ras signaling promotes the venous development at the expense of arteriogenesis during zebrafish embryogenesis. The activated N-Ras-expressing embryos showed atrophic axial arteries and expansive axial veins, leading to no definitive hematopoietic stem cell formation, the blood circulation failure and subsequently embryonic lethality. Conclusions: Our studies revealed for the first time that activated N-Ras signaling during the endothelial differentiation in vertebrates can disrupt the balance of arterial-venous specification, thus providing new insights into the pathogenesis of the congenital human vascular disease and tumorigenic angiogenesis.
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    The Histone Methyltransferase SUV39H1 Suppresses Embryonal Rhabdomyosarcoma Formation in Zebrafish
    (Public Library of Science, 2013) Albacker, Colleen Elizabeth; Storer, Narie Yoo; Langdon, Erin M.; DiBiase, Anthony; Zhou, Yi; Langenau, David; Zon, Leonard
    Epigenetics, or the reversible and heritable marks of gene regulation not including DNA sequence, encompasses chromatin modifications on both the DNA and histones and is as important as the DNA sequence itself. Chromatin-modifying factors are playing an increasingly important role in tumorigenesis, particularly among pediatric rhabdomyosarcomas (RMS), revealing potential novel therapeutic targets. We performed an overexpression screen of chromatin-modifying factors in a KRASG12D-driven zebrafish model for RMS. Here, we describe the identification of a histone H3 lysine 9 histone methyltransferase, SUV39H1, as a suppressor of embryonal RMS formation in zebrafish. This suppression is specific to the histone methyltransferase activity of SUV39H1, as point mutations in the SET domain lacked the effect. SUV39H1-overexpressing and control tumors have a similar proliferation rate, muscle differentiation state, and tumor growth rate. Strikingly, SUV39H1-overexpressing fish initiate fewer tumors, which results in the observed suppressive phenotype. We demonstrate that the delayed tumor onset occurs between 5 and 7 days post fertilization. Gene expression profiling at these stages revealed that in the context of KRASG12D overexpression, SUV39H1 may suppress cell cycle progression. Our studies provide evidence for the role of SUV39H1 as a tumor suppressor.
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    Mitochondrial Atpif1 regulates heme synthesis in developing erythroblasts
    (2012) Shah, Dhvanit I; Takahashi-Makise, Naoko; Cooney, Jeffrey D.; Li, Liangtao; Schultz, Iman J.; Pierce, Eric L.; Narla, Anupama; Seguin, Alexandra; Hattangadi, Shilpa M.; Medlock, Amy E.; Langer, Nathaniel B.; Dailey, Tamara A.; Hurst, Slater N.; Faccenda, Danilo; Wiwczar, Jessica M.; Heggers, Spencer K.; Vogin, Guillaume; Chen, Wen; Chen, Caiyong; Campagna, Dean R.; Brugnara, Carlo; Zhou, Yi; Ebert, Benjamin; Danial, Nika; Fleming, Mark; Ward, Diane M.; Campanella, Michelangelo; Dailey, Harry A.; Kaplan, Jerry; Paw, Barry Htin
    SUMMARY Defects in the availability of heme substrates or the catalytic activity of the terminal enzyme in heme biosynthesis, ferrochelatase (Fech), impair heme synthesis, and thus cause human congenital anemias1,2. The inter-dependent functions of regulators of mitochondrial homeostasis and enzymes responsible for heme synthesis are largely unknown. To uncover this unmet need, we utilized zebrafish genetic screens and cloned mitochondrial ATPase inhibitory factor 1 (atpif1) from a zebrafish mutant with profound anemia, pinotage (pnt tq209). We now report a direct mechanism establishing that Atpif1 regulates the catalytic efficiency of vertebrate Fech to synthesize heme. The loss of Atpif1 impairs hemoglobin synthesis in zebrafish, mouse, and human hematopoietic models as a consequence of diminished Fech activity, and elevated mitochondrial pH. To understand the relationship among mitochondrial pH, redox potential, [2Fe-2S] clusters, and Fech activity, we used (1) genetic complementation studies of Fech constructs with or without [2Fe-2S] clusters in pnt, and (2) pharmacological agents modulating mitochondrial pH and redox potential. The presence of [2Fe-2S] cluster renders vertebrate Fech vulnerable to Atpif1-regulated mitochondrial pH and redox potential perturbations. Therefore, Atpif1 deficiency reduces the efficiency of vertebrate Fech to synthesize heme, resulting in anemia. The novel mechanism of Atpif1 as a regulator of heme synthesis advances the understanding of mitochondrial heme homeostasis and red blood cell development. A deficiency of Atpif1 may contribute to important human diseases, such as congenital sideroblastic anemias and mitochondriopathies.
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    A Splice Site Mutation in Laminin-α2 Results in a Severe Muscular Dystrophy and Growth Abnormalities in Zebrafish
    (Public Library of Science, 2012) Gupta, Vandana; Kawahara, Genri; Myers, Jennifer A.; Chen, Aye T.; Hall, Thomas E.; Manzini, Maria Chiara; Currie, Peter D.; Zhou, Yi; Zon, Leonard; Kunkel, Louis; Beggs, Alan
    Congenital muscular dystrophy (CMD) is a clinically and genetically heterogeneous group of inherited muscle disorders. In patients, muscle weakness is usually present at or shortly after birth and is progressive in nature. Merosin deficient congenital muscular dystrophy (MDC1A) is a form of CMD caused by a defect in the laminin-α2 gene (LAMA2). Laminin-α2 is an extracellular matrix protein that interacts with the dystrophin-dystroglycan (DGC) complex in membranes providing stability to muscle fibers. In an N-ethyl-N-nitrosourea mutagenesis screen to develop zebrafish models of neuromuscular diseases, we identified a mutant fish that exhibits severe muscular dystrophy early in development. Genetic mapping identified a splice site mutation in the lama2 gene. This splice site is highly conserved in humans and this mutation results in mis-splicing of RNA and a loss of protein function. Homozygous lama2 mutant zebrafish, designated lama2cl501/cl501, exhibited reduced motor function and progressive degeneration of skeletal muscles and died at 8–15 days post fertilization. The skeletal muscles exhibited damaged myosepta and detachment of myofibers in the affected fish. Laminin-α2 deficiency also resulted in growth defects in the brain and eye of the mutant fish. This laminin-α2 deficient mutant fish represents a novel disease model to develop therapies for modulating splicing defects in congenital muscular dystrophies and to restore the muscle function in human patients with CMD.
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    Ccdc94 Protects Cells from Ionizing Radiation by Inhibiting the Expression of p53
    (Public Library of Science, 2012) Sorrells, Shelly; Carbonneau, Seth; Harrington, Erik; Chen, Aye T.; Hast, Bridgid; Milash, Brett; Major, Michael B.; Stewart, Rodney A.; Jette, Cicely; Pyati, Ujwal Jagdeesh; Zon, Leonard; Look, A.; Zhou, Yi
    DNA double-strand breaks (DSBs) represent one of the most deleterious forms of DNA damage to a cell. In cancer therapy, induction of cell death by DNA DSBs by ionizing radiation (IR) and certain chemotherapies is thought to mediate the successful elimination of cancer cells. However, cancer cells often evolve to evade the cytotoxicity induced by DNA DSBs, thereby forming the basis for treatment resistance. As such, a better understanding of the DSB DNA damage response (DSB–DDR) pathway will facilitate the design of more effective strategies to overcome chemo- and radioresistance. To identify novel mechanisms that protect cells from the cytotoxic effects of DNA DSBs, we performed a forward genetic screen in zebrafish for recessive mutations that enhance the IR–induced apoptotic response. Here, we describe radiosensitizing mutation 7 (rs7), which causes a severe sensitivity of zebrafish embryonic neurons to IR–induced apoptosis and is required for the proper development of the central nervous system. The rs7 mutation disrupts the coding sequence of ccdc94, a highly conserved gene that has no previous links to the DSB–DDR pathway. We demonstrate that Ccdc94 is a functional member of the Prp19 complex and that genetic knockdown of core members of this complex causes increased sensitivity to IR–induced apoptosis. We further show that Ccdc94 and the Prp19 complex protect cells from IR–induced apoptosis by repressing the expression of p53 mRNA. In summary, we have identified a new gene regulating a dosage-sensitive response to DNA DSBs during embryonic development. Future studies in human cancer cells will determine whether pharmacological inactivation of CCDC94 reduces the threshold of the cancer cell apoptotic response.