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  • 1
    Publication Date: 2010-03-27
    Description: Leukemia stem cells (LSCs) are capable of limitless self-renewal and are responsible for the maintenance of leukemia. Because selective eradication of LSCs could offer substantial therapeutic benefit, there is interest in identifying the signaling pathways that control their development. We studied LSCs in mouse models of acute myelogenous leukemia (AML) induced either by coexpression of the Hoxa9 and Meis1a oncogenes or by the fusion oncoprotein MLL-AF9. We show that the Wnt/beta-catenin signaling pathway is required for self-renewal of LSCs that are derived from either hematopoietic stem cells (HSC) or more differentiated granulocyte-macrophage progenitors (GMP). Because the Wnt/beta-catenin pathway is normally active in HSCs but not in GMP, these results suggest that reactivation of beta-catenin signaling is required for the transformation of progenitor cells by certain oncogenes. beta-catenin is not absolutely required for self-renewal of adult HSCs; thus, targeting the Wnt/beta-catenin pathway may represent a new therapeutic opportunity in AML.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084586/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084586/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, Yingzi -- Krivtsov, Andrei V -- Sinha, Amit U -- North, Trista E -- Goessling, Wolfram -- Feng, Zhaohui -- Zon, Leonard I -- Armstrong, Scott A -- 5P01CA66996/CA/NCI NIH HHS/ -- 5R01HL048801/HL/NHLBI NIH HHS/ -- P01 CA066996/CA/NCI NIH HHS/ -- P01 CA066996-11A1/CA/NCI NIH HHS/ -- R01 HL048801/HL/NHLBI NIH HHS/ -- R01 HL048801-16/HL/NHLBI NIH HHS/ -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2010 Mar 26;327(5973):1650-3. doi: 10.1126/science.1186624.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Hematology/Oncology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20339075" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Proliferation ; Cell Transformation, Neoplastic ; Genes, Homeobox ; Granulocyte-Macrophage Progenitor Cells/metabolism/pathology ; Hematopoietic Stem Cells/*metabolism/pathology ; Homeodomain Proteins/genetics ; Indomethacin/pharmacology ; Leukemia, Myeloid, Acute/*metabolism/*pathology ; Mice ; Mice, Inbred C57BL ; Neoplasm Proteins/genetics ; Neoplastic Stem Cells/*pathology ; *Signal Transduction ; Transduction, Genetic ; Wnt Proteins/*metabolism ; beta Catenin/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-03-06
    Description: Generation of induced pluripotent stem cells (iPSCs) by somatic cell reprogramming involves global epigenetic remodelling. Whereas several proteins are known to regulate chromatin marks associated with the distinct epigenetic states of cells before and after reprogramming, the role of specific chromatin-modifying enzymes in reprogramming remains to be determined. To address how chromatin-modifying proteins influence reprogramming, we used short hairpin RNAs (shRNAs) to target genes in DNA and histone methylation pathways, and identified positive and negative modulators of iPSC generation. Whereas inhibition of the core components of the polycomb repressive complex 1 and 2, including the histone 3 lysine 27 methyltransferase EZH2, reduced reprogramming efficiency, suppression of SUV39H1, YY1 and DOT1L enhanced reprogramming. Specifically, inhibition of the H3K79 histone methyltransferase DOT1L by shRNA or a small molecule accelerated reprogramming, significantly increased the yield of iPSC colonies, and substituted for KLF4 and c-Myc (also known as MYC). Inhibition of DOT1L early in the reprogramming process is associated with a marked increase in two alternative factors, NANOG and LIN28, which play essential functional roles in the enhancement of reprogramming. Genome-wide analysis of H3K79me2 distribution revealed that fibroblast-specific genes associated with the epithelial to mesenchymal transition lose H3K79me2 in the initial phases of reprogramming. DOT1L inhibition facilitates the loss of this mark from genes that are fated to be repressed in the pluripotent state. These findings implicate specific chromatin-modifying enzymes as barriers to or facilitators of reprogramming, and demonstrate how modulation of chromatin-modifying enzymes can be exploited to more efficiently generate iPSCs with fewer exogenous transcription factors.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3501145/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3501145/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Onder, Tamer T -- Kara, Nergis -- Cherry, Anne -- Sinha, Amit U -- Zhu, Nan -- Bernt, Kathrin M -- Cahan, Patrick -- Marcarci, B Ogan -- Unternaehrer, Juli -- Gupta, Piyush B -- Lander, Eric S -- Armstrong, Scott A -- Daley, George Q -- CA140575/CA/NCI NIH HHS/ -- R24 DK092760/DK/NIDDK NIH HHS/ -- U01 HL100001/HL/NHLBI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2012 Mar 4;483(7391):598-602. doi: 10.1038/nature10953.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Stem Cell Transplantation Program, Division of Pediatric Hematology and Oncology, Manton Center for Orphan Disease Research, Children's Hospital Boston and Dana Farber Cancer Institute, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22388813" target="_blank"〉PubMed〈/a〉
    Keywords: *Cellular Reprogramming/genetics ; Chromatin/genetics/*metabolism ; DNA Methylation/genetics ; DNA-Binding Proteins/antagonists & inhibitors/metabolism ; Fibroblasts/cytology/metabolism ; Histones/metabolism ; Homeodomain Proteins/metabolism ; Humans ; Induced Pluripotent Stem Cells/*cytology/*metabolism ; Kruppel-Like Transcription Factors/metabolism ; Methylation ; Methyltransferases/antagonists & inhibitors/biosynthesis/genetics/metabolism ; Polycomb Repressive Complex 2 ; Polycomb-Group Proteins ; Proto-Oncogene Proteins c-myc/metabolism ; RNA, Small Interfering ; RNA-Binding Proteins/metabolism ; Repressor Proteins/antagonists & inhibitors/metabolism ; Transcription Factors/antagonists & inhibitors/metabolism ; YY1 Transcription Factor/antagonists & inhibitors/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2012-03-06
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 4
    Publication Date: 2012-03-28
    Description: A growing body of data suggests the importance of epigenetic mechanisms in cancer. Polycomb repressive complex 2 (PRC2) has been implicated in self-renewal and cancer progression, and its components are overexpressed in many cancers. However, its role in cancer development and progression remains unclear. We used conditional alleles for the PRC2 components enhancer of zeste 2 (Ezh2) and embryonic ectoderm development (Eed) to characterize the role of PRC2 function in leukemia development and progression. Compared with wild-type leukemia, Ezh2-null MLL-AF9–mediated acute myeloid leukemia (AML) failed to accelerate upon secondary transplantation. However, Ezh2-null leukemias maintained self-renewal up to the third round of transplantation, indicating that Ezh2 is not strictly required for MLL-AF9 AML, but plays a role in leukemia progression. Genome-wide analyses of PRC2-mediated trimethylation of histone 3 demonstrated locus-specific persistence of H3K27me3 despite inactivation of Ezh2, suggesting partial compensation by Ezh1. In contrast, inactivation of the essential PRC2 gene, Eed, led to complete ablation of PRC2 function, which was incompatible with leukemia growth. Gene expression array analyses indicated more profound gene expression changes in Eed-null compared with Ezh2-null leukemic cells, including down-regulation of Myc target genes and up-regulation of PRC2 targets. Manipulating PRC2 function may be of therapeutic benefit in AML.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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