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  • 1
    Publication Date: 2011-12-07
    Description: Ablation of the kinases Mst1 and Mst2, orthologs of the Drosophila antiproliferative kinase Hippo, from mouse intestinal epithelium caused marked expansion of an undifferentiated stem cell compartment and loss of secretory cells throughout the small and large intestine. Although median survival of mice lacking intestinal Mst1/Mst2 is 13 wk, adenomas of the distal colon are common by this age. Diminished phosphorylation, enhanced abundance, and nuclear localization of the transcriptional coactivator Yes-associated protein 1 (Yap1) is evident in Mst1/Mst2-deficient intestinal epithelium, as is strong activation of β-catenin and Notch signaling. Although biallelic deletion of Yap1 from intestinal epithelium has little effect on intestinal development, inactivation of a single Yap1 allele reduces Yap1 polypeptide abundance to nearly wild-type levels and, despite the continued Yap hypophosphorylation and preferential nuclear localization, normalizes epithelial structure. Thus, supraphysiologic Yap polypeptide levels are necessary to drive intestinal stem cell proliferation. Yap is overexpressed in 68 of 71 human colon cancers and in at least 30 of 36 colon cancer-derived cell lines. In colon-derived cell lines where Yap is overabundant, its depletion strongly reduces β-catenin and Notch signaling and inhibits proliferation and survival. These findings demonstrate that Mst1 and Mst2 actively suppress Yap1 abundance and action in normal intestinal epithelium, an antiproliferative function that frequently is overcome in colon cancer through Yap1 polypeptide overabundance. The dispensability of Yap1 in normal intestinal homeostasis and its potent proliferative and prosurvival actions when overexpressed in colon cancer make it an attractive therapeutic target.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 2
    Publication Date: 2008-02-19
    Description: MicroRNAs are abundant in animal genomes and have been predicted to have important roles in a broad range of gene expression programmes. Despite this prominence, there is a dearth of functional knowledge regarding individual mammalian microRNAs. Using a loss-of-function allele in mice, we report here that the myeloid-specific microRNA-223 (miR-223) negatively regulates progenitor proliferation and granulocyte differentiation and activation. miR-223 (also called Mirn223) mutant mice have an expanded granulocytic compartment resulting from a cell-autonomous increase in the number of granulocyte progenitors. We show that Mef2c, a transcription factor that promotes myeloid progenitor proliferation, is a target of miR-223, and that genetic ablation of Mef2c suppresses progenitor expansion and corrects the neutrophilic phenotype in miR-223 null mice. In addition, granulocytes lacking miR-223 are hypermature, hypersensitive to activating stimuli and display increased fungicidal activity. As a consequence of this neutrophil hyperactivity, miR-223 mutant mice spontaneously develop inflammatory lung pathology and exhibit exaggerated tissue destruction after endotoxin challenge. Our data support a model in which miR-223 acts as a fine-tuner of granulocyte production and the inflammatory response.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnnidis, Jonathan B -- Harris, Marian H -- Wheeler, Robert T -- Stehling-Sun, Sandra -- Lam, Michael H -- Kirak, Oktay -- Brummelkamp, Thijn R -- Fleming, Mark D -- Camargo, Fernando D -- England -- Nature. 2008 Feb 28;451(7182):1125-9. doi: 10.1038/nature06607. Epub 2008 Feb 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18278031" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Cell Differentiation ; *Cell Proliferation ; Gene Deletion ; Granulocytes/*cytology/immunology/pathology/*physiology ; Inflammation/genetics/immunology/pathology ; Lung/pathology ; MEF2 Transcription Factors ; Mice ; Mice, Knockout ; MicroRNAs/*genetics/*metabolism ; Myogenic Regulatory Factors/genetics/metabolism ; Neutrophils/physiology ; Phenotype ; Stem Cells/*cytology
    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: 2008-08-01
    Description: MicroRNAs are endogenous approximately 23-nucleotide RNAs that can pair to sites in the messenger RNAs of protein-coding genes to downregulate the expression from these messages. MicroRNAs are known to influence the evolution and stability of many mRNAs, but their global impact on protein output had not been examined. Here we use quantitative mass spectrometry to measure the response of thousands of proteins after introducing microRNAs into cultured cells and after deleting mir-223 in mouse neutrophils. The identities of the responsive proteins indicate that targeting is primarily through seed-matched sites located within favourable predicted contexts in 3' untranslated regions. Hundreds of genes were directly repressed, albeit each to a modest degree, by individual microRNAs. Although some targets were repressed without detectable changes in mRNA levels, those translationally repressed by more than a third also displayed detectable mRNA destabilization, and, for the more highly repressed targets, mRNA destabilization usually comprised the major component of repression. The impact of microRNAs on the proteome indicated that for most interactions microRNAs act as rheostats to make fine-scale adjustments to protein output.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745094/" 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/PMC2745094/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Baek, Daehyun -- Villen, Judit -- Shin, Chanseok -- Camargo, Fernando D -- Gygi, Steven P -- Bartel, David P -- R01 GM067031/GM/NIGMS NIH HHS/ -- R01 HG003456/HG/NHGRI NIH HHS/ -- R01 HG003456-04A1/HG/NHGRI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Sep 4;455(7209):64-71. doi: 10.1038/nature07242. Epub 2008 Jul 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18668037" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Gene Expression Regulation ; HeLa Cells ; Humans ; Isotope Labeling ; Male ; Mice ; MicroRNAs/*genetics/*metabolism ; Neutrophils/metabolism ; Oligonucleotide Array Sequence Analysis ; *Protein Biosynthesis ; Proteomics ; Transfection
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2012-11-28
    Description: A remarkable feature of regenerative processes is their ability to halt proliferation once an organ's structure has been restored. The Wnt signalling pathway is the major driving force for homeostatic self-renewal and regeneration in the mammalian intestine. However, the mechanisms that counterbalance Wnt-driven proliferation are poorly understood. Here we demonstrate in mice and humans that yes-associated protein 1 (YAP; also known as YAP1)--a protein known for its powerful growth-inducing and oncogenic properties--has an unexpected growth-suppressive function, restricting Wnt signals during intestinal regeneration. Transgenic expression of YAP reduces Wnt target gene expression and results in the rapid loss of intestinal crypts. In addition, loss of YAP results in Wnt hypersensitivity during regeneration, leading to hyperplasia, expansion of intestinal stem cells and niche cells, and formation of ectopic crypts and microadenomas. We find that cytoplasmic YAP restricts elevated Wnt signalling independently of the AXIN-APC-GSK-3beta complex partly by limiting the activity of dishevelled (DVL). DVL signals in the nucleus of intestinal stem cells, and its forced expression leads to enhanced Wnt signalling in crypts. YAP dampens Wnt signals by restricting DVL nuclear translocation during regenerative growth. Finally, we provide evidence that YAP is silenced in a subset of highly aggressive and undifferentiated human colorectal carcinomas, and that its expression can restrict the growth of colorectal carcinoma xenografts. Collectively, our work describes a novel mechanistic paradigm for how proliferative signals are counterbalanced in regenerating tissues. Additionally, our findings have important implications for the targeting of YAP in human malignancies.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3536889/" 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/PMC3536889/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barry, Evan R -- Morikawa, Teppei -- Butler, Brian L -- Shrestha, Kriti -- de la Rosa, Rosemarie -- Yan, Kelley S -- Fuchs, Charles S -- Magness, Scott T -- Smits, Ron -- Ogino, Shuji -- Kuo, Calvin J -- Camargo, Fernando D -- 1K08DK096048/DK/NIDDK NIH HHS/ -- 1U01DK085527/DK/NIDDK NIH HHS/ -- AR064036/AR/NIAMS NIH HHS/ -- K08 DK096048/DK/NIDDK NIH HHS/ -- P01CA87969/CA/NCI NIH HHS/ -- P30 DK049216/DK/NIDDK NIH HHS/ -- P50CA127003/CA/NCI NIH HHS/ -- R01 AR064036/AR/NIAMS NIH HHS/ -- R01 CA131426/CA/NCI NIH HHS/ -- R01 CA151993/CA/NCI NIH HHS/ -- R01 DK091427/DK/NIDDK NIH HHS/ -- U01 DK085527/DK/NIDDK NIH HHS/ -- England -- Nature. 2013 Jan 3;493(7430):106-10. doi: 10.1038/nature11693. Epub 2012 Nov 25.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Stem Cell Program and Department of Hematology/Oncology, Children's Hospital, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23178811" target="_blank"〉PubMed〈/a〉
    Keywords: Active Transport, Cell Nucleus ; Adaptor Proteins, Signal Transducing/deficiency/genetics/*metabolism ; Animals ; *Cell Proliferation ; Colorectal Neoplasms/genetics/metabolism/pathology ; Genes, Tumor Suppressor ; Humans ; Intestines/*cytology/physiology ; Mice ; Mice, Knockout ; Neoplasm Transplantation ; Phosphoproteins/deficiency/genetics/*metabolism ; Regeneration/*physiology ; Stem Cell Niche ; Stem Cells/*cytology/*metabolism ; Thrombospondins/genetics/metabolism ; Tumor Suppressor Proteins/genetics/metabolism ; Wnt Proteins/metabolism ; Wnt Signaling Pathway
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
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  • 5
    Publication Date: 2014-10-09
    Description: It is currently thought that life-long blood cell production is driven by the action of a small number of multipotent haematopoietic stem cells. Evidence supporting this view has been largely acquired through the use of functional assays involving transplantation. However, whether these mechanisms also govern native non-transplant haematopoiesis is entirely unclear. Here we have established a novel experimental model in mice where cells can be uniquely and genetically labelled in situ to address this question. Using this approach, we have performed longitudinal analyses of clonal dynamics in adult mice that reveal unprecedented features of native haematopoiesis. In contrast to what occurs following transplantation, steady-state blood production is maintained by the successive recruitment of thousands of clones, each with a minimal contribution to mature progeny. Our results demonstrate that a large number of long-lived progenitors, rather than classically defined haematopoietic stem cells, are the main drivers of steady-state haematopoiesis during most of adulthood. Our results also have implications for understanding the cellular origin of haematopoietic disease.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4408613/" 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/PMC4408613/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sun, Jianlong -- Ramos, Azucena -- Chapman, Brad -- Johnnidis, Jonathan B -- Le, Linda -- Ho, Yu-Jui -- Klein, Allon -- Hofmann, Oliver -- Camargo, Fernando D -- DP2 OD006472/OD/NIH HHS/ -- DP2OD006472/OD/NIH HHS/ -- P30 DK049216/DK/NIDDK NIH HHS/ -- England -- Nature. 2014 Oct 16;514(7522):322-7. doi: 10.1038/nature13824. Epub 2014 Oct 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Stem Cell Program, Children's Hospital, Boston, Massachusetts 02115, USA [2] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA [3] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA. ; Stem Cell Program, Children's Hospital, Boston, Massachusetts 02115, USA. ; Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts 02115, USA. ; Department of Immunology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. ; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA. ; Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25296256" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Aging ; *Cell Lineage ; Clone Cells/*cytology/metabolism ; DNA Transposable Elements/genetics ; Female ; Genetic Markers/genetics ; *Hematopoiesis ; Hematopoietic Stem Cell Transplantation ; Hematopoietic Stem Cells/cytology/metabolism ; Male ; Mice ; Myelopoiesis ; Staining and Labeling ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
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  • 6
    Publication Date: 2002-02-05
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 7
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  • 9
    Publication Date: 2012-02-15
    Description: Heart growth is tightly controlled so that the heart reaches a predetermined size. Fetal heart growth occurs through cardiomyocyte proliferation, whereas postnatal heart growth involves primarily physiological cardiomyocyte hypertrophy. The Hippo kinase cascade is an important regulator of organ growth. A major target of this kinase cascade is YAP1, a transcriptional coactivator that is inactivated by Hippo kinase activity. Here, we used both genetic gain and loss of Yap1 function to investigate its role in regulating proliferative and physiologic hypertrophic heart growth. Fetal Yap1 inactivation caused marked, lethal myocardial hypoplasia and decreased cardiomyocyte proliferation, whereas fetal activation of YAP1 stimulated cardiomyocyte proliferation. Enhanced proliferation was particularly dramatic in trabecular cardiomyocytes that normally exit from the cell cycle. Remarkably, YAP1 activation was sufficient to stimulate proliferation of postnatal cardiomyocytes, both in culture and in the intact heart. A dominant negative peptide that blocked YAP1 binding to TEAD transcription factors inhibited YAP1 proliferative activity, indicating that this activity requires YAP1–TEAD interaction. Although Yap1 was a critical regulator of cardiomyocyte proliferation, it did not influence physiological hypertrophic growth of cardiomyocytes, because postnatal Yap1 gain or loss of function did not significantly alter cardiomyocyte size. These studies demonstrate that Yap1 is a crucial regulator of cardiomyocyte proliferation, cardiac morphogenesis, and myocardial trabeculation. Activation of Yap1 in postnatal cardiomyocytes may be a useful strategy to stimulate cardiomyocyte expansion in therapeutic myocardial regeneration.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 10
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