Abstract
Activation of Janus kinase 2 (JAK2) by chromosomal translocations or point mutations is a frequent event in haematological malignancies. JAK2 is a non-receptor tyrosine kinase that regulates several cellular processes by inducing cytoplasmic signalling cascades. Here we show that human JAK2 is present in the nucleus of haematopoietic cells and directly phosphorylates Tyr 41 (Y41) on histone H3. Heterochromatin protein 1alpha (HP1alpha), but not HP1beta, specifically binds to this region of H3 through its chromo-shadow domain. Phosphorylation of H3Y41 by JAK2 prevents this binding. Inhibition of JAK2 activity in human leukaemic cells decreases both the expression of the haematopoietic oncogene lmo2 and the phosphorylation of H3Y41 at its promoter, while simultaneously increasing the binding of HP1alpha at the same site. Tauhese results identify a previously unrecognized nuclear role for JAK2 in the phosphorylation of H3Y41 and reveal a direct mechanistic link between two genes, jak2 and lmo2, involved in normal haematopoiesis and leukaemia.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Animals
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Binding Sites
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Cell Line
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Cell Nucleus / enzymology
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Chromatin / chemistry
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Chromatin / metabolism*
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Chromobox Protein Homolog 5
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Chromosomal Proteins, Non-Histone / metabolism*
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DNA-Binding Proteins / genetics
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Gene Expression Regulation, Neoplastic
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Hematopoiesis / genetics
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Hematopoietic Stem Cells / cytology
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Hematopoietic Stem Cells / enzymology
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Histones / chemistry
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Histones / genetics
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Histones / metabolism*
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Humans
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Janus Kinase 2 / antagonists & inhibitors
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Janus Kinase 2 / metabolism*
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LIM Domain Proteins
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Leukemia / enzymology
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Leukemia / genetics
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Leukemia / metabolism
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Leukemia / pathology
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Metalloproteins / genetics
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Mice
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Oncogenes / genetics
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Phosphorylation
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Promoter Regions, Genetic / genetics
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Protein Binding
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Proto-Oncogene Proteins
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Signal Transduction
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Tyrosine / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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CBX1 protein, human
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CBX5 protein, human
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Chromatin
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Chromosomal Proteins, Non-Histone
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DNA-Binding Proteins
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Histones
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LIM Domain Proteins
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LMO2 protein, human
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Metalloproteins
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Proto-Oncogene Proteins
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Chromobox Protein Homolog 5
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Tyrosine
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JAK2 protein, human
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Janus Kinase 2