Abstract
Daxx has been shown to play an essential role in type I IFN-mediated suppression of B cell development and apoptosis. Recently, we demonstrated that Tyk2 is directly involved in IFN signaling for the induction and translocation of Daxx, which may result in growth arrest and/or apoptosis of B lymphocyte progenitors. To clarify the molecular mechanisms of how Daxx acts on growth suppression of B lymphocytes, we examined functions of a sumoylation-defective Daxx KA mutant (Daxx K630/631A), which substituted Lys 630 and Lys 631 to Ala. Importantly, Daxx KA localized in the cytoplasm, whereas wild-type Daxx localized in the nucleus. Murine pro-B cell line Ba/F3 expressing Daxx KA revealed a resistance to the IFN-induced growth suppression. It is noteworthy that treatment with an exportin inhibitor, leptomycin B, resulted in nuclear localization of Daxx KA and recovery of the IFN-induced growth suppression in Ba/F3 cells. Moreover, Daxx KA decreased the binding potential to promyelocytic leukemia protein (PML), and overexpression of PML recruited Daxx KA into PML oncogenic domains. Notably, a Daxx-small ubiquitin-related modifier fusion protein exhibited increased nuclear localization and ability to suppress cell growth in Ba/F3 cells. These results demonstrate that the IFN-induced growth suppression of B lymphocytes requires nuclear localization of Daxx through its sumoylation and proper interactions with PML.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus / genetics
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Alanine / genetics
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Amino Acid Substitution / genetics
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Animals
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B-Lymphocytes / cytology*
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B-Lymphocytes / metabolism*
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B-Lymphocytes / physiology
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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Carrier Proteins / physiology
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Cell Line
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Cell Line, Tumor
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Co-Repressor Proteins
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Cytoplasm / genetics
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Cytoplasm / metabolism
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Growth Inhibitors / antagonists & inhibitors
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Growth Inhibitors / physiology*
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HeLa Cells
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Humans
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Interferons / physiology*
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism*
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Intracellular Signaling Peptides and Proteins / physiology
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Lysine / genetics
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Mice
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Molecular Chaperones
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Neoplasm Proteins / metabolism
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Nuclear Proteins / physiology
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Promyelocytic Leukemia Protein
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Receptors, Glucocorticoid / physiology*
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Small Ubiquitin-Related Modifier Proteins / metabolism*
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Transcription Factors / metabolism
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Transcriptional Activation*
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Tumor Suppressor Proteins / metabolism
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Ubiquitin-Conjugating Enzymes / physiology
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Up-Regulation / physiology
Substances
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Carrier Proteins
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Co-Repressor Proteins
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Daxx protein, mouse
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Growth Inhibitors
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Intracellular Signaling Peptides and Proteins
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Molecular Chaperones
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Neoplasm Proteins
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Nuclear Proteins
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Pml protein, mouse
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Promyelocytic Leukemia Protein
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Receptors, Glucocorticoid
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Small Ubiquitin-Related Modifier Proteins
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Transcription Factors
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Tumor Suppressor Proteins
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PML protein, human
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Interferons
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Ubiquitin-Conjugating Enzymes
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ubiquitin-conjugating enzyme UBC9
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Lysine
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Alanine