Abstract | OBJECTIVE: Although a novel IFN-zeta/ limitin uses IFN-alpha/beta receptor, it lacks some common activities of type I IFNs. We compared effects on megakaryocyte proliferation and differentiation as well as signals for their biological activities. MATERIALS AND METHODS: Recombinant IFN-zeta/ limitin and IFN-alpha titrated with a cytopathic effect dye binding assay, were used in this study. Colony assays and serum-free suspension cultures for megakaryocytes were performed to compare their growth inhibitory effects. To analyze signals, megakaryocytes cultured in serum-free suspension cultures were stimulated and Western blotted with the indicated antibody. RESULTS: Both IFN-zeta/ limitin and IFN-alpha suppressed the proliferation of megakaryocyte progenitors without influencing their differentiation. However, much higher concentrations of IFN-zeta/ limitin were required for the growth inhibition than IFN-alpha. The growth inhibition by IFN-zeta/ limitin and IFN-alpha was significantly reduced when either Tyk2 or STAT1 was disrupted. In addition, the antisense oligonucleotides against Crk and Daxx, downstream molecules of Tyk2, greatly rescued the IFN-zeta/ limitin- and IFN-alpha-induced reduction of megakaryocyte colony numbers. In cultured megakaryocytes, IFN-zeta/ limitin induced the expression of SOCS-1 as strongly as IFN-alpha. However, IFN-zeta/ limitin induced weaker phosphorylation of Crk and lower induction of Daxx than IFN-alpha. CONCLUSIONS: Weaker signals for Crk and Daxx may participate in less megakaryocyte suppressive activity of IFN-zeta/ limitin and may distinguish IFN-zeta/ limitin from IFN-alpha in megakaryocytes. Our results extend the understanding about thrombocytopenia in patients with IFN-alpha treatment as well as the possibility for the clinical application of human homologue of IFN-zeta/ limitin or an engineered cytokine with useful features of the IFN-zeta/ limitin structure.
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Authors | Naoko Ishida, Kenji Oritani, Masamichi Shiraga, Hitoshi Yoshida, Sin-Ichiro Kawamoto, Hidetoshi Ujiie, Hiroaki Masaie, Michiko Ichii, Yoshiaki Tomiyama, Yuzuru Kanakura |
Journal | Experimental hematology
(Exp Hematol)
Vol. 33
Issue 4
Pg. 495-503
(Apr 2005)
ISSN: 0301-472X [Print] Netherlands |
PMID | 15781341
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Adaptor Proteins, Signal Transducing
- Carrier Proteins
- Co-Repressor Proteins
- Crk protein, mouse
- Cytokines
- Daxx protein, mouse
- Interferon-alpha
- Intracellular Signaling Peptides and Proteins
- Molecular Chaperones
- Nuclear Proteins
- Proto-Oncogene Proteins c-crk
- limitin
- Interferons
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Topics |
- Adaptor Proteins, Signal Transducing
(metabolism)
- Animals
- Carrier Proteins
(genetics)
- Cell Proliferation
(drug effects)
- Cells, Cultured
- Co-Repressor Proteins
- Cytokines
(pharmacology)
- Gene Expression Regulation
(drug effects)
- Interferon-alpha
(pharmacology)
- Interferons
(pharmacology)
- Intracellular Signaling Peptides and Proteins
(genetics)
- Megakaryocytes
(cytology, drug effects, metabolism)
- Mice
- Mice, Inbred C57BL
- Molecular Chaperones
- Nuclear Proteins
(genetics)
- Phosphorylation
- Proto-Oncogene Proteins c-crk
- Signal Transduction
(drug effects)
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