Differential effects of a novel IFN-zeta/limitin and IFN-alpha on signals for Daxx induction and Crk phosphorylation that couple with growth control of megakaryocytes.

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.

• 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)

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

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)