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KMID : 0425120090470020117
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Parasites, Hosts and Diseases
2009 Volume.47 No. 2 p.117 ~ p.124
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IL-4 Independent Nuclear Translocalization of STAT6 in HeLa Cells by Entry of Toxoplasma gondii
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Ahn Hye-Jin
Kim Ji-Yeon
Nam Ho-Woo
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Abstract
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Toxoplasma gondii provokes rapid and sustained nuclear translocation of the signal transducer and activator of transcription 6 (STAT6) in HeLa cells. We observed activation of STAT6 as early as 2 hr after infection with T. gondii by the nuclear translocation of fluorescence expressed from exogenously transfected pDsRed2-STAT6 plasmid and by the detection of phosphotyrosine-STAT6 in Western blot. STAT6 activation occurred only by infection with live tachyzoites but not by co-culture with killed tachyzoites or soluble T. gondii extracts. STAT6 phosphorylation was inhibited by small interfering RNA of STAT6 (siSTAT6). In view of the fact that STAT6 is a central mediator of IL-4 induced gene expression, activation of STAT6 by T. gondii infection resembles that infected host cells has been stimulated by IL-4 treatment. STAT1 was affected to increase the transcription and expression by the treatment of siSTAT6. STAT6 activation was not affected by any excess SOCS’s whereas that with IL-4 was inhibited by SOCS-1 and SOCS-3. T. gondii infection induced Eotaxin-3 gene expression which was reduced by IFN-γ. These results demonstrate that T. gondii exploits host STAT6 to take away various harmful reactions by IFN-γ. This shows, for the first time, IL-4-like action by T. gondii infection modulates microbicidal action by IFN-γ in infected cells.
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KEYWORD
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Toxoplasma gondii, entry, STAT6 phosphorylation, nuclear translocation, STAT1, IL-4, IFN-γ
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