Research Project
Grant-in-Aid for Scientific Research (C)
Recently, we found that Toxoplasma gondii produces a plant hormone, abscisic acid, and that it is essential for the infection of this parasite. So, we studied the effect of other plant hormones cytokinins on Toxoplasma gondii. We found that genes encoding the enzymes for the trans-zeatin biosynthesis in plants are present in T. gondii genome. Consistently, we detected intermediates for two possible trans-zeatin-biosynthesis pathways by MS analysis. A natural cytokinin, trans-zeatin, accelerated the proliferation of T. gondii. In contrast, a synthetic cytokinin, thidiazuron, inhibited the parasite proliferation in culture. This inhibition was also observed in laboratory animals. Since cytokinins regulate the cell cycle progression by enhancing the expression of D-type cyclin in plant, we carried out flowcytometric analysis to observe the effect of cytokinins on the cell cycle progression of T. gondii. Trans-zeatin hastened the cell cycle progression from G1 to S phase while thidiazuron caused the halt there. Quantitative-PCR(qPCR) analysis revealed that trans-zeatin upregulated the expression of one cyclin like as higher plant system, whereas thidiazuron downregulated its expression. These results suggest that this cyclin plays a crucial role in controlling the cell cycle progression in T. gondii and concomitantly its proliferation. Since cytokinins are also known to regulate chloroplast development in plants, we examined whether cytokinins affect apicoplast, which is a homologous organella to chloroplast in T. gondii. Immunofluorescence microscopy and qPCR analysis revealed trans-zeatin increased the number of apicoplasts but thidiazuron extinguished apicoplast. These result suggest that cytokinins are very important molecules to regulate the cell cycle of the parasite and division of apicoplast.
All 2012 2011 2010 2009 Other
All Journal Article (14 results) (of which Peer Reviewed: 7 results) Presentation (91 results) Remarks (1 results)
PLoS ONE
Volume: 7(3)
日生研たより
Volume: 58 Pages: 24-28
J.Exp.Med.
Volume: 208 Issue: 7 Pages: 1533-1546
10.1084/jem.20101660
公衆衛生
Volume: 76 Pages: 50-53
J. Exp. Med
Volume: 208 Pages: 1533-46
Biochem.Biophysic.Res.Comm.
Volume: 415 Issue: 2 Pages: 421-425
10.1016/j.bbrc.2011.10.085
Volume: 7 Issue: 3 Pages: e32246-e32246
10.1371/journal.pone.0032246
医事新報
Volume: 4489 Pages: 39-43
感染症・炎症・免疫
Volume: 40 Pages: 181-183
PNAS
Volume: 106 Pages: 12820-12825
蛋白質核酸酵素
Volume: 54 Pages: 1047-1052
Proceedings of the National Academy of Sciences of U.S.A. 106
Pages: 12820-12825
蛋白質・核酸・酵素 54
Pages: 1047-1052
医事新報 (印刷中)
http://web.me.com/nagamune/
