| Project/Area Number |
20790323
|
|---|
| Research Category |
Grant-in-Aid for Young Scientists (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Parasitology (including Sanitary zoology)
|
|---|
| Research Institution | National Institute of Infectious Diseases |
|---|
Principal Investigator |
TSUKUI Kumiko National Institute of Infectious Diseases, 寄生動物部, 主任研究官 (00420092)
|
|---|
| Project Period (FY) |
2008 – 2009
|
| Project Status |
Completed (Fiscal Year 2009)
|
| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2009: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2008: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
|
|---|
| Keywords | 原虫 / 感染症 / イノシトールリン脂質 / 小胞輸送 / 赤痢アメーバ / 貪食 / RhoGEF / Rac / PtdIns4P |
|---|
| Research Abstract |
To understand the roles of phosphoinositides [PtdIns] in phagocytosis of parasitic eukaryotes, we examined the interaction of phosphatidylinositol-3-phosphate [PtdIns(3)P] and putative PtdIns-P-binding proteins during phagocytosis in the enteric protozoan parasite Entamoeba histolytica. It was previously shown that phagocytosis in E. histolytica is indispensable for virulence and is inhibited by PtdIns 3-kinase inhibitors. We demonstrated by time-lapse live imaging that during the initiation of phagocytosis, the PtdIns(3)P biomarker GFP-Hrs-FYVE, was translocated to the phagocytic cup, phagosome, and to tunnel-like structures connecting the plasma membrane and phagosomes. E. histolytica possesses 12 FYVE domain-containing proteins (EhFP1-12), 11 of which also contain the RhoGEF/DH domain. Among them EhFP4 was shown to be recruited to the tunnel-like structures and to the proximal region of the phagosome. We further demonstrated that EhFP4 physically interacted with 4 of 10 predominant Rho/Rac small GTPases. Phosphoinositide binding assay showed that EhFP4 unexpectedly bound to PtdIns(4)P via the carboxyl-terminal domain and that the FYVE domain modulates the binding specificity of EhFP4 to PtdIns-P. Expression of the FYVE domain from EhFP4 inhibited phagocytosis while enhancement was observed when mammalian Hrs-FYVE domain was expressed. Altogether, we demonstrated that PtdIns(3)P, PtdIns(4)P and EhFP4 coordinately regulate phagocytosis and phagosome maturation in this parasitic eukaryote.
|
