title: Inositol 1,4,5-trisphosphate receptor determines intracellular Ca2+concentration inTrypanosoma cruzithroughout its life cycle.
abstract: Regulation of intracellular Ca2+concentration ([Ca2+]i) is vital for eukaryotic organisms. Recently, we identified a Ca2+channel (TcIP3R) associated with intracellular Ca2+stores inTrypanosoma cruzi, the parasitic protist that causes Chagas disease. In this study, we measured [Ca2+]iduring the parasite life cycle and determined whether TcIP3R is involved in the observed variations. Parasites expressing R-GECO1, a red fluorescent, genetically encoded Ca2+indicator for optical imaging that fluoresces when bound to Ca2+, were produced. Using these R-GECO1-expressing parasites to measure [Ca2+]i, we found that the [Ca2+]iin epimastigotes was significantly higher than that in trypomastigotes and lower than that in amastigotes, and we observed a positive correlation betweenTcIP3RmRNA expression and [Ca2+]iduring the parasite life cycle bothin vitroandin vivo. We also generated R-GECO1-expressing parasites with TcIP3R expression levels that were approximately 65% of wild-type (wt) levels (SKO parasites), and [Ca2+]iin the wt and SKO parasites was compared. The [Ca2+]iin SKO parasites was reduced to approximately 50-65% of that in wt parasites. These results show that TcIP3R is the determinant of [Ca2+]iinT. cruzi. Since Ca2+signaling is vital for these parasites, TcIP3R is a promising drug target for Chagas disease.
authors.affiliation: Department of Molecular and Cellular Parasitology Juntendo University School of Medicine Tokyo Japan; Health Research Institute AIST Takamatsu Kagawa Japan.
authors.forename: Muneaki
authors.initials: M
authors.lastname: Hashimoto
authors.affiliation: Biomedical Research Institute AIST Tsukuba Ibaraki Japan.
authors.forename: Motomichi
authors.initials: M
authors.lastname: Doi
authors.affiliation: Department of Pharmacology Juntendo University School of Medicine Tokyo Japan.
authors.forename: Nagomi
authors.initials: N
authors.lastname: Kurebayashi
authors.affiliation: Biomedical Research Institute AIST Tsukuba Ibaraki Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Furukawa
authors.affiliation: Department of Molecular and Cellular Parasitology Juntendo University School of Medicine Tokyo Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hirawake-Mogi
authors.affiliation: Biomedical Research Institute AIST Tsukuba Ibaraki Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ohmiya
authors.affiliation: Department of Pharmacology Juntendo University School of Medicine Tokyo Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakurai
authors.affiliation: Department of Molecular and Cellular Parasitology Juntendo University School of Medicine Tokyo Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Mita
authors.affiliation: Laboratory for Developmental Neurobiology RIKEN Brain Science Institute Saitama Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
authors.affiliation: Department of Molecular and Cellular Parasitology Juntendo University School of Medicine Tokyo Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nara
keywords: IP3 receptor; Trypanosoma cruzi; intracellular Ca2+ concentration; life cycle; live cell Imaging