title: Dual observation of the ATP-evoked small GTPase activation and Ca2+transient in astrocytes using a dark red fluorescent protein.
abstract: Intracellular signal transduction involves a number of biochemical reactions, which largely consist of protein-protein interactions and protein conformational changes. Monitoring Förster resonance energy transfer (FRET) by fluorescence lifetime imaging microscopy (FLIM), called FLIM-FRET, is one of the best ways to visualize such protein dynamics. Here, we attempted to apply dark red fluorescent proteins with significantly smaller quantum yields. Application of the dark mCherry mutants to single-molecule FRET sensors revealed that these dark mCherry mutants are a good acceptor in a pair with mRuby2. Because the FRET measurement between mRuby2 and dark mCherry requires only the red region of wavelengths, it facilitates dual observation with other signaling sensors such as genetically encoded Ca2+sensors. Taking advantage of this approach, we attempted dual observation of Ca2+and Rho GTPase (RhoA and Cdc42) activities in astrocytes and found that ATP triggers both RhoA and Cdc42 activation. In early phase, while Cdc42 activity is independent of Ca2+transient evoked by ATP, RhoA activity is Ca2+dependent. Moreover, the transient Ca2+upregulation triggers long-lasting Cdc42 and RhoA activities, thereby converting short-term Ca2+signaling to long-term signaling. Thus, the new FRET pair should be useful for dual observation of intracellular biochemical reactions.
authors.affiliation: Division of Homeostatic Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Nakahata
authors.affiliation: Division of Homeostatic Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan.|Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8585, Japan.|Core Research for Evolutional Science and Technology, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Nabekura
authors.affiliation: Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8585, Japan.|Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan.|Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Hideji
authors.initials: H
authors.lastname: Murakoshi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001253:Astrocytes / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D020549:GTP Phosphohydrolase Activators / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*; D000097573:Red Fluorescent Protein
chemical_list: D000255:Adenosine Triphosphate; D002118:Calcium; D020549:GTP Phosphohydrolase Activators; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D020764:cdc42 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D000097573:Red Fluorescent Protein; C000626589:CDC42 protein, human