title: Photobleaching-based quantitative analysis of fluorescence resonance energy transfer inside single living cell.
abstract: The current advances of fluorescence microscopy and new fluorescent probes make fluorescence resonance energy transfer (FRET) a powerful technique for studying protein-protein interactions inside living cells. It is very hard to quantitatively analyze FRET efficiency using intensity-based FRET imaging microscopy due to the presence of autofluorescence and spectral crosstalks. In this study, we for the first time developed a novel photobleaching-based method to quantitatively detect FRET efficiency (Pb-FRET) by selectively photobleaching acceptor. The Pb-FRET method requires two fluorescence detection channels: a donor channel (CH ( 1 )) to selectively detect the fluorescence from donor, and a FRET channel (CH ( 2 )) which normally includes the fluorescence from both acceptor and donor due to emission spectral crosstalk. We used the Pb-FRET method to quantitatively measure the FRET efficiency of SCAT3, a caspase-3 indicator based on FRET, inside single living cells stably expressing SCAT3 during STS-induced apoptosis. At 0, 6 and 12 h after STS treatment, the FRET efficiency of SCAT3 obtained by Pb-FRET inside living cells was verified by two-photon excitation (TPE) fluorescence lifetime imaging microscopy (FLIM). The temporal resolution of Pb-FRET method is in second time-scale for ROI photobleaching, even in microsecond time-scale for spot photobleaching. Our results demonstrate that the Pb-FRET method is independent of photobleaching degree, and is very useful for quantitatively monitoring protein-protein interactions inside single living cell.
authors: MOE Key laboratory of Laser Life Science & Institute of Laser Life Science, South China Normal University, Guangzhou, 510631, China.
authors: Longxiang
authors: L
authors: Wang
authors: Tongsheng
authors: T
authors: Chen
authors: Junle
authors: J
authors: Qu
authors: Xunbin
authors: X
authors: Wei
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D038761:Photobleaching; D019311:Staurosporine / Q000494:pharmacology
chemical_list: D005456:Fluorescent Dyes; D053148:Caspase 3; D019311:Staurosporine