Picosecond-resolution fluorescence lifetime imaging microscopy:: a useful tool for sensing molecular interactions in vivo via FRET

Fluorescence lifetime imaging microscopy (FLIM) provides a promising, robust method of detecting molecular interactions in vivo via fluorescence/Forster resonance energy transfer ( FRET), by monitoring the variation of donor fluorescence lifetime, which is insensitive to many artifacts influencing convential intensity-based measurements, e. g. fluorophore concentration, photobleaching, and spectral bleed-through. As proof of principle, we demonstrate the capability of a novel picosecond-resolution FLIM system to detect molecular interactions in a well-established FRET assay. We then apply the FLIM system to detect the molecular interaction of a transforming oncogene RhoC with a binding partner RhoGDI gamma in vivo, which is critical to understand and interfere with Rho signaling for cancer therapeutics. (c) 2007 Optical Society of America.