Direct imaging furin-controlled intracellular condensation with two-photon laser microscope

Abstract

We developed a new “smart” Eu-based probe (2) which is susceptive to furin, a protease overexpressed in cancer cells. Upon furin cleavage, 2 condenses to form oligomers and the latter self-assemble into Europium nanparticles (Eu-NPs) on site. Two-photon laser microscopy (TPLM) imaging of MDA-MB-468 cells incubated with 2 showed strong fluorescence signals from Golgi networks, suggesting 2 was under the action of furin and trapped at/near the locations of furin (i.e., Golgi networks). TPLM imaging of MDA-MB-468 cells incubated with the scrambled control of 2 (i.e., 2-Scr) at same condition only exhibits uniform, weak fluorescence signals. These results suggest that 2 could be a useful probe for TPLM imaging of furin activity in cancer cells. We describe herein a detailed protocol of cell preparation and TPLM imaging with 2.