One promising approach for in vivo studies of cell proliferation is the FUCCI system (fluorescent ubiquitination-based cell cycle indicator).Here, we report the development of a Drosophila-specific FUCCI system (Fly-FUCCI) that allows one to distinguish G1, S, and G2 phases of interphase.Fly-FUCCI relies on fluorochrome-tagged degrons from the Cyclin B and E2F1 proteins, which are degraded by the ubiquitin E3-ligases APC/C and CRL4 Cdt2 , during mitosis or the onset of S phase, respectively.These probes can track cell-cycle patterns in cultured Drosophila cells, eye and wing imaginal discs, salivary glands, the adult midgut, and probably other tissues.To support a broad range of experimental applications, we have generated a toolkit of transgenic Drosophila lines that express the Fly-FUCCI probes under control of the UASt, UASp, QUAS, and ubiquitin promoters.The Fly-FUCCI system should be a valuable tool for visualizing cell-cycle activity during development, tissue homeostasis, and neoplastic growth.

Fly-FUCCI: A Versatile Tool for Studying Cell Proliferation in Complex Tissues