Genetically encoded fluorescent probe to visualize intracellular phosphatidylinositol 3,5-bisphosphate localization and dynamics.

TitleGenetically encoded fluorescent probe to visualize intracellular phosphatidylinositol 3,5-bisphosphate localization and dynamics.
Publication TypeJournal Article
Year of Publication2013
AuthorsLi X, Wang X, Zhang X, Zhao M, Tsang WL, Zhang Y, Yau RGW, Weisman LS, Xu H
JournalProceedings of the National Academy of Sciences of the United States of America
Date Published2013 Dec 9
Abstract

Phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] is a low-abundance phosphoinositide presumed to be localized to endosomes and lysosomes, where it recruits cytoplasmic peripheral proteins and regulates endolysosome-localized membrane channel activity. Cells lacking PI(3,5)P2 exhibit lysosomal trafficking defects, and human mutations in the PI(3,5)P2-metabolizing enzymes cause lysosome-related diseases. The spatial and temporal dynamics of PI(3,5)P2, however, remain unclear due to the lack of a reliable detection method. Of the seven known phosphoinositides, only PI(3,5)P2 binds, in the low nanomolar range, to a cytoplasmic phosphoinositide-interacting domain (ML1N) to activate late endosome and lysosome (LEL)-localized transient receptor potential Mucolipin 1 (TRPML1) channels. Here, we report the generation and characterization of a PI(3,5)P2-specific probe, generated by the fusion of fluorescence tags to the tandem repeats of ML1N. The probe was mainly localized to the membranes of Lamp1-positive compartments, and the localization pattern was dynamically altered by either mutations in the probe, or by genetically or pharmacologically manipulating the cellular levels of PI(3,5)P2. Through the use of time-lapse live-cell imaging, we found that the localization of the PI(3,5)P2 probe was regulated by serum withdrawal/addition, undergoing rapid changes immediately before membrane fusion of two LELs. Our development of a PI(3,5)P2-specific probe may facilitate studies of both intracellular signal transduction and membrane trafficking in the endosomes and lysosomes.

DOI10.1016/j.molmet.2013.08.002
Alternate JournalProc. Natl. Acad. Sci. U.S.A.